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Sample records for male siberian hamsters

  1. Photoperiodic Influences on Ultradian Rhythms of Male Siberian Hamsters

    PubMed Central

    Prendergast, Brian J.; Zucker, Irving

    2012-01-01

    Seasonal changes in mammalian physiology and behavior are proximately controlled by the annual variation in day length. Long summer and short winter day lengths markedly alter the amplitude of endogenous circadian rhythms and may affect ultradian oscillations, but the threshold photoperiods for inducing these changes are not known. We assessed the effects of short and intermediate day lengths and changes in reproductive physiology on circadian and ultradian rhythms of locomotor activity in Siberian hamsters. Males were maintained in a long photoperiod from birth (15 h light/day; 15 L) and transferred in adulthood to 1 of 7 experimental photoperiods ranging from 14 L to 9 L. Decreases in circadian rhythm (CR) robustness, mesor and amplitude were evident in photoperiods ≤14 L, as were delays in the timing of CR acrophase and expansion of nocturnal activity duration. Nocturnal ultradian rhythms (URs) were comparably prevalent in all day lengths, but 15 L markedly inhibited the expression of light-phase URs. The period (τ’), amplitude and complexity of URs increased in day lengths ≤13 L. Among hamsters that failed to undergo gonadal regression in short day lengths (nonresponders), τ’ of the dark-phase UR was longer than in photoresponsive hamsters; in 13 L the incidence and amplitude of light-phase URs were greater in hamsters that did not undergo testicular regression. Day lengths as long as 14 L were sufficient to trigger changes in the waveform of CRs without affecting UR waveform. The transition from a long- to a short-day ultradian phenotype occurred for most UR components at day lengths of 12 L–13 L, thereby establishing different thresholds for CR and UR responses to day length. At the UR-threshold photoperiod of 13 L, differences in gonadal status were largely without effect on most UR parameters. PMID:22848579

  2. Photoperiodic influences on ultradian rhythms of male Siberian hamsters.

    PubMed

    Prendergast, Brian J; Zucker, Irving

    2012-01-01

    Seasonal changes in mammalian physiology and behavior are proximately controlled by the annual variation in day length. Long summer and short winter day lengths markedly alter the amplitude of endogenous circadian rhythms and may affect ultradian oscillations, but the threshold photoperiods for inducing these changes are not known. We assessed the effects of short and intermediate day lengths and changes in reproductive physiology on circadian and ultradian rhythms of locomotor activity in Siberian hamsters. Males were maintained in a long photoperiod from birth (15 h light/day; 15 L) and transferred in adulthood to 1 of 7 experimental photoperiods ranging from 14 L to 9 L. Decreases in circadian rhythm (CR) robustness, mesor and amplitude were evident in photoperiods ≤14 L, as were delays in the timing of CR acrophase and expansion of nocturnal activity duration. Nocturnal ultradian rhythms (URs) were comparably prevalent in all day lengths, but 15 L markedly inhibited the expression of light-phase URs. The period (τ'), amplitude and complexity of URs increased in day lengths ≤13 L. Among hamsters that failed to undergo gonadal regression in short day lengths (nonresponders), τ' of the dark-phase UR was longer than in photoresponsive hamsters; in 13 L the incidence and amplitude of light-phase URs were greater in hamsters that did not undergo testicular regression. Day lengths as long as 14 L were sufficient to trigger changes in the waveform of CRs without affecting UR waveform. The transition from a long- to a short-day ultradian phenotype occurred for most UR components at day lengths of 12 L-13 L, thereby establishing different thresholds for CR and UR responses to day length. At the UR-threshold photoperiod of 13 L, differences in gonadal status were largely without effect on most UR parameters.

  3. Male-induced estrus synchronization in the female Siberian hamster (Phodopus sungorus sungorus).

    PubMed

    Dodge, James C; Kristal, Mark B; Badura, Lori L

    2002-11-01

    Olfactory cues play an integral role in the organization of events that mediate reproductive success. In a variety of species, priming pheromones, in particular, are important for ensuring reproductive fitness. To date, very little research has focused on how male-emitted priming pheromones, such as those that regulate the onset of puberty and estrus synchronization in females, affect the reproductive physiology of the female Siberian hamster (Phodopus sungorus sungorus). This lack of research may be due to the physiology of the Phodopus genus; vaginal cytology cannot be used as a reliable indicator of estrus or ovulation. Using a jugular cannulation technique to determine estrous stage by blood analysis of prolactin and luteinizing hormone, we sought to determine if male priming pheromones affect estrous cyclicity in the female Siberian hamster and, if so, whether the production of these priming pheromones is androgen dependent. Our results showed that females exposed to bedding from mature, intact males showed a significantly higher incidence of proestrus 3 days later than did females exposed to the bedding of mature, gonadectomized males. Therefore, we found that not only do male Siberian hamsters emit chemical signals that induce estrus synchronization, but also that this ability is likely to be androgen dependent.

  4. Social cues attenuate photoresponsiveness of the male reproductive system in Siberian hamsters (Phodopus sungorus).

    PubMed

    Hegstrom, C D; Breedlove, S M

    1999-02-01

    Transfer of adult Siberian hamsters (Phodopus sungorus) from long (16 h light and 8 h dark, 16L:8D) to short (8L:16D) daily photoperiods induces an involution of the gonads and a cessation of reproductive behavior 8 to 10 weeks later. However, when male and female long-day hamsters were paired on transfer to short photoperiods, the males' gonads did not undergo the typical short-day response. Similarly, when male long-day hamsters were paired with refractory females (i.e., females housed in short photoperiods for at least 28 weeks so that they became unresponsive to short photoperiods), the response of the males' reproductive system to short photoperiods also was attenuated. Thus, social cues can override or delay the effects of photoperiod on the testes of this species. These results suggest that the inhibitory effects of long durations of melatonin secretion (in response to short photoperiods) on the male hypothalamic-pituitary-gonadal axis may be attenuated by social cues such as contact with the opposite sex.

  5. Simulated natural day lengths synchronize seasonal rhythms of asynchronously born male Siberian hamsters.

    PubMed

    Butler, Matthew P; Turner, Kevin W; Park, Jin Ho; Butler, James P; Trumbull, Justin J; Dunn, Sean P; Villa, Philip; Zucker, Irving

    2007-07-01

    Photoperiodism research has relied on static day lengths and abrupt transitions between long and short days to characterize the signals that drive seasonal rhythms. To identify ecologically relevant critical day lengths and to test the extent to which naturally changing day lengths synchronize important developmental events, we monitored nine cohorts of male Siberian hamsters (Phodopus sungorus) born every 2 wk from 4 wk before to 12 wk after the summer solstice in a simulated natural photoperiod (SNP). SNP hamsters born from 4 wk before to 2 wk after the solstice underwent rapid somatic and gonadal growth; among those born 4-6 wk after the solstice, some delayed puberty by many weeks, whereas others manifested early puberty. Hamsters born eight or more weeks after the solstice failed to undergo early testicular development. The transition to delayed development occurred at long day lengths, which induce early puberty when presented as static photoperiods. The first animals to delay puberty may do so predominantly on the basis of postnatal decreases in day length, whereas in later cohorts, a comparison of postnatal day length to gestational day length may contribute to arrested development. Despite differences in timing of birth and timing of puberty, autumn gonadal regression and spring gonadal and somatic growth occurred at similar calendar dates in all cohorts. Incrementally changing photoperiods exert a strong organizing effect on seasonal rhythms by providing hamsters with a richer source of environmental timing cues than are available in simple static day lengths.

  6. Urinary volatile compounds differ across reproductive phenotypes and following aggression in male Siberian hamsters.

    PubMed

    Rendon, Nikki M; Soini, Helena A; Scotti, Melissa-Ann L; Novotny, Milos V; Demas, Gregory E

    2016-10-01

    Chemical communication plays an integral role in social behavior by facilitating social encounters, allowing for the evaluation of social partners, defining territories and advertising information such as species and sex. Odors provide information about the social environment for rodents and other mammals; however, studies identifying chemical compounds and their functions have thus far focused primarily on a few species. In addition, considerably less attention has been focused on how environmental factors and behavioral context alter these compounds during periods of reproductive quiescence. We examined the effects of photoperiod and social context on chemical communication in the seasonally breeding Siberian hamster which displays modest territorial aggression during long "summer-like" days, but increased aggression in short "winter-like" days. We collected urine samples from long- and short-day male hamsters to investigate how photoperiod and subsequent changes in reproductive phenotype alter urinary volatile compound profiles. Next, we identified changes in urinary compounds before and after an aggressive encounter. Male hamsters exhibited a diverse urinary profile across photoperiods; however, long-day reproductive males showed higher levels of individual compounds when compared to short-day non-reproductive males. In addition, individual compounds were altered following an aggressive encounter; some changed only in long days whereas others changed regardless of photoperiod. Further, aggression and circulating levels of testosterone were positively correlated with urinary compounds in long-, but not short-day males. These findings suggest both photoperiod- and aggression-specific physiological regulation of urinary compounds in this species and contribute to a greater understanding of chemical communication more broadly.

  7. Urinary volatile compounds differ across reproductive phenotypes and following aggression in male Siberian hamsters.

    PubMed

    Rendon, Nikki M; Soini, Helena A; Scotti, Melissa-Ann L; Novotny, Milos V; Demas, Gregory E

    2016-10-01

    Chemical communication plays an integral role in social behavior by facilitating social encounters, allowing for the evaluation of social partners, defining territories and advertising information such as species and sex. Odors provide information about the social environment for rodents and other mammals; however, studies identifying chemical compounds and their functions have thus far focused primarily on a few species. In addition, considerably less attention has been focused on how environmental factors and behavioral context alter these compounds during periods of reproductive quiescence. We examined the effects of photoperiod and social context on chemical communication in the seasonally breeding Siberian hamster which displays modest territorial aggression during long "summer-like" days, but increased aggression in short "winter-like" days. We collected urine samples from long- and short-day male hamsters to investigate how photoperiod and subsequent changes in reproductive phenotype alter urinary volatile compound profiles. Next, we identified changes in urinary compounds before and after an aggressive encounter. Male hamsters exhibited a diverse urinary profile across photoperiods; however, long-day reproductive males showed higher levels of individual compounds when compared to short-day non-reproductive males. In addition, individual compounds were altered following an aggressive encounter; some changed only in long days whereas others changed regardless of photoperiod. Further, aggression and circulating levels of testosterone were positively correlated with urinary compounds in long-, but not short-day males. These findings suggest both photoperiod- and aggression-specific physiological regulation of urinary compounds in this species and contribute to a greater understanding of chemical communication more broadly. PMID:27212202

  8. Photoperiod and aggression induce changes in ventral gland compounds exclusively in male Siberian hamsters.

    PubMed

    Rendon, Nikki M; Soini, Helena A; Scotti, Melissa-Ann L; Weigel, Ellen R; Novotny, Milos V; Demas, Gregory E

    2016-05-01

    Chemical communication is a critical component of social behavior as it facilitates social encounters, allows for evaluation of the social partner, defines territories and resources, and advertises information such as sex and physiological state of an animal. Odors provide a key source of information about the social environment to rodents; however, studies identifying chemical compounds have thus far focused primarily on few species, particularly the house mouse. Moreover, considerably less attention has been focused on how environmental factors, reproductive phenotype, and behavioral context alter these compounds outside of reproduction. We examined the effects of photoperiod, sex, and social context on chemical communication in the seasonally breeding Siberian hamster. We sampled ventral gland secretions in both male and female hamsters before and after an aggressive encounter and identified changes in a range of volatile compounds. Next, we investigated how photoperiod, reproductive phenotype, and aggression altered ventral gland volatile compound composition across the sexes. Males exhibited a more diverse chemical composition, more sex-specific volatiles, and showed higher levels of excretion compared to females. Individual volatiles were also differentially excreted across photoperiod and reproductive phenotype, as well as differentially altered in response to an aggressive encounter. Female volatile compound composition, in contrast, did not differ across photoperiods or in response to aggression. Collectively, these data contribute to a greater understanding of context-dependent changes in chemical communication in a seasonally breeding rodent.

  9. Photoperiod and aggression induce changes in ventral gland compounds exclusively in male Siberian hamsters.

    PubMed

    Rendon, Nikki M; Soini, Helena A; Scotti, Melissa-Ann L; Weigel, Ellen R; Novotny, Milos V; Demas, Gregory E

    2016-05-01

    Chemical communication is a critical component of social behavior as it facilitates social encounters, allows for evaluation of the social partner, defines territories and resources, and advertises information such as sex and physiological state of an animal. Odors provide a key source of information about the social environment to rodents; however, studies identifying chemical compounds have thus far focused primarily on few species, particularly the house mouse. Moreover, considerably less attention has been focused on how environmental factors, reproductive phenotype, and behavioral context alter these compounds outside of reproduction. We examined the effects of photoperiod, sex, and social context on chemical communication in the seasonally breeding Siberian hamster. We sampled ventral gland secretions in both male and female hamsters before and after an aggressive encounter and identified changes in a range of volatile compounds. Next, we investigated how photoperiod, reproductive phenotype, and aggression altered ventral gland volatile compound composition across the sexes. Males exhibited a more diverse chemical composition, more sex-specific volatiles, and showed higher levels of excretion compared to females. Individual volatiles were also differentially excreted across photoperiod and reproductive phenotype, as well as differentially altered in response to an aggressive encounter. Female volatile compound composition, in contrast, did not differ across photoperiods or in response to aggression. Collectively, these data contribute to a greater understanding of context-dependent changes in chemical communication in a seasonally breeding rodent. PMID:26944610

  10. Pineal and gonadal influences on ultradian locomotor rhythms of male Siberian hamsters

    PubMed Central

    Prendergast, Brian J.; Cable, Erin J.; Cisse, Yasmine M.; Stevenson, Tyler J.; Zucker, Irving

    2013-01-01

    The extent to which changes in ultradian and circadian rhythms (URs and CRs) reflect seasonal variations in pineal melatonin secretion was assessed in male Siberian hamsters transferred from long to short day lengths. The period of the locomotor activity UR increased from 2.5 h in long days to 4.5 h in short day lengths, but this and most other features of the short-day ultradian phenotype were unaffected by pinealectomy; only the short-day increase in UR amplitude was counteracted by pineal extirpation. Virtually all UR components were unaffected by gonadectomy or replacement testosterone or estradiol treatment; changes in testicular hormone secretion appear insufficient to account for seasonal fluctuation in URs. Pinealectomy did not affect activity onsets and offsets or phase angles of CR entrainment in short and long day lengths; the duration of nocturnal activity was equivalently longer in short than long days in both pinealectomized and pineal-intact hamsters. CR robustness of pinealectomized hamsters in short days was intermediate between values of long-day and short-day sham-pinealectomized males. Hourly nocturnal locomotor activity was markedly reduced in SD, and this effect was completely reversed by PINx. We conclude that seasonal transitions in UR and CR waveforms controlled by day length are mediated primarily by melatonin-independent mechanisms, with lesser contributions from melatonin-dependent processes. Most seasonal changes in ultradian and circadian rhythms in males of this species are not influenced by gonadal hormones. URs may allow animals to respond appropriately to changing environmental contingencies. In winter reduced activity combined with temporal restructuring of activity to include longer intervals of rest may be adaptive in maintaining body temperature at lower values and down-regulating energy expenditure when above ground temperatures are extremely low. PMID:23142326

  11. Somatostatin Agonist Pasireotide Promotes a Physiological State Resembling Short-Day Acclimation in the Photoperiodic Male Siberian Hamster (Phodopus sungorus).

    PubMed

    Dumbell, R A; Scherbarth, F; Diedrich, V; Schmid, H A; Steinlechner, S; Barrett, P

    2015-07-01

    The timing of growth in seasonal mammals is inextricably linked to food availability. This is exemplified in the Siberian hamster (Phodopus sungorus), which uses the annual cycle of photoperiod to optimally programme energy expenditure in anticipation of seasonal fluctuations in food resources. During the autumn, energy expenditure is progressively minimised by physiological adaptations, including a 30% reduction in body mass, comprising a reduction in both fat and lean tissues. However, the mechanistic basis of this adaptation is still unexplained. We hypothesised that growth hormone (GH) was a likely candidate to underpin these reversible changes in body mass. Administration of pasireotide, a long-acting somatostatin receptor agonist developed for the treatment of acromegaly, to male hamsters under a long-day (LD) photoperiod produced a body weight loss. This comprised a reduction in lean and fat mass, including kidneys, testes and brown adipose tissue, typically found in short-day (SD) housed hamsters. Furthermore, when administered to hamsters switched from SD to LD, pasireotide retarded the body weight increase compared to vehicle-treated hamsters. Pasireotide did not alter photoperiod-mediated changes in hypothalamic energy balance gene expression but altered the expression of Srif mRNA expression in the periventricular nucleus and Ghrh mRNA expression in the arcuate nucleus consistent with a reduction in GH feedback and concurrent with reduced serum insulin-like growth factor-1. Conversely, GH treatment of SD hamsters increased body mass, which included increased mass of liver and kidneys. Together, these data indicate a role for the GH axis in the determination of seasonal body mass of the Siberian hamster.

  12. Acute Downregulation of Type II and Type III Iodothyronine Deiodinases by Photoperiod in Peripubertal Male and Female Siberian Hamsters

    PubMed Central

    Kampf-Lassin, August; Prendergast, Brian J.

    2013-01-01

    Availability of the thyroid hormone triiodothyronine (T3) in the mediobasal hypothalamus plays a central role in seasonal reproductive responses to photoperiod. Across many vertebrates, Type 2 iodothyronine deiodinase (DIO2) is elevated under reproductively stimulatory long days (LD) and synthesizes the conversion of thyroxine to T3; type 3 iodothyronine deiodinase (DIO3) reduces T3 production and signaling, and is upregulated under reproductively-inhibitory short days (SD). In Siberian hamsters, regulation of hypothalamic T3 is dominated by dio3 expression, whereas dio2 expression is less-consistently affected by photoperiod. In adult hamsters, changes in deiodinase mRNA expression typically require several weeks to manifest, but it is not known whether or how quickly these mechanisms are engaged during the rapid responses to photoperiod observed in young, peri-pubertal hamsters. This experiment tested the hypotheses that (1) deiodinase responses to photoperiod are accelerated in juvenile hamsters and (2) photoperiodic downregulation of deiodinase expression occurs more rapidly than upregulation. Hypothalamic dio2 and dio3 mRNA expression was quantified in male and female Siberian hamsters that were weaned on postnatal day 18 (PND 18) into SD or remained in their natal LD, and on PND 31 were exposed to a single long or short day. In SD males and females, a single long day inhibited dio3 mRNA expression, but did not increase dio2 mRNA. In LD males, a single short day rapidly inhibited dio2 mRNA expression, but did not stimulate expression of dio3 mRNA. Downregulation of dio2 and dio3 mRNAs precedes gonadotrophin responses to day length. Rapid photoperiodic inhibition of deiodinase mRNAs may initiate changes in thyroid hormone signaling in advance of longer-term, melatonin-dependent, responses. PMID:23891658

  13. Acute downregulation of Type II and Type III iodothyronine deiodinases by photoperiod in peripubertal male and female Siberian hamsters.

    PubMed

    Kampf-Lassin, August; Prendergast, Brian J

    2013-11-01

    Availability of the thyroid hormone triiodothyronine (T3) in the mediobasal hypothalamus plays a central role in seasonal reproductive responses to photoperiod. Across many vertebrates, Type 2 iodothyronine deiodinase (DIO2) is elevated under reproductively stimulatory long days (LD) and synthesizes the conversion of thyroxine to T3; Type 3 iodothyronine deiodinase (DIO3) reduces T3 production and signaling, and is upregulated under reproductively-inhibitory short days (SD). In Siberian hamsters, regulation of hypothalamic T3 is dominated by dio3 expression, whereas dio2 expression is less-consistently affected by photoperiod. In adult hamsters, changes in deiodinase mRNA expression typically require several weeks to manifest, but it is not known whether or how quickly these mechanisms are engaged during the rapid responses to photoperiod observed in young, peri-pubertal hamsters. This experiment tested the hypotheses that (1) deiodinase responses to photoperiod are accelerated in juvenile hamsters and (2) photoperiodic downregulation of deiodinase expression occurs more rapidly than upregulation. Hypothalamic dio2 and dio3 mRNA expression was quantified in male and female Siberian hamsters that were weaned on postnatal day 18 (PND 18) into SD or remained in their natal LD, and on PND 31 were exposed to a single long or short day. In SD males and females, a single long day inhibited dio3 mRNA expression, but did not increase dio2 mRNA. In LD males, a single short day rapidly inhibited dio2 mRNA expression, but did not stimulate expression of dio3 mRNA. Downregulation of dio2 and dio3 mRNAs precedes gonadotrophin responses to day length. Rapid photoperiodic inhibition of deiodinase mRNAs may initiate changes in thyroid hormone signaling in advance of longer-term, melatonin-dependent, responses.

  14. Differential alteration of the reproductive axis by testosterone and estrogen in peripubertal and adult male Siberian hamsters (Phodopus sungorus).

    PubMed

    Pak, Toni R; Lynch, G Robert; Tsai, Pei-San

    2002-09-01

    In male Siberian hamsters, administration of adult physiological levels of testosterone (T) and estrogen (E2) to juveniles inhibited pubertal onset by distinct pathways. It is presently unclear if T and E2 also exert an inhibitory effect on the reproductive function of sexually mature and sexually maturing hamsters. This study aims to determine if there is an age-dependent decline in the sensitivity of the hypothalamic-pituitary-gonadal (HPG) axis to these inhibitory steroids and if their actions remain distinct. Peripubertal and adult male Siberian hamsters were implanted with a silastic capsule containing T, E2, or cholesterol (Ch, control). Testosterone treatment significantly reduced testes mass and length and impaired spermatogenesis in both ages. In contrast, E2 treatment reduced testes mass only in peripubertal, but not adult, animals. In fact, E2 treatment significantly increased testes mass in adults without altering spermatogenesis. In addition, circulating E2 is very high immediately prior to pubertal onset and declines thereafter. Our results showed the inhibitory effects of T persist into adulthood whereas those of E2 subside as the animals become sexually mature. The decreased sensitivity of the HPG axis to the inhibitory effects of E2 in adult animals and the high level of circulating E2 immediately prior to pubertal onset suggest E2 may play an important role in the regulation of puberty in this species.

  15. Short-day aggression is independent of changes in cortisol or glucocorticoid receptors in male Siberian hamsters (Phodopus sungorus).

    PubMed

    Scotti, Melissa-Ann L; Rendon, Nikki M; Greives, Timothy J; Romeo, Russell D; Demas, Gregory E

    2015-06-01

    Testosterone mediates aggression in many vertebrates. In some species, aggression remains high during the non-breeding season (e.g., winter), when testosterone levels are low. In Siberian hamsters (Phodopus sungorus), we have demonstrated photoperiodic changes in aggression with hamsters housed in short, "winter-like" days displaying significantly more territorial aggression than long-day animals, despite low levels of testosterone. The mechanisms by which photoperiod regulates aggression, however, remain largely unknown. Adrenocortical hormones (e.g., glucocorticoids) have been implicated in mediating seasonal aggression; circulating concentrations of these hormones have been correlated with aggression in some species. The goal of this study was to examine the role of cortisol and glucocorticoid receptors in mediating photoperiodic changes in aggression in male Siberian hamsters. Males were housed in long or short days and treated with either exogenous cortisol or vehicle. Circulating levels of cortisol, adrenal cortisol content, and aggression were quantified. Lastly, photoperiodic effects on glucocorticoid receptor (GR) protein levels were quantified in limbic brain regions associated with aggression, including medial prefrontal cortex, amygdala, and hippocampus. Short-day hamsters were more aggressive than long-day hamsters, however cortisol treatment did not affect aggression. Photoperiod had no effect on serum or adrenal cortisol or GR levels in the brain regions examined. Taken together, these data suggest that increases in cortisol levels do not cause increases associated with short-day aggression, and further that GR protein levels are not associated with photoperiodic changes in aggression. The results of this study contribute to our understanding of the role of adrenocortical steroids in mediating seasonal aggression.

  16. Dissociation of Ultradian and Circadian Phenotypes in Female and Male Siberian Hamsters

    PubMed Central

    Prendergast, Brian J.; Cisse, Yasmine M.; Cable, Erin J.; Zucker, Irving

    2013-01-01

    Three experiments addressed whether pronounced alterations in the circadian system yielded concomitant changes in ultradian timing. Female Siberian hamsters were housed in a 16L:8D photoperiod after being subjected to a disruptive phase-shifting protocol that produced 3 distinct permanent circadian phenotypes: some hamsters entrained their circadian rhythms (CRs) with predominantly nocturnal locomotor activity (ENTR), others displayed free-running CRs (FR), and a third cohort was circadian arrhythmic (ARR). The period of the ultradian locomotor rhythm (UR) did not differ among the 3 circadian phenotypes; neuroendocrine generation of URs remains viable in the absence of coherent circadian organization and appears to be mediated by substrates functionally and anatomically distinct from those that generate CRs. Pronounced light-dark differences in several UR characteristics in ENTR hamsters were completely absent in circadian arrhythmic hamsters. The disruptive phase-shifting protocol may compromise direct visual input to ultradian oscillators but more likely indirectly affects URs by interrupting visual afference to the circadian system. Additional experiments documented that deuterium oxide and constant light, each of which substantially lengthened the period of free-running CRs, failed to change the period of concurrently monitored URs. The resistance of URs to deuteration contrasts with the slowing of virtually all other biological timing processes, including CRs. Considered together, the present results point to the existence of separable control mechanisms for generation of circadian and ultradian rhythms. PMID:22855573

  17. Dissociation of ultradian and circadian phenotypes in female and male Siberian hamsters.

    PubMed

    Prendergast, Brian J; Cisse, Yasmine M; Cable, Erin J; Zucker, Irving

    2012-08-01

    Three experiments addressed whether pronounced alterations in the circadian system yielded concomitant changes in ultradian timing. Female Siberian hamsters were housed in a 16L:8D photoperiod after being subjected to a disruptive phase-shifting protocol that produced 3 distinct permanent circadian phenotypes: some hamsters entrained their circadian rhythms (CRs) with predominantly nocturnal locomotor activity (ENTR), others displayed free-running CRs (FR), and a third cohort was circadian arrhythmic (ARR). The period of the ultradian locomotor rhythm (UR) did not differ among the 3 circadian phenotypes; neuroendocrine generation of URs remains viable in the absence of coherent circadian organization and appears to be mediated by substrates functionally and anatomically distinct from those that generate CRs. Pronounced light-dark differences in several UR characteristics in ENTR hamsters were completely absent in circadian arrhythmic hamsters. The disruptive phase-shifting protocol may compromise direct visual input to ultradian oscillators but more likely indirectly affects URs by interrupting visual afference to the circadian system. Additional experiments documented that deuterium oxide and constant light, each of which substantially lengthened the period of free-running CRs, failed to change the period of concurrently monitored URs. The resistance of URs to deuteration contrasts with the slowing of virtually all other biological timing processes, including CRs. Considered together, the present results point to the existence of separable control mechanisms for generation of circadian and ultradian rhythms.

  18. Sleep deprivation attenuates endotoxin-induced cytokine gene expression independent of day length and circulating cortisol in male Siberian hamsters (Phodopus sungorus).

    PubMed

    Ashley, Noah T; Walton, James C; Haim, Achikam; Zhang, Ning; Prince, Laura A; Fruchey, Allison M; Lieberman, Rebecca A; Weil, Zachary M; Magalang, Ulysses J; Nelson, Randy J

    2013-07-15

    Sleep is restorative, whereas reduced sleep leads to negative health outcomes, such as increased susceptibility to disease. Sleep deprivation tends to attenuate inflammatory responses triggered by infection or exposure to endotoxin, such as bacterial lipopolysaccharide (LPS). Previous studies have demonstrated that Siberian hamsters (Phodopus sungorus), photoperiodic rodents, attenuate LPS-induced fever, sickness behavior and upstream pro-inflammatory gene expression when adapted to short day lengths. Here, we tested whether manipulation of photoperiod alters the suppressive effects of sleep deprivation upon cytokine gene expression after LPS challenge. Male Siberian hamsters were adapted to long (16 h:8 h light:dark) or short (8 h:16 h light:dark) photoperiods for >10 weeks, and were deprived of sleep for 24 h using the multiple platform method or remained in their home cage. Hamsters received an intraperitoneal injection of LPS or saline (control) 18 h after starting the protocol, and were killed 6 h later. LPS increased liver and hypothalamic interleukin-1 (IL-1) and tumor necrosis factor-alpha (TNF) gene expression compared with vehicle. Among LPS-challenged hamsters, sleep deprivation reduced IL-1 mRNA levels in liver and hypothalamus, but not TNF. IL-1 attenuation was independent of circulating baseline cortisol, which did not increase after sleep deprivation. Conversely, photoperiod altered baseline cortisol, but not pro-inflammatory gene expression in sleep-deprived hamsters. These results suggest that neither photoperiod nor glucocorticoids influence the suppressive effect of sleep deprivation upon LPS-induced inflammation.

  19. Circadian rhythms of photorefractory siberian hamsters remain responsive to melatonin.

    PubMed

    Butler, Matthew P; Paul, Matthew J; Turner, Kevin W; Park, Jin Ho; Driscoll, Joseph R; Kriegsfeld, Lance J; Zucker, Irving

    2008-04-01

    Short day lengths increase the duration of nocturnal melatonin (Mel) secretion, which induces the winter phenotype in Siberian hamsters. After several months of continued exposure to short days, hamsters spontaneously revert to the spring-summer phenotype. This transition has been attributed to the development of refractoriness of Mel-binding tissues, including the suprachiasmatic nucleus (SCN), to long-duration Mel signals. The SCN of Siberian hamsters is required for the seasonal response to winter-like Mel signals, and becomes refractory to previously effective long-duration Mel signals restricted to this area. Acute Mel treatment phase shifts circadian locomotor rhythms of photosensitive Siberian hamsters, presumably by affecting circadian oscillators in the SCN. We tested whether seasonal refractoriness of the SCN to long-duration Mel signals also renders the circadian system of Siberian hamsters unresponsive to Mel. Males manifesting free-running circadian rhythms in constant dim red light were injected with Mel or vehicle for 5 days on a 23.5-h T-cycle beginning at circadian time 10. Mel injections caused significantly larger phase advances in activity onset than did the saline vehicle, but the magnitude of phase shifts to Mel did not differ between photorefractory and photosensitive hamsters. Similarly, when entrained to a 16-h light/8-h dark photocycle, photorefractory and photosensitive hamsters did not differ in their response to Mel injected 4 h before the onset of the dark phase. Activity onset in Mel-injected hamsters was masked by light but was revealed to be significantly earlier than in vehicle-injected hamsters upon transfer to constant dim red light. The acute effects of melatonin on circadian behavioral rhythms are preserved in photorefractory hamsters.

  20. Torpor shortens the period of Siberian hamster circadian rhythms.

    PubMed

    Thomas, E M; Jewett, M E; Zucker, I

    1993-10-01

    We investigated the influence of ambient and body temperature (Ta and Tb) on circadian rhythms of gonadectomized male Siberian hamsters. Animals that entered torpor (Tb < 30 degrees C) had significantly shorter circadian periods (tau s) than did nontorpid hamsters at a Ta of 13 degrees C (24.17 +/- 0.05 vs. 24.33 +/- 0.04 h). The tau s of homeothermic hamsters were not affected by Ta change. Short-term decreases in Tb, rather than changes in Ta, appear to affect tau. Access to activity wheels inhibited expression of torpor in short daylengths and was associated with significant increases in body mass. Running wheel activity can mask or block specific short-day responses.

  1. Interval timer control of puberty in photoinhibited Siberian hamsters.

    PubMed

    Park, Jin Ho; Kauffman, Alexander S; Paul, Matthew J; Butler, Matthew P; Beery, Annaliese K; Costantini, Ruth M; Zucker, Irving

    2006-10-01

    Puberty, which is markedly delayed in male Siberian hamsters (Phodopus sungorus) born into short day lengths, is controlled by an interval timer regulated by the duration of nocturnal melatonin secretion. Properties of the interval timer were assessed by perturbing normal patterns of melatonin secretion in males gestated and maintained thereafter in 1 of 2 short day lengths, 10 h light/day (10 L) or 12L. Melatonin secretion of short-day hamsters was suppressed by constant light treatment or modified by daily injection of propranolol to mimic nocturnal melatonin durations typical of long-day hamsters. Constant light treatment during weeks 3 to 5 induced early incomplete gonadal growth in 12L but not 10 L hamsters but did not affect late onset of gonadal development indicative of puberty in either photoperiod. Propranolol treatment during postnatal weeks 3 to 5 induced transient growth of the testes and ultimately delayed the timing of puberty by 3 weeks. Similar treatments between weeks 5 and 7 or on alternate weeks for 24 weeks did not affect the interval timer. The first 2 weeks after weaning may constitute a critical period during which the interval timer is highly responsive to photoperiod. Alternatively, the hamsters' photoperiodic history rather than age or developmental stage may be the critical variable. The interpolation of long-day melatonin signals at the time of weaning does not appear to reset the interval timer to its zero position but may reduce timer responsiveness to long-day melatonin signals several weeks later.

  2. Neonatal monosodium glutamate treatment counteracts circadian arrhythmicity induced by phase shifts of the light-dark cycle in female and male Siberian hamsters

    PubMed Central

    Prendergast, Brian J.; Onishi, Kenneth G.; Zucker, Irving

    2013-01-01

    Studies of rats and voles suggest that distinct pathways emanating from the anterior hypothalamic-retrochiasmatic area and the mediobasal hypothalamic arcuate nucleus independently generate ultradian rhythms (URs) in hormone secretion and behavior. We evaluated the hypothesis that destruction of arcuate nucleus (ARC) neurons, in concert with dampening of suprachiasmatic nucleus (SCN) circadian rhythmicity, would compromise the generation of ultradian rhythms (URs) of locomotor activity. Siberian hamsters of both sexes treated neonatally with monosodium glutamate (MSG) that destroys ARC neurons were subjected in adulthood to a circadian disrupting phase-shift protocol (DPS) that produces SCN arrhythmia. MSG treatments induced hypogonadism and obesity, and markedly reduced the size of the optic chiasm and primary optic tracts. MSG-treated hamsters exhibited normal entrainment to the light-dark cycle, but MSG treatment counteracted the circadian arrhythmicity induced by the DPS protocol: only 6% of MSG-treated hamsters exhibited circadian arrhythmia, whereas 50% of control hamsters were circadian disrupted. In MSG-treated hamsters that retained circadian rhythmicity after DPS treatment, quantitative parameters of URs appeared normal, but in the 2 MSG-treated hamsters that became circadian arrhythmic after DPS, both dark-phase and light-phase URs were abolished. Although preliminary, these data are consistent with reports in voles suggesting that the combined disruption of SCN and ARC function impairs the expression of behavioral URs. The data also suggest that light thresholds for entrainment of circadian rhythms may be lower than those required to disrupt circadian organization. PMID:23701725

  3. Neonatal monosodium glutamate treatment counteracts circadian arrhythmicity induced by phase shifts of the light-dark cycle in female and male Siberian hamsters.

    PubMed

    Prendergast, Brian J; Onishi, Kenneth G; Zucker, Irving

    2013-07-12

    Studies of rats and voles suggest that distinct pathways emanating from the anterior hypothalamic-retrochiasmatic area and the mediobasal hypothalamic arcuate nucleus independently generate ultradian rhythms (URs) in hormone secretion and behavior. We evaluated the hypothesis that destruction of arcuate nucleus (ARC) neurons, in concert with dampening of suprachiasmatic nucleus (SCN) circadian rhythmicity, would compromize the generation of ultradian rhythms (URs) of locomotor activity. Siberian hamsters retain-->of both sexes treated neonatally with monosodium glutamate (MSG) that destroys ARC neurons were subjected in adulthood to a circadian disrupting phase-shift protocol (DPS) that produces SCN arrhythmia. MSG treatments induced hypogonadism and obesity, retain-->and markedly reduced the size of the optic chiasm and optic nerves. MSG-treated hamsters exhibited normal entrainment to the light-dark cycle, but MSG treatretain-->ment counteracted the circadian arrhythmicity induced by the DPS protocol: only 6% of retain-->MSG-treated hamsters exhibited circadian arrhythmia, whereas 50% of control hamsters were circadian disrupted. In MSG-treated hamsters that retained circadian rhythmicity after DPS treatment, quantitative parameters of URs appeared normal, but in the two MSG-treated hamsters that became circadian arrhythmic after DPS, both dark-phase and light-phase URs were abolished. Although preliminary, these data are consistent with reports in voles suggesting that the combined disruption of SCN and ARC function impairs the expression of behavioral URs. The data also suggest that light thresholds for entrainment of circadian rhythms may be lower than those required to disrupt circadian organization.

  4. Aging, reproduction, and the melatonin rhythm in the Siberian hamster.

    PubMed

    Horton, T H; Yellon, S M

    2001-06-01

    The present study tested the hypothesis that responsiveness to melatonin, the presence of the melatonin rhythm in circulation, and parameters of the GnRH neuron system are sustained across the aging continuum in Siberian hamsters. Afternoon melatonin injections induced testicular atrophy in 42% of aged males compared with 100% of adult males. The proportion of aged males failing to respond to the melatonin injections was similar to the proportion that failed to undergo testicular regression upon exposure to short days. Exposure to short days induced testicular atrophy in juvenile and adult hamsters; however, regression was incomplete or absent in 43% of aged males. The nocturnal rise in melatonin was similar with regard to duration and peak amplitude, and appropriate with respect to photoperiod in 25-day-old juveniles, adult (5 months), and aged (17 months) hamsters. Neither advanced age nor timed melatonin treatments affected GnRH neuron numbers or distribution. Fertility was maintained in aged and adult males to a comparable extent with respect to latency to first litter and number of pups per litter; reproductive success was dramatically reduced in aged compared with adult females. Because melatonin rhythms accurately reflect day length information throughout the continuum from puberty to advanced age, the present evidence suggests that limitations in testis regression in response to short days or exogenous melatonin in a subset of aged males result from a reduced ability to respond to melatonin. In the wild, failure to undergo testicular regression in the presence of shortening day lengths may extend the breeding season of aged males.

  5. Photoperiodic regulation of circulating leukocytes in juvenile Siberian hamsters: mediation by melatonin and testosterone.

    PubMed

    Prendergast, Brian J; Hotchkiss, Andrew K; Nelson, Randy J

    2003-12-01

    The reproductive system of Siberian hamsters (Phodopus sungorus) undergoes rapid phenotypic responses to changes in day length that occur around the time of weaning. The present experiments tested whether the immune system of Siberian hamsters is similarly photoperiodic early in life and whether photoperiodic changes in melatonin or gonadal hormone secretions mediate any such responses to day length. Circulating blood leukocyte concentrations (WBC) were measured in juvenile male Siberian hamsters that were gestated in long-days (LD), transferred to short-days (SD) on the day of birth, and subsequently either remained in SD or were transferred from SD to LD at 18 days of age (day 18). WBC values were comparable between LD and SD hamsters on day 18. Between day 18 and day 32, SD hamsters exhibited a 3-fold increase in WBC, whereas LD hamsters failed to undergo a significant increase in WBC during this interval. WBC of LD hamsters was significantly lower than that of SD hamsters on day 25 and on day 32. In LD housed males, peripheral injections of melatonin delivered so as to extend the nocturnal duration of elevated endogenous melatonin secretion (i.e., provided in late afternoon) on days 18-31 increased WBC as measured on day 32. Peripubertal (day 17) gonadectomy abolished the immunosuppressive effect of LD exposure on WBC, and treatment with silastic implants containing testosterone suppressed WBC independent of photoperiod treatment. These data indicate that juvenile Siberian hamsters are immunologically responsive to photoperiod and that the leukocyte responses to day length are the result of melatonin-mediated effects of photoperiod on testicular hormone secretion.

  6. Circadian arrhythmia dysregulates emotional behaviors in aged Siberian hamsters

    PubMed Central

    Prendergast, Brian J.; Onishi, Kenneth G.; Patel, Priyesh N.; Stevenson, Tyler J.

    2014-01-01

    Emotional behaviors are influenced by the circadian timing system. Circadian disruptions are associated with depressive-like symptoms in clinical and preclinical populations. Circadian rhythm robustness declines markedly with aging and may contribute to susceptibility to emotional dysregulation in aged individuals. The present experiments used a model of chronic circadian arrhythmia generated noninvasively, via a series of circadian-disruptive light treatments, to investigate interactions between circadian desynchrony and aging on depressive- and anxiety-like behaviors, and on limbic neuroinflammatory gene expression that has been linked with emotionality. We also examined whether a social manipulation (group housing) would attenuate effects of arrhythmia on emotionality. In aged (14-18 months of age) male Siberian hamsters, circadian arrhythmia increased behavioral despair and decreased social motivation, but decreased exploratory anxiety. These effects were not evident in younger (5-9 months of age) hamsters. Social housing (3-5 hamsters/cage) abolished the effects of circadian arrhythmia on emotionality. Circadian arrhythmia alone was without effect on hippocampal or cortical interleukin-1β (IL-1β) and indoleamine 2,3-dioxygenase (Ido) mRNA expression in aged hamsters, but social housing decreased hippocampal IL-1β and Ido mRNAs. The data demonstrate that circadian disruption can negatively impact affective state, and that this effect is pronounced in older individuals. Although clear associations between circadian arrhythmia and constitutive limbic proinflammatory activity were not evident, the present data suggest that social housing markedly inhibits constitutive hippocampal IL-1β and Ido activity, which may contribute to the ameliorating effects of social housing on a number of emotional behaviors. PMID:24333374

  7. Circadian arrhythmia dysregulates emotional behaviors in aged Siberian hamsters.

    PubMed

    Prendergast, Brian J; Onishi, Kenneth G; Patel, Priyesh N; Stevenson, Tyler J

    2014-03-15

    Emotional behaviors are influenced by the circadian timing system. Circadian disruptions are associated with depressive-like symptoms in clinical and preclinical populations. Circadian rhythm robustness declines markedly with aging and may contribute to susceptibility to emotional dysregulation in aged individuals. The present experiments used a model of chronic circadian arrhythmia generated noninvasively, via a series of circadian-disruptive light treatments, to investigate interactions between circadian desynchrony and aging on depressive- and anxiety-like behaviors, and on limbic neuroinflammatory gene expression that has been linked with emotionality. We also examined whether a social manipulation (group housing) would attenuate effects of arrhythmia on emotionality. In aged (14-18 months of age) male Siberian hamsters, circadian arrhythmia increased behavioral despair and decreased social motivation, but decreased exploratory anxiety. These effects were not evident in younger (5-9 months of age) hamsters. Social housing (3-5 hamsters/cage) abolished the effects of circadian arrhythmia on emotionality. Circadian arrhythmia alone was without effect on hippocampal or cortical interleukin-1β (IL-1β) and indoleamine 2,3-dioxygenase (Ido) mRNA expression in aged hamsters, but social housing decreased hippocampal IL-1β and Ido mRNAs. The data demonstrate that circadian disruption can negatively impact affective state, and that this effect is pronounced in older individuals. Although clear associations between circadian arrhythmia and constitutive limbic proinflammatory activity were not evident, the present data suggest that social housing markedly inhibits constitutive hippocampal IL-1β and Ido activity, which may contribute to the ameliorating effects of social housing on a number of emotional behaviors.

  8. Long-term daily melatonin infusion induces a large increase in N-acetyltransferase activity, hydroxyindole-O-methyltransferase activity, and melatonin content in the Harderian gland and eye of pinealectomized male Siberian hamsters (Phodopus sungorus).

    PubMed

    Djeridane, Y; Pitrosky, B; Vivien-Roels, B; Simonneaux, V; Kirsch, R; Pévet, P

    2000-09-01

    The effects of long-term daily melatonin infusions on the melatonin synthetic pathway in the Harderian glands and eyes of male Siberian hamsters were studied. Hamsters were pinealectomized (PX) and infused daily for 8 hr with either melatonin (6 microg/hr) or vehicle for 7 days in short photoperiod (SP, 10L:14D), followed by 14 wk in either SP (SP group) or in constant darkness (DD group). After the infusion period (15 wk), the infusion was stopped and animals were transferred into SP for 3 wk. The hamsters were then killed at midday or midnight. Exogenous melatonin infusion caused an increase in the Harderian gland weight, which was still evident 3 wk after the end of the treatment. In addition, exogenous melatonin increased endogenous melatonin concentrations (4-fold) and hydroxyindole-O-methyltransferase (HIOMT) activity (2-fold). N-acetyltransferase (NAT) activity, however, was not increased, and no day/night difference in melatonin content and HIOMT activity was observed in the Harderian glands. In the eye, melatonin infusions significantly increased day and night-time melatonin levels (up to 3-fold) and both NAT and HIOMT activities (up to 3.5-fold). This effect of melatonin treatment was observed in both SP and DD groups. These observations demonstrate that exogenously-infused melatonin at relatively high doses activates the synthesis of endogenous melatonin in the Harderian gland and eye of the Siberian hamster. Circulating levels of melatonin were also markedly increased, indicating that in these conditions melatonin may be released from extra-pineal sites.

  9. Sex differences in Siberian hamster ultradian locomotor rhythms.

    PubMed

    Prendergast, Brian J; Stevenson, Tyler J; Zucker, Irving

    2013-02-17

    Sex differences in ultradian activity rhythms (URs) and circadian rhythms (CRs) were assessed in Siberian hamsters kept in long day (LD) or short day (SD) photoperiods for 40 weeks. For both sexes URs of locomotor activity were more prevalent, greater in amplitude and more robust in SDs. The UR period was longer in females than males in both day lengths. The reproductive system underwent regression and body mass declined during the initial 10 weeks of SD treatment, and in both sexes these traits spontaneously reverted to the LD phenotype at or before 40 weeks in SD, reflecting the development of neuroendocrine refractoriness to SD patterns of melatonin secretion. Hamsters of both sexes, however, continued to display SD-like URs at the 40 weeks time point. CRs were less prevalent and the waveform less robust and lower in amplitude in SDs than LDs; the SD circadian waveform also did not revert to the long-day phenotype after 40 weeks of SD treatment. Short day lengths enhanced ultradian and diminished circadian rhythms in both sexes. Day length controls several UR characteristics via gonadal steroid and melatonin-independent mechanisms. Sex differences in ultradian timing may contribute to sex diphenisms in rhythms of sleep, food intake and exercise.

  10. Sex differences in Siberian hamster ultradian locomotor rhythms.

    PubMed

    Prendergast, Brian J; Stevenson, Tyler J; Zucker, Irving

    2013-02-17

    Sex differences in ultradian activity rhythms (URs) and circadian rhythms (CRs) were assessed in Siberian hamsters kept in long day (LD) or short day (SD) photoperiods for 40 weeks. For both sexes URs of locomotor activity were more prevalent, greater in amplitude and more robust in SDs. The UR period was longer in females than males in both day lengths. The reproductive system underwent regression and body mass declined during the initial 10 weeks of SD treatment, and in both sexes these traits spontaneously reverted to the LD phenotype at or before 40 weeks in SD, reflecting the development of neuroendocrine refractoriness to SD patterns of melatonin secretion. Hamsters of both sexes, however, continued to display SD-like URs at the 40 weeks time point. CRs were less prevalent and the waveform less robust and lower in amplitude in SDs than LDs; the SD circadian waveform also did not revert to the long-day phenotype after 40 weeks of SD treatment. Short day lengths enhanced ultradian and diminished circadian rhythms in both sexes. Day length controls several UR characteristics via gonadal steroid and melatonin-independent mechanisms. Sex differences in ultradian timing may contribute to sex diphenisms in rhythms of sleep, food intake and exercise. PMID:23333554

  11. Neuropeptide Y induces torpor-like hypothermia in Siberian hamsters.

    PubMed

    Paul, Matthew J; Freeman, David A; Park, Jin Ho; Dark, John

    2005-09-01

    Intracerebroventricular (ICV) injections of neuropeptide Y (NPY) are known to decrease body temperature (Tb) of laboratory rats by 1-3 degrees C. Several NPY pathways in the brain terminate in hypothalamic structures involved in energy balance and thermoregulation. Laboratory rats are homeothermic, maintaining Tb within a narrow range. We examined the effect of ICV injected NPY on Tb in the heterothermic Siberian hamster (Phodopus sungorus), a species that naturally undergoes daily torpor in which Tb decreases by as much as 15-20 degrees C. Minimum effective dose was determined in preliminary testing then various doses of NPY were tested in cold-acclimated Siberian hamsters while food was withheld. NPY markedly reduced Tb in the heterothermic Siberian hamster. In addition, the reduction in Tb in 63% of the observations was sufficient to reach the criterion for daily torpor (Tb < 32 degrees C for at least 30 min). Neither the incidence of torpor nor its depth or duration was related to NPY dose. Both likelihood and magnitude of response varied within animals on different test days. NPY decreased 24-h food intake and this was exaggerated in the animals reaching criterion for torpor; the decrease in food intake was positively correlated with the magnitude of the decrease in Tb. The mild hypothermia seen in homeothermic laboratory rats after NPY injected ICV is exaggerated, often greatly, in the heterothermic Siberian hamster. NPY treatment may be activating hypothalamic systems that normally integrate endogenous torpor-producing signals and initiate torpor.

  12. Hematologic, serologic, and histologic profile of aged Siberian hamsters (Phodopus sungorus).

    PubMed

    McKeon, Gabriel P; Nagamine, Claude M; Ruby, Norman F; Luong, Richard H

    2011-05-01

    Biologic samples from 18 (12 female, 6 male) Siberian hamsters (Phodopus sungorus) representing an aged colony (17 to 27 mo) were examined. Values for CBC and serum biochemical parameters were determined, and macroscopic and microscopic pathologic evaluations were performed. Blood urea nitrogen levels were significantly higher in male (54.2 ± 14 mg/dL) compared with female (35.3 ± 22 mg/dL) hamsters and correlated histologically with a higher incidence of chronic glomerulonephropathy in males (5 of 6 males; 0 of 12 females). All 18 hamsters had histologic evidence of follicular mite infestation. Half (6 of 12) of the female hamsters showed cystic rete ovarii. Other histologic findings included thymic or thyroid branchial cysts (3 of 18), focal enteritis (2 of 18), and single cases of hepatic hemangiosarcoma, renal adenoma, subcutaneous mast cell tumor, cutaneous sebaceous adenoma, cutaneous trichofolliculoma, squamous papilloma of the nonglandular stomach, epididymal cholesteatoma, pyometra, and pituitary craniopharyngeal cyst. This study is the first published report of hematologic and serum chemical values for any population of Siberian hamsters and the first published report showing a potential male predisposition for chronic progressive glomerulonephropathy and a potential female predisposition for cystic rete ovarii.

  13. Melatonin attenuates photic disruption of circadian rhythms in Siberian hamsters.

    PubMed

    Ruby, N F; Kang, T; Heller, H C

    1997-10-01

    Body temperature (Tb) was recorded via a biotelemetry system from 28 adult male Siberian hamsters maintained in a light-dark (LD) cycle of 16 h light/day for several months. After Tb was recorded for 3 wk, the LD cycle was phase delayed by extending the light phase by 5 h for 1 day; animals remained on a 16:8 LD cycle for the remainder of the experiment. Hamsters were injected daily with melatonin or vehicle solution for several weeks, beginning either 2 mo after (experiment 1) or on the day of (experiment 2) the phase shift; injections occurred within 30 min of dark onset. In experiment 1, 75% of animals free ran with circadian periods >24 h, beginning on the day of the phase shift, and never reentrained to the LD cycle; no hamsters unambiguously entrained to daily injections. In contrast, 78% of animals in experiment 2 entrained to melatonin injections, and 71% of those animals subsequently reentrained to the photocycle when the injection regimen ended. No vehicle-treated animals entrained to the injection schedule. Melatonin had no effect on daily mean Tb and Tb rhythm amplitude in either experiment; however, melatonin doubled the duration of a hyperthermic response that occurred after each injection. Thus melatonin can prevent loss of entrainment induced by a phase shift of the LD cycle but cannot restore entrainment to free-running animals. Failure to reentrain in the presence of two appropriately coordinated entraining agents also suggests that a phase shift of the photocycle can diminish the sensitivity of the circadian system to both photic and nonphotic input.

  14. Photoperiodic regulation of FGF21 production in the Siberian hamster.

    PubMed

    Samms, Ricardo J; Fowler, Maxine J; Cooper, Scott; Emmerson, Paul; Coskun, Tamer; Adams, Andrew C; Kharitonenkov, Alexei; Tsintzas, Kostas; Ebling, Francis J P

    2014-06-01

    This article is part of a Special Issue "Energy Balance". FGF21 is an endocrine member of the fibroblast growth factor superfamily that has been shown to play an important role in the physiological response to nutrient deprivation. Food restriction enhances hepatic FGF21 production, which serves to engage an integrated response to energy deficit. Specifically, elevated FGF21 levels lead to reduced gluconeogenesis and increased hepatic ketogenesis. However, circulating FGF21 concentrations also paradoxically rise in states of metabolic dysfunction such as obesity. Furthermore, multiple peripheral tissues also produce FGF21 in addition to the liver, raising questions as to its endocrine and paracrine roles in the control of energy metabolism. The objectives of this study were to measure plasma FGF21 concentrations in the Siberian hamster, a rodent which undergoes a seasonal cycle of fattening and body weight gain in the long days (LD) of summer, followed by reduction of appetite and fat catabolism in the short days (SD) of winter. Groups of adult male hamsters were raised in long days, and then exposed to SD for up to 12 weeks. Chronic exposure of LD animals to SD led to a significant increase in circulating FGF21 concentrations. This elevation of circulating FGF21 was preceded by an increase in liver FGF21 protein production evident as early as 4 weeks of exposure to SD. FGF21 protein abundance was also increased significantly in interscapular brown adipose tissue, with a positive correlation between plasma levels of FGF21 and BAT protein abundance throughout the experimental period. Epididymal white adipose tissue and skeletal muscle (gastrocnemius) also produced FGF21, but levels did not change in response to a change in photoperiod. In summary, a natural programmed state of fat catabolism was associated with increased FGF21 production in the liver and BAT, consistent with the view that FGF21 has a role in adapting hamsters to the hypophagic winter state.

  15. Exogenous T3 mimics long day lengths in Siberian hamsters.

    PubMed

    Freeman, David A; Teubner, Brett J W; Smith, Carlesia D; Prendergast, Brian J

    2007-06-01

    Siberian hamsters (Phodopus sungorus) exhibit seasonal cycles of reproduction driven by changes in day length. Day length is encoded endogenously by the duration of nocturnal melatonin (Mel) secretion from the pineal gland. Short-duration Mel signals stimulate reproduction and long-duration signals inhibit reproduction. The mechanism by which Mel signals are decoded at the level of neural target tissues remains uncharacterized. In Siberian hamsters, exposure to short day lengths or injections of Mel in long days results in a decrease in hypothalamic expression of type 2 iodothyronine deiodinase (Dio2) mRNA. Dio2 catalyzes the conversion of the thyroid hormone thyroxine to triiodothyronine (T3). Thus exposure to short and long day lengths should decrease and increase hypothalamic T3 concentrations, respectively. We tested the hypothesis that exogenous T3 administered to short-day hamsters would mimic exposure to long day lengths with respect to gonadal stimulation. Hamsters gestated and raised in short day lengths that exhibited photoinhibition of the testes were given daily subutaneous injections of T3 or saline vehicle for 4 wk beginning at week 12 of life. The results indicate that exogenous T3 induced gonadal growth in short-day hamsters and delayed spontaneous gonadal development by an interval equal to the number of weeks during which T3 was administered. T3 injections delayed gonadal regression if given coincident with the transfer of hamsters from long to short day lengths. These results suggest that T3 mimics long day exposure in Siberian hamsters and may serve as an intermediate step between the Mel rhythm and the reproductive response.

  16. The thalamic intergeniculate leaflet modulates photoperiod responsiveness in Siberian hamsters.

    PubMed

    Freeman, David A; Dhandapani, Krishnan M; Goldman, Bruce D

    2004-11-26

    Siberian hamsters are seasonal breeders that use changes in day length to synchronize their reproductive effort with those times of the year most favorable for successful reproduction. The ability of Siberian hamsters to measure and respond to changes in day length depends upon accurate photoentrainment of the circadian clock in the suprachiasmatic nucleus (SCN) of the hypothalamus. Two pathways have been characterized through which entraining stimuli reach the SCN: the retinohypothalamic tract (RHT), which transmits light information from the retinae, and the geniculohypothalamic tract (GHT) from the intergeniculate leaflet of the thalamus (IGL), which is involved in transmitting both photic and nonphotic cues. Ablating the IGL/GHT results in only modest alterations in entrainment to static day lengths and fails to interfere with seasonal responses induced by transfer from static long day to static short day lengths. Because several studies suggest that the IGL may be involved in tracking the time of dusk and dawn, we sought to determine whether an intact IGL is necessary for hamsters to respond to a simulated natural photoperiod (SNP) in which the time of dusk and dawn gradually changes in a pattern approximating the rate of change in day length that occurs during autumn at the latitude this species inhabits in nature. The results indicate that neurochemical lesions of the IGL alter both the pattern of circadian entrainment and photoperiodic responsiveness of Siberian hamsters to an SNP. Both intact and IGL-lesioned hamsters exhibited testicular regression in shortening day lengths, but only IGL-intact hamsters exhibited seasonal pelage molt.

  17. Pharmacokinetics of extracellular melatonin in Siberian hamster forebrain.

    PubMed

    Ferreira, S A; Rollag, M D; Glass, J D

    1996-09-16

    In vivo brain microdialysis was used to characterize the pharmacokinetics of subcutaneously injected melatonin in the anterior hypothalamic-preoptic area (AH-POA) of the male Siberian hamster. Animals with a microdialysis probe implanted in the AH-POA were treated with a subcutaneous melatonin injection at 0900 h (3 h after lights-on) or 2000 h (2 h prior to lights-off). Treatment with 2.5 or 0.25 mg/kg dosages of melatonin in saline vehicle induced peak concentrations of melatonin in AH-POA microdialysates within 20 min of injection (165 +/- 34 and 18 +/- 8 pg/20 min, respectively). For the 2.5 and 0.25 mg/kg dosages, the half-life of the absorbed melatonin (t 1/2 elimination) was less than 20 min, and the concentrations fell to baseline within 60 min after injection. There were no significant time of day effects on the kinetic profile of extracellular melatonin associated with either of these dosages. These results confirm the rapid accumulation and clearance of extracellular melatonin in the vicinity of its putative target tissues.

  18. Hypothalamic gene expression rapidly changes in response to photoperiod in juvenile Siberian hamsters (Phodopus sungorus).

    PubMed

    Herwig, A; Petri, I; Barrett, P

    2012-07-01

    Siberian hamsters are seasonal mammals that survive a winter climate by making adaptations in physiology and behaviour. This includes gonadal atrophy, reduced food intake and body weight. The underlying central mechanisms responsible for the physiological adaptations are not fully established but involve reducing hypothalamic tri-iodthyronine (T3) levels. Juvenile Siberian hamsters born or raised in short days (SD) respond in a similar manner, although with an inhibition of gonadal development and growth instead of reversing an established long day (LD) phenotype. Using juvenile male hamsters, the present study aimed to investigate whether the central mechanisms are similar before the establishment of the mature LD phenotype. By in situ hybridisation, we examined the response of genes involved in thyroid hormone (Dio2 and Dio3, which determine hypothalamic T3 levels) and glucose/glutamate metabolism in the ependymal layer, histamine H3 receptor and VGF as representatives of the highly responsive dorsomedial posterior arcuate nucleus (dmpARC), and somatostatin, a hypothalamic neuropeptide involved in regulating the growth axis. Differential gene expression of type 2 and type 3 deiodinase in the ependymal layer, histamine H3 receptor in the dmpARC and somatostatin in the ARC was established by the eighth day in SD. These changes are followed by alterations in glucose metabolism related genes in the ependymal layer by day 16 and increased secretogranin expression in the dmpARC by day 32. In conclusion, our data demonstrate similar but rapid and highly responsive changes in gene expression in the brain of juvenile Siberian hamsters in response to a switch from LD to SD. The data also provide a temporal definition of gene expression changes relative to physiological adaptations of body weight and testicular development and highlight the likely importance of thyroid hormone availability as an early event in the adaptation of physiology to a winter climate in juvenile

  19. Reproductive responses to photoperiod persist in olfactory bulbectomized Siberian hamsters (Phodopus sungorus).

    PubMed

    Prendergast, Brian J; Pyter, Leah M; Galang, Jerome; Kay, Leslie M

    2009-03-01

    In reproductively photoperiodic Syrian hamsters, removal of the olfactory bulbs (OBx) leads to a marked and sustained increase in gonadotrophin secretion which prevents normal testicular regression in short photoperiods. In contrast, among reproductively nonphotoperiodic laboratory strains of rats and mice, bulbectomy unmasks reproductive responses to photoperiod. The role of the olfactory bulbs has been proposed to have opposite effects on responsiveness to photoperiod, depending on the photoperiodicity of the reproductive system; however, Syrian hamsters are the only reproductively photoperiodic rodent species for which the role of the olfactory bulb in reproductive endocrinology has been assessed. This experiment evaluated the role of the olfactory bulbs in the photoperiodic control of reproduction in Siberian hamsters (Phodopus sungorus), an established model species for the study of neural substrates mediating seasonality. Relative to control hamsters housed in long days (15 h light/day), exposure of adult male hamsters to short days (9h light/day) for 8 weeks led to a temporal expansion of the pattern of nocturnal locomotor activity, testicular regression, decreases in testosterone (T) production, and undetectable levels of plasma follicle-stimulating hormone (FSH). Bilateral olfactory bulbectomy failed to affect any of these responses to short days. The patterns of entrainment to long and short days suggests that pre-pineal mechanisms involved in photoperiodic timekeeping are functioning normally in OBx hamsters. The absence of increases in FSH following bulbectomy in long days is incompatible with the hypothesis that the olfactory bulbs provide tonic inhibition of the HPG axis in this species. In marked contrast to Syrian hamsters, the olfactory bulbs of Siberian hamsters play essentially no role in the modulation of tonic gonadotrophin production or gonadotrophin responses to photoperiod.

  20. Pineal-independent regulation of photo-nonresponsiveness in the Siberian hamster (Phodopus sungorus).

    PubMed

    Prendergast, B J; Freeman, D A

    1999-02-01

    The pineal hormone melatonin influences circadian rhythms and also mediates reproductive responses to photoperiod. The authors tested whether pinealectomy influences circadian oscillators responsible for induction of nonresponsiveness to short day lengths by preventing normal short-day patterns of circadian entrainment. Adult male Siberian hamsters were pinealectomized or sham operated, maintained in either 18 h light per day (18L) or 15L for 10 weeks, and then tested for responsiveness to 10L. Because pinealectomized hamsters do not show gonadal regression in short day lengths, responsiveness was assessed by measuring phase angle of entrainment and the length of the nightly activity period following transfer to 10L. The incidence of nonresponsiveness was significantly higher in 18L hamsters than in 15L hamsters but was unaffected by pineal status. Fully 88% of 18L hamsters failed to entrain to 10L in the normal short-day manner; the duration of nightly activity remained compressed, and the phase angle of entrainment was large and negative relative to lights off. The 15L hamsters entrained normally to 10L. Exposure to constant light after 10L treatment was equally effective in inducing arrhythmicity in pinealectomized and intact hamsters. Changes in the period of morning and evening circadian oscillators subsequent to 18L treatment did not predict circadian responsiveness to short photoperiod. Long-day induction of photo-nonresponsiveness, which prevents winter responses to short day lengths, occurs independently of pineal melatonin feedback on the circadian system.

  1. Molecular and immunological characterization of the first allergenic lipocalin in hamster: the major allergen from Siberian hamster (Phodopus sungorus).

    PubMed

    Torres, José Alberto; de Las Heras, Manuel; Maroto, Aroa Sanz; Vivanco, Fernando; Sastre, Joaquín; Pastor-Vargas, Carlos

    2014-08-22

    The most frequent pet allergy is to cat and dog, but in recent years, it has become increasingly popular to have other pets, and the risk of exposure to new allergens is more prevalent. The list of new pets includes hamsters, and one of the most popular hamsters is the Siberian hamster (Phodopus sungorus). The aim of this study was the characterization and cloning of the major allergen from this hamster. The study of its allergenicity and cross-reactivity could improve the specific diagnosis and treatment for hamster-allergic patients. Thirteen Siberian hamster-allergic patients were recruited at the outpatient clinic. Protein extracts were prepared from the hair, urine, and salivary glands of four hamster species (European, golden, Siberian, and Roborovski). IgE-binding proteins were detected by immunoblotting and identified by mass spectrometry. The recombinant protein was produced in Escherichia coli and then purified by metal chelate affinity chromatography. The allergenic properties of the recombinant protein were tested by ELISA and immunoblotting, and biological activity was tested according to capacity for basophil activation. Three IgE-binding proteins were identified in extracts obtained from Siberian hamster hair, urine, and salivary glands. All proteins corresponded to the same protein, which was identified as a lipocalin. This lipocalin had no cross-reactivity with common and golden hamsters. The recombinant allergen was cloned and purified, showing similar IgE reactivity in vitro to Siberian hamster protein extracts. Also, the recombinant allergen was capable of producing biological activation in vivo. The major Siberian hamster allergen was cloned, and allergenic properties were characterized, providing a new tool for specific diagnosis of allergy to Siberian hamster.

  2. Short day lengths delay development of the SNB neuromuscular system in the Siberian hamster, Phodopus sungorus.

    PubMed

    Hegstrom, C D; Breedlove, S M

    1998-06-15

    The Siberian hamster, Phodopus sungorus, breeds seasonally. In the laboratory, the seasonal breeding can be controlled by photoperiod, which affects the durations of nightly melatonin secretions. Winterlike short day lengths induce gonadal regression in adult animals, and pups born and maintained in short days undergo gonadal development much later than animals born into long days. The spinal nucleus of the bulbocavernosus (SNB) and its target muscles, the bulbocavernosus (BC) and levator ani (LA), comprise a sexually dimorphic, androgensensitive neuromuscular system involved in male reproduction. The SNB neuromuscular system was studied in male Siberian hamsters maintained from conception in short-day (8:16 h light/dark cycle) versus long-day (16:8 h light/dark cycle) conditions. At 40-47 days of age, development of three components of the SNB neuromuscular system were all significantly delayed in hamsters raised in the short photoperiod: BC/LA muscle weight, the size of SNB motoneuronal somata, and the area of the neuromuscular junctions at the BC/LA muscles of short-day hamsters were each significantly reduced relative to those of longday counterparts. Thus, development of the SNB reproductive system is delayed under short day lengths in this species.

  3. Histaminergic regulation of seasonal metabolic rhythms in Siberian hamsters.

    PubMed

    I'anson, Helen; Jethwa, Preeti H; Warner, Amy; Ebling, Francis J P

    2011-06-01

    We investigated whether histaminergic tone contributes to the seasonal catabolic state in Siberian hamsters by determining the effect of ablation of histaminergic neurons on food intake, metabolic rate and body weight. A ribosomal toxin (saporin) conjugated to orexin-B was infused into the ventral tuberomammillary region of the hypothalamus, since most histaminergic neurons express orexin receptors. This caused not only 75-80% loss of histaminergic neurons in the posterior hypothalamus, but also some loss of other orexin-receptor expressing cells e.g. MCH neurons. In the long-day anabolic state, lesions produced a transient post-surgical decrease in body weight, but the hamsters recovered and maintained constant body weight, whereas weight gradually increased in sham-lesioned hamsters. VO(2) in the dark phase was significantly higher in the lesioned hamsters compared to shams, and locomotor activity also tended to be higher. In a second study in short days, sham-treated hamsters showed the expected seasonal decrease in body weight, but weight remained constant in the lesioned hamsters, as in the long-day study. Lesioned hamsters consumed more during the early dark phase and less during the light phase due to an increase in the frequency of meals during the dark and decreased meal size during the light, and their cumulative food intake in their home cages was greater than in the control hamsters. In summary, ablation of orexin-responsive cells in the posterior hypothalamus blocks the short-day induced decline in body weight by preventing seasonal hypophagia, evidence consistent with the hypothesis that central histaminergic mechanisms contribute to long-term regulation of body weight.

  4. Effects of sex and scotorefractory state on obesity induced by photostimulation and serum leptin in Siberian hamsters (Phodopus sungorus).

    PubMed

    Cudney, Sarah E; Place, Ned J

    2012-12-01

    The rising prevalence of obesity is associated with an increasing incidence of heart disease, diabetes and other health risks. In addition, severe cases of obesity are associated with an even greater risk of morbidity and mortality. Therefore, animal models of morbid obesity are required to better elucidate the underlying mechanisms. Our investigations in the Siberian hamster (Phodopus sungorus) suggest that pronounced obesity can be reliably induced in this species without relying on genetic manipulation or overly fatty and palatable foods. In a prior study on reproductive aging in female Siberian hamsters, we incidentally observed marked obesity in a group of hamsters that were exposed to a particular photoperiodic regime. In short day (SD) lengths, Siberian hamsters inhibit their reproductive physiology and reduce food intake and body mass. However, hamsters become refractory to SD after 15-20weeks and revert to the long day (LD) phenotype. In the previous study, refractory animals appeared to be particularly sensitive to photostimulation (transfer to LD), in terms of increasing body mass. To test the hypothesis that refractoriness to SD predisposes hamsters to severe obesity, we photostimulated females and males in different states of SD responsiveness (inhibited or refractory). We determined that photostimulation during the SD-refractory state is particularly effective in inducing pronounced obesity and high serum leptin concentration in female hamsters. We propose that this experimental framework is a useful model to investigate the factors and signals that create a predisposition to excessive food intake and body mass, without having to rely on genetic or dietary manipulations.

  5. The Chemistry of Cold: Mechanisms of Torpor Regulation in the Siberian Hamster.

    PubMed

    Cubuk, Ceyda; Bank, Jonathan H H; Herwig, Annika

    2016-01-01

    Siberian hamsters use spontaneous daily torpor, a state of hypometabolism and hypothermia, to save energy during winter. Multiple neuroendocrine signals set the scene for spontaneous torpor to occur, and several brain areas have been identified as potential sites for torpor regulation. Here, we summarize the known mechanisms of a fascinating physiological state in the Siberian hamster.

  6. Social thermoregulation and torpor in the Siberian hamster.

    PubMed

    Jefimow, Małgorzata; Głabska, Marta; Wojciechowski, Michał S

    2011-04-01

    Social thermoregulation and huddling bring about energy benefits to animals sharing a nest because of the smaller surface-to-volume ratio of a huddle and the higher local temperature in the nest. We tested whether living in groups and huddling affect daily torpor, metabolic rate and seasonal changes in the body mass of a small heterothermic rodent, the Siberian hamster (Phodopus sungorus), housed under semi-natural conditions both singly and in groups of four litter-mates. We predicted that in hamsters housed in groups: (1) synchronized torpor bouts would be longer and deeper than non-synchronized ones but shallower than in solitary hamsters, (2) seasonal variations in metabolic rate would be lower than in solitary hamsters, and (3) the winter decrease in body mass would be smaller in grouped than in singly housed hamsters. We found that group housing led to a smaller decrease in body mass in winter, and affected the length and depth of daily torpor. In group-living hamsters more than 50% of all torpor episodes were synchronized and torpid animals were often found in huddles formed of all cage-mates. The longest and deepest torpor bouts in groups were recorded when all animals in a group entered torpor simultaneously. Although the minimum body temperature during torpor was higher, torpor duration was slightly longer than in solitary hamsters. We did not record significant differences in the body mass-adjusted rate of oxygen consumption between solitary and grouped animals, either in the cold or at the lower critical temperature. We conclude that social thermoregulation enables maintenance of a larger body mass, and thus a larger body fat content, which can ensure better body condition at the beginning of the reproductive season.

  7. Histiocytic Sarcoma and Bilateral Facial Vein Thrombosis in a Siberian Hamster (Phodopus sungorus).

    PubMed

    Coble, Dondrae J; Shoemaker, Margaret; Harrington, Bonnie; Dardenne, Adrienne D; Bolon, Brad

    2015-04-01

    A 21-mo-old, male Siberian hamster (Phodopus sungorus) presented with left-sided facial swelling, proptosis of the left eye, and blepharospasm of the right eye. The hamster had been used only for breeding. Because of the poor prognosis, the hamster was euthanized without additional diagnostic assays or treatments. Routine gross pathologic evaluation demonstrated exophthalmos and presumptive hyphema of the left eye, bilateral facial edema, freely movable nodules within the mesentery, white foci within the liver, and a large mass effacing the cranial pole of the right kidney. On histologic evaluation, the mesenteric nodules and liver foci expressed histiocytic marker CD163 and thus were diagnosed as sites of histiocytic sarcoma, whereas the kidney mass was a well-differentiated renal cell carcinoma. The facial swelling resulted from bilateral, chronic, severe, branching thrombi in many facial veins. Additional age-related histopathologic findings were observed in other organs, including diffuse glomerulopathy, nesidioblastosis (pancreatic islet neoformation), and multiple foci of severe cartilage degeneration in the axial skeleton. To our knowledge, this report provides the first description of histiocytic sarcoma in a Siberian hamster. PMID:25926398

  8. Histiocytic Sarcoma and Bilateral Facial Vein Thrombosis in a Siberian Hamster (Phodopus sungorus).

    PubMed

    Coble, Dondrae J; Shoemaker, Margaret; Harrington, Bonnie; Dardenne, Adrienne D; Bolon, Brad

    2015-04-01

    A 21-mo-old, male Siberian hamster (Phodopus sungorus) presented with left-sided facial swelling, proptosis of the left eye, and blepharospasm of the right eye. The hamster had been used only for breeding. Because of the poor prognosis, the hamster was euthanized without additional diagnostic assays or treatments. Routine gross pathologic evaluation demonstrated exophthalmos and presumptive hyphema of the left eye, bilateral facial edema, freely movable nodules within the mesentery, white foci within the liver, and a large mass effacing the cranial pole of the right kidney. On histologic evaluation, the mesenteric nodules and liver foci expressed histiocytic marker CD163 and thus were diagnosed as sites of histiocytic sarcoma, whereas the kidney mass was a well-differentiated renal cell carcinoma. The facial swelling resulted from bilateral, chronic, severe, branching thrombi in many facial veins. Additional age-related histopathologic findings were observed in other organs, including diffuse glomerulopathy, nesidioblastosis (pancreatic islet neoformation), and multiple foci of severe cartilage degeneration in the axial skeleton. To our knowledge, this report provides the first description of histiocytic sarcoma in a Siberian hamster.

  9. Histiocytic Sarcoma and Bilateral Facial Vein Thrombosis in a Siberian Hamster (Phodopus sungorus)

    PubMed Central

    Coble, Dondrae J; Shoemaker, Margaret; Harrington, Bonnie; Dardenne, Adrienne D; Bolon, Brad

    2015-01-01

    A 21-mo-old, male Siberian hamster (Phodopus sungorus) presented with left-sided facial swelling, proptosis of the left eye, and blepharospasm of the right eye. The hamster had been used only for breeding. Because of the poor prognosis, the hamster was euthanized without additional diagnostic assays or treatments. Routine gross pathologic evaluation demonstrated exophthalmos and presumptive hyphema of the left eye, bilateral facial edema, freely movable nodules within the mesentery, white foci within the liver, and a large mass effacing the cranial pole of the right kidney. On histologic evaluation, the mesenteric nodules and liver foci expressed histiocytic marker CD163 and thus were diagnosed as sites of histiocytic sarcoma, whereas the kidney mass was a well-differentiated renal cell carcinoma. The facial swelling resulted from bilateral, chronic, severe, branching thrombi in many facial veins. Additional age-related histopathologic findings were observed in other organs, including diffuse glomerulopathy, nesidioblastosis (pancreatic islet neoformation), and multiple foci of severe cartilage degeneration in the axial skeleton. To our knowledge, this report provides the first description of histiocytic sarcoma in a Siberian hamster. PMID:25926398

  10. Homeostatic regulation of sleep in arrhythmic Siberian hamsters.

    PubMed

    Larkin, Jennie E; Yokogawa, Tohei; Heller, H Craig; Franken, Paul; Ruby, Norman F

    2004-07-01

    Sleep is regulated by independent yet interacting circadian and homeostatic processes. The present study used a novel approach to study sleep homeostasis in the absence of circadian influences by exposing Siberian hamsters to a simple phase delay of the photocycle to make them arrhythmic. Because these hamsters lacked any circadian organization, their sleep homeostasis could be studied in the absence of circadian interactions. Control animals retained circadian rhythmicity after the phase shift and re-entrained to the phase-shifted photocycle. These animals displayed robust daily sleep-wake rhythms with consolidated sleep during the light phase beginning about 1 h after light onset. This marked sleep-wake pattern was circadian in that it persisted in constant darkness. The distribution of sleep in the arrhythmic hamsters over 24 h was similar to that in the light phase of rhythmic animals. Therefore, daily sleep amounts were higher in arrhythmic animals compared with rhythmic ones. During 2- and 6-h sleep deprivations (SD), it was more difficult to keep arrhythmic hamsters awake than it was for rhythmic hamsters. Because the arrhythmic animals obtained more non-rapid eye movement sleep (NREMS) during the SD, they showed a diminished compensatory response in NREMS EEG slow-wave activity during recovery sleep. When amounts of sleep during the SD were taken into account, there were no differences in sleep homeostasis between experimental and control hamsters. Thus loss of circadian control did not alter the homeostatic response to SD. This supports the view that circadian and homeostatic influences on sleep regulation are independent processes.

  11. Melatonin production accompanies arousal from daily torpor in Siberian hamsters.

    PubMed

    Larkin, Jennie E; Yellon, Steven M; Zucker, Irving

    2003-01-01

    Arousal from deep hibernation is accompanied by a transient rise of melatonin (Mel) in circulation; there are no comparable analyses of Mel concentrations in species that undergo much shallower, shorter duration episodes of daily torpor. Serum Mel concentrations were determined during arousal from both natural daily torpor and torpor induced by 2-deoxy-D-glucose (2-DG) treatment (2,500 mg/kg, intraperitoneal [IP]); blood samples were drawn from the retro-orbital sinus of anesthetized Siberian hamsters. For animals kept in darkness during torpor, Mel concentrations were highest during early arousal when thermogenesis is maximal, and they decreased as body temperature increased during arousal and returned to baseline once euthermia was reestablished. In hamsters kept in the light during the torpor bout, Mel concentrations were elevated above basal values during arousal, but the response was significantly blunted in comparison with values recorded in darkness. Increased Mel concentrations were detected in hamsters only during arousal from torpor (either natural or 2-DG induced) and were not simply a result of the drug treatment; hamsters that remained euthermic or manifested mild hypothermia after drug treatment maintained basal Mel concentrations. We propose that increased Mel production may reflect enhanced sympathetic activation associated with intense thermogenesis during arousal from torpor rather than an adjustment of the circadian rhythm of Mel secretion.

  12. Photoperiod and stress regulation of corticosteroid receptor, brain-derived neurotrophic factor, and glucose transporter GLUT3 mRNA in the hippocampus of male Siberian hamsters (Phodopus sungorus).

    PubMed

    Walton, J C; Grier, A J; Weil, Z M; Nelson, R J

    2012-06-28

    In response to changing day lengths, small photoperiodic rodents have evolved a suite of adaptations to survive the energetic bottlenecks of winter. Among these adaptations are changes in metabolism, adiposity, and energy balance. Whereas hypothalamic and neuroendocrine regulation of these adaptations has been extensively studied, the impact of day length, and interaction of day length and stress, on the energy balance of neurons within the central nervous system remains unspecified. Thus, we exposed male Siberian hamsters (Phodopus sungorus) to either short or long day lengths for 14 weeks to induce the full suite of adaptive responses, exposed them to 4h of restraint, and then measured relative mRNA expression in the hippocampus for low- and high-affinity glucocorticoid receptors (glucocorticoid receptor (GR), mineralocorticoid receptor (MR)), brain-derived neurotrophic factor (BDNF), and the neuron-specific glucose transporter GLUT3. Independent of photoperiod, restraint elevated plasma cortisol (CORT) concentrations and reduced expression of GR, MR, and BDNF. Neither restraint nor photoperiod significantly altered GLUT3 expression. Among all groups, plasma cortisol concentrations were negatively correlated with GR and MR expression. MR, BDNF, and GLUT3 levels were positively correlated with one another, even when controlling for photoperiod and CORT. Taken together, these results suggest that, as peripheral energy balance changes across day length in this photoperiodic species, the neurons of the hippocampus do not alter relative gene expression levels of three proteins involved in monitoring neuronal glucose regulation and morphology.

  13. Gonadal hormone-dependent and -independent regulation of immune function by photoperiod in Siberian hamsters.

    PubMed

    Prendergast, Brian J; Baillie, Scott R; Dhabhar, Firdaus S

    2008-02-01

    Siberian hamsters (Phodopus sungorus) exhibit changes in reproductive and immune function in response to seasonal variations in day length. Exposure to short days induces gonadal regression and inhibits testosterone secretion. In parallel, short days enhance immune function: increasing leukocyte numbers and attenuating cytokine and behavioral responses to infection. We examined whether photoperiodic changes in leukocyte phenotypes and sickness behaviors are dependent on concurrent photoperiodic changes in gonadal function. Male hamsters were gonadectomized or sham-gonadectomized and either exposed to short days (9 h light/day; SD) or kept in their natal long-day (15 h light/day; LD) photoperiod for 10-13 wk. Blood samples were obtained for leukocyte enumeration, and hamsters were challenged with bacterial LPS, which induced behavioral (anorexia, reductions in nest building) and somatic (weight loss) sickness responses. Among gonad-intact hamsters, exposure to SD increased total and CD62L+ lymphocytes and CD3+ T lymphocytes in blood and significantly attenuated LPS-induced sickness responses. Independent of photoperiod, castration alone increased total and CD62L+ lymphocyte and CD3+ T lymphocyte numbers and attenuated somatic and anorexic sickness responses. Among castrated hamsters, SD exposure increased lymphocyte numbers and suppressed sickness behaviors. In castrated hamsters, the magnitude of most immunological effects of SD were diminished relative to those evident in gonad-intact hamsters. The SD phenotype in several measures of immunity can be instated via elimination of gonadal hormones alone; however, photoperiodic effects on immune function persist even in castrated hamsters. Thus, photoperiod affects the immune system and neural-immune interactions underlying sickness behaviors via gonadal hormone-dependent and -independent mechanisms.

  14. Testicular and somatic growth in Siberian hamsters depend on the melatonin-free interval between twice daily melatonin signals.

    PubMed

    Freeman, D A; Larkin, J E; Seliby, L

    2002-03-01

    In Siberian hamsters, day length is encoded by the duration of the nocturnal melatonin signal; short and long melatonin signals over the course of several weeks stimulate and inhibit somatic and gonadal development, respectively, in prepubertal males. We sought to determine whether juvenile male Siberian hamsters respond to multiple melatonin signals each day and the manner in which the sequence of melatonin signals and the duration of the melatonin-free interval between signals affects development. Twenty-one day old male Siberian hamsters, gestated and maintained in a short-day photoperiod of 10 h light/day (10 L), were transferred to constant light to suppress endogenous melatonin secretion and received s.c. infusions of melatonin or saline for 12 days. Hamsters infused with saline retained small testes, whereas one short melatonin infusion each day resulted in significant testicular growth. Other hamsters were provided with two melatonin signals each day, one long (9 h) and one short (4 or 5 h); the order in which these signals was administered and the duration of the melatonin-free interval after each signal varied between groups. In asymmetrical melatonin infusions, the first and second daily infusions were followed by 3-h and 7-h melatonin-free intervals, respectively, whereas in symmetrical infusions, each melatonin signal was followed by a 5-h melatonin-free interval. In the asymmetrical sequence, the melatonin signal that immediately preceded the longer melatonin-free interval determined the rate gonadal growth. Equal melatonin-free intervals after each of the long and short daily melatonin infusions produced intermediate increases in gonadal and somatic development. The hypothalamic-pituitary-gonadal axis of Siberian hamsters can respond to multiple melatonin signals each day, with the rate of testicular growth determined primarily by the duration of the melatonin-free interval following each infusion.

  15. Dim nocturnal illumination alters coupling of circadian pacemakers in Siberian hamsters, Phodopus sungorus.

    PubMed

    Gorman, M R; Elliott, J A

    2004-08-01

    The circadian pacemaker of mammals comprises multiple oscillators that may adopt different phase relationships to determine properties of the coupled system. The effect of nocturnal illumination comparable to dim moonlight was assessed in male Siberian hamsters exposed to two re-entrainment paradigms believed to require changes in the phase relationship of underlying component oscillators. In experiment 1, hamsters were exposed to a 24-h light-dark-light-dark cycle previously shown to split circadian rhythms into two components such that activity is divided between the two daily dark periods. Hamsters exposed to dim illumination (<0.020 lx) during each scotophase were more likely to exhibit split rhythms compared to hamsters exposed to completely dark scotophases. In experiment 2, hamsters were transferred to winter photoperiods (10 h light, 14 h dark) from two different longer daylengths (14 h or 18 h light daily) in the presence or absence of dim nighttime lighting. Dim nocturnal illumination markedly accelerated adoption of the winter phenotype as reflected in the expansion of activity duration, gonadal regression and weight loss. The two experiments demonstrate substantial efficacy of light intensities generally viewed as below the threshold of circadian systems. Light may act on oscillator coupling through rod-dependent mechanisms.

  16. Artificial light at night alters delayed-type hypersensitivity reaction in response to acute stress in Siberian hamsters.

    PubMed

    Bedrosian, Tracy A; Aubrecht, Taryn G; Kaugars, Katherine E; Weil, Zachary M; Nelson, Randy J

    2013-11-01

    Several physiological and behavioral processes rely on precisely timed light information derived from the natural solar cycle. Using this information, traits have adapted to allow individuals within specific niches to optimize survival and reproduction, but urbanization by humans has significantly altered natural habitats. Nighttime light exposure alters immune function in several species, which could lead to decreased fitness or survival, particularly in the face of an environmental challenge. We exposed male Siberian hamsters (Phodopus sungorus) to five lux of light at night for four weeks, and then administered six hours of acute restraint stress. Delayed-type hypersensitivity (DTH) response was assessed immediately following stress. Acute restraint increased the DTH reaction in dark nights, but exposure to nighttime light prevented this response. Exposure to light at night prolonged the DTH response in non-stressed control hamsters. These results suggest that light pollution may significantly alter physiological responses in Siberian hamsters, particularly in response to a salient environmental challenge such as stress.

  17. Learned magnetic compass orientation by the Siberian hamster, Phodopus sungorus

    SciTech Connect

    Deutschlander, Mark E.; Freake, Michael J.; Borland, Christopher; Phillips, John B.; Madden, R C.; Anderson, Larry E.; Wilson, B W.

    2003-04-01

    Magnetic orientation has been demonstrated in Siberian hamsters, Phodopus sungorus. The behavior, using a nest building assay, shows a directional preference in nest position and appears in this animal to be a learned behavior. Hamsters were housed prior to testing in rectangular cages aligned along perpendicular axes. When subsequently tested in a radially-symmetrical arena, the hamsters positioned their nests in a bimodal distribution that coincided with the magnetic direction of the long-axis of the holding cages. In addition, results are presented that illustrate some of the factors that can influence behavioral responses to the magnetic field. In particular for P. sungorus, holding conditions prior to testing and the presence of non-magnetic cues may influence the strength and expression of magnetic orientation. Failure to consider these and other factors may help to explain why previous attempts to demonstrate magnetic orientation in a number of rodent species have failed or, when positive results have been obtained, have been difficult to replicate in other laboratories.

  18. The Siberian hamster as a model for study of the mammalian photoperiodic mechanism.

    PubMed

    Goldman, B D

    1999-01-01

    The Siberian hamster has been a useful model for studies of mammalian photoperiodism for a number of reasons: 1) Siberian hamsters are hardy animals that are easily maintained and bred in the laboratory. 2) The species exhibits a large number of seasonal, photoperiod-driven, pineal-dependent responses. Thus, the Siberian hamster is an excellent species in which to examine whether several different types of photoperiod responses share similar mechanistic features with respect to their control by MEL. Are all the responses cued to the duration of the nocturnal MEL peak? Does MEL act at a single site to influence all the types of responses, or are there separate MEL target sites for different responses? 3) Juvenile Siberian hamsters exhibit an unusually rapid (for mammals) response to photoperiod change or to MEL treatments, making them ideal subjects for certain types of photoperiod-related studies. 4) Populations of Siberian hamsters show individual variations in photoperiod responsiveness, and the differences are at least partly heritable. These hamsters also exhibit strong influences of environmental history on short day responsiveness. Thus, the species may be a valuable model for the investigation of both genetic and environmental influences on the photoperiodic mechanism. 5) Siberian hamsters have proved to be useful animals in which to study maternal influences on the developing photoperiodic mechanism of the fetus.

  19. Housing condition alters immunological and reproductive responses to day length in Siberian hamsters (Phodopus sungorus).

    PubMed

    Weil, Zachary M; Workman, Joanna L; Nelson, Randy J

    2007-08-01

    During winter, increased thermoregulatory demands coincide with limited food availability necessitating physiological tradeoffs among expensive physiological processes resulting in seasonal breeding among small mammals. In the laboratory, short winter-like day lengths induce regression of the reproductive tract, but also enhance many aspects of immune function. It remains unspecified the extent to which bolstered immune responses in short days represent enhanced immune function per se compared to long days or represents energetic disinhibition mediated by the regression of the reproductive tract. Cohabitation of male Siberian hamsters with intact female conspecifics can block short-day reproductive regression. We sought to determine whether female cohabitation could also block the enhanced immune function associated with short days. Adult male Siberian hamsters were housed in long or short day lengths in one of three housing conditions: (1) single-housed, (2) housed with a same sex littermate, or (3) housed with an ovariectomized female. Delayed-type hypersensitivity (DTH) responses were assessed after 8 weeks of photoperiod treatment. Housing with an ovariectomized female was not sufficient to block short-day reproductive regression, but prevented short-day enhancement of DTH responses. Housing with a male littermate did not alter reproductive or immune responses in either photoperiod. These data suggest that short day enhancement of immune function is independent of photoperiod-mediated changes in the reproductive system.

  20. Hypothalamic ventricular ependymal thyroid hormone deiodinases are an important element of circannual timing in the Siberian hamster (Phodopus sungorus).

    PubMed

    Herwig, Annika; de Vries, Emmely M; Bolborea, Matei; Wilson, Dana; Mercer, Julian G; Ebling, Francis J P; Morgan, Peter J; Barrett, Perry

    2013-01-01

    Exposure to short days (SD) induces profound changes in the physiology and behaviour of Siberian hamsters, including gonadal regression and up to 30% loss in body weight. In a continuous SD environment after approximately 20 weeks, Siberian hamsters spontaneously revert to a long day (LD) phenotype, a phenomenon referred to as the photorefractory response. Previously we have identified a number of genes that are regulated by short photoperiod in the neuropil and ventricular ependymal (VE) cells of the hypothalamus, although their importance and contribution to photoperiod induced physiology is unclear. In this refractory model we hypothesised that the return to LD physiology involves reversal of SD expression levels of key hypothalamic genes to their LD values and thereby implicate genes required for LD physiology. Male Siberian hamsters were kept in either LD or SD for up to 39 weeks during which time SD hamster body weight decreased before increasing, after more than 20 weeks, back to LD values. Brain tissue was collected between 14 and 39 weeks for in situ hybridization to determine hypothalamic gene expression. In VE cells lining the third ventricle, expression of nestin, vimentin, Crbp1 and Gpr50 were down-regulated at 18 weeks in SD photoperiod, but expression was not restored to the LD level in photorefractory hamsters. Dio2, Mct8 and Tsh-r expression were altered by SD photoperiod and were fully restored, or even exceeded values found in LD hamsters in the refractory state. In hypothalamic nuclei, expression of Srif and Mc3r mRNAs was altered at 18 weeks in SD, but were similar to LD expression values in photorefractory hamsters. We conclude that in refractory hamsters not all VE cell functions are required to establish LD physiology. However, thyroid hormone signalling from ependymal cells and reversal of neuronal gene expression appear to be essential for the SD refractory response.

  1. Hypothalamic Ventricular Ependymal Thyroid Hormone Deiodinases Are an Important Element of Circannual Timing in the Siberian Hamster (Phodopus sungorus)

    PubMed Central

    Bolborea, Matei; Wilson, Dana; Mercer, Julian G.; Ebling, Francis J. P.; Morgan, Peter J.; Barrett, Perry

    2013-01-01

    Exposure to short days (SD) induces profound changes in the physiology and behaviour of Siberian hamsters, including gonadal regression and up to 30% loss in body weight. In a continuous SD environment after approximately 20 weeks, Siberian hamsters spontaneously revert to a long day (LD) phenotype, a phenomenon referred to as the photorefractory response. Previously we have identified a number of genes that are regulated by short photoperiod in the neuropil and ventricular ependymal (VE) cells of the hypothalamus, although their importance and contribution to photoperiod induced physiology is unclear. In this refractory model we hypothesised that the return to LD physiology involves reversal of SD expression levels of key hypothalamic genes to their LD values and thereby implicate genes required for LD physiology. Male Siberian hamsters were kept in either LD or SD for up to 39 weeks during which time SD hamster body weight decreased before increasing, after more than 20 weeks, back to LD values. Brain tissue was collected between 14 and 39 weeks for in situ hybridization to determine hypothalamic gene expression. In VE cells lining the third ventricle, expression of nestin, vimentin, Crbp1 and Gpr50 were down-regulated at 18 weeks in SD photoperiod, but expression was not restored to the LD level in photorefractory hamsters. Dio2, Mct8 and Tsh-r expression were altered by SD photoperiod and were fully restored, or even exceeded values found in LD hamsters in the refractory state. In hypothalamic nuclei, expression of Srif and Mc3r mRNAs was altered at 18 weeks in SD, but were similar to LD expression values in photorefractory hamsters. We conclude that in refractory hamsters not all VE cell functions are required to establish LD physiology. However, thyroid hormone signalling from ependymal cells and reversal of neuronal gene expression appear to be essential for the SD refractory response. PMID:23637944

  2. Pubertal growth of the medial amygdala delayed by short photoperiods in the Siberian hamster, Phodopus sungorus.

    PubMed

    Cooke, Bradley M; Jordan, Cynthia L; Breedlove, S Marc

    2007-09-01

    We investigated whether puberty influences the morphology of the medial nucleus of the amygdala (MeA) by comparing Siberian hamsters (Phodopus sungorus) that had been raised from birth in either long day (LD; 16:8 h light:dark) or short day (SD; 8:16) photoperiods. Hamsters were sacrificed at 42-49 days of age, at which point all LD hamsters were reproductively mature, as evidenced by adult-like testes weights (mean: 657 mg). In contrast, the testes weights of the SD hamsters were low (mean: 31 mg), indicating that the SD photoperiod had delayed puberty. The regional volume and mean soma size of the four MeA subnuclei was estimated bilaterally by stereological procedures. In the posterior dorsal and ventral MeA subnuclei, regional volume was 22-25% larger, and mean soma size 18% larger, in LD males than SD males. Unbiased cell counts in the posterior dorsal MeA showed that LD and SD hamsters have equivalent neuron numbers. In the anterior MeA subnuclei, regional volumes and soma sizes from LD and SD hamsters were equivalent. Additionally, the regional volume of the posteroventral subnucleus was larger in the right hemisphere than the left, but this laterality did not respond to photoperiod manipulation. These results suggest that the extant neurons within the posterior MeA, a steroid-sensitive nucleus implicated in socio-sexual behavior, grow in response to the elevated levels of circulating androgen accompanying puberty, and that photoperiodic regulation of puberty affects morphological maturation of this nucleus.

  3. Photoperiod Regulates vgf-Derived Peptide Processing in Siberian Hamsters.

    PubMed

    Noli, Barbara; Brancia, Carla; Pilleri, Roberta; D'Amato, Filomena; Messana, Irene; Manconi, Barbara; Ebling, Francis J P; Ferri, Gian-Luca; Cocco, Cristina

    2015-01-01

    VGF mRNA is induced in specific hypothalamic areas of the Siberian hamster upon exposure to short photoperiods, which is associated with a seasonal decrease in appetite and weight loss. Processing of VGF generates multiple bioactive peptides, so the objective of this study was to determine the profile of the VGF-derived peptides in the brain, pituitary and plasma from Siberian hamsters, and to establish whether differential processing might occur in the short day lean state versus long day fat. Antisera against short sequences at the C- or N- termini of proVGF, as well as against NERP-1, TPGH and TLQP peptides, were used for analyses of tissues, and both immunohistochemistry and enzyme linked immunosorbent assay (ELISA) coupled with high-performance liquid (HPLC) or gel chromatography were carried out. VGF peptide immunoreactivity was found within cortex cholinergic perikarya, in multiple hypothalamic nuclei, including those containing vasopressin, and in pituitary gonadotrophs. ELISA revealed that exposure to short day photoperiod led to a down-regulation of VGF immunoreactivity in the cortex, and a less pronounced decrease in the hypothalamus and pituitary, while the plasma VGF levels were not affected by the photoperiod. HPLC and gel chromatography both confirmed the presence of multiple VGF-derived peptides in these tissues, while gel chromatography showed the presence of the VGF precursor in all tissues tested except for the cortex. These observations are consistent with the view that VGF-derived peptides have pleiotropic actions related to changing photoperiod, possibly by regulating cholinergic systems in the cortex, vasopressin hypothalamic pathways, and the reproductive axis.

  4. Photoperiod Regulates vgf-Derived Peptide Processing in Siberian Hamsters

    PubMed Central

    Noli, Barbara; Brancia, Carla; Pilleri, Roberta; D’Amato, Filomena; Messana, Irene; Manconi, Barbara; Ebling, Francis J. P.; Ferri, Gian-Luca; Cocco, Cristina

    2015-01-01

    VGF mRNA is induced in specific hypothalamic areas of the Siberian hamster upon exposure to short photoperiods, which is associated with a seasonal decrease in appetite and weight loss. Processing of VGF generates multiple bioactive peptides, so the objective of this study was to determine the profile of the VGF-derived peptides in the brain, pituitary and plasma from Siberian hamsters, and to establish whether differential processing might occur in the short day lean state versus long day fat. Antisera against short sequences at the C- or N- termini of proVGF, as well as against NERP-1, TPGH and TLQP peptides, were used for analyses of tissues, and both immunohistochemistry and enzyme linked immunosorbent assay (ELISA) coupled with high-performance liquid (HPLC) or gel chromatography were carried out. VGF peptide immunoreactivity was found within cortex cholinergic perikarya, in multiple hypothalamic nuclei, including those containing vasopressin, and in pituitary gonadotrophs. ELISA revealed that exposure to short day photoperiod led to a down-regulation of VGF immunoreactivity in the cortex, and a less pronounced decrease in the hypothalamus and pituitary, while the plasma VGF levels were not affected by the photoperiod. HPLC and gel chromatography both confirmed the presence of multiple VGF-derived peptides in these tissues, while gel chromatography showed the presence of the VGF precursor in all tissues tested except for the cortex. These observations are consistent with the view that VGF-derived peptides have pleiotropic actions related to changing photoperiod, possibly by regulating cholinergic systems in the cortex, vasopressin hypothalamic pathways, and the reproductive axis. PMID:26555143

  5. Possible mechanisms of weight loss of Siberian hamsters (Phodopus sungorus sungorus) exposed to short photoperiod.

    PubMed

    Atgié, C; Sauvant, P; Ambid, L; Carpéné, C

    2009-12-01

    Several weeks of short day photoperiod (SD) exposure promote a dramatic decrease of white adipose tissue (WAT) mass in Siberian hamsters(Phodopus sungorus sungorus). This slimming effect is accompanied by changes in the adipocyte responsiveness to adrenergic stimulation that are still under debate. We investigated whether possible changes in the antilipolytic responses, and/or lipogenic activities could be involved in such lipid deposition/mobilisation imbalance. Male Siberian hamsters were exposed for 11 weeks to SD or long day photoperiod and basal or stimulated lipolytic and lipogenic activities were measured on white adipocytes. As expected, the body mass of SD-animals was decreased. Besides a slight reduction in the basal lipolysis and in the maximal response to dibutyryl-cAMP, the responses to adrenergic and non-adrenergic lipolytic agents (forskolin, adenosine deaminase) were similar in both groups. Fat mass loss was likely not resulting from changes in the lipolytic responses of adipocytes to biogenic amines (e.g. octopamine), which were unaltered, or to a direct lipolytic stimulation by melatonin or histamine, which were inactive. Antilipolytic responses to insulin or tyramine were slightly decreased in SD-adipocytes. Basal or insulin-stimulated lipid accumulation in WAT, measured by glucose incorporation into lipids, did not change after SD-exposure. However, a significant decrease in the lipoprotein lipase activity was observed in the WAT of SDanimals. Despite the observed changes, the weight loss of SD-exposed Siberian hamsters was likely not resulting only from impaired antilipolytic orde novo lipogenic activities in white adipocytes, but either from other dramatic changes occurring during seasonal photoperiod-sensitive body weight regulation. PMID:20358351

  6. Affective responses to changes in day length in Siberian hamsters (Phodopus sungorus).

    PubMed

    Prendergast, Brian J; Nelson, Randy J

    2005-06-01

    The goal of these experiments was to test the hypothesis that day length influences anxious- and depressive-like behaviors in reproductively photoperiodic rodents. Male and female Siberian hamsters (Phodopus sungorus) were exposed to long (16 h light/day; LD) or short (8 h light/day; SD) photoperiods beginning at the time of weaning (day 18). Two weeks later hamsters were subjected to a series of behavioral tests to quantify anxiety-and depressive-like behaviors. In an elevated plus maze, SD males exhibited longer latencies to enter an open arm, entered fewer open arms, and spent less time exploring open arms relative to LD hamsters. SD males were likewise slower to enter either of the distal arms of a completely enclosed T-maze, and in a hunger-motivated exploratory paradigm SD males were slower to enter an open arena for food as compared to LD males. In a forced-swimming model of behavioral despair, SD males exhibited immobility sooner, more often, and for a greater total amount of time relative to LD males. Total activity levels, aversiveness to light, olfactory function, and limb strength were unaffected by SD, suggesting that the behavioral changes consequent to SD are not attributable to sensory or motor deficits, but rather may arise from changes in general affective state. The anxiogenic and depressive effects of SD were largely absent in female hamsters. Together the results indicate that adaptation to short photoperiods is associated with increased expression of anxiety- and depressive-like behaviors relative to those observed under LD photoperiod conditions. PMID:15721056

  7. Metabolic influences on circadian rhythmicity in Siberian and Syrian hamsters exposed to long photoperiods.

    PubMed

    Challet, E; Kolker, D E; Turek, F W

    2000-01-01

    Calorie restriction and other situations of reduced glucose availability in rodents alter the entraining effects of light on the circadian pacemaker located in the suprachiasmatic nuclei. Siberian and Syrian hamsters are photoperiodic species that are sexually active when exposed to long summer-like photoperiods, while both species show opposite changes in body mass when transferred from long to short or short to long days. Because metabolic cues may fine tune the photoperiodic responses via the suprachiasmatic nuclei, we tested whether timed calorie restriction can alter the photic synchronization of the light-entrainable pacemaker in these two hamster species exposed to long photoperiods. Siberian and Syrian hamsters were exposed to 16 h:8 h light:dark cycles and received daily hypocaloric (75% of daily food intake) or normocaloric diet (100% of daily food intake) 4 h after light onset. Four weeks later, hamsters were transferred to constant darkness and fed ad libitum. The onset of the nocturnal pattern of locomotor activity was phase advanced by 1.5 h in calorie-restricted Siberian hamsters, but not in Syrian hamsters. The lack of phase change in calorie-restricted Syrian hamsters was also observed in individuals exposed to 14 h:10 h dim light:dark cycles and fed with lower hypocaloric food (i.e. 60% of daily food intake) 2 h after light onset. Moreover, in hamsters housed in constant darkness and fed ad lib., light-induced phase shifts of the locomotor activity in Siberian hamsters, but not in Syrian hamsters were significantly reduced when glucose utilization was blocked by pretreatment with 500 mg/kg i.p. 2-deoxy-D-glucose. Taken together, these results show that the photic synchronization of the light-entrainable pacemaker can be modulated by metabolic cues in Siberian hamsters, but not in Syrian hamsters maintained on long days.

  8. Influence of the olfactory bulbs on blood leukocytes and behavioral responses to infection in Siberian hamsters.

    PubMed

    Prendergast, Brian J; Galang, Jerome; Kay, Leslie M; Pyter, Leah M

    2009-05-01

    Surgical removal of the olfactory bulb alters several aspects of immunological activity. This study investigated the role of the olfactory bulbs in the control of behavioral responses to simulated infection, and the environmental modulation of sickness behaviors by changes in day length. Adult male Siberian hamsters (Phodopus sungorus) were subjected to bilateral olfactory bulbectomy (OBx) or a sham surgical procedure, and were then exposed to long(15 h light/day; LD) or short (9 h light/day; SD) photoperiods for 8–12 weeks, after which circulating leukocytes and behavioral responses (anorexia, anhedonia, cachexia) to simulated gram-negative bacterial infections (i.p. lipopolysaccharide [LPS] treatment;0.625 mg/kg) were quantified. OBx treatment altered the effects of photoperiod on immune function in a trait-specific manner. LPS-induced anorexia was exacerbated in SD-OBx hamsters; LPS-induced anhedonia was exacerbated in LD-OBx hamsters; and photoperiodic differences in circulating leukocytes and LPS-induced cachexia were eliminated by OBx. Plasma cortisol concentrations did not differ between LD and SD hamsters, irrespective of olfactory bulb integrity. The data indicate that photoperiod affects immune function via OB-dependent and -independent mechanisms, and that changes in cortisol production are not required for photoperiodic changes in sickness behaviors to manifest.

  9. Differential effects of multiple short day lengths on body weights of gonadectomized siberian hamsters.

    PubMed

    Gorman, Michael R

    2003-01-01

    Siberian hamsters (Phodopus sungorus) maintained under simulated natural photoperiods exhibit marked reductions in body weight as day lengths decrease in summer and fall. This experiment assessed whether the component of the seasonal body weight rhythm that is independent of gonadal hormones exhibits a graded dependence on decreasing day lengths or whether the entire program of weight loss is triggered by the crossing of a single critical day length in late summer. Male hamsters born into a photoperiod with 13 h light and 11 h dark (i.e., 13L : 11D) were castrated and transferred to simulated natural photoperiod for early April at 40 degrees N latitude. At the summer solstice (15L : 9D) some hamsters remained on that photoperiod whereas others experienced gradual decreases in day length. Three additional groups were moved to static photoperiods when day lengths had subsequently declined to 13L : 11D, 11L : 13D, or 9L : 15D, respectively. Day lengths decreasing to 13L : 11D were sufficient to suppress body weight but were less inhibitory than further decreases in day length. Hamsters identified as photononresponsive on the basis of daily activity rhythms increased body weight monotonically. These results establish that steroid-independent modulation of body weight depends on photoperiod in a graded fashion.

  10. Constant darkness restores entrainment to phase-delayed Siberian hamsters.

    PubMed

    Ruby, Norman F; Joshi, Nirav; Heller, H Craig

    2002-12-01

    Over 90% of Siberian hamsters (Phodopus sungorus) fail to reentrain to a 5-h phase delay of a 16:8-h photocycle. Because constant darkness (DD) restores rhythms disrupted by constant light, we tested whether DD could also restore entrainment. DD began 0, 5, or 14 days after a 5-h phase delay, and the light-dark cycle was reinstated 14 days later. All hamsters exposed to DD on day 0 reentrained, whereas 42% reentrained irrespective of whether DD began 5 or 14 days later. For these latter two groups, tau (tau) and alpha (alpha) in DD predicted reentrainment; animals that reentrained had a mean tau and alpha of 24.1 and 8.9 h, respectively, whereas those that failed to reentrain maintained a mean tau and alpha of 25.0 and of 7.1 h, respectively. Restoration of entrainment by DD is somewhat paradoxical because it suggests that reentrainment to the photocycle was prevented by continued exposure to that same photocycle. The dichotomy of circadian responses to DD suggests "entrainment" phenotypes that are similar to those of photoperiodic responders and nonresponders.

  11. Monosodium glutamate-induced arcuate nucleus damage affects both natural torpor and 2DG-induced torpor-like hypothermia in Siberian hamsters.

    PubMed

    Pelz, Kimberly M; Routman, David; Driscoll, Joseph R; Kriegsfeld, Lance J; Dark, John

    2008-01-01

    Siberian hamsters (Phodopus sungorus) have the ability to express daily torpor and decrease their body temperature to approximately 15 degrees C, providing a significant savings in energy expenditure. Daily torpor in hamsters is cued by winterlike photoperiods and occurs coincident with the annual nadirs in body fat reserves and chronic leptin concentrations. To better understand the neural mechanisms underlying torpor, Siberian hamster pups were postnatally treated with saline or MSG to ablate arcuate nucleus neurons that likely possess leptin receptors. Body temperature was studied telemetrically in cold-acclimated (10 degrees C) male and female hamsters moved to a winterlike photoperiod (10:14-h light-dark cycle) (experiments 1 and 2) or that remained in a summerlike photoperiod (14:10-h light-dark cycle) (experiment 3). In experiment 1, even though other photoperiodic responses persisted, MSG-induced arcuate nucleus ablations prevented the photoperiod-dependent torpor observed in saline-treated Siberian hamsters. MSG-treated hamsters tended to possess greater fat reserves. To determine whether reductions in body fat would increase frequency of photoperiod-induced torpor after MSG treatment, hamsters underwent 2 wk of food restriction (70% of ad libitum) in experiment 2. Although food restriction did increase the frequency of torpor in both MSG- and saline-treated hamsters, it failed to normalize the proportion of MSG-treated hamsters undergoing photoperiod-dependent torpor. In experiment 3, postnatal MSG treatments reduced the proportion of hamsters entering 2DG-induced torpor-like hypothermia by approximately 50% compared with saline-treated hamsters (38 vs. 72%). In those MSG-treated hamsters that did become hypothermic, their minimum temperature during hypothermia was significantly greater than comparable saline-treated hamsters. We conclude that 1) arcuate nucleus mechanisms mediate photoperiod-induced torpor, 2) food-restriction-induced torpor may also be

  12. Early regulation of hypothalamic arcuate nucleus CART gene expression by short photoperiod in the Siberian hamster.

    PubMed

    Mercer, Julian G; Ellis, Claire; Moar, Kim M; Logie, Tracy J; Morgan, Peter J; Adam, Clare L

    2003-03-28

    Cocaine- and amphetamine-regulated transcript (CART) mRNA is expressed in a number of hypothalamic nuclei including the arcuate nucleus (ARC). An increase in CART gene expression in the ARC of juvenile female Siberian hamsters (Phodopus sungorus) 14 days after transfer to short photoperiod at weaning and prior to major divergence of body weight trajectory in this seasonal mammal implicates CART in the induction of programmed weight change. In the current series of experiments, elevated CART mRNA in short photoperiod juvenile female animals relative to long photoperiod controls was apparent throughout the caudal-rostral extent of the ARC after 14 days, but was not observed when short photoperiod exposure was limited to 4-7 days. Elevated CART gene expression was also observed in juvenile males 14 days after transfer to short photoperiod at weaning, in adult female hamsters 14 days after transfer to short photoperiod and in adult male hamsters 21 days after transfer to short photoperiod. There were no consistent trends in expression levels of other energy balance-related genes with these relatively short duration photoperiod manipulations, suggesting that CART may be involved in short photoperiod-programmed body weight regulation.

  13. Sustained hormonal responses of Siberian hamsters (Phodopus sungorus) to a single longer day at weaning.

    PubMed

    Whaling, C S; Kelly, K K; Finley, C M; Spears, N; Licht, P; Zucker, I

    1993-09-01

    Siberian hamsters undergo gonadal development for several weeks after exposure to a single longer day at weaning. To characterize changes in gonadotropin secretion after a single acute light stimulus, hamsters housed in a long photoperiod (16L:8D) were given a single longer day (20L:4D) or maintained in the 16L:8D photoperiod at 19 days of age and transferred to a short photoperiod (8L:16D) on Day 20. Elevated plasma FSH concentrations were detected in male hamsters at 5, 7, and 12 but not at 17 days after the single longer day. Melatonin treatment during light exposure and on two succeeding nights blocked the stimulatory effect of light on the reproductive axis; melatonin injections limited to one night were marginally effective. Pinealectomy during the dark phase of the photocycle and the resultant truncation of the melatonin signal for one night did not stimulate a greater degree of gonadal development than pinealectomy during the light phase. We conclude that the single extra 4-h light pulse at weaning alters hypothalamic-pituitary function for approximately 2 wk. Trophic effects of the light pulse appear to be mediated by suppression of melatonin secretion for several days; one truncate melatonin signal is not sufficient to simulate the effects of a single long day on the reproductive axis.

  14. Adaptation to short photoperiods augments circadian food anticipatory activity in Siberian hamsters

    PubMed Central

    Bradley, Sean P.; Prendergast, Brian J.

    2014-01-01

    Both the light-dark cycle and the timing of food intake can entrain circadian rhythms. Entrainment to food is mediated by a food entrainable circadian oscillator (FEO) that is formally and mechanistically separable from the hypothalamic light-entrainable oscillator. This experiment examined whether seasonal changes in day length affect the function of the FEO in male Siberian hamsters (Phodopus sungorus). Hamsters housed in long (LD; 15 h light/day) or short (SD; 9 h light/day) photoperiods were subjected to a timed-feeding schedule for 10 days, during which food was available only during a 5 h interval of the light phase. Running wheel activity occurring within a 3 h window immediately prior to actual or anticipated food delivery was operationally-defined as food anticipatory activity (FAA). After the timed-feeding interval, hamsters were fed ad libitum, and FAA was assessed 2 and 7 days later via probe trials of total food deprivation. During timed-feeding, all hamsters exhibited increases FAA, but FAA emerged more rapidly in SD; in probe trials, FAA was greater in magnitude and persistence in SD. Gonadectomy in LD did not induce the SD-like FAA phenotype, indicating that withdrawal of gonadal hormones is not sufficient to mediate the effects of photoperiod on FAA. Entrainment of the circadian system to light markedly affects the functional output of the FEO via gonadal hormone-independent mechanisms. Rapid emergence and persistent expression of FAA in SD may reflect a seasonal adaptation that directs behavior toward sources of nutrition with high temporal precision at times of year when food is scarce. PMID:24666779

  15. Adaptation to short photoperiods augments circadian food anticipatory activity in Siberian hamsters.

    PubMed

    Bradley, Sean P; Prendergast, Brian J

    2014-06-01

    This article is part of a Special Issue "Energy Balance". Both the light-dark cycle and the timing of food intake can entrain circadian rhythms. Entrainment to food is mediated by a food entrainable circadian oscillator (FEO) that is formally and mechanistically separable from the hypothalamic light-entrainable oscillator. This experiment examined whether seasonal changes in day length affect the function of the FEO in male Siberian hamsters (Phodopus sungorus). Hamsters housed in long (LD; 15 h light/day) or short (SD; 9h light/day) photoperiods were subjected to a timed-feeding schedule for 10 days, during which food was available only during a 5h interval of the light phase. Running wheel activity occurring within a 3h window immediately prior to actual or anticipated food delivery was operationally-defined as food anticipatory activity (FAA). After the timed-feeding interval, hamsters were fed ad libitum, and FAA was assessed 2 and 7 days later via probe trials of total food deprivation. During timed-feeding, all hamsters exhibited increases FAA, but FAA emerged more rapidly in SD; in probe trials, FAA was greater in magnitude and persistence in SD. Gonadectomy in LD did not induce the SD-like FAA phenotype, indicating that withdrawal of gonadal hormones is not sufficient to mediate the effects of photoperiod on FAA. Entrainment of the circadian system to light markedly affects the functional output of the FEO via gonadal hormone-independent mechanisms. Rapid emergence and persistent expression of FAA in SD may reflect a seasonal adaptation that directs behavior toward sources of nutrition with high temporal precision at times of year when food is scarce.

  16. Experimentally induced sickness decreases food intake, but not hoarding, in Siberian hamsters (Phodopus sungorus).

    PubMed

    Durazzo, Alfredo; Proud, Kevin; Demas, Gregory E

    2008-11-01

    A wide range of physiological and behavioral alterations occur in response to sickness. Sickness behaviors, rather than incidental by-products or side-effects of acute illness, serve as adaptive functional responses that allow animals to cope with a pathogenic challenge. Among the more salient sickness behaviors is a reduction in food intake; virtually all sick animals display marked decreases in this behavior. Food intake, however, is only one component of the food-related behavioral repertoire. For many mammalian species, food hoarding represents a substantial portion of the total energetic budget. Here we tested the effects of experimental sickness on food hoarding and food intake in a naturally food hoarding species, Siberian hamsters (Phodopus sungorus). Adult male and female hamsters received injections of lipopolysaccharide (LPS) to induce sickness or control injections. LPS-induced sickness resulted in a marked decrease in food intake in both males and females, but did not decrease hoarding in either sex. These results support previous findings suggesting that food hoarding and food intake appear to be differentially regulated at the physiological level.

  17. Identification, expression, and physiological functions of Siberian hamster gonadotropin-inhibitory hormone.

    PubMed

    Ubuka, Takayoshi; Inoue, Kazuhiko; Fukuda, Yujiro; Mizuno, Takanobu; Ukena, Kazuyoshi; Kriegsfeld, Lance J; Tsutsui, Kazuyoshi

    2012-01-01

    Gonadotropin-inhibitory hormone (GnIH) is a hypothalamic neuropeptide that inhibits gonadotropin secretion in birds and mammals. To further understand its physiological roles in mammalian reproduction, we identified its precursor cDNA and endogenous mature peptides in the Siberian hamster brain. The Siberian hamster GnIH precursor cDNA encoded two RFamide-related peptide (RFRP) sequences. SPAPANKVPHSAANLPLRF-NH(2) (Siberian hamster RFRP-1) and TLSRVPSLPQRF-NH(2) (Siberian hamster RFRP-3) were confirmed as mature endogenous peptides by mass spectrometry from brain samples purified by immunoaffinity chromatography. GnIH mRNA expression was higher in long days (LD) compared with short days (SD). GnIH mRNA was also highly expressed in SD plus pinealectomized animals, whereas expression was suppressed by melatonin, a nocturnal pineal hormone, administration. GnIH-immunoreactive (-ir) neurons were localized to the dorsomedial region of the hypothalamus, and GnIH-ir fibers projected to hypothalamic and limbic structures. The density of GnIH-ir perikarya and fibers were higher in LD and SD plus pinealectomized hamsters than in LD plus melatonin or SD animals. The percentage of GnRH neurons receiving close appositions from GnIH-ir fiber terminals was also higher in LD than SD, and GnIH receptor was expressed in GnRH-ir neurons. Finally, central administration of hamster RFRP-1 or RFRP-3 inhibited LH release 5 and 30 min after administration in LD. In sharp contrast, both peptides stimulated LH release 30 min after administration in SD. These results suggest that GnIH peptides fine tune LH levels via its receptor expressed in GnRH-ir neurons in an opposing fashion across the seasons in Siberian hamsters.

  18. Hypothalamic neuropeptide systems and anticipatory weight change in Siberian hamsters.

    PubMed

    Adam, C L; Mercer, J G

    2001-01-01

    Seasonal animals are able both to programme changes in body weight in response to annual changes in photoperiod (anticipatory regulation) and to correct changes in body weight caused by imposed energetic demand (compensatory regulation). Experimental evidence from the Siberian hamster suggests that seasonally appropriate body weight is continually reset according to photoperiodic history, even when actual body weight is driven away from this target weight by manipulation of energy intake. These characteristics constitute the "sliding set point" of seasonal body weight regulation. To define the mechanisms and molecules underlying anticipatory body weight regulation, we are investigating the involvement of hypothalamic systems with an established role in the compensatory defence of body weight. Weight loss or restricted growth induced by short days (SD) results in low circulating leptin compared with long day (LD) controls. However, this chronic low leptin signal is read differently from acute low leptin resulting from food deprivation; leptin receptor gene expression in the hypothalamic arcuate nucleus (ARC) is lower in SD, whereas food deprivation increases expression levels, suggesting changes in sensitivity to leptin feedback. SD alterations in mRNA levels for a number of hypothalamic neuropeptide and receptor genes appear counter-intuitive for a SD body weight trajectory. However, early increases in ARC cocaine-and amphetamine-regulated transcript (CART) gene expression in SDs could be involved in driving body weight loss or growth restriction. The sites of photoperiod interaction with energy balance neuronal circuitry and the neurochemical encoding of body weight set point require full characterisation. Study of anticipatory regulation in seasonal animals offers new insight into body weight regulation across mammalian species, including man.

  19. Skeletal bone morphology is resistant to the high amplitude seasonal leptin cycle in the Siberian hamster.

    PubMed

    Rousseau, K; Atcha, Z; Denton, J; Cagampang, F R A; Ennos, A R; Freemont, A J; Loudon, A S I

    2005-09-01

    Recent studies have suggested that the adipocyte-derived hormone, leptin, plays a role in the regulation of metabolism. Here, we tested this hypothesis in the seasonally breeding Siberian hamster, as this species exhibits profound seasonal changes in adiposity and circulating leptin concentrations driven by the annual photoperiodic cycle. Male hamsters were kept in either long (LD) or short (SD) photoperiods. Following exposure to short photoperiods for 8 weeks animals exhibited a significant weight-loss and a 16-fold reduction of serum leptin concentrations. At Week 9, animals in both photoperiods were infused with leptin or PBS via osmotic mini-pump for 14 days. Chronic leptin infusion mimicked LD-like concentrations in SD-housed animals and caused a further decline in body weight and adipose tissue. In LD-housed animals, leptin infusion resulted in a significant elevation of serum concentrations above natural LD-like levels, but had no discernable effect on body weight or overall adiposity. Both bending and compression characteristics and histomorphometric measurements of trabecular bone mass were unaltered by leptin treatment or photoperiod. Our data therefore show that despite a high natural amplitude cycle of leptin, this hormone has no apparent role in the regulation of bone metabolism, and therefore do not support recent propositions that this hormone is an important component in the metabolism of bone tissue.

  20. Evidence that the circadian system mediates photoperiodic nonresponsiveness in Siberian hamsters: the effect of running wheel access on photoperiodic responsiveness.

    PubMed

    Freeman, D A; Goldman, B D

    1997-04-01

    Juvenile male Siberian hamsters from a line of hamsters selected for nonresponsiveness to short photoperiod (PNRj) and animals from the general colony (UNS) were separated at weaning into two groups. Group 1 males were moved into short days (10 h light:14 h dark [10L:14D]) with free access to running wheels (RW). Group 2 animals were the male siblings of Group 1 hamsters; they were moved at the same time into the same room, but were housed in cages without access to RW. Group 2 hamsters only had access to RW for the final week of short-day exposure (Week 8). Animals were blood sampled at the time of sacrifice for analysis of serum prolactin (PRL) and follicle-stimulating hormone (FSH) concentrations. At sacrifice, paired testis weights were obtained and pelage color was scored. Animals from the UNS line showed the expected declines in testis weight, body weight, and serum concentrations of both PRL and FSH, regardless of the presence or absence of RW. These animals also exhibited a high proportion of individuals molting to winter-type pelage. By contrast, a marked difference was noted between siblings from the PNRj line depending on whether RW access was provided at the time of weaning. Animals with access to RW exhibited identical responses to those of the UNS responder animals, whereas PNRj animals without access to RW showed no adjustments to short days (i.e., testis regression, pelage molt, expansion of alpha). In a second experiment, PNRj and UNS males were placed in constant darkness (DD), with or without RW access. The results of this experiment indicated that PNRj animals respond to DD regardless of the presence or absence of RW. In DD, PNRj hamsters also exhibited significantly longer free-running period lengths (taus) than did UNS hamsters; all the PNRj hamsters had taus > 24 h, whereas none of the UNS hamsters had a tau > 24 h. These results indicate that PNRj hamsters retain the proper neural pathways for responding to short day lengths and establish a

  1. Early photoperiod history and short-day responsiveness in Siberian hamsters.

    PubMed

    Goldman, Sharry L; Goldman, Bruce D

    2003-03-01

    Siberian hamsters exhibit seasonal, photoperiod influenced cycles of reproductive activity, body size, pelage characteristics, and thermoregulatory behavior. Laboratory populations generally exhibit inter-individual variability in expression of photoperiod responsiveness, with a subset of individuals that fail to show the species typical responses to short photoperiod. This variability is partly explained by a genetic component, as it has been possible to increase the number of short-day nonresponders by artificial selection. Responsiveness to short photoperiod is also substantially influenced by photoperiod history in this species; hamsters that have been raised under long (16L) or very long (18L) day lengths are less likely to exhibit winter-type responses to short days as compared to hamsters raised under an intermediate (14L) day length. In the present experiment, we examined effects of age and early photoperiod history in a strain of Siberian hamsters that had been selected for short-day nonresponsiveness. Hamsters transferred into short photoperiod on the day of birth were uniform in exhibiting winter-type responses. However, hamsters raised until 25 days of age in either continuous illumination or in 16L exhibited variation in responsiveness when subsequently moved into short photoperiod. We conclude that virtually all hamsters of the short-day nonresponsive strain are born responsive to short days. Subsequent development of resistance to potential short day effects is dependent on age and/or photoperiod history.

  2. Neuropeptides and anticipatory changes in behaviour and physiology: seasonal body weight regulation in the Siberian hamster.

    PubMed

    Mercer, Julian G; Tups, Alexander

    2003-11-01

    The Siberian hamster, Phodopus sungorus, is a powerful model of physiological body weight regulation. This seasonal model offers the potential to distinguish between the compensatory neuroendocrine systems that defend body weight against imposed negative energy balance, and those that are involved in the programming of the level of body weight that will be defended-a seasonally appropriate body weight. Of the known, studied, components of the hypothalamic energy balance system, the anorexogenic peptide, cocaine- and amphetamine-regulated transcript (CART), is the only candidate where gene expression changes in a manner consistent with a role in initiating or sustaining photoperiod-induced differences in body weight trajectory. Siberian hamsters effect a reversible biannual switch in leptin sensitivity in which only short day (SD)-acclimated hamsters that have undergone a reduction in body weight, adiposity and plasma leptin are sensitive to peripheral exogenous leptin. The suppressor of cytokine signalling protein, SOCS3, appears to be the molecular correlate of this seasonal sensitivity.

  3. Cholecystokinin-33 acutely attenuates food foraging, hoarding and intake in Siberian hamsters.

    PubMed

    Teubner, Brett J W; Bartness, Timothy J

    2010-04-01

    Neurochemicals that stimulate food foraging and hoarding in Siberian hamsters are becoming more apparent, but we do not know if cessation of these behaviors is due to waning of excitatory stimuli and/or the advent of inhibitory factors. Cholecystokinin (CCK) may be such an inhibitory factor as it is the prototypic gastrointestinal satiety peptide and is physiologically important in decreasing food intake in several species including Siberian hamsters. Systemic injection of CCK-33 in laboratory rats decreases food intake, doing so to a greater extent than CCK-8. We found minimal effects of CCK-8 on food foraging and hoarding previously in Siberian hamsters, but have not tested CCK-33. Therefore, we asked: Does CCK-33 decrease normal levels or food deprivation-induced increases in food foraging, hoarding and intake? Hamsters were housed in a wheel running-based foraging system with simulated burrows to test the effects of peripheral injections of CCK-33 (13.2, 26.4, or 52.8 microg/kg body mass), with or without a preceding 56 h food deprivation. The highest dose of CCK-33 caused large baseline reductions in all three behaviors for the 1st hour post-injection compared with saline; in addition, the intermediate CCK-33 dose was sufficient to curtail food intake and foraging during the 1st hour. In food-deprived hamsters, we used a 52.8 microg/kg body mass dose of CCK-33 which decreased food intake, hoarding, and foraging almost completely compared with saline controls for 1h. Therefore, CCK-33 appears to be a potent inhibitor of food intake, hoarding, and foraging in Siberian hamsters.

  4. Co-infection of the Siberian hamster (Phodopus sungorus) with a novel Helicobacter sp. and Campylobacter sp.

    PubMed

    Nagamine, Claude M; Shen, Zeli; Luong, Richard H; McKeon, Gabriel P; Ruby, Norman F; Fox, James G

    2015-05-01

    We report the isolation of a novel helicobacter isolated from the caecum of the Siberian hamster (Phodopus sungorus). Sequence analysis showed 97% sequence similarity to Helicobacter ganmani. In addition, we report the co-infection of these Siberian hamsters with a Campylobacter sp. and a second Helicobacter sp. with 99% sequence similarity to Helicobacter sp. flexispira taxon 8 (Helicobacter bilis), a species isolated previously from patients with bacteraemia. Gross necropsy and histopathology did not reveal any overt pathological lesions of the liver and gastrointestinal tract that could be attributed to the Helicobacter or Campylobacter spp. infections. This is the first helicobacter to be identified in the Siberian hamster and the first report of co-infection of Helicobacter spp. and Campylobacter sp. in asymptomatic Siberian hamsters. PMID:25752854

  5. Co-infection of the Siberian hamster (Phodopus sungorus) with a novel Helicobacter sp. and Campylobacter sp.

    PubMed Central

    Shen, Zeli; Luong, Richard H.; McKeon, Gabriel P.; Ruby, Norman F.; Fox, James G.

    2015-01-01

    We report the isolation of a novel helicobacter isolated from the caecum of the Siberian hamster (Phodopus sungorus). Sequence analysis showed 97 % sequence similarity to Helicobacter ganmani. In addition, we report the co-infection of these Siberian hamsters with a Campylobacter sp. and a second Helicobacter sp. with 99 % sequence similarity to Helicobacter sp. flexispira taxon 8 (Helicobacter bilis), a species isolated previously from patients with bacteraemia. Gross necropsy and histopathology did not reveal any overt pathological lesions of the liver and gastrointestinal tract that could be attributed to the Helicobacter or Campylobacter spp. infections. This is the first helicobacter to be identified in the Siberian hamster and the first report of co-infection of Helicobacter spp. and Campylobacter sp. in asymptomatic Siberian hamsters. PMID:25752854

  6. Co-infection of the Siberian hamster (Phodopus sungorus) with a novel Helicobacter sp. and Campylobacter sp.

    PubMed

    Nagamine, Claude M; Shen, Zeli; Luong, Richard H; McKeon, Gabriel P; Ruby, Norman F; Fox, James G

    2015-05-01

    We report the isolation of a novel helicobacter isolated from the caecum of the Siberian hamster (Phodopus sungorus). Sequence analysis showed 97% sequence similarity to Helicobacter ganmani. In addition, we report the co-infection of these Siberian hamsters with a Campylobacter sp. and a second Helicobacter sp. with 99% sequence similarity to Helicobacter sp. flexispira taxon 8 (Helicobacter bilis), a species isolated previously from patients with bacteraemia. Gross necropsy and histopathology did not reveal any overt pathological lesions of the liver and gastrointestinal tract that could be attributed to the Helicobacter or Campylobacter spp. infections. This is the first helicobacter to be identified in the Siberian hamster and the first report of co-infection of Helicobacter spp. and Campylobacter sp. in asymptomatic Siberian hamsters.

  7. Diet affects resting, but not basal metabolic rate of normothermic Siberian hamsters acclimated to winter.

    PubMed

    Gutowski, Jakub P; Wojciechowski, Michał S; Jefimow, Małgorzata

    2011-12-01

    We examined the effect of different dietary supplements on seasonal changes in body mass (m(b)), metabolic rate (MR) and nonshivering thermogenesis (NST) capacity in normothermic Siberian hamsters housed under semi-natural conditions. Once a week standard hamster food was supplemented with either sunflower and flax seeds, rich in polyunsaturated fatty acids (FA), or mealworms, rich in saturated and monounsaturated FA. We found that neither of these dietary supplements affected the hamsters' normal winter decrease in m(b) and fat content nor their basal MR or NST capacity. NST capacity of summer-acclimated hamsters was lower than that of winter-acclimated ones. The composition of total body fat reflected the fat composition of the dietary supplements. Resting MR below the lower critical temperature of the hamsters, and their total serum cholesterol concentration were lower in hamsters fed a diet supplemented with mealworms than in hamsters fed a diet supplemented with seeds. These results indicate that in mealworm-fed hamsters energy expenditure in the cold is lower than in animals eating a seed-supplemented diet, and that the degree of FA unsaturation of diet affects energetics of heterotherms, not only during torpor, but also during normothermy.

  8. Decrease of food intake by MC4-R agonist MTII in Siberian hamsters in long and short photoperiods.

    PubMed

    Schuhler, Sandrine; Horan, Tracey L; Hastings, Michael H; Mercer, Julian G; Morgan, Peter J; Ebling, Francis J P

    2003-01-01

    We investigated the role of the hypothalamic melanocortin system in the regulation of food intake in the Siberian hamster, which shows a profound seasonal decrease in food intake and body weight in short photoperiod (SP). In male hamsters maintained in long photoperiod (LP), intracerebroventricular injection of melanotan II (MTII) just before lights off significantly decreased food intake relative to vehicle treatment over the 6-h observation period. Similar effects were observed in age-matched hamsters after exposure to a short daylength for 9 wk, when body weight had significantly decreased. There was no clear difference in either the magnitude of response or the dose required for half-maximal inhibition of food intake in hamsters in SP compared with those in LP. MTII significantly increased grooming in both LP and SP. Our results indicate that the melanocortin system is a potent short-term regulator of food intake. However, the lack of differential response or sensitivity to MTII treatment in the obese (LP) vs. lean (SP) states does not support the hypothesis that changes in this melanocortin pathway underlie the long-term decrease in food intake that occurs in this seasonal model.

  9. Leptin mediates seasonal variation in some but not all symptoms of sickness in Siberian hamsters.

    PubMed

    Carlton, Elizabeth D; Demas, Gregory E

    2014-11-01

    Many seasonally breeding species, including Siberian hamsters (Phodopus sungorus), exhibit seasonal variation in sickness responses. One hypothesis regarding the mechanism of this variation is that sickness intensity tracks an animal's energetic state, such that sickness is attenuated in the season that an animal has the lowest fat stores. Energetic state may be signaled via leptin, an adipose hormone that provides a signal of fat stores. Siberian hamsters respond to extended housing in short, winter-like days by reducing fat stores and leptin levels, relative to those housed in long, summer-like days. Sickness responses are also attenuated in short-day hamsters as compared to long-day hamsters. We hypothesized that leptin provides a physiological signal by which seasonally breeding animals modulate sickness responses, such that animals with higher leptin levels show increased sickness intensity. To test this, we provided short-day hamsters with a long-day-like leptin signal and assessed their responses to lipopolysaccharide (LPS), a sickness-inducing antigen. We compared these responses to short-day vehicle-, long-day vehicle-, and long-day leptin-treated hamsters. Unexpectedly, LPS induced a hypothermic response (rather than fever) in all groups. Short-day vehicle-treated hamsters exhibited the greatest LPS-induced hypothermia, and leptin treatment attenuated this response, making hypothermia more long-day-like. Contrary to our hypothesis, short-day leptin-treated hamsters showed the least pronounced LPS-induced anorexia among all groups. These results suggest that leptin may mediate some but not all aspects of seasonal sickness variation in this species. Future studies should be targeted at determining roles of other energetic hormones in regulating seasonal sickness response variation.

  10. Leptin mediates seasonal variation in some but not all symptoms of sickness in Siberian hamsters

    PubMed Central

    Carlton, Elizabeth D.; Demas, Gregory E.

    2014-01-01

    Many seasonally breeding species, including Siberian hamsters (Phodopus sungorus), exhibit seasonal variation in sickness responses. One hypothesis regarding the mechanism of this variation is that sickness intensity tracks an animal's energetic state, such that sickness is attenuated in the season that an animal has the lowest fat stores. Energetic state may be signaled via leptin, an adipose hormone that provides a signal of fat stores. Siberian hamsters respond to extended housing in short, winter-like days by reducing fat stores and leptin levels, relative to those housed in long, summer-like days. Sickness responses are also attenuated in short-day hamsters as compared to long-day hamsters. We hypothesized that leptin provides a physiological signal by which seasonally breeding animals modulate sickness responses, such that animals with higher leptin levels show increased sickness intensity. To test this, we provided short-day hamsters with a long-day-like leptin signal and assessed their responses to lipopolysaccharide (LPS), a sickness-inducing antigen. We compared these responses to short-day vehicle-, long-day vehicle-, and long-day leptin-treated hamsters. Unexpectedly, LPS induced a hypothermic response (rather than fever) in all groups. Short-day vehicle-treated hamsters exhibited the greatest LPS-induced hypothermia, and leptin treatment attenuated this response, making hypothermia more long-day-like. Contrary to our hypothesis, short-day leptin-treated hamsters showed the least pronounced LPS-induced anorexia among all groups. These results suggest that leptin may mediate some but not all aspects of seasonal sickness variation in this species. Future studies should be targeted at determining roles of other energetic hormones in regulating seasonal sickness response variation. PMID:25461974

  11. Asymmetric learning to avoid heterospecific males in Mesocricetus hamsters.

    PubMed

    delBarco-Trillo, Javier; Johnston, Robert E

    2012-08-01

    If a female mates with a male of a closely related species, her fitness is likely to decline. Consequently, females may develop behavioral mechanisms to avoid mating with heterospecific males. In some species, one such mechanism is for adult females to learn to discriminate against heterospecific males after exposure to such males. We have previously shown that adult, female Syrian hamsters (Mesocricetus auratus) learn to discriminate against male Turkish hamsters (Mesocricetus brandti) after exposure to a single heterospecific male during 8 days across a wire-mesh barrier. Here we repeated that experiment but this time we exposed female Turkish hamsters to a male Syrian hamster for 8 days and then measured sexual and aggressive behaviors towards that heterospecific male and towards a conspecific male. In contrast to female Syrian hamsters, female Turkish hamsters did not differ in their latency to go into lordosis or in any measure of aggression towards either type of male. Female Turkish hamsters spent less time in lordosis with the heterospecific male, but the percentage of trials in which females copulated with conspecific and heterospecific males did not differ. When comparing females from both species that had been exposed to a heterospecific male for 8days, female Syrian hamsters copulated less and were more aggressive towards the heterospecific male compared to the behavior of female Turkish hamsters. We discuss how this asymmetric response between females of the two species may be due to the much larger geographical range of Turkish hamsters compared to Syrian hamsters.

  12. Photoperiodic changes in endocannabinoid levels and energetic responses to altered signalling at CB1 receptors in Siberian hamsters.

    PubMed

    Ho, J M; Smith, N S; Adams, S A; Bradshaw, H B; Demas, G E

    2012-07-01

    Siberian hamsters (Phodopus sungorus) adapt to seasonal environmental conditions with marked changes in body mass, primarily in the form of adiposity. Winter-like conditions (e.g. short days) are sufficient to decrease body mass by approximately 30% in part via reductions in food intake. The neuroendocrine mechanisms responsible for these changes are not well understood, and homeostatic orexigenic/anorexigenic systems of the hypothalamus provide little explanation. We investigated the potential role of endocannabinoids, which are known modulators of appetite and metabolism, in mediating seasonal changes in energy balance. Specifically, we housed hamsters in long or short days for 0, 3, or 9 weeks and measured endocannabinoid levels in the hypothalamus, brainstem, liver and retroperitoneal white adipose tissue (RWAT). An additional group of males housed in short days for 25 weeks were also compared with long-day controls. Following 9 weeks in short days, levels of the endocannabinoid 2-arachidonoylglycerol (2-AG) were significantly elevated in RWAT and reduced in brainstem, although they returned to long-day levels by week 25 in short-day males that had cycled back to summer-like energy balance. Endocannabinoid levels in these tissues correlated significantly with adiposity and change in body mass. No photoperiodic changes were observed in the hypothalamus or liver; however, sex differences in 2-AG levels were found in the liver (males > females). We further tested the effects of CB(1) receptor signalling on ingestive behaviour. Five daily injections of CB(1) antagonist SR141716 significantly reduced food intake and body mass but not food hoarding. Although the CB(1) agonist arachidonyl-2-chloroethylamide did not appreciably affect either ingestive behaviour, body mass was significantly elevated following 2 days of injections. Taken altogether, these findings demonstrate that endocannabinoid levels vary with sex and photoperiod in a site-specific manner, and that

  13. Dim light at night disrupts the short-day response in Siberian hamsters.

    PubMed

    Ikeno, Tomoko; Weil, Zachary M; Nelson, Randy J

    2014-02-01

    Photoperiodic regulation of physiology, morphology, and behavior is crucial for many animals to survive seasonally variable conditions unfavorable for reproduction and survival. The photoperiodic response in mammals is mediated by nocturnal secretion of melatonin under the control of a circadian clock. However, artificial light at night caused by recent urbanization may disrupt the circadian clock, as well as the photoperiodic response by blunting melatonin secretion. Here we examined the effect of dim light at night (dLAN) (5lux of light during the dark phase) on locomotor activity rhythms and short-day regulation of reproduction, body mass, pelage properties, and immune responses of male Siberian hamsters. Short-day animals reduced gonadal and body mass, decreased spermatid nuclei and sperm numbers, molted to a whiter pelage, and increased pelage density compared to long-day animals. However, animals that experienced short days with dLAN did not show these short-day responses. Moreover, short-day specific immune responses were altered in dLAN conditions. The nocturnal activity pattern was blunted in dLAN hamsters, consistent with the observation that dLAN changed expression of the circadian clock gene, Period1. In addition, we demonstrated that expression levels of genes implicated in the photoperiodic response, Mel-1a melatonin receptor, Eyes absent 3, thyroid stimulating hormone receptor, gonadotropin-releasing hormone, and gonadotropin-inhibitory hormone, were higher in dLAN animals than those in short-day animals. These results suggest that dLAN disturbs the circadian clock function and affects the molecular mechanisms of the photoperiodic response.

  14. Environmental induction of photononresponsiveness in the Siberian hamster, Phodopus sungorus.

    PubMed

    Gorman, M R; Zucker, I

    1997-03-01

    In seasonally breeding rodent species, a fraction of the population is unresponsive to short day lengths (DL) and remains reproductively competent during winter. We previously observed that incidence of nonresponsiveness to short days was affected by photoperiodic history. Here we tested whether exposure to long DL (18 h light/day; 18L) renders animals unresponsive to short DL (10L). Hamsters, maintained from birth in 10L, were transferred at week 6 to 18L or 14L. Ten weeks later (week 16), groups were transferred to 10L for 10 wk. All hamsters maintained in short DL from birth had undeveloped testes at week 6. At week 26, however, 92% of hamsters previously kept in 18L failed to undergo complete gonadal regression in 10L, compared with only 10% of hamsters previously in 14L. Entrainment of locomotor activity in 10L in nonresponsive hamsters resembled that typically observed under long DL. Exposure to 18L may induce nonresponsiveness by altering interactions of component circadian oscillators that mediate gonadal regression in short DL.

  15. Pineal-dependent and -independent effects of photoperiod on immune function in Siberian hamsters (Phodopus sungorus)

    PubMed Central

    Wen, Jarvi C.; Dhabhar, Firdaus S.; Prendergast, Brian J.

    2010-01-01

    Siberian hamsters (Phodopus sungorus) exhibit reproductive and immunological responses to photoperiod. Short (<10-h light/day) days induce gonadal atrophy, increase leukocyte concentrations, and attenuate thermoregulatory and behavioral responses to infection. Whereas hamster reproductive responses to photoperiod are dependent on pineal melatonin secretion, the role of the pineal in short-day induced changes in immune function is not fully understood. To examine this, adult hamsters were pinealectomized (PINx) or sham-PINx, and transferred to short days (9-h light/day; SD) or kept in their natal long-day (15-h light/day; LD) photoperiod. Intact and PINx hamsters housed in LD maintained large testes over the next 12 weeks; sham-PINx hamsters exhibited gonadal regression in SD, and PINx abolished this effect. Among pineal-intact hamsters, blood samples revealed increases in leukocyte, lymphocyte, CD62L+ lymphocyte, and T cell counts in SD relative to LD; PINx did not affect leukocyte numbers in LD hamsters, but abolished the SD increase in these measures. Hamsters were then treated with bacterial lipopolysaccharide (LPS), which induced thermoregulatory (fever), behavioral (anorexia, reductions in nest building), and somatic (weight loss) sickness responses in all groups. Among pineal-intact hamsters, febrile and behavioral responses to LPS were attenuated in SD relative to LD. PINx did not affect sickness responses to LPS in LD hamsters, but abolished the ameliorating effects of SD on behavioral responses to LPS. Surprisingly, PINx failed to abolish the effect of SD on fever. In common with the reproductive system, PINx induces the LD phenotype in most aspects of the immune system. The pineal gland is required for photoperiodic regulation of circulating leukocytes and neural-immune interactions that mediate select aspects of sickness behaviors. PMID:17022983

  16. Maternal pinealectomy increases depressive-like responses in Siberian hamster offspring.

    PubMed

    Workman, Joanna L; Weil, Zachary M; Tuthill, Christiana R; Nelson, Randy J

    2008-06-01

    This study investigated the effect of maternal pinealectomy and postnatal pinealectomy on affective responses. Siberian hamsters were born to either pinealectomized or sham-operated dams and then underwent pinealectomy or a sham operation. Maternal pinealectomy increased depressive-like responses of offspring in the forced swim test. Maternal pinealectomy increased rearing behaviour and postnatal pinealectomy increased locomotor behaviour in the open field test. These results suggest that prenatal melatonin organizes adult affective responses.

  17. Orchestration of gene expression across the seasons: Hypothalamic gene expression in natural photoperiod throughout the year in the Siberian hamster

    PubMed Central

    Petri, Ines; Diedrich, Victoria; Wilson, Dana; Fernández-Calleja, José; Herwig, Annika; Steinlechner, Stephan; Barrett, Perry

    2016-01-01

    In nature Siberian hamsters utilize the decrement in day length following the summer solstice to implement physiological adaptations in anticipation of the forthcoming winter, but also exploit an intrinsic interval timer to initiate physiological recrudescence following the winter solstice. However, information is lacking on the temporal dynamics in natural photoperiod of photoperiodically regulated genes and their relationship to physiological adaptations. To address this, male Siberian hamsters born and maintained outdoors were sampled every month over the course of one year. As key elements of the response to photoperiod, thyroid hormone signalling components were assessed in the hypothalamus. From maximum around the summer solstice (late-June), Dio2 expression rapidly declined in advance of physiological adaptations. This was followed by a rapid increase in Mct8 expression (T3/T4 transport), peaking early-September before gradually declining to minimum expression by the following June. Dio3 showed a transient peak of expression beginning late-August. A recrudescence of testes and body mass occurred from mid-February, but Dio2 expression remained low until late-April of the following year, converging with the time of year when responsiveness to short-day length is re-established. Other photoperiodically regulated genes show temporal regulation, but of note is a transient peak in Gpr50 around late-July. PMID:27406810

  18. Acute melatonin treatment alters dendritic morphology and circadian clock gene expression in the hippocampus of Siberian hamsters.

    PubMed

    Ikeno, Tomoko; Nelson, Randy J

    2015-02-01

    In the hippocampus of Siberian hamsters, dendritic length and dendritic complexity increase in the CA1 region whereas dendritic spine density decreases in the dentate gyrus region at night. However, the underlying mechanism of the diurnal rhythmicity in hippocampal neuronal remodeling is unknown. In mammals, most daily rhythms in physiology and behaviors are regulated by a network of circadian clocks. The central clock, located in the hypothalamus, controls melatonin secretion at night and melatonin modifies peripheral clocks by altering expression of circadian clock genes. In this study, we examined the effects of acute melatonin treatment on the circadian clock system as well as on morphological changes of hippocampal neurons. Male Siberian hamsters were injected with melatonin in the afternoon; 4 h later, mRNA levels of hypothalamic and hippocampal circadian clock genes and hippocampal neuron dendritic morphology were assessed. In the hypothalamus, melatonin treatment did not alter Period1 and Bmal1 expression. However, melatonin treatment increased both Period1 and Bmal1 expression in the hippocampus, suggesting that melatonin affected molecular oscillations in the hippocampus. Melatonin treatment also induced rapid remodeling of hippocampal neurons; melatonin increased apical dendritic length and dendritic complexity in the CA1 region and reduced the dendritic spine density in the dentate gyrus region. These data suggest that structural changes in hippocampal neurons are regulated by a circadian clock and that melatonin functions as a nighttime signal to coordinate the diurnal rhythm in neuronal remodeling.

  19. Orchestration of gene expression across the seasons: Hypothalamic gene expression in natural photoperiod throughout the year in the Siberian hamster.

    PubMed

    Petri, Ines; Diedrich, Victoria; Wilson, Dana; Fernández-Calleja, José; Herwig, Annika; Steinlechner, Stephan; Barrett, Perry

    2016-07-11

    In nature Siberian hamsters utilize the decrement in day length following the summer solstice to implement physiological adaptations in anticipation of the forthcoming winter, but also exploit an intrinsic interval timer to initiate physiological recrudescence following the winter solstice. However, information is lacking on the temporal dynamics in natural photoperiod of photoperiodically regulated genes and their relationship to physiological adaptations. To address this, male Siberian hamsters born and maintained outdoors were sampled every month over the course of one year. As key elements of the response to photoperiod, thyroid hormone signalling components were assessed in the hypothalamus. From maximum around the summer solstice (late-June), Dio2 expression rapidly declined in advance of physiological adaptations. This was followed by a rapid increase in Mct8 expression (T3/T4 transport), peaking early-September before gradually declining to minimum expression by the following June. Dio3 showed a transient peak of expression beginning late-August. A recrudescence of testes and body mass occurred from mid-February, but Dio2 expression remained low until late-April of the following year, converging with the time of year when responsiveness to short-day length is re-established. Other photoperiodically regulated genes show temporal regulation, but of note is a transient peak in Gpr50 around late-July.

  20. Orchestration of gene expression across the seasons: Hypothalamic gene expression in natural photoperiod throughout the year in the Siberian hamster.

    PubMed

    Petri, Ines; Diedrich, Victoria; Wilson, Dana; Fernández-Calleja, José; Herwig, Annika; Steinlechner, Stephan; Barrett, Perry

    2016-01-01

    In nature Siberian hamsters utilize the decrement in day length following the summer solstice to implement physiological adaptations in anticipation of the forthcoming winter, but also exploit an intrinsic interval timer to initiate physiological recrudescence following the winter solstice. However, information is lacking on the temporal dynamics in natural photoperiod of photoperiodically regulated genes and their relationship to physiological adaptations. To address this, male Siberian hamsters born and maintained outdoors were sampled every month over the course of one year. As key elements of the response to photoperiod, thyroid hormone signalling components were assessed in the hypothalamus. From maximum around the summer solstice (late-June), Dio2 expression rapidly declined in advance of physiological adaptations. This was followed by a rapid increase in Mct8 expression (T3/T4 transport), peaking early-September before gradually declining to minimum expression by the following June. Dio3 showed a transient peak of expression beginning late-August. A recrudescence of testes and body mass occurred from mid-February, but Dio2 expression remained low until late-April of the following year, converging with the time of year when responsiveness to short-day length is re-established. Other photoperiodically regulated genes show temporal regulation, but of note is a transient peak in Gpr50 around late-July. PMID:27406810

  1. Individual differences in circadian waveform of Siberian hamsters under multiple lighting conditions.

    PubMed

    Evans, Jennifer A; Elliott, Jeffrey A; Gorman, Michael R

    2012-10-01

    Because the circadian clock in the mammalian brain derives from a network of interacting cellular oscillators, characterizing the nature and bases of circadian coupling is fundamental to understanding how the pacemaker operates. Various phenomena involving plasticity in circadian waveform have been theorized to reflect changes in oscillator coupling; however, it remains unclear whether these different behavioral paradigms reference a unitary underlying process. To test whether disparate coupling assays index a common mechanism, we examined whether there is covariation among behavioral responses to various lighting conditions that produce changes in circadian waveform. Siberian hamsters, Phodopus sungorus, were transferred from long to short photoperiods to distinguish short photoperiod responders (SP-R) from nonresponders (SP-NR). Short photoperiod chronotyped hamsters were subsequently transferred, along with unselected controls, to 24-h light:dark:light: dark cycles (LDLD) with dim nighttime illumination, a procedure that induces bifurcated entrainment. Under LDLD, SP-R hamsters were more likely to bifurcate their rhythms than were SP-NR hamsters or unselected controls. After transfer from LDLD to constant dim light, SP-R hamsters were also more likely to become arrhythmic compared to SP-NR hamsters and unselected controls. In contrast, short photoperiod chronotype did not influence more transient changes in circadian waveform. The present data reveal a clear relationship in the plasticity of circadian waveform across 3 distinct lighting conditions, suggesting a common mechanism wherein individual differences reflect variation in circadian coupling.

  2. Feeding schedule controls circadian timing of daily torpor in SCN-ablated Siberian hamsters.

    PubMed

    Paul, Matthew J; Kauffman, Alexander S; Zucker, Irving

    2004-06-01

    Timing of daily torpor was assessed in suprachiasmatic nucleus-ablated (SCNx) and sham-ablated Siberian hamsters fed restricted amounts of food each day either in the light or dark phase of a 14:10 light-dark cycle. Eighty-five percent of sham-ablated and 45% of SCNx hamsters displayed a preferred hour for torpor onset. In each group, time of torpor onset was not random but occurred at a mean hour that differed significantly from chance. Time of food presentation almost completely accounted for the timing of torpor onset in SCNx animals and significantly affected timing of this behavior in intact hamsters. These results suggest that the circadian pacemaker in the SCN controls the time of torpor onset indirectly by affecting timing of food intake, rather than by, or in addition to, direct neural and humoral outputs to relevant target tissues.

  3. Differential expression of matrix metalloproteinases during stimulated ovarian recrudescence in Siberian hamsters (Phodopus sungorus).

    PubMed

    Salverson, Trevor J; McMichael, Greer E; Sury, Jonathan J; Shahed, Asha; Young, Kelly A

    2008-02-01

    The matrix metalloproteinases (MMPs) are a family of extracellular matrix-cleaving enzymes involved in ovarian remodeling. In many non-tropical species, including Siberian hamsters, ovarian remodeling is necessary for the functional changes associated with seasonal reproduction. We evaluated MMPs and their endogenous inhibitors (TIMPs), during photoperiod-induced ovarian recrudescence in Siberian hamsters. Hamsters were transferred from long day (LD; 16:8) to short day (SD; 8:16) photoperiods for 14weeks, and then returned to LD for 0, 1, 2, 4, or 8weeks for collection of ovaries and plasma. Post-transfer (PT) LD exposure increased body and ovarian mass. Number of corpora lutea and antral, but not preantral follicles increased in PT groups. Plasma estradiol concentrations were lower in PT weeks 0-4, and returned to LD levels at PT week 8. No change was observed in relative MMP/TIMP mRNA levels at PT week 0 (SD week 14) as compared to LD. Photostimulation increased MMP-2 mRNA at PT week 8 as compared to PT weeks 0-1. MMP-14 mRNA expression peaked at PT weeks 1-2 as compared to LD levels, while MMP-13 expression was low during this time. TIMP-1 mRNA peaked at PT week 8 as compared to PT weeks 0-4. No changes were noted in MMP-9 and TIMP-2 mRNA expression. In general, MMP/TIMP protein immunodetection followed the same patterns with most staining occurring in granulosa cells of follicles and corpora lutea. Our data suggest that mRNA and protein for several members of the MMP/TIMP families are expressed in Siberian hamster ovaries during recrudescence. Because of the variation observed in expression patterns, MMPs and TIMPs may be differentially involved with photostimulated return to ovarian function.

  4. Timing of Maternal Immunization Affects Immunological and Behavioral Outcomes of Adult Offspring in Siberian Hamsters (Phodopus sungorus).

    PubMed

    French, Susannah S; Chester, Emily M; Demas, Gregory E

    2016-07-01

    Maternal influences are an important contributing factor to offspring survival, development, and behavior. Common environmental pathogens can induce maternal immune responses and affect subsequent development of offspring. There are likely sensitive periods during pregnancy when animals are particularly vulnerable to environmental disruption. Here we characterize the effects of maternal immunization across pregnancy and postpartum on offspring physiology and behavior in Siberian hamsters (Phodopus sungorus). Hamsters were injected with the antigen keyhole limpet hemocyanin (KLH) (1) prior to pairing with a male (premating), (2) at separation (postmating), (3) at midpregnancy, or (4) after birth (lactation). Maternal food intake, body mass, and immunity were monitored throughout gestation, and litters were measured weekly for growth until adulthood when social behavior, hormone concentrations, and immune responses were determined. We found that immunizations altered maternal immunity throughout pregnancy and lactation. The effects of maternal treatment differed between male and female offspring. Aggressive behavior was enhanced in offspring of both sexes born to mothers treated postmating and thus early in pregnancy relative to other stages. In contrast, maternal treatment and maternal stage differentially affected innate immunity in males and females. Offspring cortisol, however, was unaffected by maternal treatment. Collectively, these data demonstrate that maternal immunization affects offspring physiology and behavior in a time-dependent and sex-specific manner. More broadly, these findings contribute to our understanding of the effects of maternal immune activation, whether it be from environmental exposure or immunization, on immunological and behavioral responses of offspring. PMID:27320639

  5. Skeleton photoperiods alter delayed-type hypersensitivity responses and reproductive function of Siberian hamsters (Phodopus sungorus).

    PubMed

    Gatien, M L; Hotchkiss, A K; Dhabhar, F S; Nelson, R J

    2005-11-01

    Photoperiod (day length) can modulate immune function. Whether these photoperiodic effects on immune function are mediated directly by a circadian photoperiodic time measurement system or indirectly by nonspecific (e.g. stressful) effects of light is unknown. To discriminate between these two possibilities, Siberian hamsters (Phodopus sungorus) were housed in either long or short photoperiods (LD 16 : 8 h or LD 8 : 16 h) or in 'skeleton' long or short photoperiods (LD 1 : 14 h: LD 1 : 8 h or LD 1 : 6 h: LD 1 : 16 h). In the skeleton photoperiods, both long- and short-day animals received 2 h of light per day. After 10 weeks in their respective photoperiods, hamsters were tested for an antigen specific immune response using a delayed type hypersensitivity (DTH) model. Reproductive and endocrine responses of hamsters in each of the skeleton photoperiods were equivalent to those in standard long or short days, respectively. Hamsters in skeleton short days and LD 8 : 16 increased DTH responses compared to hamsters in both long-day groups. DTH responses were equivalent in both long-day groups. These results suggest that the influences of day length on immune function potentially are due to circadian photoperiodic time measurement systems.

  6. An Intact Dorsomedial Posterior Arcuate Nucleus is Not Necessary for Photoperiodic Responses in Siberian Hamsters1

    PubMed Central

    Teubner, Brett J.W.; Leitner, Claudia; Thomas, Michael A.; Ryu, Vitaly; Bartness, Timothy J.

    2015-01-01

    Seasonal responses of many animal species are triggered by changes in daylength and its transduction into a neuroendocrine signal by the pineal gland through the nocturnal duration of melatonin (MEL) release. The precise central sites necessary to receive, transduce, and relay the short day (SD) fall-winter MEL signals into seasonal responses and changes in physiology and behavior are unclear. In Siberian hamsters, SDs trigger decreases in body and lipid mass, testicular regression and pelage color changes. Several candidate genes and their central sites of expression have been proposed as components of the MEL transduction system with considerable recent focus on the arcuate nucleus (ARC) and its component, the dorsomedial posterior arcuate nucleus (dmpARC). This site has been postulated as a critical relay of SD information through the modulation of a variety of neurochemicals/receptors important for the control of energy balance. Here the necessity of an intact dmpARC for SD responses was tested by making electrolytic lesions of the Siberian hamster dmpARC and then exposing them to either long days (LD) or SDs for 12 weeks. The SD typical decreases in body and fat mass, food intake, testicular volume, serum testosterone concentrations, pelage color change and increased UCP-1 protein expression (a proxy for brown adipose tissue thermogenesis) all occurred despite the lack of an intact dmpARC. Although the Siberian hamster dmpARC contains photoperiod-modulated constituents, these data demonstrate that an intact dmpARC is not necessary for SD responses and not integral to the seasonal energy- and reproductive-related responses measured here. PMID:25647158

  7. An intact dorsomedial posterior arcuate nucleus is not necessary for photoperiodic responses in Siberian hamsters.

    PubMed

    Teubner, Brett J W; Leitner, Claudia; Thomas, Michael A; Ryu, Vitaly; Bartness, Timothy J

    2015-04-01

    Seasonal responses of many animal species are triggered by changes in daylength and its transduction into a neuroendocrine signal by the pineal gland through the nocturnal duration of melatonin (MEL) release. The precise central sites necessary to receive, transduce, and relay the short day (SD) fall-winter MEL signals into seasonal responses and changes in physiology and behavior are unclear. In Siberian hamsters, SDs trigger decreases in body and lipid mass, testicular regression and pelage color changes. Several candidate genes and their central sites of expression have been proposed as components of the MEL transduction system with considerable recent focus on the arcuate nucleus (ARC) and its component, the dorsomedial posterior arcuate nucleus (dmpARC). This site has been postulated as a critical relay of SD information through the modulation of a variety of neurochemicals/receptors important for the control of energy balance. Here the necessity of an intact dmpARC for SD responses was tested by making electrolytic lesions of the Siberian hamster dmpARC and then exposing them to either long days (LD) or SDs for 12wks. The SD typical decreases in body and fat mass, food intake, testicular volume, serum testosterone concentrations, pelage color change and increased UCP-1 protein expression (a proxy for brown adipose tissue thermogenesis) all occurred despite the lack of an intact dmpARC. Although the Siberian hamster dmpARC contains photoperiod-modulated constituents, these data demonstrate that an intact dmpARC is not necessary for SD responses and not integral to the seasonal energy- and reproductive-related responses measured here.

  8. An intact dorsomedial posterior arcuate nucleus is not necessary for photoperiodic responses in Siberian hamsters.

    PubMed

    Teubner, Brett J W; Leitner, Claudia; Thomas, Michael A; Ryu, Vitaly; Bartness, Timothy J

    2015-04-01

    Seasonal responses of many animal species are triggered by changes in daylength and its transduction into a neuroendocrine signal by the pineal gland through the nocturnal duration of melatonin (MEL) release. The precise central sites necessary to receive, transduce, and relay the short day (SD) fall-winter MEL signals into seasonal responses and changes in physiology and behavior are unclear. In Siberian hamsters, SDs trigger decreases in body and lipid mass, testicular regression and pelage color changes. Several candidate genes and their central sites of expression have been proposed as components of the MEL transduction system with considerable recent focus on the arcuate nucleus (ARC) and its component, the dorsomedial posterior arcuate nucleus (dmpARC). This site has been postulated as a critical relay of SD information through the modulation of a variety of neurochemicals/receptors important for the control of energy balance. Here the necessity of an intact dmpARC for SD responses was tested by making electrolytic lesions of the Siberian hamster dmpARC and then exposing them to either long days (LD) or SDs for 12wks. The SD typical decreases in body and fat mass, food intake, testicular volume, serum testosterone concentrations, pelage color change and increased UCP-1 protein expression (a proxy for brown adipose tissue thermogenesis) all occurred despite the lack of an intact dmpARC. Although the Siberian hamster dmpARC contains photoperiod-modulated constituents, these data demonstrate that an intact dmpARC is not necessary for SD responses and not integral to the seasonal energy- and reproductive-related responses measured here. PMID:25647158

  9. Cathinone increases body temperature, enhances locomotor activity, and induces striatal c-fos expression in the Siberian hamster.

    PubMed

    Jones, S; Fileccia, E L; Murphy, M; Fowler, M J; King, M V; Shortall, S E; Wigmore, P M; Green, A R; Fone, K C F; Ebling, F J P

    2014-01-24

    Cathinone is a β-keto alkaloid that is the major active constituent of khat, the leaf of the Catha edulis plant that is chewed recreationally in East Africa and the Middle East. Related compounds, such as methcathinone and mephedrone have been increasing in popularity as recreational drugs, resulting in the recent proposal to classify khat as a Class C drug in the UK. There is still limited knowledge of the pharmacological effects of cathinone. This study examined the acute effects of cathinone on core body temperature, locomotor and other behaviors, and neuronal activity in Siberian hamsters. Adult male hamsters, previously implanted with radio telemetry devices, were treated with cathinone (2 or 5mg/kg i.p.), the behavioral profile scored and core body temperature and locomotor activity recorded by radio telemetry. At the end of the study, hamsters received vehicle or cathinone (5mg/kg) and neuronal activation in the brain was determined using immunohistochemical evaluation of c-fos expression. Cathinone dose-dependently induced significant (p<0.0001) increases in both temperature and locomotor activity lasting 60-90min. Cathinone (2mg/kg) increased rearing (p<0.02), and 5mg/kg increased both rearing (p<0.001) and lateral head twitches (p<0.02). Both cathinone doses decreased the time spent at rest (p<0.001). The number of c-fos immunopositive cells were significantly increased in the striatum (p<0.0001) and suprachiasmatic nucleus (p<0.05) following cathinone, indicating increased neuronal activity. There was no effect of cathinone on food intake or body weight. It is concluded that systemic administration of cathinone induces significant behavioral changes and CNS activation in the hamster.

  10. Ontogeny of a photic response in the suprachiasmatic nucleus in the Siberian hamster (Phodopus sungorus).

    PubMed

    Duffield, G E; Dickerson, J M; Alexander, I H; Ebling, F J

    1995-05-01

    The ontogeny of photic responsiveness in the suprachiasmatic nucleus of the Siberian hamster (Phodopus sungorus) was studied using the enhanced expression of the immediate early gene c-fos as a marker of neuronal activation. c-fos expression was assessed by immunocytochemical localization of its protein product. Hamsters were kept on a 16 h light:8 h dark photocycle. The adult Siberian hamster showed a marked increase in the number of c-fos-immunoreactive (c-fos-ir) cells within the suprachiasmatic nuclei (SCN) in response to a 1 h light pulse delivered 1-3 h after lights off, in comparison to controls kept in the dark. This is consistent with previous studies in the Syrian hamster and rat. The development of the photic response was examined. The first study investigated the effects of a light pulse on c-fos induction in pups at 5, 9, 12 and 24 postnatal days of age (PD). The suprachiasmatic region was identified by immunocytochemical localization of peptide-histidine-isoleucine in adjacent sections, a peptide expressed early in the development of the rodent SCN. The distribution of c-fos-ir cells was also compared with the location of retinal efferents, as determined by intraocular injection of the tract tracer cholera toxin B subunit 24 h previously. At PD 9, 12 and 24, significant increases in the number of c-fos-ir cells occurred in the light pulsed animals in comparison to age-matched control animals which were moved within the non-illuminated room to provide a 'dark' pulse.(ABSTRACT TRUNCATED AT 250 WORDS)

  11. Daily variations in the influence of noradrenaline on preferred ambient temperature of the Siberian hamster.

    PubMed

    Jefimow, Małgorzata; Wojciechowski, Michał; Tegowska, Eugenia

    2003-04-01

    Daily variations in sensitivity to noradrenaline (NA) and the activation of nonshivering thermogenesis (NST) are important for survival under a potentially wide range of environmental conditions. However, little is known regarding the ability of the Siberian hamster and other species to activate NST in the day and night when they may be subjected to marked variations in environmental temperature. In this study, the effects of acclimation temperature and time of day on the behavioral thermoregulatory response to NA injections in Siberian hamsters (Phodopus sungorus) was investigated. Hamsters were acclimated for 4 weeks to 23 degrees C and a L:D 12:12 h photoperiod. After acclimation, preferred ambient temperatures (PT(a)) in saline- and NA-injected animals were measured continuously in the temperature gradient system. NA (0.6 mg/kg; s.c.) was given every 4 h while PT(a) was monitored. After NA injections there was a rapid drop in PT(a), decreasing to approximately 15 degrees C within 10-20 min after each NA injection. Following 4 weeks of acclimation to 10 degrees C and a L:D 8:16 h photoperiod, the same hamsters were re-tested in the temperature gradient system. Cold acclimation led to an accentuation in the behavioral response with a decrease in PT(a) of approximately 10 degrees C. The maximal decrease in preferred ambient temperatures was recorded during the light phase of the day and during the second part of the night. Lowering of PT(a) after NA allows for rapid dissipation of the heat from NST. Overall, the behavioral response reflects the daily changes in brown adipose tissue sensitivity to NA and thus capacity for NST.

  12. Photoperiod-dependent modulation of anti-Müllerian hormone in female Siberian hamsters, Phodopus sungorus.

    PubMed

    Kabithe, Esther W; Place, Ned J

    2008-03-01

    Fertility and fecundity decline with advancing age in female mammals, but reproductive aging was decelerated in Siberian hamsters (Phodopus sungorus) raised in a short-day (SD) photoperiod. Litter success was significantly improved in older hamsters when reared in SD and the number of primordial follicles was twice that of females held in long days (LD). Because anti-Müllerian hormone (AMH) appears to inhibit the recruitment of primordial follicles in mice, we sought to determine whether the expression patterns of AMH differ in the ovaries and serum of hamsters raised in SD versus LD. Ovaries of SD female hamsters are characterized by a paucity of follicular development beyond the secondary stage and are endowed with an abundance of large eosinophilic cells, which may derive from granulosa cells of oocyte-depleted follicles. In ovaries from 10-week-old SD hamsters, we found that the so-called 'hypertrophied granulosa cells' were immunoreactive for AMH, as were granulosa cells within healthy-appearing primary and secondary follicles. Conversely, ovaries from age-matched LD animals lack the highly eosinophilic cells present in SD ovaries. Therefore, AMH staining in LD was limited to primary and secondary follicles that are comparable in number to those found in SD ovaries. The substantially greater AMH expression in SD ovaries probably reflects the abundance of hypertrophied granulosa cells in SD ovaries and their relative absence in LD ovaries. The modulation of ovarian AMH by day length is a strong mechanistic candidate for the preservation of primordial follicles in female hamsters raised in a SD photoperiod.

  13. Photoperiodic regulation of the orexigenic effects of ghrelin in Siberian hamsters.

    PubMed

    Bradley, Sean P; Pattullo, Lucia M; Patel, Priyesh N; Prendergast, Brian J

    2010-09-01

    Animals living in temperate climates with predictable seasonal changes in food availability may use seasonal information to engage different metabolic strategies. Siberian hamsters decrease costs of thermoregulation during winter by reducing food intake and body mass in response to decreasing or short-day lengths (SD). These experiments examined whether SD reduction in food intake in hamsters is driven, at least in part, by altered behavioral responses to ghrelin, a gut-derived orexigenic peptide which induces food intake via NPY-dependent mechanisms. Relative to hamsters housed in long-day (LD) photoperiods, SD hamsters consumed less food in response to i.p. treatment with ghrelin across a range of doses from 0.03 to 3 mg/kg. To determine whether changes in photoperiod alter behavioral responses to ghrelin-induced activation of NPY neurons, c-Fos and NPY expression were quantified in the arcuate nucleus (ARC) via double-label fluorescent immunocytochemistry following i.p. treatment with 0.3 mg/kg ghrelin or saline. Ghrelin induced c-Fos immunoreactivity (-ir) in a greater proportion of NPY-ir neurons of LD relative to SD hamsters. In addition, following ghrelin treatment, a greater proportion of ARC c-Fos-ir neurons were identifiable as NPY-ir in LD relative to SD hamsters. Changes in day length markedly alter the behavioral response to ghrelin. The data also identify photoperiod-induced changes in the ability of ghrelin to activate ARC NPY neurons as a possible mechanism by which changes in day length alter food intake.

  14. HIOMT drives the photoperiodic changes in the amplitude of the melatonin peak of the Siberian hamster.

    PubMed

    Ribelayga, C; Pévet, P; Simonneaux, V

    2000-05-01

    In the pineal, melatonin (Mel) is synthesized from serotonin by arylalkylamine-N-acetyltransferase (AA-NAT) and hydroxyindole-O-methyltransferase (HIOMT). Although it is clear that AA-NAT drives the daily rhythm in Mel synthesis, the mechanisms involved in the photoperiodic changes of the amplitude of the Mel peak, as observed in the Siberian hamster, remain to be determined. We investigated the characteristics of AA-NAT and HIOMT in Siberian hamsters kept either under a short (SP) or a long photoperiod (LP). The amplitude of the nocturnal peak of Mel was about two times higher under SP than under LP, whereas AA-NAT activity was about two times smaller under SP. In contrast, a twofold increase of HIOMT activity was observed under SP compared with LP. No change in the affinity of the enzymes for their substrates was observed between the two photoperiods. Our data strongly suggest that the photoperiodic variations in the amplitude of the nocturnal peak of Mel are driven by HIOMT, thereby promoting an important physiological role for this enzyme in the seasonal regulation of Mel production.

  15. MT1 melatonin receptors mediate somatic, behavioral, and reproductive neuroendocrine responses to photoperiod and melatonin in Siberian hamsters (Phodopus sungorus).

    PubMed

    Prendergast, Brian J

    2010-02-01

    Environmental day length drives nocturnal pineal melatonin secretion, which in turn generates or entrains seasonal cycles of physiology, reproduction, and behavior. In mammals, melatonin (MEL) binds to a number of receptor subtypes including high-affinity (MT1 and MT2) and low-affinity (MT3, nuclear orphan receptors) binding sites, which are distributed throughout the central nervous system and periphery. The MEL receptors that mediate photoperiodic reproductive and behavioral responses to MEL have not been identified in a reproductively photoperiodic species. Here I tested the hypothesis that MT1 receptors are necessary and sufficient to engage photoperiodic responses by challenging male Siberian hamsters (Phodopus sungorus), a species that does not express functional MT2 receptors, with ramelteon (RAM), a specific MT1/MT2 receptor agonist. In hamsters housed in a long-day photoperiod, late-afternoon RAM treatment inhibited gonadotropin secretion, induced gonadal regression, and suppressed food intake and body mass, mimicking effects of MEL. In addition, chronic (24 h/d) RAM infusions were sufficient to obscure endogenous MEL signaling, and these treatments attenuated gonadal regression in short days. Together, the outcomes indicate that signaling at the MT1 receptor is sufficient and necessary to mediate the effects of photoperiod-driven changes in MEL on behavior and reproductive function in a reproductively photoperiodic mammal.

  16. Exogenous insulin enhances humoural immune responses in short-day, but not long-day, Siberian hamsters (Phodopus sungorus).

    PubMed

    Garcia, Nicholas W; Greives, Timothy J; Zysling, Devin A; French, Susannah S; Chester, Emily M; Demas, Gregory E

    2010-07-22

    Many animals experience marked seasonal fluctuations in environmental conditions. In response, animals display adaptive alterations in physiology and behaviour, including seasonal changes in immune function. During winter, animals must reallocate finite energy stores from relatively costly, less exigent systems (e.g. reproduction and immunity) to systems critical for immediate survival (e.g. thermoregulation). Seasonal changes in immunity are probably mediated by neuroendocrine factors signalling current energetic state. One potential hormonal candidate is insulin, a metabolic hormone released in response to elevated blood glucose levels. The aim of the present study was to explore the potential role of insulin in signalling energy status to the immune system in a seasonally breeding animal, the Siberian hamster (Phodopus sungorus). Specifically, exogenous insulin was administered to male hamsters housed in either long 'summer-like' or short 'winter-like' days. Animals were then challenged with an innocuous antigen and immune responses were measured. Insulin treatment significantly enhanced humoural immune responses in short, but not long days. In addition, insulin treatment increased food intake and decreased blood glucose levels across photoperiodic treatments. Collectively, these data support the hypothesis that insulin acts as an endocrine signal integrating seasonal energetic changes and immune responses in seasonally breeding rodents.

  17. In vivo but not in vitro leptin enhances lymphocyte proliferation in Siberian hamsters (Phodopus sungorus).

    PubMed

    Demas, Gregory E

    2010-04-01

    Mounting an immune response requires a relatively substantial investment of energy and marked reductions in energy availability can suppress immune function and presumably increase disease susceptibility. We have previously demonstrated that a moderate reduction in energy stores by partial surgical lipectomy impairs humoral immunity of Siberian hamsters (Phodopus sungorus) and is mediated, in part, by changes in the adipose tissue hormone leptin. The goals of the present study were to assess the role of leptin in cell-mediated immunity and to determine if the potential effects of leptin on immunity are via the direct actions of this hormone on lymphocytes, or indirect, via the sympathetic nervous system (SNS). In Experiment 1, hamsters received osmotic minipumps containing either murine leptin (0.5 microl/h) or vehicle alone for 10 days and splenocyte proliferation in response to the T-cell mitogen Concanavalin A (Con A) was determined. In Experiment 2, Con A-induced splenocyte proliferation was tested in the presence or absence of leptin in vitro. In Experiment 3, exogenous leptin was administered to intact or sympathetically denervated hamsters. Hamsters treated with in vivo leptin displayed increased splenocyte proliferation compared with control hamsters receiving vehicle. In contrast, in vitro leptin had no effect on splenocyte proliferation. Sympathetic denervation attenuated, but did not block, leptin-induced increases in immunity. Taken together, these results are consistent with the idea that leptin can enhance cell-mediated immunity; the SNS appears to contribute, least in part, to leptin-induced increases in immunity. Importantly, these findings confirm previous studies that leptin serves as an important endocrine link between energy balance and immunity.

  18. Matrix metalloproteinase inhibition influences aspects of photoperiod stimulated ovarian recrudescence in Siberian hamsters

    PubMed Central

    Shahed, Asha; Simmons, Jamie; Featherstone, Sydney L; Young, Kelly A.

    2015-01-01

    Blocking matrix metalloproteinase (MMP) activity in vivo with inhibitor GM6001 impedes photostimulated ovarian recrudescence in photoregressed Siberian hamsters. Since direct and indirect effects of MMPs influence a myriad of ovarian functions, we investigated the effect of in vivo MMP inhibition during recrudescence on ovarian mRNA expression of steroidogenic acute regulatory protein (StAR), 3β-hy-droxysteroid dehydrogenase (3β-HSD), Cyp19a1 aromatase, epidermal growth factor receptor (EGFR), amphiregulin (Areg), estrogen receptors (Esr1 and Esr2), tissue inhibitors of MMPs (TIMP-1,-2,-3), proliferating cell nuclear antigen (PCNA), vascular endothelial growth factor A (VEGFA), its receptor VEGFR-2, and angiopoietin-2 (Ang-2). Female Siberian hamsters were randomly assigned to one of four photoperiod groups: stimulatory long (LD) or inhibitory short (SD) photoperiods, or transferred from SD to LD for 2 weeks (post-transfer, PT). Half of the PT hamsters were injected (ip) daily with GM6001 (PTG). SD exposure reduced ovarian StAR, 3β-HSD, Cyp19a1, Esr1, Esr2, TIMPs 2–3, PCNA, VEGFR-2 and Ang-2 mRNA expression (p < 0.05), and 2 weeks of photostimulation restored mRNA expression of 3β-HSD and PCNA and increased Areg and VEGFA mRNA expression in the PT group. GM6001 treatment during photostimulation (PTG) increased TIMP-1, -2 and -3 and PCNA mRNA, but inhibited Areg mRNA expression compared to PT. Neither photoperiod nor GM6001 altered EGFR expression. Results of this study suggest that in vivo inhibition of MMP activity by GM6001 may impede ovarian recrudescence, particularly follicular growth, in two ways: (1) directly by partially inhibiting the release of EGFR ligands like Areg, thereby potentially affecting EGFR activation and its downstream pathway, and (2) indirectly by its effect on TIMPs which themselves can affect proliferation, angiogenesis and follicular growth. PMID:25910436

  19. Evidence for a direct effect of melatonin on mitochondrial genome expression of Siberian hamster brown adipocytes.

    PubMed

    Prunet-Marcassus, B; Ambid, L; Viguerie-Bascands, N; Pénicaud, L; Casteilla, L

    2001-03-01

    Photoperiod variations are known to participate in the regulation of energy balance in different rodent species via melatonin, a neurosecretory product synthesized by the pineal gland during the night. A direct effect of melatonin on adipose tissue has been suggested since binding sites for the indole have been described on brown adipocytes. The aim of this study was to investigate a genetic effect of melatonin on isolated Siberian hamster brown adipocytes using differential display RT-PCR (DDRT-PCR). Brown adipose cells were isolated from brown adipose tissue and treated for 3 hr with 0.1 and 10 microM melatonin. Total RNA was extracted and DDRT-PCR experiments were performed. A differential band, which disappeared after melatonin treatment, was detected. After confirmation and cloning, the corresponding cDNA fragment B18 was sequenced. B18 had 85 and 81% similarity with a portion of rat and mouse cytochrome b mRNA, respectively, suggesting that B18 corresponds to hamster cytochrome b. This hypothesis was confirmed by the close parallel between the changes in mRNA content, detected by B18, and by cytochrome b mRNA content, detected by a rat probe. Cytochrome b mRNA is encoded by the mitochondrial genome, suggesting a similar effect of melatonin on the whole mitochondrial transcripts. Indeed, 3 hr of treatment with melatonin (10 nM and 0.1 microM) decreased by 44% mitochondrial transcript contents. This work constitutes the first evidence of a direct biological effect of melatonin on Siberian hamster brown adipocytes.

  20. Matrix metalloproteinase inhibition influences aspects of photoperiod stimulated ovarian recrudescence in Siberian hamsters.

    PubMed

    Shahed, Asha; Simmons, Jamie J; Featherstone, Sydney L; Young, Kelly A

    2015-05-15

    Blocking matrix metalloproteinase (MMP) activity in vivo with inhibitor GM6001 impedes photostimulated ovarian recrudescence in photoregressed Siberian hamsters. Since direct and indirect effects of MMPs influence a myriad of ovarian functions, we investigated the effect of in vivo MMP inhibition during recrudescence on ovarian mRNA expression of steroidogenic acute regulatory protein (StAR), 3β-hydroxysteroid dehydrogenase (3β-HSD), Cyp19a1 aromatase, epidermal growth factor receptor (EGFR), amphiregulin (Areg), estrogen receptors (Esr1 and Esr2), tissue inhibitors of MMPs (TIMP-1,-2,-3), proliferating cell nuclear antigen (PCNA), vascular endothelial growth factor A (VEGFA), its receptor VEGFR-2, and angiopoietin-2 (Ang-2). Female Siberian hamsters were randomly assigned to one of four photoperiod groups: stimulatory long (LD) or inhibitory short (SD) photoperiods, or transferred from SD to LD for 2 weeks (post-transfer, PT). Half of the PT hamsters were injected (ip) daily with GM6001 (PTG). SD exposure reduced ovarian StAR, 3β-HSD, Cyp19a1, Esr1, Esr2, TIMPs 2-3, PCNA, VEGFR-2 and Ang-2 mRNA expression (p<0.05), and 2 weeks of photostimulation restored mRNA expression of 3β-HSD and PCNA and increased Areg and VEGFA mRNA expression in the PT group. GM6001 treatment during photostimulation (PTG) increased TIMP-1, -2 and -3 and PCNA mRNA, but inhibited Areg mRNA expression compared to PT. Neither photoperiod nor GM6001 altered EGFR expression. Results of this study suggest that in vivo inhibition of MMP activity by GM6001 may impede ovarian recrudescence, particularly follicular growth, in two ways: (1) directly by partially inhibiting the release of EGFR ligands like Areg, thereby potentially affecting EGFR activation and its downstream pathway, and (2) indirectly by its effect on TIMPs which themselves can affect proliferation, angiogenesis and follicular growth.

  1. Increased photic sensitivity for phase resetting but not melatonin suppression in Siberian hamsters under short photoperiods.

    PubMed

    Glickman, G L; Harrison, E M; Elliott, J A; Gorman, M R

    2014-03-01

    Light regulates a variety of behavioral and physiological processes, including activity rhythms and hormone secretory patterns. Seasonal changes in the proportion of light in a day (photoperiod) further modulate those functions. Recently, short (SP) versus long days (LP) were found to markedly increase light sensitivity for phase shifting in Syrian hamsters. To our knowledge, photoperiod effects on light sensitivity have not been studied in other rodents, nor is it known if they generalize to other circadian responses. We tested whether photic phase shifting and melatonin suppression vary in Siberian hamsters maintained under LP or SP. Select irradiances of light were administered, and shifts in activity were determined. Photic sensitivity for melatonin suppression was examined in a separate group of animals via pulses of light across a 4 log-unit photon density range, with post-pulse plasma melatonin levels determined via RIA. Phase shifting and melatonin suppression were greater at higher irradiances for both LP and SP. The lower irradiance condition was below threshold for phase shifts in LP but not SP. Melatonin suppression did not vary by photoperiod, and the half saturation constant for fitted sigmoid curves was similar under LP and SP. Thus, the photoperiodic modulation of light sensitivity for phase shifting is conserved across two hamster genera. The dissociation of photoperiod effects on photic phase shifting and melatonin suppression suggests that the modulation of sensitivity occurs downstream of the common retinal input pathway. Understanding the mechanistic basis for this plasticity may yield therapeutic targets for optimizing light therapy practices.

  2. Increased photic sensitivity for phase resetting but not melatonin suppression in Siberian hamsters under short photoperiods

    PubMed Central

    Glickman, GL; Harrison, EM; Elliott, JA; Gorman, MR

    2014-01-01

    Light regulates a variety of behavioral and physiological processes, including activity rhythms and hormone secretory patterns. Seasonal changes in the proportion of light in a day (photoperiod) further modulate those functions. Recently, short (SP) versus long days (LP) were found to markedly increase light sensitivity for phase shifting in Syrian hamsters. To our knowledge, photoperiod effects on light sensitivity have not been studied in other rodents nor is it known if they generalize to other circadian responses. We tested whether photic phase shifting and melatonin suppression vary in Siberian hamsters maintained under LP or SP. Select irradiances of light were administered, and shifts in activity were determined. Photic sensitivity for melatonin suppression was examined in a separate group of animals via pulses of light across a 4 log-unit photon density range, with post-pulse plasma melatonin levels determined via RIA. Phase shifting and melatonin suppression were greater at higher irradiances for both LP and SP. The lower irradiance condition was below threshold for phase shifts in LP but not SP. Melatonin suppression did not vary by photoperiod, and the half saturation constant for fitted sigmoid curves was similar under LP and SP. Thus, photoperiodic modulation of light sensitivity for phase shifting is conserved across two hamster genera. The dissociation of photoperiod effects on photic phase shifting and melatonin suppression suggests modulation of sensitivity occurs downstream of the common retinal input pathway. Understanding the mechanistic basis for this plasticity may yield therapeutic targets for optimizing light therapy practices. PMID:24440383

  3. Influence of pelage insulation and ambient temperature on energy intake and growth of juvenile Siberian hamsters.

    PubMed

    Batavia, Mariska; Matsushima, Ayako; Eboigboden, Osaretin; Zucker, Irving

    2010-10-01

    Both growth and thermoregulation are energetically costly, and many studies implicate an energetic tradeoff between them. Moreover, fur is known to ameliorate thermoregulatory costs in adult mammals, but its role in maintaining energy balance during growth is unclear. This study tested for an energetic tradeoff between growth and thermoregulation in juvenile Siberian hamsters (Phodopus sungorus) and the effect of an insulative pelage on intrinsic growth rate. Hamsters weaned at 18 days of age and left fully furred or deprived of all dorsal fur by shaving at 20 days of age, were housed at 10 degrees C or 23 degrees C. Body mass, length, and food consumption were measured until hamsters were 35 days old. Thermal challenge, whether by low ambient temperature or shaving, resulted in increased food intake and decreased efficiency at converting food into body mass. Body mass and length were not affected by the thermal challenges. These results suggest that there is no mandatory tradeoff between growth and thermoregulation in this species, particularly when food is in abundant supply. Although fur was not necessary for normal growth to proceed, it ameliorated energetic costs associated with thermoregulation, and may play a role in maintaining energy balance under conditions of limited food availability.

  4. Maternal entrainment of the developing circadian system in the Siberian hamster (Phodopus sungorus).

    PubMed

    Duffield, G E; Ebling, F J

    1998-08-01

    The aim of these studies was to investigate maternal entrainment of developing circadian locomotor activity rhythms in the Siberian hamster. In Experiment 1, mothers were transferred from a 16:8 LD cycle into constant dim red light (DD) from the day of parturition, and wheel-running activity of the mother and pups was individually monitored from the time of weaning. The phases of the individual pups' rhythms were found to be synchronized both to the phase of the mother and to the phase of lights off (ZT 12) of the photo cycle that the mother was exposed to until the day of parturition. To investigate whether this synchrony might reflect direct effects of light acting upon the fetal circadian system in late gestation, the experiment was repeated but with mothers placed into DD early in pregnancy (< or = day 7 of gestation). The results were similar to the first study, suggesting that the mother rather than the photo cycle during the latter part of gestation entrains the developing circadian system. The third experiment investigated whether this entrainment occurred during the postnatal period. Breeding pairs were maintained on alternative light-dark cycles, LD and DL, that were 12 h out of phase. Litters born to mothers on one light-dark cycle were exchanged on the day of birth with foster mothers from the reversed light-dark cycle, then raised in DD. Control litters exchanged between mothers from the same light-dark cycle had similar litter synchrony as shown by nonfostered litters of Experiment 1. However, pups cross-fostered with mothers on reversed LD cycles showed a very different distribution of pup phases. Pups were not synchronized to their natural mother but to their foster mother. Moreover, pups were more scattered over the 24-h period and were found to be significantly synchronized to the phase of the reversed LD cycle. These results demonstrate the occurrence of postnatal entrainment in the Siberian hamster. The increased scatter produced by the cross

  5. Phenotypic differences in reentrainment behavior and sensitivity to nighttime light pulses in siberian hamsters.

    PubMed

    Ruby, Norman F; Barakat, Monique T; Heller, H Craig

    2004-12-01

    Spontaneous reentrainment to phase shifts of the photocycle is a fundamental property of all circadian systems. Siberian hamsters are, however, unique in this regard because most fail to reentrain when the LD cycle (16-h light/day) is phase delayed by 5 h. In the present study, the authors compared reentrainment responses in hamsters from 2 colonies. One colony descended from animals trapped in the wild more than 30 years ago (designated "nonentrainers"), and the other colony was outbred as recently as 13 years ago (designated "entrainers"). As reported previously, only 10% of hamsters from the nonentrainer colony reentrained to a 5-h phase delay of the LD cycle. By contrast, 75% of animals from the entrainer colony reentrained to the phase shift. Another goal of this study was to test the hypothesis that failure to reentrain was a consequence of light exposure during the middle of the night on the day of the 5-h phase delay. This hypothesis was tested by exposing animals to 2 h of light during the early, middle, or late part of the night and then subjecting them on the next day to a 3-h phase delay of the photocycle, which is a phase shift to which all hamsters normally reentrain. All animals from both colonies reentrained when light pulses occurred early in the night, but more animals from the entrainer colony, compared to the nonentrainer colony, reentrained when the light pulse occurred in the middle or late part of the night. The phenotypic variation in reentrainment responses is similar to the variation in photoperiodic responsiveness previously reported for these 2 colonies. Phenotypic variation in both traits is due to underlying differences in circadian organization and suggests a common genetic basis for reentrainment responses and photoperiodic responsiveness.

  6. Photoperiod and social cues influence the medial amygdala but not the bed nucleus of the stria terminalis in the Siberian hamster.

    PubMed

    Cooke, B M; Hegstrom, C D; Keen, A; Breedlove, S M

    2001-10-12

    We investigated whether the posterodorsal nucleus of the medial amygdala (MePD) and the posteromedial nucleus of the bed nucleus of the stria terminalis (BSTpm) undergo structural changes in response to photoperiod or social environment in the Siberian hamster, a seasonally breeding rodent. Adult male hamsters were either kept in long days (LD; 15:9 h light:dark) from birth or were transferred at 12-16 weeks of age to short days (SD; 8:16) and housed with a male conspecific for 11 weeks. Other males were transferred to SD but were housed with an unrelated female conspecific from LD. Males transferred to SD without a female cagemate displayed testicular regression, but males transferred to SD with a female cagemate did not. The regional volume and average soma size of the BSTpm and the MePD were estimated using Nissl-stained brain sections. Neither photoperiod nor social condition modified either of the BSTpm measures. Among males housed in same-sex groups, the average soma size in the MePD was significantly smaller in SD males than in LD males. Cohabitation with a female resulted in MePD volumes indistinguishable from LD males. These results indicate that the MePD, a nucleus implicated in socio-sexual behavior, can respond to photoperiodic as well as to social cues.

  7. Photoperiod affects distribution of dynorphin A in the brain of Siberian hamster.

    PubMed

    Meyza, Ksenia Z; Sotowska-Brochocka, Jolanta

    2006-01-01

    Dynorphin A1-77 (DYN A1-17) acting in the CNS is known to affect thermoregulation, water and energy balance in the short time scale. In this study a long-term alteration of these functions induced by changes of day length in the highly photoperiodic species, the Siberian hamster (Phodopus sungorus) was studied using immunohistochemistry for DYN A1-17. We found that in the long day (LD, L:D 16 h:8 h) more brain areas express DYN A1-17 peptide than in the short day (SD, L:D 8 h:16 h) conditions. Structures of the hypothalamo-pituitary axis as well as cells of the ependyma, subcomissural organ and choroid plexus of the lateral and third brain ventricles are immunoreactive to anti-dynorphin IgG only in the LD. This might indicate a seasonal regulatory role of DYN A1-17 in physiological adaptations to severe climate changes.

  8. Photoperiod-dependent modulation of cardiac excitation contraction coupling in the Siberian hamster.

    PubMed

    Dibb, K M; Hagarty, C L; Loudon, A S I; Trafford, A W

    2005-03-01

    In mammals, changes in photoperiod regulate a diverse array of physiological and behavioral processes, an example of which in the Siberian hamster (Phodopus sungorus) is the expression of bouts of daily torpor following prolonged exposure to a short photoperiod. During torpor, body temperature drops dramatically; however, unlike in nonhibernating or nontorpid species, the myocardium retains the ability to contract and is resistant to the development of arrhythmias. In the present study, we sought to determine whether exposure to a short photoperiod results in alterations to cardiac excitation-contraction coupling, thus potentially enabling the heart to survive periods of low temperature during torpor. Experiments were performed on single ventricular myocytes freshly isolated from the hearts of Siberian hamsters that had been exposed to either 12 wk of short-day lengths (SD) or 12 wk of long-day lengths (LD). In SD-acclimated animals, the amplitude of the systolic Ca(2+) transient was increased (e.g., from 142 +/- 17 nmol/l in LD to 229 +/- 31 nmol/l in SD at 4 Hz; P < 0.001). The increased Ca(2+) transient amplitude in the SD-acclimated animals was not associated with any change in the shape or duration of the action potential. However, sarcoplasmic reticulum Ca(2+) content measured after current-clamp stimulation was increased in the SD-acclimated animals (at 4 Hz, 110 +/- 5 vs. 141 +/- 15 mumol/l, P < 0.05). We propose that short photoperiods reprogram the function of the cardiac sarcoplasmic reticulum, resulting in an increased Ca(2+) content, and that this may be a necessary precursor for maintenance of cardiac function during winter torpor.

  9. Photoperiodic regulation of satiety mediating neuropeptides in the brainstem of the seasonal Siberian hamster (Phodopus sungorus).

    PubMed

    Helwig, Michael; Archer, Zoë A; Heldmaier, Gerhard; Tups, Alexander; Mercer, Julian G; Klingenspor, Martin

    2009-07-01

    Central regulation of energy balance in seasonal mammals such as the Siberian hamster is dependent on the precise integration of short-term satiety information arising from the gastrointestinal tract with long-term signals on the status of available energy reserves (e.g. leptin) and prevailing photoperiod. Within the central nervous system, the brainstem nucleus of the solitary tract (NTS) and the parabrachial nucleus (PBN) are major relay nuclei that transmit information from the gastrointestinal tract to higher forebrain centres. We extended studies on the seasonal programming of the hypothalamus to examine the effect of the photoperiod on neuropeptidergic circuitries of this gut-brain axis. In the NTS and PBN we performed gene expression and immunoreactivity (-ir) studies on selected satiety-related neuropeptides and receptors: alpha-melanocyte stimulating hormone, melanocortin-3 receptor, melanocortin-4 receptor (MC4-R), growth hormone secretagogue-receptor, cocaine- and amphetamine-regulated transcript, preproglucagon (PPG), glucagon-like peptide 1 (GLP-1), cholecystokinin (CCK), peptide YY, galanin, neurotensin, and corticotrophin releasing hormone (CRH). Gene expression of PPG and MC4-R, and -ir of CCK and GLP-1, in the NTS were up-regulated after 14 weeks in long-day photoperiod (16 h light:8 h dark) compared to short-days (8 h light:16 h dark), whereas CRH-ir and NT-ir were increased in short-days within the PBN. We suggest that brainstem neuroendocrine mechanisms contribute to the long-term regulation of body mass in the Siberian hamster by a photoperiod-related modulation of satiety signalling.

  10. Role of NPY and its receptor subtypes in foraging, food hoarding, and food intake by Siberian hamsters.

    PubMed

    Day, Diane E; Keen-Rhinehart, Erin; Bartness, Timothy J

    2005-07-01

    Fasting has widespread physiological and behavioral effects such as increases in arcuate nucleus neuropeptide Y (NPY) gene expression in rodents, including Siberian hamsters. Fasting also stimulates foraging and food hoarding (appetitive ingestive behaviors) by Siberian hamsters but does relatively little to change food intake (consummatory ingestive behavior). Therefore, we tested the effects of third ventricular NPY Y1 ([Pro(34)]NPY) or Y5 ([D-Trp(34)]NPY) receptor agonists on these ingestive behaviors using a wheel running-based food delivery system coupled with simulated burrow housing. Siberian hamsters had 1) no running wheel access and free food, 2) running wheel access and free food, or 3) foraging requirements (10 or 50 revolutions/pellet). NPY (1.76 nmol) stimulated food intake only during the first 4 h postinjection ( approximately 200-1,000%) and mostly in hamsters with a foraging requirement. The Y1 receptor agonist markedly increased food hoarding (250-1,000%), increased foraging as well as wheel running per se, and had relatively little effect on food intake (<250%). Unlike NPY, the Y5 agonist significantly increased food intake, especially in foraging animals ( approximately 225-800%), marginally increased food hoarding (250-500%), and stimulated foraging and wheel running 4-24 h postinjection, with the distribution of earned pellets favoring eating versus hoarding across time. Across treatments, food hoarding predominated early postinjection, whereas food intake tended to do so later. Collectively, NPY stimulated both appetitive and consummatory ingestive behaviors in Siberian hamsters involving Y1/Y5 receptors, with food hoarding and foraging/wheel running (appetitive) more involved with Y1 receptors and food intake (consummatory) with Y5 receptors.

  11. Pregnancy-induced changes in ultradian rhythms persist in circadian arrhythmic Siberian hamsters.

    PubMed

    Wang, Z Yan; Cable, Erin J; Zucker, Irving; Prendergast, Brian J

    2014-07-01

    The impact of pregnancy and lactation on ultradian rhythms (URs) and circadian rhythms (CRs) of locomotor activity was assessed in circadian rhythmic and arrhythmic Siberian hamsters maintained in a long-day photoperiod (16h light/day). Progressive decrements in CR robustness and amplitude over the course of gestation were accompanied by enhanced URs. Dark-phase UR period and amplitude increased during early gestation and complexity and robustness increased during late gestation. The persistence of pregnancy-associated enhancements of URs in circadian arrhythmic (ARR) hamsters suggests that reproductive modulation of the UR waveform is not dependent on coherent circadian organization. The increased incidence of dark-phase URs appeared more rapidly in ARR dams than entrained (ENTR) dams. Throughout gestation, the percentage of dams with dark-phase URs was significantly greater in the ARR group. Gestational increases in UR complexity and robustness emerged earlier and were greater in ARR than ENTR dams. The attenuation of CRs during lactation is correlated with increased expression of URs. Relaxation of circadian control of the dam's behavior may increase fitness by permitting more efficient interactions with circadian arrhythmic pups.

  12. Pregnancy-induced changes in ultradian rhythms persist in circadian arrhythmic Siberian hamsters

    PubMed Central

    Wang, Z. Yan; Cable, Erin J.; Zucker, Irving; Prendergast, Brian J.

    2015-01-01

    The impact of pregnancy and lactation on ultradian rhythms (URs) and circadian rhythms (CRs) of locomotor activity was assessed in circadian rhythmic and arrhythmic Siberian hamsters maintained in a long-day photoperiod (16 h light/day). Progressive decrements in CR robustness and amplitude over the course of gestation were accompanied by enhanced URs. Dark-phase UR period and amplitude increased during early gestation and complexity and robustness increased during late gestation. The persistence of pregnancy-associated enhancements of URs in circadian arrhythmic (ARR) hamsters suggests that reproductive modulation of the UR waveform is not dependent on coherent circadian organization. The increased incidence of dark-phase URs appeared more rapidly in ARR dams than entrained (ENTR) dams. Throughout gestation, the percentage of dams with dark-phase URs was significantly greater in the ARR group. Gestational increases in UR complexity and robustness emerged earlier and were greater in ARR than ENTR dams. The attenuation of CRs during lactation is correlated with increased expression of URs. Relaxation of circadian control of the dam's behavior may increase fitness by permitting more efficient interactions with circadian arrhythmic pups. PMID:24798705

  13. Photoperiodic regulation of androgen receptor and steroid receptor coactivator-1 in Siberian hamster brain.

    PubMed

    Tetel, Marc J; Ungar, Todd C; Hassan, Brett; Bittman, Eric L

    2004-11-24

    Seasonal changes in the neuroendocrine actions of gonadal steroid hormones are triggered by fluctuations in daylength. The mechanisms responsible for photoperiodic influences upon the feedback and behavioral effects of testosterone in Siberian hamsters are poorly understood. We hypothesized that daylength regulates the expression of androgen receptor (AR) and/or steroid receptor coactivator-1 (SRC-1) in specific forebrain regions. Hamsters were castrated and implanted with either oil-filled capsules or low doses of testosterone; half of the animals remained in 16L/8D and the rest were kept in 10L/14D for the ensuing 70 days. The number of AR-immunoreactive (AR-ir) cells was regulated by testosterone in medial amygdala and caudal arcuate, and by photoperiod in the medial preoptic nucleus and the posterodorsal medial amygdala. A significant interaction between photoperiod and androgen treatment was found in medial preoptic nucleus and posterodorsal medial amygdala. The molecular weight and distribution of SRC-1 were similar to reports in other rodent species, and short days reduced the number of SRC-1-ir cells in posteromedial bed nucleus of the stria terminalis (BNST) and posterodorsal medial amygdala. A significant interaction between androgen treatment and daylength in regulation of SRC-1-ir was found in anterior medial amygdala. The present results indicate that daylength-induced fluctuations in SRC-1 and AR expression may contribute to seasonally changing effects of testosterone.

  14. Morphological and electrophysiological characterization of the adult Siberian hamster optic nerve.

    PubMed

    James, Emma L; Peacock, Veronique A H; Ebling, Francis J P; Brown, Angus M

    2010-12-01

    Electrophysiological recordings and transmission electron microscopy were used to characterize the compound action potential (CAP) and morphology, respectively, of the optic nerve in the Siberian hamster. The CAP was polyphasic in nature, comprising four separate but overlapping peaks, thereby implying that four sub-populations of axons defined by conduction velocity are present in the nerve. The histological analysis of nerves from four animals revealed a cross-sectional area of 128,171 μm(2) containing 78,109 axons. All of the axons were myelinated, and measurements of axon surface area revealed values ranging from 0.09 to 9.92 μm(2), although 68.3% were <1 μm(2). In the regions of the nerve sampled, the area occupied by axons varied from 10.2 to 80.1%, but in 72.5% of these regions the axons occupied between 50 and 70% of the total cross-sectional area. All regions of the nerve expressed small axons, but larger axons (>2.5 μm(2)) were selectively distributed throughout the nerve. We conclude that the CAP recorded from hamster optic nerve displays four distinct peaks; however, morphological analysis failed to reveal a similar distribution of axon sizes.

  15. Reversal of photoschedule in spring does not prevent photorefractoriness in Siberian hamsters.

    PubMed

    Jefimow, Małgorzata; Wojciechowski, Michał S; Tegowska, Eugenia

    2005-11-01

    We studied the influence of light-dark (L:D) cycle reversal on daily variations in the brown adipose tissue (BAT) capacity for nonshivering thermogenesis (NST) in Siberian hamsters (Phodopus sungorus). Continuous and simultaneous measurements of BAT temperature (T(BAT)) and preferred ambient temperature (PT(a)) were made after noradrenaline (NA) injections administered every 4 hr. First, hamsters were acclimated for 4 weeks to an ambient temperature (T(a)) of 23 degrees C and 12L:12D, and then to a reversed photoschedule 12D:12L for 8 weeks. The same was done after a 4- and 8-week acclimation period at the same T(a). We found that after photoschedule reversal, the re-entrainment of T(BAT) and PT(a) rhythms preceded re-entrainment of the NST rhythm. The daily rhythms of T(BAT) and PT(a) were fully re-entrained after 4 weeks of acclimation to the reversed photoschedule, but rhythmicity of the response to NA disappeared. This rhythm was restored in hamsters acclimated to a reversed photoschedule for 8 weeks. We suggest that the daily rhythm of NST capacity is not responsible for generating the rhythm of body temperature (T(b)). Rather, it is a result of the daily rhythm of T(b), but adjusts to the new environment more slowly than the T(b) rhythm. When a daily rhythm of NST was present, the increase in T(BAT) after NA injection was inversely correlated with the pre-injection T(BAT). In addition, NA-induced changes in PT(a) reflected the intensity of NST in BAT; namely, increased T(BAT) was correlated with the post-injection decrease in PT(a). When the increase in T(BAT) was large, animals chose a lower T(a) to dissipate excessive heat and prevent overheating. In the course of the experiments, we recorded a decreased mean NST capacity and increased body mass of hamsters. These changes are representative of the time of photorefractoriness and a transition to a summer status. Despite prolonged exposure to an intermediate day length (12 hr of light) and photoschedule

  16. Inhibition of matrix metalloproteinases in Siberian hamsters impedes photostimulated recrudescence of ovaries.

    PubMed

    Whited, Julie; Shahed, Asha; McMichael, Carling F; Young, Kelly A

    2010-12-01

    Exposure of Siberian hamsters to short photoperiod for 14 weeks induces ovarian regression. Subsequent transfer to long photoperiod restores ovarian function, and 2 weeks of photostimulation increases plasma estradiol (E(2)), antral follicles, and corpora lutea (CL). Because tissue remodeling involved with photostimulated ovarian recrudescence is associated with differential expression of matrix metalloproteinases (MMPs), we hypothesized that inhibiting MMP activity using a broad-spectrum in vivo MMP inhibitor, GM6001, would curtail recrudescence. One group of hamsters was placed in long days (LD; 16 h light:8 h darkness) for 16 weeks. Another group was placed in inhibitory short days (SD; 8 h light:16 h darkness) for 14 weeks. A third group was placed in SD for 14 weeks and transferred to LD for 2 weeks to stimulate recrudescence. During weeks 14-16, animals were either not treated or treated daily with i.p. injections of GM6001 (20 mg/kg) or vehicle (DMSO). GM6001 reduced gelatinase activity and decreased immunohistochemical staining for MMP1, MMP2, and MMP3 compared with vehicle. No differences between controls, vehicle, or GM6001 treatment were observed among LD animals, despite a trend toward reduction in CL and E(2) with GM6001. Although SD reduced ovarian function, photostimulation of transferred controls increased uterine mass, plasma E(2), appearance of antral follicles, and CL. With GM6001 treatment, photostimulation failed to increase uterine mass, plasma E(2), antral follicles, or CL. These data show, for the first time, that in vivo GM6001 administration inhibits MMP activity in hamster ovaries during photostimulation, and indicate that this inhibition may impede photostimulated recrudescence of ovaries. This study suggests an intriguing link between MMP activity and return to ovarian function during photostimulated recrudescence.

  17. Thermal acclimation and nutritional history affect the oxidation of different classes of exogenous nutrients in Siberian hamsters, Phodopus sungorus.

    PubMed

    McCue, Marshall D; Voigt, Christian C; Jefimow, Małgorzata; Wojciechowski, Michał S

    2014-11-01

    During acclimatization to winter, changes in morphology and physiology combined with changes in diet may affect how animals use the nutrients they ingest. To study (a) how thermal acclimation and (b) nutritional history affect the rates at which Siberian hamsters (Phodopus sungorus) oxidize different classes of dietary nutrients, we conducted two trials in which we fed hamsters one of three (13) C-labeled compounds, that is, glucose, leucine, or palmitic acid. We predicted that under acute cold stress (3 hr at 2°C) hamsters previously acclimated to cold temperatures (10°C) for 3 weeks would have higher resting metabolic rate (RMR) and would oxidize a greater proportion of dietary fatty acids than animals acclimated to 21°C. We also investigated how chronic nutritional stress affects how hamsters use dietary nutrients. To examine this, hamsters were fed four different diets (control, low protein, low lipid, and low-glycemic index) for 2 weeks. During cold challenges, hamsters previously acclimated to cold exhibited higher thermal conductance and RMR, and also oxidized more exogenous palmitic acid during the postprandial phase than animals acclimated to 21°C. In the nutritional stress trial, hamsters fed the low protein diet oxidized more exogenous glucose, but not more exogenous palmitic acid than the control group. The use of (13) C-labeled metabolic tracers combined with breath testing demonstrated that both thermal and nutritional history results in significant changes in the extent to which animals oxidize dietary nutrients during the postprandial period.

  18. Nature's knockout: the Mel1b receptor is not necessary for reproductive and circadian responses to melatonin in Siberian hamsters.

    PubMed

    Weaver, D R; Liu, C; Reppert, S M

    1996-11-01

    The pineal hormone melatonin regulates seasonal reproduction and influences the timing of circadian rhythms. The Mel1a and Mel1b receptors are the high-affinity melatonin receptors present in mammals. Unexpectedly, the Mel1b receptor gene of the Siberian hamster, Phodopus sungorus, cannot encode a functional receptor; two nonsense mutations are present within the coding region. Southern blot analysis indicates that this is a single copy gene. The Mel1b receptor gene is nonfunctional in outbred populations of P. sungorus and Phodopus campbelli. Siberian hamsters lacking a functional Mel1b receptor nevertheless show seasonal reproductive and circadian responses to melatonin, indicating that the Mel1b receptor is not necessary for these responses. These data support the hypothesis that the Mel1a receptor, which does encode a functional receptor in this species, mediates reproductive and circadian responses to melatonin.

  19. Different neural melatonin-target tissues are critical for encoding and retrieving day length information in Siberian hamsters.

    PubMed

    Teubner, B J W; Freeman, D A

    2007-02-01

    Siberian hamsters exhibit several seasonal rhythms in physiology and behaviour, including reproduction, energy balance, body mass, and pelage colouration. Unambiguous long- and short day lengths stimulate and inhibit reproduction, respectively. Whether gonadal growth or regression occurs in an intermediate day length (e.g. 14 h L : 10 h D; 14L), depends on whether the antecedent day lengths were shorter (10L) or longer (16L). Variations in day length are encoded by the duration of nocturnal pineal melatonin secretion, which is decoded at several neural melatonin target tissues to control testicular structure and function. We assessed participation of three such structures in the acquisition and retrieval of day length information. Elimination of melatonin signalling to the nucleus reuniens (NRe), but not to the suprachiasmatic nucleus (SCN) or paraventricular thalamus (PVt), interfered with the acquisition of a long day reproductive response, whereas the obscuring of melatonin signals to the SCN and the NRe, but not to the PVt, interfered with the photoperiod history response. The SCN and NRe contribute in different ways to the melatonin-based system that mediates seasonal rhythms in male reproduction.

  20. Anatomical and functional characterisation of a dopaminergic system in the suprachiasmatic nucleus of the neonatal Siberian hamster.

    PubMed

    Duffield, G E; McNulty, S; Ebling, F J

    1999-05-24

    In altricial rodents, maternal influences entrain the developing circadian system in the perinatal period before the capacity to respond directly to photic cues develops. The aim of these studies was to investigate the potential role of dopamine in this process in the Siberian hamster. An initial study investigated the ontogeny of retinal innervation of the suprachiasmatic nuclei (SCN) by using cholera toxin B subunit as a tracer. This revealed that retinal fibres first innervate the SCN on postnatal day 3 (PD3), and ingrowth of fibres is extensive by PD6. In situ hybridisation studies revealed the presence of D1-dopamine receptor (D1-R) mRNA in the SCN on PD2, and levels of expression were similar in PD6 pups and adult hamsters. Immunocytochemical staining for tyrosine hydroxylase revealed abundant catecholaminergic fibres within the ventromedial zone of the SCN from the day of birth through PD20; however, in contrast, few fibres were present in adult SCN. Dopamine-beta-hydroxylase-immunoreactive fibres were absent from the neonatal and adult SCN, suggesting that the fibres in the SCN are dopaminergic. The function of this dopaminergic system was investigated by determining the effects of D1-R agonists on the expression of the immediate-early gene c-fos in the SCN. This was assessed in pups ages PD1- PD5 by in situ hybridisation and immunocytochemical localisation of its protein product. No induction was seen in the SCN, in marked contrast to studies in the developing rat. A final series of studies investigated dopaminergic function by determining whether a D1-agonist could induce phosphorylation of Ca2+/cyclic AMP response element-binding protein (CREB) on Ser133. Hypothalamic slices containing SCN taken from PD1 and PD2 hamsters were treated with D1-R agonists, and levels of phosphorylated CREB were assayed by Western blots. Phosphorylation of CREB was stimulated by D1-R agonists in both Syrian and Siberian hamster hypothalamus, but the response was far greater

  1. Twice Daily Melatonin Peaks in Siberian but not Syrian Hamsters under 24 h Light:Dark:Light:Dark Cycles

    PubMed Central

    Raiewski, Evan E.; Elliott, Jeffrey A.; Evans, Jennifer A.; Glickman, Gena L.; Gorman, Michael R.

    2016-01-01

    The daily pattern of blood borne melatonin varies seasonally under the control of a multi-oscillator circadian pacemaker. Here we examine patterns of melatonin secretion and locomotor activity in Siberian and Syrian hamsters entrained to bimodal LDLD8:4:8:4 and LD20:4 lighting schedules that facilitate novel temporal arrangements of component circadian oscillators. Under LDLD, both species robustly bifurcated wheel-running activity in distinct day scotophase (DS) and night scotophase (NS) bouts. Siberian hamsters displayed significant melatonin increases during each scotophase in LDLD, and in the single daily scotophase of LD20:4. The bimodal melatonin secretion pattern persisted in acutely extended 16 h scotophases. Syrian hamsters, in contrast, showed no significant increases in plasma melatonin during either scotophase of LDLD8:4:8:4 or in LD20:4. In this species, detectable levels were observed only when the day scotophase of LDLD was acutely extended to yield 16 h of darkness. Established species differences in the phase lag of nocturnal melatonin secretion relative to activity onset may underlie the above contrast: In non-bifurcated entrainment to 24 h LD cycles, Siberian hamsters show increased melatonin secretion within ~ 2 h after activity onset, whereas in Syrian hamsters, detectable melatonin secretion phase lags activity onset and the L/D transition by at least 4 h. The present results provide new evidence indicating multi-oscillator regulation of the waveform of melatonin secretion, specifically, the circadian control of the onset, offset, and duration of nocturnal secretion. PMID:23003567

  2. Twice daily melatonin peaks in Siberian but not Syrian hamsters under 24 h light:dark:light:dark cycles.

    PubMed

    Raiewski, Evan E; Elliott, Jeffrey A; Evans, Jennifer A; Glickman, Gena L; Gorman, Michael R

    2012-11-01

    The daily pattern of blood-borne melatonin varies seasonally under the control of a multi-oscillator circadian pacemaker. Here we examine patterns of melatonin secretion and locomotor activity in Siberian and Syrian hamsters entrained to bimodal LDLD8:4:8:4 and LD20:4 lighting schedules that facilitate novel temporal arrangements of component circadian oscillators. Under LDLD, both species robustly bifurcated wheel-running activity in distinct day scotophase (DS) and night scotophase (NS) bouts. Siberian hamsters displayed significant melatonin increases during each scotophase in LDLD, and in the single daily scotophase of LD20:4. The bimodal melatonin secretion pattern persisted in acutely extended 16 h scotophases. Syrian hamsters, in contrast, showed no significant increases in plasma melatonin during either scotophase of LDLD8:4:8:4 or in LD20:4. In this species, detectable levels were observed only when the DS of LDLD was acutely extended to yield 16 h of darkness. Established species differences in the phase lag of nocturnal melatonin secretion relative to activity onset may underlie the above contrast: In non-bifurcated entrainment to 24 h LD cycles, Siberian hamsters show increased melatonin secretion within ≈ 2 h after activity onset, whereas in Syrian hamsters, detectable melatonin secretion phase lags activity onset and the L/D transition by at least 4 h. The present results provide new evidence indicating multi-oscillator regulation of the waveform of melatonin secretion, specifically, the circadian control of the onset, offset and duration of nocturnal secretion.

  3. Rapid changes in ovarian mRNA induced by brief photostimulation in Siberian hamsters (Phodopus sungorus).

    PubMed

    Shahed, Asha; McMichael, Carling F; Young, Kelly A

    2015-11-01

    This study sought to characterize the rapid intraovarian mRNA response of key folliculogenic factors that may contribute to the restoration of folliculogenesis during 2-10 days of photostimulation in Siberian hamsters. Adult hamsters were exposed to short photoperiod (8L:16D) for 14 weeks (SD). A subset were then transferred to long photoperiod (16L:8D) for 2 (PT day-2), 4 (PT day-4), or 10 days (PT day-10). Quantitative real-time PCR was used to measure intraovarian mRNA expression of: gonadotropin releasing hormone (GnRH), follicle stimulating hormone β-subunit (FSHβ-subunit), luteinizing hormone β-subunit (LHβ-subunit), FSH and LH receptors, estrogen receptors α and β (Esr1 and Esr2), matrix metalloproteinase (MMP)-2 and -9, anti-Müllerian hormone (AMH), inhibin-α subunit, fibroblast growth factor-2 (FGF-2) and proliferating cell nuclear antigen (PCNA). Compared to SD, plasma FSH concentrations increased on PT day-4 and the number of antral follicles and corpora lutea increased on PT day-10. FSHR and inhibin-α mRNA expression also increased on PT day-4, whereas LHR and proliferation marker PCNA both increased on PT day-10 as compared to SD. Esr1 mRNA increased on PT day-2 and remained significantly increased as compared to SD, whereas Esr1 mRNA increased only on PT day-2, similar to FGF-2 and MMP-2 results. No differences were observed in mRNA expression in ovarian GnRH, FSHβ- and LHβ-subunits, AMH, and MMP-9 mRNA with 2-10 days of photostimulation. Rapid increases in intraovarian FSHR and inhibin-α mRNA and antral follicle/corpora lutea numbers suggest that the ovary is primed to react quickly to the FSH released in response to brief periods of photostimulation.

  4. Agouti-related protein increases food hoarding more than food intake in Siberian hamsters.

    PubMed

    Day, Diane E; Bartness, Timothy J

    2004-01-01

    Agouti-related protein (AgRP), an endogenous melanocortin 3/4 receptor antagonist, appears to play an important role in the control of food intake and energy balance because exogenous administration in rats and overexpression in mice result in hyperphagia and body mass gain. Furthermore, arcuate nucleus AgRP mRNA is increased with fasting in laboratory rats and mice and is decreased with refeeding. In Siberian hamsters, fasting also increases arcuate nucleus AgRP mRNA, but these animals increase food hoarding, rather than food intake with refeeding. Therefore, we tested whether exogenous AgRP increased food hoarding in this species. Hamsters were trained in a hoarding/foraging apparatus to run a programmed number of wheel revolutions to earn food pellets. Four doses of AgRP-(83-132) or vehicle were injected into the third ventricle at the beginning of the dark phase, and food hoarding, food intake, and foraging were measured at various time points subsequently. Overall, food hoarding was stimulated as much as 10 times more than food intake, and both responses occurred as early as 1 h after injection. Food hoarding was increased the greatest at the lowest dose (0.1 nmol), whereas food intake was increased the greatest at the second lowest dose (1 nmol). Food intake and especially food hoarding were increased up to seven days after the AgRP injections. Foraging was increased at all AgRP doses except the highest dose (100 nmol). These results suggest that AgRP triggers the search for food in this species, and once they find it, hoarding predominates over eating.

  5. Photoperiod differentially regulates the expression of Per1 and ICER in the pars tuberalis and the suprachiasmatic nucleus of the Siberian hamster.

    PubMed

    Messager, S; Hazlerigg, D G; Mercer, J G; Morgan, P J

    2000-08-01

    Previous studies demonstrated that the clock gene Per1 and the transcription factor ICER are expressed rhythmically in the suprachiasmatic nucleus (SCN) and in the pars tuberalis (PT). In the Syrian hamster the duration of photoperiod affects the amplitude of gene expression in the PT, and melatonin administered before lights-on suppressed the peak of Per1/ICER expression; these effects were not seen in the SCN. It was speculated that the inefficacy of melatonin was due to the low density of melatonin receptors in the SCN of this species. The aim of the present study was to determine whether this phenomenon also occurs in the Siberian hamster, which expresses a higher density of melatonin receptors in the SCN. Male Siberian hamsters were housed in long days (16 h light : 8 h dark) or short days (8 h light : 16 h dark) and expression of Per1 and ICER mRNA was studied by in situ hybridization. The expression of Per1 and ICER mRNA in the PT peaked 3 h following lights-on (ZT3) under both photoperiods. The amplitudes of these peaks were greatly attenuated under short photoperiod. In the SCN, the duration of Per1 gene expression was proportional to the length of the light phase, but only a modest amplitude effect was observed. Injections of melatonin (25 microg) 1 h before lights-on significantly reduced the expression of both genes in the PT at ZT3, but had no effect in the SCN. These data demonstrate that photoperiod-dependent amplitude modulation of Per1 and ICER gene expression in the PT is conserved across species, and reinforce the argument that this phenomenon is driven by melatonin.

  6. FosB in the suprachiasmatic nucleus of the Syrian and Siberian hamster.

    PubMed

    Ebling, F J; Maywood, E S; Mehta, M; Hancock, D C; McNulty, S; De Bono, J; Bray, S J; Hastings, M H

    1996-01-01

    The suprachiasmatic nucleus (SCN) generates circadian rhythms of behavior and hormone secretion in mammals, and integrates responses to light and nonphotic stimuli to synchronize such rhythms with the external environment. Previous studies have demonstrated a close association between the induction of the immediate early gene (IEG) c-fos in the SCN by light and phase shifts of circadian rhythms induced by light, but nonphotic stimuli (e.g., arousal), which also cause phase shifts, do not increase c-fos expression in the SCN. Because c-fos is now known to be a member of a large family of IEGs which can regulate transcription and thus cellular function, the aim of the current study was to determine whether induction of another member of this immediate early gene family, fosB, is associated with photic and nonphotic phase shifts. An antiserum that recognizes a unique peptide sequence derived from FosB was produced so that the expression of fosB could be investigated in cells within the SCN by immunocytochemical detection of its protein product. The regional distribution of FosB-immunoreactive (ir) cells in the SCN of Syrian and Siberian hamsters was broadly similar to that for c-Fos-ir cells. However, whereas c-fos expression in the SCN was constitutively low, but could be massively induced by light at particular circadian phases, FosB-ir cells were present at all circadian phases studied, irrespective of photic stimulation, and light only produced marginal increases in the number of FosB-ir cells compared with nonstimulated controls. Moreover, blockade of glutamatergic neurotransmission by pretreatment of hamsters with the NMDA receptor antagonist MK801 significantly reduced photic induction of c-Fos-ir cells, but did not influence the number of FosB-ir cells in the SCN. Finally, an arousing nonphotic stimulus known to cause phase advances in wheel-running behavior in Syrian hamsters did not alter significantly the number of FosB-ir cells in the SCN. These

  7. Chronic exposure to dim light at night suppresses immune responses in Siberian hamsters.

    PubMed

    Bedrosian, Tracy A; Fonken, Laura K; Walton, James C; Nelson, Randy J

    2011-06-23

    Species have been adapted to specific niches optimizing survival and reproduction; however, urbanization by humans has dramatically altered natural habitats. Artificial light at night (LAN), termed 'light pollution', is an often overlooked, yet increasing disruptor of habitats, which perturbs physiological processes that rely on precise light information. For example, LAN alters the timing of reproduction and activity in some species, which decreases the odds of successful breeding and increases the threat of predation for these individuals, leading to reduced fitness. LAN also suppresses immune function, an important proxy for survival. To investigate the impact of LAN in a species naive to light pollution in its native habitat, immune function was examined in Siberian hamsters derived from wild-caught stock. After four weeks exposure to dim LAN, immune responses to three different challenges were assessed: (i) delayed-type hypersensitivity (DTH), (ii) lipopolysaccharide-induced fever, and (iii) bactericide activity of blood. LAN suppressed DTH response and reduced bactericide activity of blood after lipopolysaccharide treatment, in addition to altering daily patterns of locomotor activity, suggesting that human encroachment on habitats via night-time lighting may inadvertently compromise immune function and ultimately fitness.

  8. Analysis of adrenergic regulation of melatonin synthesis in Siberian hamster pineal emphasizes the role of HIOMT.

    PubMed

    Ceinos, R M; Chansard, M; Revel, F; Calgari, C; Míguez, J M; Simonneaux, V

    2004-01-01

    Seasonal variations of environmental factors are translated into annual fluctuations in synthesis and release of melatonin, which in turn acts as a neuroendocrine messenger for the synchronization of annual functions. So far, most studies performed to understand the regulation of melatonin synthesis have used the non seasonal laboratory rat. It was demonstrated that nocturnal melatonin synthesis depends on alpha- and beta-adrenergic activation of the enzyme arylalkylamine N-acetyltransferase (AA-NAT). In this study, we investigated the mechanisms of melatonin synthesis in the Siberian hamster, a seasonal species with marked photoperiodic variation in melatonin peak duration and amplitude. A beta-adrenergic receptor agonist alone markedly stimulated AA-NAT activity and melatonin synthesis and release. An alpha-adrenergic receptor agonist, while having no effect per se, potentiated the beta-adrenergic stimulation of AA-NAT activity both in vitro and in vivo. Strikingly, the potentiation of AA-NAT activity did not result in a potentiation of melatonin synthesis, suggesting that the rate of melatonin production is limited downstream in the metabolic pathway, most probably at the level of hydroxyindole-O-methyltransferase (HIOMT). HIOMT presented a constitutively high activity that was not acutely (within hours) stimulated by beta-adrenergic agonist, but was rather up-regulated by chronic application of the agonist. This long-term beta-adrenergic regulation may explain the reported large photoperiodic variation of HIOMT activity that drives the photoperiodic variation in melatonin peak.

  9. Photoperiod and testosterone regulate androgen receptor immunostaining in the Siberian hamster brain.

    PubMed

    Bittman, Eric L; Ehrlich, David A; Ogdahl, Justyne L; Jetton, Amy E

    2003-09-01

    Day length regulates the effects of gonadal steroids on gonadotropin secretion and behavior in seasonal breeders. To determine whether this influence of photoperiod results from changes in androgen receptor expression in Siberian hamster brain regions that regulate neuroendocrine function, androgen receptor immunostaining was examined in castrated animals given either no androgen replacement or one of three doses of testosterone (T) resulting in physiological serum concentrations. Half of the animals were housed under inhibitory photoperiod conditions, and immunostaining was quantified 11 days later. Measurement of serum gonadotropin and prolactin concentrations confirmed that androgen exerted graded effects on pituitary function but that the animals were killed before photoperiodic influences had fully developed. T significantly increased the numbers of androgen receptor-immunoreactive cells in every brain region examined. Photoperiod exerted no significant influence on androgen receptor-immunoreactive cell number in the arcuate nucleus, bed nucleus of the stria terminalis (BNST), medial preoptic nucleus, or in medial amygdala. An interaction between T and photoperiod was observed in the BNST and in the rostral and middle portions of the arcuate nucleus. Although increasing concentrations of T resulted in more intense cellular immunostaining in the BNST and arcuate, this effect was not influenced by day length. These results indicate that relatively short-duration (11 days) exposure to inhibitory photoperiod triggers localized and regionally specific changes in androgen receptor expression.

  10. Distributed forebrain sites mediate melatonin-induced short-day responses in Siberian hamsters.

    PubMed

    Leitner, Claudia; Bartness, Timothy J

    2010-07-01

    The pineal hormone melatonin (MEL) is the key initiator in regulating seasonal photoperiodic responses; however, the central sites that mediate short day (SD) winter-like responses, such as testicular regression and decreases in white adipose tissue (WAT) mass, by Siberian hamsters are not precisely known. WAT is innervated by the sympathetic nervous system, and several forebrain sites that are part of the sympathetic nervous system outflow to WAT coexpress MEL(1a) receptor mRNA [e.g. suprachiasmatic nucleus, subzona incerta (SubZi), dorsomedial nucleus of the hypothalamus, nucleus reunions and paraventricular nuclei of the thalamus]. We tested the involvement of these sites in MEL-triggered SD responses. A long duration, SD-like MEL signal was applied site specifically for 5 wk, with sc and third ventricle MEL application serving as positive controls. Whereas SD MEL signals delivered to each of these sites were able to induce testicular regression, all but the paraventricular nuclei of the thalamus also trigger SD-induced decreases in body mass. Third ventricle, sc, suprachiasmatic nucleus, or SubZi MEL application also decreased WAT mass, and only sc and SubZi MEL application decreased food intake. Collectively these data suggest a distributed system of MEL-sensitive brain sites sufficient to mediate these SD responses, the redundancy of which suggests its importance for appropriate seasonal responses critical for overwintering.

  11. An odorant-binding protein as a new allergen from Siberian hamster (Phodopus sungorus).

    PubMed

    Torres, J A; Pastor-Vargas, C; de las Heras, M; Vivanco, F; Cuesta, Javier; Sastre, J

    2012-01-01

    A case of anaphylaxis following a bite from a Siberian hamster (SH; Phodopus sungorus) is described. Skin prick tests with hair, urine and salivary gland extracts from SH were positive, while the tests were negative for hair extracts from other rodents. IgE immunoblotting with the patient serum revealed 3 IgE-binding bands of about 18, 21 and 23 kDa. When the patient's serum was preincubated with rabbit, mouse and gerbil hair extracts, no inhibition of the 3 SH IgE-binding bands was demonstrated. Proteins extracted from the 3 bands were analyzed by N-terminal sequencing and matrix-assisted laser desorption/ionization time-of-flight tandem mass spectrometry, and peptides were sequenced. IgE-binding bands were identified as being an odorant-binding protein belonging to the lipocalin family. Analysis of the 3 IgE-binding bands found in the hair, urine and salivary glands of SH showed a new allergenic protein lacking cross-reactivity with allergens from other rodents. The 3 bands likely correspond to isoforms of a single allergen.

  12. Post-natal growth of the gastrointestinal tract of the Siberian hamster: morphometric analysis.

    PubMed

    Wołczuk, K; Kobak, J

    2014-12-01

    Post-natal growth of the gastrointestinal tract of the Siberian hamster was studied in newborn and 3-, 7-, 14-, 21-, 42- and 90-day-old animals. Morphometric measurements and calculations were carried out: length and internal surface of gastrointestinal tract segments, size (height, width, surface) and density of villi as well as allometric growth rate of the length and internal surface of the segments with respect to the body mass. The fastest growth rate of the gastrointestinal tract segments was noticed during the first 3 days of the post-natal life. Nevertheless, significant regional differences in their growth rate were found. The increase in the length and internal surface of the large intestine was fastest, while the smallest increase was observed in the oesophagus. All segments of the gastrointestinal tract except oesophagus exhibited a positive allometric relationship to the body mass from birth till final weaning, whereas during the post-weaning period, the increase was isometric. Thus, at birth, the gastrointestinal tract segments were relatively smaller compared with those observed in adults, but then, the gastrointestinal tract grew faster than the rest of the body and reached its adult proportions just before the transition to solid food. Most probably, reaching the adult structure of the gastrointestinal tract before the final weaning is an essential condition for the proper growth of an organism after the weaning.

  13. Photoperiodic regulation of histamine H3 receptor and VGF messenger ribonucleic acid in the arcuate nucleus of the Siberian hamster.

    PubMed

    Barrett, Perry; Ross, Alexander W; Balik, Ales; Littlewood, Pauline A; Mercer, Julian G; Moar, Kim M; Sallmen, Tina; Kaslin, Jan; Panula, Pertti; Schuhler, Sandrine; Ebling, Francis J; Ubeaud, Caroline; Morgan, Peter J

    2005-04-01

    To survive winter the Siberian hamster has evolved profound physiological and behavioral adaptations, including a moult to winter pelage, regression of the reproductive axis, onset of daily torpor and increased capacity for thermogenesis. However, one of the most striking adaptations is the catabolism of intraabdominal and sc fat reserves contributing to the loss of up to 40% of body weight. These physiological and behavioral adaptations are photoperiodically driven, yet neither the site(s) in the brain nor the molecular mechanism(s) involved in the regulation of these profound adaptations is known. Here we report a dynamic regulation of gene expression in a dorsal region of the medial posterior area of the arcuate nucleus (dmpARC) of the Siberian and Syrian hamster brain in response to altered photoperiod. We show mRNA for the histamine H3 receptor is down-regulated and VGF is up-regulated in the dmpARC in hamsters switched from long- to short-day photoperiod. These data provide further evidence to support the view that the dmpARC is a major site to relay photoperiodic changes and as a site for the long-term regulation of seasonal physiology and behavior.

  14. Thyrotrophin-releasing hormone decreases feeding and increases body temperature, activity and oxygen consumption in Siberian hamsters.

    PubMed

    Schuhler, S; Warner, A; Finney, N; Bennett, G W; Ebling, F J P; Brameld, J M

    2007-04-01

    Thyrotrophin-releasing hormone (TRH) is known to play an important role in the control of food intake and energy metabolism in addition to its actions on the pituitary-thyroid axis. We have previously shown that central administration of TRH decreases food intake in Siberian hamsters. This species is being increasingly used as a physiological rodent model in which to understand hypothalamic control of long-term changes in energy balance because it accumulates fat reserves in long summer photoperiods, and decreases food intake and body weight when exposed to short winter photoperiods. The objectives of our study in Siberian hamsters were: (i) to investigate whether peripheral administration of TRH would mimic the effects of central administration of TRH on food intake and whether these effects would differ dependent upon the ambient photoperiod; (ii) to determine whether TRH would have an effect on energy expenditure; and (iii) to investigate the potential sites of action of TRH. Both peripheral (5-50 mg/kg body weight; i.p.) and central (0.5 microg/ml; i.c.v.) administration of TRH decreased food intake, and increased locomotor activity, body temperature and oxygen consumption in the Siberian hamster, with a rapid onset and short duration of action. Systemic treatment with TRH was equally effective in suppressing feeding regardless of ambient photoperiod. The acute effects of TRH are likely to be centrally mediated and independent of its role in the control of the production of thyroid hormones. We conclude that TRH functions to promote a catabolic energetic state by co-ordinating acute central and chronic peripheral (thyroid-mediated) function.

  15. Light at night alters daily patterns of cortisol and clock proteins in female Siberian hamsters.

    PubMed

    Bedrosian, T A; Galan, A; Vaughn, C A; Weil, Z M; Nelson, R J

    2013-06-01

    Humans and other organisms have adapted to a 24-h solar cycle in response to life on Earth. The rotation of the planet on its axis and its revolution around the sun cause predictable daily and seasonal patterns in day length. To successfully anticipate and adapt to these patterns in the environment, a variety of biological processes oscillate with a daily rhythm of approximately 24 h in length. These rhythms arise from hierarchally-coupled cellular clocks generated by positive and negative transcription factors of core circadian clock gene expression. From these endogenous cellular clocks, overt rhythms in activity and patterns in hormone secretion and other homeostatic processes emerge. These circadian rhythms in physiology and behaviour can be organised by a variety of cues, although they are most potently entrained by light. In recent history, there has been a major change from naturally-occurring light cycles set by the sun, to artificial and sometimes erratic light cycles determined by the use of electric lighting. Virtually every individual living in an industrialised country experiences light at night (LAN) but, despite its prevalence, the biological effects of such unnatural lighting have not been fully considered. Using female Siberian hamsters (Phodopus sungorus), we investigated the effects of chronic nightly exposure to dim light on daily rhythms in locomotor activity, serum cortisol concentrations and brain expression of circadian clock proteins (i.e. PER1, PER2, BMAL1). Although locomotor activity remained entrained to the light cycle, the diurnal fluctuation of cortisol concentrations was blunted and the expression patterns of clock proteins in the suprachiasmatic nucleus and hippocampus were altered. These results demonstrate that chronic exposure to dim LAN can dramatically affect fundamental cellular function and emergent physiology.

  16. Schiff base protonation changes in Siberian hamster ultraviolet cone pigment photointermediates.

    PubMed

    Mooney, Victoria L; Szundi, Istvan; Lewis, James W; Yan, Elsa C Y; Kliger, David S

    2012-03-27

    Molecular structure and function studies of vertebrate ultraviolet (UV) cone visual pigments are needed to understand the molecular evolution of these photoreceptors, which uniquely contain unprotonated Schiff base linkages between the 11-cis-retinal chromophore and the opsin proteins. In this study, the Siberian hamster ultraviolet cone pigment (SHUV) was expressed and purified in an n-dodecyl-β-D-maltoside suspension for optical characterization. Time-resolved absorbance measurements, over a spectral range from 300 to 700 nm, were taken for the purified pigment at time delays from 30 ns to 4.64 s after photoexcitation using 7 ns pulses of 355 nm light. The resulting data were fit globally to a sum of exponential functions after noise reduction using singular-value decomposition. Four exponentials best fit the data with lifetimes of 1.4 μs, 210 μs, 47 ms, and 1 s. The first photointermediate species characterized here is an equilibrated mixture similar to the one formed after rhodopsin's Batho intermediate decays into equilibrium with its successor, BSI. The extremely large red shift of the SHUV Batho component relative to the pigment suggests that SHUV Batho has a protonated Schiff base and that the SHUV cone pigment itself has an unprotonated Schiff base. In contrast to SHUV Batho, the portion of the equilibrated mixture's spectrum corresponding to SHUV BSI is well fit by a model spectrum with an unprotonated Schiff base. The spectra of the next two photointermediate species revealed that they both have unprotonated Schiff bases and suggest they are analogous to rhodopsin's Lumi I and Lumi II species. After decay of SHUV Lumi II, the correspondence with rhodopsin photointermediates breaks down and the next photointermediate, presumably including the G protein-activating species, is a mixture of protonated and unprotonated Schiff base photointermediate species.

  17. 4-Vinylcyclohexene diepoxide reduces fertility in female Siberian hamsters when treated during their reproductively active and quiescent states.

    PubMed

    Roosa, Kristen A; Mukai, Motoko; Place, Ned J

    2015-01-01

    The industrial compound 4-vinylcyclohexene diepoxide (VCD) destroys ovarian follicles and reduces fertility in rodents, but to date VCD has not been tested in species that experience seasonal anestrus. To determine if VCD destroys follicles when administered during reproductive quiescence, Siberian hamsters were treated with VCD (240mg/kg i.p. daily for 10 days) during short days, and outcomes were compared with reproductively active females that were maintained and treated in long days. Primordial follicle numbers were significantly reduced by VCD under both day lengths, and reproductive quiescence in short days did not appear to render the ovaries less susceptible to VCD-induced follicle depletion. Independent of day length and reproductive state, VCD-treated hamsters weaned substantially fewer offspring than controls. These results suggest that time of year may not be an important consideration for optimizing use of VCD in the field when the target pest species is a seasonally breeding rodent.

  18. Photoperiod and acute energy deficits interact on components of the thyroid hormone system in hypothalamic tanycytes of the Siberian hamster.

    PubMed

    Herwig, Annika; Wilson, Dana; Logie, Tracy J; Boelen, Anita; Morgan, Peter J; Mercer, Julian G; Barrett, Perry

    2009-05-01

    In the Siberian hamster, seasonal weight loss occurs gradually over many weeks during autumn and winter. This is driven by a regulatory mechanism that is able to integrate duration of exposure to short days (SDs) with the size of body energy reserves. After food restriction in SDs, followed by ad libitum refeeding, body weight of the hamster does not return to its former level; rather, it increases to a level defined by the length of time spent in SDs. In this report, we show that components of the thyroid hormone system that are involved in seasonal weight loss change expression in response to 48 h of starvation. Eight weeks in an SD photoperiod induced weight loss in the Siberian hamster. In the hypothalamus of these hamsters, type II deiodinase expression was decreased and type III deiodinase expression was induced, but there was no change in hypothalamic neuropeptide Y or thyrotropin-releasing hormone gene expression. For the first time, we show that the thyroid hormone transporter monocarboxylate transporter 8 is expressed in tanycytes and is increased in response to an SD photoperiod. Food restriction (48 h of starvation) reversed the direction of gene expression change for type II and III deiodinase and monocarboxylate transporter 8 induced by SD photoperiods. Furthermore, fasting increased neuropeptide Y expression and decreased thyrotropin-releasing hormone expression. VGF, a gene upregulated in SDs in the dorsal region of the medial posterior area of the arcuate nucleus, was not changed by starvation. These data point to a mechanism whereby energy deprivation can interact with an SD photoperiod on hypothalamic tanycytes to regulate components of the thyroid hormone system involved in photoperiodic regulation of seasonal physiology.

  19. Photoperiod regulates genes encoding melanocortin 3 and serotonin receptors and secretogranins in the dorsomedial posterior arcuate of the Siberian hamster.

    PubMed

    Nilaweera, K N; Archer, Z A; Campbell, G; Mayer, C-D; Balik, A; Ross, A W; Mercer, J G; Ebling, F J P; Morgan, P J; Barrett, P

    2009-02-01

    The mechanism(s) involved in the regulation of the seasonal-appropriate body weight of the Siberian hamster are currently unknown. We have identified photoperiodically regulated genes including VGF in a sub-region of the arcuate nucleus termed the dorsomedial posterior arcuate (dmpARC). Gene expression changes in this nucleus so far account for a significant number of those reported as photoperiodically regulated and are therefore likely to contribute to seasonal physiological responses of the hamsters. The present study aimed to identify additional genes expressed in the dmpARC regulated by photoperiod that could be involved in regulating the activity of this nucleus with respect to seasonal physiology of the Siberian hamster. Using laser capture microdissection coupled with a microarray analysis and a candidate gene approach, we have identified several photoperiodically regulated genes in the dmpARC that are known to have roles in secretory and intracellular signalling pathways. These include secretogranin (sg) III and SgVI (secretory pathway), melanocortin 3 receptor (MC3-R) and serotonin (5-HT) receptors 2A and 7 (signalling pathway), all of which increase in expression under a short photoperiod. The spatial relationship between receptor signalling and potential secretory pathways was investigated by dual in situ hybridisation, which revealed that 5-HT2A and 5-HT7 receptors are expressed in neurones expressing VGF mRNA and that a sub-population (approximately 40%) of these neurones express MC3-R. These gene expression changes in dmpARC neurones may reflect the functional requirement of these neurones for seasonal physiological responses of the hamster.

  20. Short-days induce weight loss in Siberian hamsters despite overexpression of the agouti-related peptide gene.

    PubMed

    Jethwa, P H; Warner, A; Fowler, M J; Murphy, M; de Backer, M W; Adan, R A H; Barrett, P; Brameld, J M; Ebling, F J P

    2010-06-01

    Many vertebrates express profound annual cycles of body fattening, although it is not clear whether these represent differential activity of the central pathways known to mediate homeostatic control of food intake and energy expenditure, or whether the recent discovery of a major role for pars tuberalis-ependymal signalling points towards novel mechanisms. We examined this in the Siberian hamster (Phodopus sungorus) by using gene transfection to up-regulate a major orexigenic peptide, agouti-related peptide (AgRP), and then determined whether this increased anabolic drive could prevent the short-day induced winter catabolic state. Infusions of a recombinant adeno-associated virus encoding an AgRP construct into the hypothalamus of hamsters in the long-day obese phase of their seasonal cycle produced a 20% gain in body weight over 6 weeks compared to hamsters receiving a control reporter construct, reflecting a significant increase in food intake and a significant decrease in energy expenditure. However, all hamsters showed a significant, prolonged decrease in body weight when exposed to short photoperiods, despite the hamsters expressing the AgRP construct maintaining a higher food intake and lower energy expenditure relative to the control hamsters. Visualisation of the green fluorescent protein reporter and analysis of AgRP-immunoreactivity confirmed widespread expression of the construct in the hypothalamus, which was maintained for the 21-week duration of the study. In conclusion, the over-expression of AgRP in the hypothalamus produced a profoundly obese state but did not block the seasonal catabolic response, suggesting a separation of rheostatic mechanisms in seasonality from those maintaining homeostasis of energy metabolism.

  1. Estrogen receptor immunoreactivity in prepubertal and adult male Syrian hamsters.

    PubMed

    Romeo, R D; Diedrich, S L; Sisk, C L

    1999-04-23

    Estrogen and estrogen receptors (ER) are involved in the expression of steroid-dependent male sexual behavior and negative feedback regulation of the hypothalamic-pituitary-gonadal axis. The purpose of the present experiment was to determine whether there are pubertal changes in ER expression in brain that are correlated with pubertal changes in responsiveness to steroid negative feedback and behavioral activation. We found equivalent numbers of ER-immunoreactive (ER-ir) cells in castrated prepubertal and adult male hamsters in nuclei that comprise the neural circuit that mediate male sexual behavior. Therefore, increases in the number of cells in these nuclei that express ER are not correlated with the increased behavioral responsiveness to steroid hormone shown by hamsters after puberty. The number of ER-ir cells in the ventral medial hypothalamus was less in adults compared with juveniles. This pubertal decrease in ER expression is correlated with the decreased responsiveness to steroid negative feedback in the adult.

  2. Fos-like immunoreactivity in Siberian hamster brain during initiation of torpor-like hypothermia induced by 2DG.

    PubMed

    Park, Jin Ho; Dark, John

    2007-08-01

    Systemic 2-deoxy-d-glucose (2DG) produces pronounced torpor-like hypothermia (not< approximately 15 degrees C) in the Siberian hamster. Siberian hamsters are heterothermic, naturally undergoing photoperiod-dependent torpor during winter-like photoperiods. Fos was used to identify neural structures activated during the initiation of torpor-like hypothermia induced by 2DG treatment. The Fos-like immunoreactivity (Fos-li) in the area postrema and nucleus of the solitary tract that predominantly characterizes other 2DG-induced responses was absent during 2DG-induced torpor in the present experiment. Fos-li was seen in a number of forebrain and hindbrain sites during entry into hypothermia, but the densest Fos-li was found in the parvocellular portion of the paraventricular nucleus. Fos-li in the medial nucleus of the amygdala and the dorsal lateral septum also distinguished 2DG-induced torpor from other 2DG-induced behaviors. The possible involvement of neuropeptide Y pathways during 2DG-induced expression of reversible hypothermia is discussed.

  3. Photoperiodic regulation of glycogen metabolism, glycolysis, and glutamine synthesis in tanycytes of the Siberian hamster suggests novel roles of tanycytes in hypothalamic function.

    PubMed

    Nilaweera, Kanishka; Herwig, Annika; Bolborea, Matei; Campbell, Gill; Mayer, Claus D; Morgan, Peter J; Ebling, Francis J P; Barrett, Perry

    2011-11-01

    The objective of this study is to investigate the impact of photoperiod on the temporal and spatial expression of genes involved in glucose metabolism in the brain of the seasonal mammal Phodopus sungorus (Siberian hamster). In situ hybridization was performed on brain sections obtained from male hamsters held in long photoperiod (high body weight and developed testes) or short photoperiod (reduced body weight with testicular regression). This analysis revealed upregulation in expression of genes involved in glycogen and glucose metabolism in short photoperiod and localized to the tanycyte layer of the third ventricle. On the basis of these data and a previously identified photoperiod-dependent increase in activity of neighboring hypothalamic neurons, we hypothesized that the observed expression changes may reflect alteration in either metabolic fuel or precursor neurotransmitter supply to surrounding neurons. Gene expression analysis was performed for genes involved in lactate and glutamate transport. This analysis showed that the gene for the lactate transporter MCT2 and glutamate transporter GLAST was decreased in the tanycyte layer in short photoperiod. Expression of mRNA for glutamine synthetase, the final enzyme in the synthesis of the neuronal neurotransmitter precursor, glutamine, was also decreased in short photoperiod. These data suggest a role for tanycytes in modulating glutamate concentrations and neurotransmitter supply in the hypothalamic environment.

  4. Complete Genome Sequence of Phodopus sungorus Papillomavirus Type 1 (PsPV1), a Novel Member of the Pipapillomavirus Genus, Isolated from a Siberian Hamster.

    PubMed

    Kocjan, Boštjan J; Hošnjak, Lea; Račnik, Joško; Zadravec, Marko; Poljak, Mario

    2014-04-10

    We report the complete genomic sequence of Phodopus sungorus papillomavirus type 1 (PsPV1), isolated from an anogenital lesion of a Siberian hamster. PsPV1 is taxonomically classified in the genus Pipapillomavirus and is most closely related to Mesocricetus auratus papillomavirus 1 (MaPV1).

  5. Photoperiod affects the diurnal rhythm of hippocampal neuronal morphology of Siberian hamsters.

    PubMed

    Ikeno, Tomoko; Weil, Zachary M; Nelson, Randy J

    2013-11-01

    Individuals of many species can regulate their physiology, morphology, and behavior in response to annual changes of day length (photoperiod). In mammals, the photoperiodic signal is mediated by a change in the duration of melatonin, leading to alterations in gene expressions, neuronal circuits, and hormonal secretion. The hippocampus is one of the most plastic structures in the adult brain and hippocampal neuronal morphology displays photoperiod-induced differences. Because the hippocampus is important for emotional and cognitive behaviors, photoperiod-driven remodeling of hippocampal neurons is implicated in seasonal differences of affect, including seasonal affective disorder (SAD) in humans. Because neuronal architecture is also affected by the day-night cycle in several brain areas, we hypothesized that hippocampal neuronal morphology would display a diurnal rhythm and that day length would influence that rhythm. In the present study, we examined diurnal and seasonal differences in hippocampal neuronal morphology, as well as mRNA expression of the neurotrophic factors (i.e., brain-derived neurotrophic factor [Bdnf], tropomyosin receptor kinase B [trkB; a receptor for BDNF], and vascular endothelial growth factor [Vegf]) and a circadian clock gene, Bmal1, in the hippocampus of Siberian hamsters. Diurnal rhythms in total length of dendrites, the number of primary dendrites, dendritic complexity, and distance of the furthest intersection from the cell body were observed only in long-day animals; however, diurnal rhythms in the number of branch points and mean length of segments were observed only in short-day animals. Spine density of dendrites displayed diurnal rhythmicity with different peak times between the CA1 and DG subregions and between long and short days. These results indicate that photoperiod affects daily morphological changes of hippocampal neurons and the daily rhythm of spine density, suggesting the possibility that photoperiod-induced adjustments

  6. Photoperiod-dependent regulation of carboxypeptidase E affects the selective processing of neuropeptides in the seasonal Siberian hamster (Phodopus sungorus).

    PubMed

    Helwig, M; Herwig, A; Heldmaier, G; Barrett, P; Mercer, J G; Klingenspor, M

    2013-02-01

    The production of bioactive peptides from biologically inactive precursors involves extensive post-translational processing, including enzymatic cleavage by proteolytic peptidases. Endoproteolytic prohormone-convertases initially cleave the precursors of many neuropeptides at specific amino acid sequences to generate intermediates with basic amino acid extensions on their C-termini. Subsequently, the related exopeptidases, carboxypeptidases D and E (CPD and CPE), are responsible for removing these amino acids before the peptides achieve biological activity. We investigated the effect of photoperiod on the processing of the neuropeptide precursor pro-opiomelanocortin (POMC) and its derived neuropeptides, α-melanocyte-stimulating hormone (MSH) and β-endorphin (END), within the hypothalamus of the seasonal Siberian hamster (Phodopus sungorus). We thus compared hypothalamic distribution of CPD, CPE, α-MSH and β-END using immunohistochemistry and measured the enzyme activity of CPE and concentrations of C-terminally cleaved α-MSH in short-day (SD; 8 : 16 h light/dark) and long-day (LD; 16 : 8 h light/dark) acclimatised hamsters. Increased immunoreactivity (-IR) of CPE, as well as higher CPE activity, was observed in SD. This increase was accompanied by more β-END-IR cells and substantially higher levels of C- terminally cleaved α-MSH, as determined by radioimmunoassay. Our results suggest that exoproteolytic cleavage of POMC-derived neuropeptides is tightly regulated by photoperiod in the Siberian hamster. Higher levels of biological active α-MSH- and β-END in SD are consistent with the hypothesis that post-translational processing is a key event in the regulation of seasonal energy balance.

  7. Hypothalamic neuropeptide gene expression during recovery from food restriction superimposed on short-day photoperiod-induced weight loss in the Siberian hamster.

    PubMed

    Archer, Zoë A; Moar, Kim M; Logie, Tracy J; Reilly, Laura; Stevens, Valerie; Morgan, Peter J; Mercer, Julian G

    2007-09-01

    Previously, 40% food restriction of male Siberian hamsters over 21 days in short-day (SD) photoperiod induced characteristic changes in expression of hypothalamic arcuate nucleus energy balance genes; mRNAs for neuropeptide Y, agouti-related peptide, and leptin receptor were upregulated, and those of proopiomelanocortin and cocaine- and amphetamine-regulated transcript were depressed. The present study examined the effect of refeeding hamsters for 6 days (approximately 50% recovery of weight differential) or 19 days (resumption of appropriate weight trajectory). Hyperphagia continued throughout refeeding, but differences in fat pad weights and leptin levels had disappeared after 19 days. Cocaine- and amphetamine-regulated transcript gene expression was depressed by prior restriction in both refed groups. The depressive effect of prior restriction on proopiomelanocortin gene expression had disappeared after 19 days of refeeding. There was no effect of prior food restriction on neuropeptide Y or agouti-related peptide gene expression. Expression of the anorexigenic brain-derived neurotrophic factor was downregulated in the ventromedial nucleus after SD exposure for 12 wk. In the SD food restriction study, there were effects of photoperiod on brain-derived neurotrophic factor gene expression but not of prior food restriction. Hypothalamic energy balance genes in the hamster respond asynchronously to return to a seasonally appropriate body weight. The achievement of this weight rather than the weight at which caloric restriction was imposed is the critical factor. The differential responses of hypothalamic energy balance genes to food restriction and refeeding are poorly characterized in any species, a critical issue given their potential relevance to human weight loss strategies that involve caloric restriction.

  8. The suppressor of cytokine signalling 3, SOCS3, may be one critical modulator of seasonal body weight changes in the Siberian hamster, Phodopus sungorus.

    PubMed

    Tups, A; Barrett, P; Ross, A W; Morgan, P J; Klingenspor, M; Mercer, J G

    2006-02-01

    The Siberian hamster, Phodopus sungorus, exhibits a remarkable cycle of body weight, reproduction and leptin sensitivity in response to a seasonal change in photoperiod. In the present study, we investigated the hypothesis that the suppressor of cytokine signalling 3 (SOCS3) plays a critical role in the regulation of the seasonal body weight cycle. We analysed arcuate nucleus SOCS3 gene expression in short day length (SD; 8 : 16 h light/dark) acclimated Siberian hamsters that were transferred back to long day length (LD; 16 : 8 h light/dark) and in hamsters that spontaneously became photorefractory to SD induced by prolonged exposure. SD acclimated hamsters that were transferred back to LD for 1, 2, 3, 4 or 6 weeks, increased arcuate nucleus SOCS3 gene expression to the LD level within 2 weeks, and maintained this higher level thereafter. The early increase of SOCS3 gene expression preceded the LD-induced rise in body weight by approximately 3 weeks. Hamsters kept in SD for an extended period (25 weeks), began to become refractory to SD and to increase body weight. By this time, there was no difference in level of SOCS3 gene expression between LD and SD photoperiods, although body weight was still suppressed in SD hamsters. Finally, we addressed whether SOCS3 gene expression is related to SD-induced gonadal regression or to body weight decrease by comparing Siberian hamsters with Syrian hamsters. The latter exhibited substantial SD-induced gonadal regression but only limited seasonal changes in body weight. Acclimation to either LD or SD for 14 weeks had no effect on SOCS3 gene expression. This implies that arcuate nucleus SOCS3 gene expression is unlikely to be related to seasonal cycles in reproductive activity. Taken together, the findings further strengthen our hypothesis that SOCS3 may be one molecular trigger of seasonal cycles in body weight.

  9. Phenotypic flexibility of energetics in acclimated Siberian hamsters has a narrower scope in winter than in summer.

    PubMed

    Boratyński, Jan S; Jefimow, Małgorzata; Wojciechowski, Michał S

    2016-04-01

    As photoperiod shortens with the approach of winter, small mammals should reduce their energy expenditure to survive periods of food limitation. However, within seasons, animals should balance their energy budgets as abiotic conditions change, sometimes unpredictably; cold spells should increase heat production, while warm spells should do the opposite. Therefore, we addressed specific questions about the possible interactions between seasonal acclimatization and the intra-seasonal phenotypic flexibility of metabolic rate. We hypothesized that phenotypic flexibility in small mammals differs seasonally and is greater in summer than in winter, and predicted that seasonal adjustments in energetics, which are driven by photoperiod, overwhelm the influence of variations in the thermal environment. We measured body mass, basal metabolic rate (BMR), facultative non-shivering thermogenesis (fNST), body temperature, and calculated minimum thermal conductance in Siberian hamsters Phodopus sungorus. Animals were acclimated to winter-like, and then to summer-like conditions and, within each season, were exposed twice, for 3 weeks to 10, 20 or 28 °C. We used differences between values measured after these short acclimation periods as a measure of the scope of phenotypic flexibility. After winter acclimation, hamsters were lighter, had lower whole animal BMR, higher fNST than in summer, and developed heterothermy. After these short acclimations to the above-mentioned temperatures, hamsters showed reversible changes in BMR and fNST; however, these traits were less flexible in winter than in summer. We conclude that seasonal acclimation affects hamster responses to intra-seasonal variations in the thermal environment. We argue that understanding seasonal changes in phenotypic flexibility is crucial for predicting the biological consequences of global climate changes.

  10. Phenotypic flexibility of energetics in acclimated Siberian hamsters has a narrower scope in winter than in summer.

    PubMed

    Boratyński, Jan S; Jefimow, Małgorzata; Wojciechowski, Michał S

    2016-04-01

    As photoperiod shortens with the approach of winter, small mammals should reduce their energy expenditure to survive periods of food limitation. However, within seasons, animals should balance their energy budgets as abiotic conditions change, sometimes unpredictably; cold spells should increase heat production, while warm spells should do the opposite. Therefore, we addressed specific questions about the possible interactions between seasonal acclimatization and the intra-seasonal phenotypic flexibility of metabolic rate. We hypothesized that phenotypic flexibility in small mammals differs seasonally and is greater in summer than in winter, and predicted that seasonal adjustments in energetics, which are driven by photoperiod, overwhelm the influence of variations in the thermal environment. We measured body mass, basal metabolic rate (BMR), facultative non-shivering thermogenesis (fNST), body temperature, and calculated minimum thermal conductance in Siberian hamsters Phodopus sungorus. Animals were acclimated to winter-like, and then to summer-like conditions and, within each season, were exposed twice, for 3 weeks to 10, 20 or 28 °C. We used differences between values measured after these short acclimation periods as a measure of the scope of phenotypic flexibility. After winter acclimation, hamsters were lighter, had lower whole animal BMR, higher fNST than in summer, and developed heterothermy. After these short acclimations to the above-mentioned temperatures, hamsters showed reversible changes in BMR and fNST; however, these traits were less flexible in winter than in summer. We conclude that seasonal acclimation affects hamster responses to intra-seasonal variations in the thermal environment. We argue that understanding seasonal changes in phenotypic flexibility is crucial for predicting the biological consequences of global climate changes. PMID:26803319

  11. Exogenous T₃ elicits long day-like alterations in testis size and the RFamides Kisspeptin and gonadotropin-inhibitory hormone in short-day Siberian hamsters.

    PubMed

    Henson, Jerad R; Carter, Sara N; Freeman, David A

    2013-06-01

    Siberian hamsters (Phodopus sungorus) exhibit robust seasonal rhythms of reproduction driven by changes in day length. Day length is encoded endogenously by the duration of nocturnal melatonin (Mel) secretion from the pineal gland. Short duration Mel signals stimulate whereas long duration Mel signals inhibit reproduction. The mechanism by which Mel regulates the reproductive axis has not been fully characterized. In Siberian hamsters, the thyroid hormone triiodothyronine (T₃) is thought to be part of the photoperiodic mechanism. The availability of T₃ is decreased in hamsters housed in short day lengths, and injections of exogenous T₃ stimulate testicular growth in short-day (SD) Siberian hamsters. Thus, T₃ acts as a neuroendocrine intermediate between the Mel rhythm and the reproductive axis. The RFamides kisspeptin (Kiss1) and gonadotropin-inhibitory hormone (GnIH) also act as a link between the Mel rhythm and the reproductive axis. Expression of both of these neuropeptides is regulated by photoperiod and Mel. Kiss1 stimulates, and GnIH inhibits, the reproductive axis in long-day housed hamsters. It remains unknown whether T₃ acts through changes in RFamide expression in the regulation of reproduction or whether these molecules act independently of one another. We tested the hypothesis that exogenous T₃ administered to SD hamsters, a treatment that stimulates testicular growth, would also result in alterations in the patterns of Kiss1- and GnIH-immunoreactivity. Administration of T₃ to SD hamsters resulted in significant testicular growth as well as a long day-like pattern of RFamide peptide expression. Thus, exogenous T₃ elicited increased numbers of Kiss1-positive cells in the hypothalamic anteroventral periventricular nucleus, decreased numbers of Kiss1-positive cells in the arcuate nucleus, and a greater number of GnIH-positive cells in the dorsomedial hypothalamus compared with SD controls. The results are consistent with the hypothesis that

  12. Rapid photoperiod-induced increase in detectable GnRH mRNA-containing cells in Siberian hamster.

    PubMed

    Porkka-Heiskanen, T; Khoshaba, N; Scarbrough, K; Urban, J H; Vitaterna, M H; Levine, J E; Turek, F W; Horton, T H

    1997-12-01

    To determine whether changes in gonadotropin-releasing hormone (GnRH) neurons are early indicators of photostimulation, Siberian hamsters were placed in short days (6:18-h light-dark) at 3 (experiment 1) or 6 (experiment 2) wk of age where they were held for 3 (experiment 1) or 4 (experiment 2) wk. Hamsters were then moved to long photoperiod (16:8-h light-dark). In experiment 1, brains were collected 1-21 days after transfer from short to long days. In experiment 2, brains were collected only on the second morning of long day exposure. Long and short day controls were included in both experiments. Cells containing GnRH mRNA, as visualized by in situ hybridization, were counted. As expected, there were no differences in the number of detectable GnRH mRNA-containing cells among animals chronically exposed to long or short photoperiods. However, on the second morning after transfer from short to long photoperiod, a positive shift in the distribution of GnRH mRNA-containing cells occurred relative to the respective controls in the two experiments. Increases in follicle-stimulating hormone secretion and gonadal growth occurred days later. In conclusion, a rapid but transient increase in the distribution of detectable GnRH mRNA-containing cells is an early step in the photostimulation of the hypothalamic-pituitary-gonadal axis.

  13. Investigation into the regulation of the circadian system by dopamine and melatonin in the adult Siberian hamster (Phodopus sungorus).

    PubMed

    Duffield, G E; Hastings, M H; Ebling, F J

    1998-11-01

    Dopamine and melatonin have both been implicated in mediating maternal influences on the developing circadian system of altricial rodents. The aim of these studies was to investigate their role in the entrainment of the circadian system of the adult Siberian hamster (Phodopus sungorus). In-situ hybridization revealed that D1-dopamine receptor (D1-R) mRNA was expressed in the adult suprachiasmatic nucleus (SCN) at levels comparable to neonates. As dopamine has been postulated to mimic photic stimulation during early development, experiment 1 compared the effects of a D1-R agonist and a light pulse on free-running wheel running rhythms in hamsters maintained in constant dim red light. A phase response curve to light was generated, revealing clear phase delays early in the subjective night, and large phase advances in the late subjective night. However, the D1-R agonist (SKF 81297, 2 mg/kg, s.c.) did not produce consistent phase shifts at any circadian phase. Experiment 2 tested the ability of this dopaminergic agonist to modulate photic responses of the circadian system. Free-running animals were pre-treated with SKF 81297 (2 mg/kg, s.c.) 30 min before a 15 min light pulse given early or late in the subjective night. This agonist had no effect on the magnitude of phase shifts at either circadian time. In experiment 3, light pulses at CT13-15 induced expression of the immediate early gene c-fos in the SCN, as assessed by immunocytochemistry for the protein product. In contrast, SKF 81297 (2 mg/kg, s.c.) at the same phase did not induce c-fos in the SCN, despite marked c-fos induction in the caudate-putamen, nor did it affect photic induction of c-fos in the SCN. To investigate whether dopamine might be involved in nonphotic regulation of the circadian system in adult hamsters, experiment 4 compared the response of free-running hamsters to a series of injections of SKF 81297 (2 mg/kg, s.c.) or melatonin (1 mg/kg, s.c.), since melatonin receptor expression in the SCN

  14. The role of histamine 3 receptors in the control of food intake in a seasonal model of obesity: the Siberian hamster.

    PubMed

    Jethwa, Preeti H; Barrett, Perry; Turnbull, Yvonne; Enright, Rachel A; Warner, Amy; Murphy, Michelle; Ebling, Francis J P

    2009-03-01

    Siberian hamsters develop hypophagia and increase catabolism of fat reserves in response to short photoperiods resulting in a natural loss of body weight in winter. We previously found that histamine 3 receptor (H3R) mRNA in the posterior hypothalamus is significantly decreased in short photoperiods. We hypothesized that this lower expression of H3R might contribute to the winter hypophagic state, therefore we examined the effects of the H3R agonist imetit and inverse agonists clobenpropit and thioperamide on food intake. We expressed the Siberian hamster H3R receptor in vitro and confirmed that imetit, clobenpropit and thioperamide are bound specifically, thus validating them as tools to investigate the role of H3R in vivo. Intracerebroventricular administration of histamine decreased food intake in hamsters in the fat summer state. Administration of imetit to hamsters in the lean state increased food intake, whereas administration of inverse agonists decreased food intake, though this was associated with decreased locomotor activity. Both H3R inverse agonists prevented the nocturnal rise in body temperature indicating additional effects on energy expenditure. In summary, our results suggest that increased availability of central histamine or the reduction of H3R activity decrease food intake. These effects are similar to those observed in hamsters in short photoperiods.

  15. Diurnal profiles of hypothalamic energy balance gene expression with photoperiod manipulation in the Siberian hamster, Phodopus sungorus.

    PubMed

    Ellis, Claire; Moar, Kim M; Logie, Tracy J; Ross, Alexander W; Morgan, Peter J; Mercer, Julian G

    2008-04-01

    Hypothalamic energy balance genes have been examined in the context of seasonal body weight regulation in the Siberian hamster. Most of these long photoperiod (LD)/short photoperiod (SD) comparisons have been of tissues collected at a single point in the light-dark cycle. We examined the diurnal expression profile of hypothalamic genes in hamsters killed at 3-h intervals throughout the light-dark cycle after housing in LD or SD for 12 wk. Gene expression of neuropeptide Y, agouti-related peptide, proopiomelanocortin, cocaine- and amphetamine-regulated transcript, long-form leptin receptor, suppressor of cytokine signaling-3, melanocortin-3 receptor, melanocortin-4 receptor, and the clock gene Per1 as control were measured by in situ hybridization in hypothalamic nuclei. Effects of photoperiod on gene expression and leptin levels were generally consistent with previous reports. A clear diurnal variation was observed for Per1 in the suprachiasmatic nucleus in both photoperiods. Temporal effects on expression of energy balance genes were restricted to long-form leptin receptor in the arcuate nucleus and ventromedial nucleus, where similar diurnal expression profiles were observed, and melanocortin-4 receptor in the paraventricular nucleus; these effects were only observed in LD hamsters. There was no variation in serum leptin concentration. The 24-h profiles of hypothalamic energy balance gene expression broadly confirm photoperiodic differences that were observed previously, based on single time point comparisons, support the growing consensus that these genes have a limited role in seasonal body weight regulation, and further suggest limited involvement in daily rhythms of food intake.

  16. Central administration of thyrotropin releasing hormone (TRH) and related peptides inhibits feeding behavior in the Siberian hamster.

    PubMed

    Steward, Carolyn A; Horan, Tracey L; Schuhler, Sandrine; Bennett, Geoffrey W; Ebling, Francis J P

    2003-04-15

    Centrally acting thyrotropin releasing hormone (TRH), independent of endocrine action, has been shown to regulate several metabolic and behavioral parameters in rats, including food intake and locomotor activity. The present study investigated and compared the effects of central TRH on feeding behavior in Siberian hamsters exposed to long (LP) or short (SP) photoperiods, which induce natural physiological states of obesity and leanness respectively. The effects of two TRH analogues, RX77368 (a metabolically stable TRH analogue) and TRH-Gly (an endogenous precursor to TRH with putative preferential action at the central TRH receptor, TRH-R2), were also investigated. All peptides were infused via the third ventricle (i.c.v.). Food intake was measured, and the proportion of time spent interacting with food, active or resting was scored. TRH (5 microg) significantly reduced food intake without producing associated changes in activity in hamsters maintained in both LP (p < 0.001) and SP (p < 0.05). A lower dose of TRH (0.5 microg) only decreased feeding significantly (p < 0.01) in hamsters exposed to SP, indicating that there may be an underlying difference in sensitivity to TRH depending on metabolic state. RX77368 (1 microg) produced substantial hypophagia (p < 0.001) and decreased the proportion of time spent interacting with food, but, unlike TRH, may produce this via an increase in locomotor activity. TRH-Gly (5 microg) produced a small decrease in food intake (p < 0.05), lasting for 6 h. We conclude that TRH and TRH analogues possess anorexigenic capacities in this species, with a likely site of action in the hypothalamus. Increased sensitivity to the hypophagic effects of central TRH may contribute to the long-term catabolic state induced by short photoperiods.

  17. Conserved expression of the glutamate NMDA receptor 1 subunit splice variants during the development of the Siberian hamster suprachiasmatic nucleus.

    PubMed

    Duffield, Giles E; Mikkelsen, Jens D; Ebling, Francis J P

    2012-01-01

    Glutamate neurotransmission and the N-methyl-D-aspartate receptor (NMDAR) are central to photic signaling to the master circadian pacemaker located in the hypothalamic suprachiasmatic nucleus (SCN). NMDARs also play important roles in brain development including visual input circuits. The functional NMDAR is comprised of multiple subunits, but each requiring the NR1 subunit for normal activity. The NR1 can be alternatively spliced to produce isoforms that confer different functional properties on the NMDAR. The SCN undergoes extensive developmental changes during postnatal life, including synaptogenesis and acquisition of photic signaling. These changes are especially important in the highly photoperiodic Siberian hamster, in which development of sensitivity to photic cues within the SCN could impact early physiological programming. In this study we examined the expression of NR1 isoforms in the hamster at different developmental ages. Gene expression in the forebrain was quantified by in situ hybridization using oligonucleotide probes specific to alternatively spliced regions of the NR1 heteronuclear mRNA, including examination of anterior hypothalamus, piriform cortex, caudate-putamen, thalamus and hippocampus. Gene expression analysis within the SCN revealed the absence of the N1 cassette, the presence of the C2 cassette alone and the combined absence of C1 and C2 cassettes, indicating that the dominant splice variants are NR1-2a and NR1-4a. Whilst we observe changes at different developmental ages in levels of NR1 isoform probe hybridization in various forebrain structures, we find no significant changes within the SCN. This suggests that a switch in NR1 isoform does not underlie or is not produced by developmental changes within the hamster SCN. Consistency of the NR1 isoforms would ensure that the response of the SCN cells to photic signals remains stable throughout life, an important aspect of the function of the SCN as a responder to environmental changes

  18. Orexin A-like immunoreactivity in the hypothalamus and thalamus of the Syrian hamster (Mesocricetus auratus) and Siberian hamster (Phodopus sungorus), with special reference to circadian structures.

    PubMed

    McGranaghan, P A; Piggins, H D

    2001-06-22

    The orexins are recently discovered neuropeptides that reportedly play a role in energy homeostasis, in addition to various other physiological processes. The synthesis of orexin A undergoes diurnal variation in certain areas of the brain, while the mutation of the orexin receptor 2 gene has been implicated in canine narcolepsy. Since the circadian pacemaker in the suprachiasmatic nucleus modulates the sleep/wake cycle, there is a putative role for orexins in the mammalian circadian system. In this study, immunohistochemical techniques were used to determine the distribution of orexin A in the structures of the hypothalamus and thalamus of Syrian and Siberian hamsters. In both species, the pattern of immunoreactivity was similar. Cells immunoreactive for orexin A were noted in the lateral hypothalamic area. Immunoreactive varicose orexin A fibres were found throughout the hypothalamus. The suprachiasmatic nucleus possessed little or no immunoreactive orexin A fibres in its core, but had fibres at its periphery. The thalamus of both species contained comparatively few immunoreactive fibres, which were mainly localised around the midline. The thalamic intergeniculate leaflet contained a plexus of immunoreactive orexin A fibres throughout its rostro-caudal extent. Three areas of the brainstem, the dorsal and median raphe nuclei and the locus coeruleus, were also investigated owing to their relevance to the circadian system and all were found to contain immunoreactive orexin A fibres. The presence of orexin A-immunoreactive fibres in the neural architecture of the mammalian circadian system suggests an important role for orexin A in circadian timekeeping processes.

  19. Photoperiodic regulation of leptin sensitivity in the Siberian hamster, Phodopus sungorus, is reflected in arcuate nucleus SOCS-3 (suppressor of cytokine signaling) gene expression.

    PubMed

    Tups, Alexander; Ellis, Claire; Moar, Kim M; Logie, Tracy J; Adam, Clare L; Mercer, Julian G; Klingenspor, Martin

    2004-03-01

    We present the first evidence that suppressor of cytokine signaling-3 (SOCS3), a protein inhibiting Janus kinase/signal transducer and activator of transcription (STAT) signaling distal of the leptin receptor, conveys seasonal changes in leptin sensitivity in the Siberian hamster. Food deprivation (48 h) reduced SOCS3 gene expression in hamsters acclimated to either long (LD) or short (SD) photoperiods, suggesting that leptin signals acute starvation regardless of photoperiod. However, SOCS3 mRNA levels were substantially lower in the hypothalamic arcuate nucleus of hamsters acclimated to SD than in those raised in LD. In juveniles raised in LD, a rapid increase in SOCS3 mRNA was observed within 4 d of weaning, which was completely prevented by transfer to SD on the day of weaning. The early increase in SOCS3 gene expression in juvenile hamsters in LD clearly preceded the establishment of different body weight trajectories in LD and SD. In adult LD hamsters, SOCS3 mRNA was maintained at an elevated level despite the chronic food restriction imposed to lower body weight and serum leptin to or even below SD levels. A single injection of leptin in SD hamsters elevated SOCS3 mRNA to LD levels, whereas leptin treatment had no effect on SOCS3 gene expression in LD hamsters. Our results suggest that the development of leptin resistance in LD-acclimated hamsters involves SOCS3-mediated suppression of leptin signaling in the arcuate nucleus. Increased SOCS3 expression in LD hamsters is independent of body fat and serum leptin levels, suggesting that the photoperiod is able to trigger the biannual reversible switch in leptin sensitivity.

  20. The circadian cycle of mPER clock gene products in the suprachiasmatic nucleus of the siberian hamster encodes both daily and seasonal time.

    PubMed

    Nuesslein-Hildesheim, B; O'Brien, J A; Ebling, F J; Maywood, E S; Hastings, M H

    2000-08-01

    The circadian clock in the hypothalamic suprachiasmatic nuclei (SCN) regulates the pattern of melatonin secretion from the pineal gland such that the duration of release reflects the length of the night. This seasonally specific endocrine cue mediates annual timing in photoperiodic mammals. The aim of this study was to investigate how changes in photoperiod influence the cyclic expression of recently identified clock gene products (mPER and mTIM) in the SCN of a highly seasonal mammal, the Siberian hamster (Phodopus sungorus). Immunocytochemical studies indicate that the abundance of both mPER1 and mPER2 (but not mTIM) in the SCN exhibits very pronounced, synchronous daily cycles, peaking approximately 12 h after lights-on. These rhythms are circadian in nature as they continue approximately under free-running conditions. Their circadian waveform is modulated by photoperiod such that the phase of peak mPER expression is prolonged under long photoperiods. mPER1 protein is also expressed in the pars tuberalis of Siberian hamsters. In hamsters adapted to long days, the expression of mPER1 is elevated at the start of the light phase. In contrast, there is no clear elevation in mPER1 levels in the pars tuberalis of hamsters held on short photoperiods. These results indicate that core elements of the circadian clockwork are sensitive to seasonal time, and that encoding and decoding of seasonal information may be mediated by the actions of these transcriptional modulators.

  1. Photoperiod regulates multiple gene expression in the suprachiasmatic nuclei and pars tuberalis of the Siberian hamster (Phodopus sungorus).

    PubMed

    Johnston, Jonathan D; Ebling, Francis J P; Hazlerigg, David G

    2005-06-01

    Photoperiod regulates the seasonal physiology of many mammals living in temperate latitudes. Photoperiodic information is decoded by the master circadian clock in the suprachiasmatic nuclei (SCN) of the hypothalamus and then transduced via pineal melatonin secretion. This neurochemical signal is interpreted by tissues expressing melatonin receptors (e.g. the pituitary pars tuberalis, PT) to drive physiological changes. In this study we analysed the photoperiodic regulation of the circadian clockwork in the SCN and PT of the Siberian hamster. Female hamsters were exposed to either long or short photoperiod for 8 weeks and sampled at 2-h intervals across the 24-h cycle. In the SCN, rhythmic expression of the clock genes Per1, Per2, Cry1, Rev-erbalpha, and the clock-controlled genes arginine vasopressin (AVP) and d-element binding protein (DBP) was modulated by photoperiod. All of these E-box-containing genes tracked dawn, with earlier peak mRNA expression in long, compared to short, photoperiod. This response occurred irrespective of the presence of additional regulatory cis-elements, suggesting photoperiodic regulation of SCN gene expression through a common E-box-related mechanism. In long photoperiod, expression of Cry1 and Per1 in the PT tracked the onset and offset of melatonin secretion, respectively. However, whereas Cry1 tracked melatonin onset in short period, Per1 expression was not detectably rhythmic. We therefore propose that, in the SCN, photoperiodic regulation of clock gene expression primarily occurs via E-boxes, whereas melatonin-driven signal transduction drives the phasing of a subset of clock genes in the PT, independently of the E-box.

  2. Antibody-Mediated Inhibition of the FGFR1c Isoform Induces a Catabolic Lean State in Siberian Hamsters.

    PubMed

    Samms, Ricardo J; Lewis, Jo E; Lory, Alex; Fowler, Maxine J; Cooper, Scott; Warner, Amy; Emmerson, Paul; Adams, Andrew C; Luckett, Jeni C; Perkins, Alan C; Wilson, Dana; Barrett, Perry; Tsintzas, Kostas; Ebling, Francis J P

    2015-11-16

    Hypothalamic tanycytes are considered to function as sensors of peripheral metabolism. To facilitate this role, they express a wide range of receptors, including fibroblast growth factor receptor 1 (FGFR1). Using a monoclonal antibody (IMC-H7) that selectively antagonizes the FGFR1c isoform, we investigated possible actions of FGFR1c in a natural animal model of adiposity, the Siberian hamster. Infusion of IMC-H7 into the third ventricle suppressed appetite and increased energy expenditure. Likewise, peripheral treatment with IMC-H7 decreased appetite and body weight and increased energy expenditure and fat oxidation. A greater reduction in body weight and caloric intake was observed in response to IMC-H7 during the long-day fat state as compared to the short-day lean state. This enhanced response to IMC-H7 was also observed in calorically restricted hamsters maintained in long days, suggesting that it is the central photoperiodic state rather than the peripheral adiposity that determines the response to FGFR1c antagonism. Hypothalamic thyroid hormone availability is controlled by deiodinase enzymes (DIO2 and DIO3) expressed in tanycytes and is the key regulator of seasonal cycles of energy balance. Therefore, we determined the effect of IMC-H7 on hypothalamic expression of these deiodinase enzymes. The reductions in food intake and body weight were always associated with decreased expression of DIO2 in the hypothalamic ependymal cell layer containing tanycytes. These data provide further support for the notion the tanycytes are an important component of the mechanism by which the hypothalamus integrates central and peripheral signals to regulate energy intake and expenditure.

  3. The thyrotropin-releasing hormone secretory system in the hypothalamus of the Siberian hamster in long and short photoperiods.

    PubMed

    Ebling, F J P; Wilson, D; Wood, J; Hughes, D; Mercer, J G; Morgan, P J; Barrett, P

    2008-05-01

    Thyrotropin-releasing hormone (TRH) is not only essential for the regulation of the pituitary-thyroid axis, but also exerts complementary effects on energy metabolism within the brain. We hypothesised that increased activity of the TRH secretory system may contribute to seasonal adaptations in the Siberian hamster whereby food intake is decreased in winter, and catabolism of fat stores is increased to support thermogenesis. We determined the distribution of TRH producing neurones and TRH-R1 receptor expressing cells in the hypothalamus, and investigated whether photoperiod regulated this system. TRH-immunoreactive (ir) cell somata and preproTRH mRNA expression were found to be widely distributed throughout the medial hypothalamus, with particular clusters in the paraventricular nucleus, the medial preoptic area and periventricular nucleus, and in the dorsomedial hypothalamus extending into the lateral hypothalamic area. A partial sequence encoding TRH-R1 was cloned from hamster hypothalamic cDNA and used to generate a riboprobe for in situ hybridisation studies. TRH-R1 mRNA expressing cells were abundant throughout the hypothalamus, corresponding to the widespread presence of TRH-ir fibres. Photoperiod did not affect the expression of preproTRH mRNA in any region, and the only significant change in TRH-R1 expression was in the dorsomedial posterior arcuate region. This wide distribution of TRH-producing and receptive cells in the hypothalamus is consistent with its hypothesised neuromodulatory roles in the short-term homeostatic control of appetite, thermoregulation and energy expenditure, but the lack of photoperiodic change in TRH mRNA expression does not support the hypothesis that changes in this system underlie long-term seasonal changes in body weight.

  4. Timing of light pulses and photoperiod on the diurnal rhythm of hippocampal neuronal morphology of Siberian hamsters.

    PubMed

    Ikeno, T; Weil, Z M; Nelson, R J

    2014-06-13

    Rapid remodeling of neurons provides the brain with flexibility to adjust to environmental fluctuations. In Siberian hamsters, hippocampal dendritic morphology fluctuates across the day. To reveal the regulatory mechanism of diurnal remodeling of hippocampal neurons, we investigated the effects of light signals applied under different photoperiodic conditions on dendritic morphology. A 4-h dark pulse during the morning of long days (LD) increased basilar dendritic length, as well as complexity of basilar dendrites of neurons in the CA1. A light pulse during the late night in short days (SD) reduced basilar dendrite branching and increased primary apical dendrites of CA1 neurons. Spine density of dentate gyrus (DG) dendrites was increased by a dark pulse in LD and spine density of CA1 basilar dendrites was decreased by a light pulse in SD. These results indicate that light signals induce rapid remodeling of dendritic morphology in a hippocampal subregion-specific manner. A light pulse in SD decreased hippocampal expression of fetal liver kinase 1 (Flk1), a receptor for vascular endothelial growth factor (VEGF), raising the possibility that VEGF-FLK1 signaling might be involved in the rapid decrease of branching or spine density of CA1 basilar dendrites by light.

  5. Short photoperiod-induced decrease of histamine H3 receptors facilitates activation of hypothalamic neurons in the Siberian hamster.

    PubMed

    Barrett, P; van den Top, M; Wilson, D; Mercer, J G; Song, C K; Bartness, T J; Morgan, P J; Spanswick, D

    2009-08-01

    Nonhibernating seasonal mammals have adapted to temporal changes in food availability through behavioral and physiological mechanisms to store food and energy during times of predictable plenty and conserve energy during predicted shortage. Little is known, however, of the hypothalamic neuronal events that lead to a change in behavior or physiology. Here we show for the first time that a shift from long summer-like to short winter-like photoperiod, which induces physiological adaptation to winter in the Siberian hamster, including a body weight decrease of up to 30%, increases neuronal activity in the dorsomedial region of the arcuate nucleus (dmpARC) assessed by electrophysiological patch-clamping recording. Increased neuronal activity in short days is dependent on a photoperiod-driven down-regulation of H3 receptor expression and can be mimicked in long-day dmpARC neurons by the application of the H3 receptor antagonist, clobenproprit. Short-day activation of dmpARC neurons results in increased c-Fos expression. Tract tracing with the trans-synaptic retrograde tracer, pseudorabies virus, delivered into adipose tissue reveals a multisynaptic neuronal sympathetic outflow from dmpARC to white adipose tissue. These data strongly suggest that increased activity of dmpARC neurons, as a consequence of down-regulation of the histamine H3 receptor, contributes to the physiological adaptation of body weight regulation in seasonal photoperiod.

  6. Graded response to short photoperiod during development and early adulthood in Siberian hamsters and the effects on reproduction as females age

    PubMed Central

    Place, Ned J.; Cruickshank, Jenifer

    2009-01-01

    Short day (SD) lengths delay puberty, suppress ovulation, inhibit sexual behavior, and decelerate reproductive aging in female Siberian hamsters (Phodopus sungorus). To date, the modulation of the age-associated decline in reproductive outcomes has only been demonstrated in female hamsters experiencing different day lengths during development. To determine if developmental delay is necessary for photo-inhibition to decelerate reproductive aging, hamsters raised in LD were transferred to SD as young adults and remained there for 6 months. Females that demonstrated the most immediate and sustained photo-inhibition were found to have greater numbers of ovarian primordial follicles at advanced ages (9 and 12 months) than did females held in LD, nonresponders to SD, and females with a marginal SD-response. Similarly, for females raised in SD from conception to 6 months of age, prolonged developmental delay was associated with greater numbers of primordial follicles at later ages as compared to hamsters that became refractory to SD. A robust response to SD in juvenile and adult hamsters is associated with decelerated reproductive aging, which may result in greater reproductive success in older females as compared to age-matched individuals demonstrating a more modest response to SD. PMID:19470367

  7. Circadian Disruption Alters the Effects of Lipopolysaccharide Treatment on Circadian and Ultradian Locomotor Activity and Body Temperature Rhythms of Female Siberian Hamsters.

    PubMed

    Prendergast, Brian J; Cable, Erin J; Stevenson, Tyler J; Onishi, Kenneth G; Zucker, Irving; Kay, Leslie M

    2015-12-01

    The effect of circadian rhythm (CR) disruption on immune function depends on the method by which CRs are disrupted. Behavioral and thermoregulatory responses induced by lipopolysaccharide (LPS) treatment were assessed in female Siberian hamsters in which circadian locomotor activity (LMA) rhythms were eliminated by exposure to a disruptive phase-shifting protocol (DPS) that sustains arrhythmicity even when hamsters are housed in a light-dark cycle. This noninvasive treatment avoids genome manipulations and neurological damage associated with other models of CR disruption. Circadian rhythmic (RHYTH) and arrhythmic (ARR) hamsters housed in a 16L:8D photocycle were injected with bacterial LPS near the onset of the light (zeitgeber time 1; ZT1) or dark (ZT16) phase. LPS injections at ZT16 and ZT1 elicited febrile responses in both RHYTH and ARR hamsters, but the effect was attenuated in the arrhythmic females. In ZT16, LPS inhibited LMA in the dark phase immediately after injection but not on subsequent nights in both chronotypes; in contrast, LPS at ZT1 elicited more enduring (~4 day) locomotor hypoactivity in ARR than in RHYTH hamsters. Power and period of dark-phase ultradian rhythms (URs) in LMA and Tb were markedly altered by LPS treatment, as was the power in the circadian waveform. Disrupted circadian rhythms in this model system attenuated responses to LPS in a trait- and ZT-specific manner; changes in UR period and power are novel components of the acute-phase response to infection that may affect energy conservation.

  8. Complementary histological and genomic analyses reveal marked differences in the developmental trajectories of ovaries in Siberian hamsters raised in long- and short-day lengths.

    PubMed

    Park, Sung-Un; Bernstein, Adrien N; Place, Ned J

    2014-03-01

    Siberian hamsters (Phodopus sungorus) delay sexual development when raised in short-day (SD; 10 hr light: 14 hr dark) conditions, which leads to delayed onset of estrous cycles and ovulations as compared to females raised in long-day (LD; 16 hr light: 8 hr dark) conditions. In addition to the absence of pre-ovulatory follicles and corpora lutea, the ovaries of SD-reared Siberian hamsters are characterized by an abundance of hypertrophied granulosa cells (HGCs) that surround atretic oocytes. To determine the age at which the histology of LD and SD ovaries first diverge, including the initial appearance of HGCs in SD conditions, we examined hamster ovaries histologically at 1, 2, 3, 4, 6, 8, 10, and 12 weeks of age. After identifying subtle differences in LD and SD ovarian histology at 4 weeks of age, we searched for differences in ovarian gene expression at 3 and 8 weeks of age, which correspond to the ages when ovarian histology do not differ (3 weeks) versus the earliest age when HGCs were observed (8 weeks). At 3 weeks, only 14 genes were differentially expressed in LD and SD ovaries, whereas 183 genes were differentially expressed at 8 weeks. Overall, our findings demonstrate that ovarian development under SD conditions is not simply arrested at an early stage of LD development, but rather utilizes a developmental path that is distinct from that used in LD ovaries.

  9. Sex differences in photoperiod control of antigen-specific primary and secondary humoral immunity in Siberian Hamsters.

    PubMed

    Hadley, Allison R; Tran, Long T; Fagoaga, Omar R; Nehlsen-Cannarella, Sandra L; Yellon, Steven M

    2002-07-01

    Photoperiod was hypothesized to mediate T cell-dependent B cell production of IgM and IgG. Antigens induced production of specific immunoglobulins; serum IgM but not IgG, was higher in males in long vs. short days (16 vs. 8 h light/day) and similarly among all groups of females. A second immunization with KLH robustly enhanced serum IgM, as well as IgG; increases were blunted in short- vs. long-day males but not in females. Thus, in male but not female hamsters, winter-like short days restrain aspects of primary and secondary humoral immune responses to xenoantigens. Actions on lymphocyte activities or clonal expansion are in considerations.

  10. Multiple melatonin target tissues mediate termination of photorefractoriness by long day lengths in Siberian hamsters.

    PubMed

    Teubner, Brett J W; Smith, Carlesia D; Freeman, David A

    2008-12-01

    The development of refractoriness to the short-day melatonin rhythm in mid-winter triggers recrudescence of the photoinhibited reproductive system of many rodents. As a result, over-wintering animals attain reproductive competence prior to the onset of spring conditions that favor successful reproduction. While in the photorefractory state, hamsters are insensitive to short day lengths and the associated long-duration melatonin rhythm. Prior to regaining sensitivity to short day length inhibition of reproduction, hamsters must first be exposed to 10 to 12 weeks of long, summer-like day lengths and the associated short-duration melatonin rhythm. The neural melatonin target tissues that mediate the breaking of photorefractoriness by long day lengths have not been identified. Long day length information is thought to be communicated to the reproductive axis through the actions of melatonin at the reuniens nucleus of the thalamus (NRe) and the SCN of the hypothalamus. The authors report that the SCN and the NRe also participate in the breaking of reproductive photorefractoriness by long day lengths. Micro-implants of melatonin that were left in place for 12 weeks during exposure to long day lengths and that act locally on these brain nuclei to obscure the endogenous melatonin rhythm, and thus ambient day length information, blocked the breaking of refractoriness. Identical melatonin implants located in another melatonin target tissue, the paraventricular nucleus of the thalamus, did not interfere with the breaking of reproductive refractoriness. By contrast, breaking of refractoriness of the seasonal body mass response did not follow the pattern exhibited by the reproductive response. The results suggest that these melatonin target tissues serve distinct but overlapping roles in the photoperiodic mechanism.

  11. Mitochondrial metabolism during daily torpor in the dwarf Siberian hamster: role of active regulated changes and passive thermal effects.

    PubMed

    Brown, Jason C L; Gerson, Alexander R; Staples, James F

    2007-11-01

    During daily torpor in the dwarf Siberian hamster, Phodopus sungorus, metabolic rate is reduced by 65% compared with the basal rate, but the mechanisms involved are contentious. We examined liver mitochondrial respiration to determine the possible role of active regulated changes and passive thermal effects in the reduction of metabolic rate. When assayed at 37 degrees C, state 3 (phosphorylating) respiration, but not state 4 (nonphosphorylating) respiration, was significantly lower during torpor compared with normothermia, suggesting that active regulated changes occur during daily torpor. Using top-down elasticity analysis, we determined that these active changes in torpor included a reduced substrate oxidation capacity and an increased proton conductance of the inner mitochondrial membrane. At 15 degrees C, mitochondrial respiration was at least 75% lower than at 37 degrees C, but there was no difference between normothermia and torpor. This implies that the active regulated changes are likely more important for reducing respiration at high temperatures (i.e., during entrance) and/or have effects other than reducing respiration at low temperatures. The decrease in respiration from 37 degrees C to 15 degrees C resulted predominantly from a considerable reduction of substrate oxidation capacity in both torpid and normothermic animals. Temperature-dependent changes in proton leak and phosphorylation kinetics depended on metabolic state; proton leakiness increased in torpid animals but decreased in normothermic animals, whereas phosphorylation activity decreased in torpid animals but increased in normothermic animals. Overall, we have shown that both active and passive changes to oxidative phosphorylation occur during daily torpor in this species, contributing to reduced metabolic rate.

  12. Differential Ovarian Expression of KiSS-1 and GPR-54 During the Estrous Cycle and Photoperiod Induced Recrudescence in Siberian Hamsters (Phodopus sungorus)

    PubMed Central

    Shahed, Asha; Young, Kelly A.

    2008-01-01

    Kisspeptins, coded by the KiSS-1 gene, regulate aspects of the reproductive axis by stimulating GnRH release via the G protein coupled receptor, GPR54. Recent reports show that KiSS/GPR54 may be key mediators in photoperiod-controlled reproduction in seasonal breeders, and that KiSS-1/GPR54 are expressed in the hypothalamus, ovaries, placenta, and pancreas. This study examined the expression of KiSS-1/GPR54 mRNA and protein in ovaries of Siberian hamsters (Phodopus sungorus). Ovaries from cycling hamsters were collected during proestrus (P), estrus (E), diestrus I (DI), and diestrus II (DII). To examine KiSS-1/GPR54 during stimulated recrudescence, additional hamsters were maintained either in long day (LD 16L:8D, control) or short day (SD 8L:16D) for 14 weeks and then transferred to LD for 0–8 weeks. Staining of KiSS-1/GPR54 protein was detected by immunohistochemistry in steroidogenic cells of preantral and antral follicles, and corpora lutea. Immunostaining peaked in P and E, but decreased in the diestrus stages (p<0.05). In recrudescing ovaries, KiSS-1/GPR54 immunostaining was low after 14 wks of SD exposure (post transfer [PT] wk0), and increased during the early weeks of recrudescence. Expression of KiSS-1/GPR54 mRNA was low with short day exposure, but increased during recrudescence and was higher at PT wk8 as compared to PTwks 0 and 2 (p<0.05). The elevated KiSS-1/ GPR54 expression during P and E suggests a potential role in ovulation in Siberian hamsters. Transient increases in KiSS-1/GPR54 expression following LD stimulation are also suggestive of possible involvement in ovulation and/or restoration of ovarian function. PMID:18937338

  13. Photoperiodic regulation of cellular retinol binding protein, CRBP1 [corrected] and nestin in tanycytes of the third ventricle ependymal layer of the Siberian hamster.

    PubMed

    Barrett, Perry; Ivanova, Elena; Graham, E Scott; Ross, Alexander W; Wilson, Dana; Plé, Helene; Mercer, Julian G; Ebling, Francis J; Schuhler, Sandrine; Dupré, Sandrine M; Loudon, Andrew; Morgan, Peter J

    2006-12-01

    Tanycytes in the ependymal layer of the third ventricle act both as a barrier and a communication gateway between the cerebrospinal fluid, brain and portal blood supply to the pituitary gland. However, the range, importance and mechanisms involved in the function of tanycytes remain to be explored. In this study, we have utilized a photoperiodic animal to examine the expression of three unrelated gene sequences in relation to photoperiod-induced changes in seasonal physiology and behaviour. We demonstrate that cellular retinol binding protein [corrected] (CRBP1), a retinoic acid transport protein, GPR50, an orphan G-protein-coupled receptor and nestin, an intermediate filament protein, are down-regulated in short-day photoperiods. The distribution of the three sequences is very similar, with expression located in cells with tanycyte morphology in the region of the ependymal layer where tanycytes are located. Furthermore, CRBP1 expression in the ependymal layer is shown to be independent of a circadian clock and altered testosterone levels associated with testicular regression in short photo-period. Pinealectomy of Siberian hamsters demonstrates CRBP1 expression is likely to be dependent on melatonin output from the pineal gland. This provides evidence that tanycytes are seasonally responsive cells and are likely to be an important part of the mechanism to facilitate seasonal physiology and behaviour in the Siberian hamster.

  14. Melatonin rhythm onset in the adult siberian hamster: influence of photoperiod but not 60-Hz magnetic field exposure on melatonin content in the pineal gland and in circulation.

    PubMed

    Yellon, S M; Truong, H N

    1998-02-01

    To determine the relationship between pineal melatonin production and its appearance in circulation, the rising phase of the pineal and serum melatonin rhythm was studied in the adult Siberian hamster. Melatonin concentrations increased in the pineal gland and in serum at 1.50 and 1.75 h, respectively, relative to lights off in long days (16 h of light/day) and at 2.00 and 2.75 h, respectively, in short days (10 h of light/day). Thus, a photoperiod-dependent melatonin rise in circulation lagged production by the pineal gland by 0.50 h--a delay of 0.75 h in short-day hamsters versus 0.25 h in long-day hamsters. Following initiation of this rise, concentrations that were typical of the nighttime peak were achieved within 2 h of melatonin rhythm onset, regardless of photoperiod. To determine whether clock control of the rising phase of the melatonin rhythm, in the absence of photoperiod cues, may be disrupted by perturbations in the ambient magnetic field, hamsters in constant darkness were acutely exposed to a 1-Gauss, 60-Hz magnetic field for 15 min or were daily exposed to this treatment for 14 or 21 days. Neither the melatonin rise in pineal content or circulation during subjective night was affected by acute or chronic magnetic field exposures; testes regression similarly occurred in sham and daily magnetic field-exposed hamsters in constant darkness. These findings indicate that magnetic field exposures are unlikely to serve as a zeitgeber for the circadian mechanism that controls onset of the melatonin rhythm; rather, photoperiod is a predominant cue that may differentially regulate the rising phase of melatonin production in the pineal gland and concentration in circulation.

  15. Male golden hamster in male reproductive toxicology testing: Assessment of protective activity of selenium in acute cadmium intoxication

    SciTech Connect

    Wiodarczyk, B.; Biernacki, B.; Minta, M.; Juszkiewicz, T.; Kozaczynski, W.

    1995-06-01

    The golden hamster has a short history as a laboratory animal. In spite of this, it has been extensively used as a subject for biomedical research. The hamster has also been utilized in toxicological evaluations, especially in teratology studies. Results of these investigations reveal that laboratory hamsters are very sensitive to many chemical compounds, including: drugs, food additives, industrial chemicals, heavy metals, and other environmental contaminants. The animals most frequently used in toxicological investigations are rats and mice. This is also true in male reproductive toxicology. Apparent differences in species sensitivity to chemical compounds suggest a need to examine a new species in this field of toxicology. A good example of chemical specific differences in species sensitivity is the testicular toxicity of 1,2-dibromo-3-chloropropane (DBCP), which was a testicular toxicant in humans and in rats, but it was not effective, even at relatively high dose levels, in the mouse. From our own vast experience in using hamsters in toxicological studies, we decided to use this laboratory animal in male reproductive toxicology screening tests. The purpose of this study was to determine the suitability of golden hamsters as an experimental animal species for male reproductive toxicology testing. To this effect we have chosen selenium and cadmium as test agents as they were well known for their spectacular effect on the male reproductive system. 13 refs., 1 tab.

  16. Effects of 60 Hz magnetic field exposure on the pineal and hypothalamic-pituitary-gonadal axis in the Siberian hamster (Phodopus sungorus).

    PubMed

    Wilson, B W; Matt, K S; Morris, J E; Sasser, L B; Miller, D L; Anderson, L E

    1999-01-01

    Experiments using the dwarf Siberian hamster Phodopus sungorus were carried out to determine possible neuroendocrine consequences of one-time and repeated exposures to 60 Hz magnetic fields (MF). Animals were maintained in either a short-light (SL, 8 h light:16 h dark) or long-light (LL, 16 h light:8 h dark) photoperiod. Acute (one-time, 15 min) exposure of male SL animals to a linearly polarized, horizontally oriented, 60 Hz MF (0.1 mT) gave rise to a statistically significant (P < .005) reduction in pineal melatonin content as determined 3 and 5 h after onset of darkness. In LL animals, acute exposure to 0.10 mT resulted in a significant decrease in pineal melatonin as measured 4 h after onset of darkness, whereas acute exposure to 50 microT showed no effect compared with sham exposure. In SL animals, an increase in norepinephrine was observed in the medial basal hypothalamus (including the suprachiasmatic nucleus) after acute exposure (P < .01). Daily MF exposure of SL animals to a combination of steady-state and on/off 60 Hz magnetic fields (intermittent exposure) at 0.1 mT for 1 h per day for 16 days was associated with a reduction in melatonin concentrations at 4 h after onset of darkness and an increase in blood prolactin concentrations (P < .05). Exposure of SL animals to a steady state 60 Hz MF for 3 h/day for 42 days resulted in a statistically significant reduction in body weight (ANOVA: P > .05), compared with sham-exposed SL animals. At 42 days, however, no significant changes in overnight melatonin or prolactin levels were detected. In both repeated exposure experiments, gonadal weights were lowest in the MF-exposed groups. This difference was statistically significant (P < .05) after 42 days of exposure. These data indicate that both one-time and repeated exposure to a 0.1 mT, 60 Hz MF can give rise to neuroendocrine responses in Phodopus.

  17. Partner preference in male hamsters: steroids, sexual experience and chemosensory cues.

    PubMed

    Ballard, Cortney L; Wood, Ruth I

    2007-05-16

    This study investigated the effects of gonadal steroids on sexual motivation in male Syrian hamsters, using partner preference as a model. Male hamsters were assigned to 5 groups: control (n=4), Intact-->Orchx (n=8), Orchx-->Orchx+T (n=7), olfactory bulbectomy (BulbX, n=5), and vomeronasal organ lesion (VnoX, n=8). Each male was tested for partner preference before and after sexual experience. Unlike rats, sexually-inexperienced gonad-intact male hamsters preferred the receptive female to a stimulus male. However, sexual experience did not enhance preference for the stimulus female. Castration (Orchx) reduced sexual motivation: Orchx males showed no significant preference for the stimulus female. Subsequently, intact males were castrated (Intact-->Orchx) and Orchx males received a testosterone implant (Orchx-->Orchx+T) to determine the time course of gonadal hormones on partner preference and mating behavior. Partner preference changed significantly in both groups within 6 weeks. In Intact-->Orchx males, preference for the stimulus female decreased while Orchx-->Orchx+T males increased their preference for the stimulus female. However, significant changes in mating behavior preceded the alterations in partner preference. Chemosensory cues are also important for partner preference. After BulbX, preference for the stimulus female significantly decreased. However, VnoX failed to block partner preference. These results show that partner preference may be even more dependent on testosterone than is sexual behavior. Furthermore, while chemosensory cues are essential for sexual motivation, the vomeronasal organ is not required for partner preference.

  18. Daily and photoperiodic melatonin binding changes in the suprachiasmatic nuclei, paraventricular thalamic nuclei, and pars tuberalis of the female Siberian hamster (Phodopus sungorus).

    PubMed

    Recio, J; Pévet, P; Vivien-Roels, B; Míguez, J M; Masson-Pévet, M

    1996-12-01

    Using quantitative autoradiography, 2-(125)I-melatonin binding was investigated throughout the light:dark cycle in the suprachiasmatic nuclei (SCN), paraventricular nuclei (PVT), and pars tuberalis (PT) of adult female Siberian hamsters kept for 10 weeks in either long or short photoperiods (LP or SP, respectively). Plasma melatonin concentrations were measured by radioimmunoassay, and the sexual status of the animals was established by visual inspection of vaginal smears and by weighing uteri after sacrifice. The SCN displayed neither daily nor photoperiod-dependent variations in specific binding. Melatonin receptors in these nuclei would be regulated neither by plasma melatonin nor by the light:dark cycle or sexual steroids. By contrast, melatonin receptor density in the PT displayed both strong daily (maximal values during the first half of the light period and minimal values during the night) and photoperiod-dependent (maximal values in LP) variations. These variations dependent on changes in the maximal binding (Bmax) without differences in the dissociation constant (Kd). Daily melatonin receptor densities in the PT of LP- and SP-exposed animals might be regulated by the dark:light transition but not by melatonin. Daily profiles of 2-(125)I-melatonin-specific binding in the PT were independent of photoperiod. Factors underlying the photoperiod-related variations presently are unknown. Concerning the PVT, weak variations in specific binding were detected in SP only when time points were grouped according to the light or dark periods. It is not yet possible to conclude whether they have any physiological relevance. These results show clearly that the regulation of melatonin receptors varies among structures (SCN, PVT, and PT) in the Siberian hamster and is also totally different from that found in the rat.

  19. Reproductive, neuroendocrine, and immune consequences of acute exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin in the Siberian hamster.

    PubMed

    Yellon, S M; Singh, D; Garrett, T M; Fagoaga, O R; Nehlsen-Cannarella, S L

    2000-08-01

    The present study tested the hypothesis that acute treatment with 2, 3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) impairs fertility, disrupts the nocturnal melatonin rhythm, and suppresses lymphocyte function. Adult Siberian hamsters administered 2 or 100 microg TCDD/kg body weight/0.2 ml sesame oil had a delayed latency to first litter and an increased adult mortality compared to hamsters given 0.1 microg/kg or vehicle. Within 75 days of TCDD treatment, full reproductive capabilities were achieved. Moreover, the nocturnal melatonin rhythm was not disrupted in adults administered TCDD or in their progeny. Lymphocyte activity varied with respect to time of day and treatment. Lymphocyte proliferation was enhanced at night irrespective of TCDD treatment; during the day, 2 wk after the 2-microg/kg treatment, blastogenesis was reduced compared to that in the 0.1-microg/kg group or in vehicle-treated controls. In contrast, TCDD did not affect the mixed lymphocyte reaction in response to allogeneic antigen when assessed at 2 and 20 wk post-treatment. Thus, findings indicate that TCDD produced acute effects on fertility, mortality, and systemic lymphocyte proliferation, but long-lasting effects on specific aspects of reproductive, neuroendocrine, and immune cell functions were not observed.

  20. Melatonin induces gene-specific effects on rhythmic mRNA expression in the pars tuberalis of the Siberian hamster (Phodopus sungorus).

    PubMed

    Wagner, Gabriela C; Johnston, Jonathan D; Tournier, Benjamin B; Ebling, Francis J P; Hazlerigg, David G

    2007-01-01

    In mammals, circadian and photoperiodic information is encoded in the pineal melatonin signal. The pars tuberalis (PT) of the pituitary is a melatonin target tissue, which transduces photoperiodic changes and drives seasonal changes in prolactin secretion from distal lactotroph cells. Measurement of photoperiodic time in the PT is believed to occur through melatonin dependent changes in clock gene expression, although it is unclear whether the PT should be considered a melatonin sensitive peripheral oscillator. We tested this hypothesis in the Siberian hamster (Phodopus sungorus) firstly by investigating the effects of melatonin injection, and secondly by determining whether temporal variation in gene expression within the PT persists in the absence of a rhythmic melatonin signal. Hamsters preconditioned to long days were treated with melatonin during the late light phase, to advance the timing of the nocturnal melatonin peak, or placed in constant light for one 24 h cycle, thereby suppressing endogenous melatonin secretion. Gene expression in the PT was measured by in situ hybridization. We show that melatonin rapidly induces cry1 mRNA expression without the need for a prolonged melatonin-free interval, acutely inhibits mt1 expression, advances the timing of peak rev-erb alpha expression and modulates per1 expression. With the exception of cry1, these genes continue to show temporal changes in expression over a first cycle in the absence of a melatonin signal. Our data are consistent with the hypothesis that the hamster PT contains a damped endogenous circadian oscillator, which requires a rhythmic melatonin signal for long-term synchronization.

  1. Intraovarian expression of GnRH-1 and gonadotropin mRNA and protein levels in Siberian hamsters during the estrus cycle and photoperiod induced regression/recrudescence.

    PubMed

    Shahed, Asha; Young, Kelly A

    2011-01-15

    The hypothalamic-pituitary-gonadal (HPG) axis is the key reproductive regulator in vertebrates. While gonadotropin releasing hormone (GnRH), follicle stimulating (FSH), and luteinizing (LH) hormones are primarily produced in the hypothalamus and pituitary, they can be synthesized in the gonads, suggesting an intraovarian GnRH-gonadotropin axis. Because these hormones are critical for follicle maturation and steroidogenesis, we hypothesized that this intraovarian axis may be important in photoperiod-induced ovarian regression/recrudescence in seasonal breeders. Thus, we investigated GnRH-1 and gonadotropin mRNA and protein expression in Siberian hamster ovaries during (1) the estrous cycle; where ovaries from cycling long day hamsters (LD;16L:8D) were collected at proestrus, estrus, diestrus I, and diestrus II and (2) during photoperiod induced regression/recrudescence; where ovaries were collected from hamsters exposed to 14 weeks of LD, short days (SD;8L:16D), or 8 weeks post-transfer to LD after 14 weeks SD (PT). GnRH-1, LHβ, FSHβ, and common α subunit mRNA expression was observed in cycling ovaries. GnRH-1 expression peaked at diestrus I compared to other stages (p < 0.05). FSHβ and LHβ mRNA levels peaked at proestrus and diestrus I (p < 0.05), with no change in the α subunit across the cycle (p > 0.05). SD exposure decreased ovarian mass and plasma estradiol concentrations (p<0.05) and increased GnRH-1, LHβ, FSHβ, and α subunit mRNA expression as compared to LD and, except for LH, compared to PT (p < 0.05). GnRH and gonadotropin protein was also dynamically expressed across the estrous cycle and photoperiod exposure. The presence of cycling intraovarian GnRH-1 and gonadotropin mRNA suggests that these hormones may be locally involved in ovarian maintenance during SD regression and/or could potentially serve to prime ovaries for rapid recrudescence.

  2. Photic regulation of mt1 melatonin receptors in the Siberian hamster pars tuberalis and suprachiasmatic nuclei: involvement of the circadian clock and intergeniculate leaflet.

    PubMed

    Schuster, C; Gauer, F; Guerrero, H; Lakhdar-Ghazal, N; Pevet, P; Masson-Pevet, M

    2000-03-01

    In the Siberian hamster suprachiasmatic nuclei and pars tuberalis of the pituitary, high affinity mt1 melatonin receptors are present. We have previously shown that night applied light pulse induced an increase in mt1 mRNA expression in the suprachiasmatic nuclei of this species, independently of the endogenous melatonin. Here, we report the photic regulation of melatonin receptor density and mRNA expression in the suprachiasmatic nuclei and pars tuberalis of pinealectomized Siberian hamsters and the implication in this control of either the circadian clock or the intergeniculate leaflet. The results show that: (1) A 1-h light pulse, delivered during the night, induces a transitory increase in mt1 mRNA expression in the suprachiasmatic nuclei and pars tuberalis. After 3 h this increase has totally disappeared (suprachiasmatic nuclei) or is greatly reduced (pars tuberalis). (2) The melatonin receptor density, in the suprachiasmatic nuclei, is not affected by 1 or 3 h of light, while it is strongly increased in the pars tuberalis. (3) In hamsters kept in constant darkness, the mt1 mRNA rise is gated to the subjective night in the suprachiasmatic nuclei and pars tuberalis. In contrast, the light-induced increase in melatonin binding is also observed in the subjective day in the pars tuberalis. (4) intergeniculate leaflet lesion totally inhibits the mt1 mRNA expression rise in the suprachiasmatic nuclei, while it has no effect on the light-induced increase in mt1 mRNA in the pars tuberalis. However, the light-induced increase in melatonin receptor density is totally prevented by the intergeniculate leaflet lesion in the pars tuberalis. These results show that: (1) the photic regulations of mt1 mRNA expression and receptor density are independent of each other in both the suprachiasmatic nuclei and pars tuberalis; and (2) the circadian clock and the intergeniculate leaflet are implicated in the photic regulation of melatonin receptors but their level of action differs

  3. PARTNER PREFERENCE IN MALE HAMSTERS: STEROIDS, SEXUAL EXPERIENCE AND CHEMOSENSORY CUES

    PubMed Central

    Ballard, Cortney L.; Wood, Ruth I.

    2007-01-01

    This study investigated the effects of gonadal steroids on sexual motivation in male Syrian hamsters, using partner preference as a model. Male hamsters were assigned to 5 groups: control (n=4), Intact→Orchx (n=8), Orchx→Orchx+T (n=7), olfactory bulbectomy (BulbX, n=5), and vomeronasal organ lesion (VnoX, n=8). Each male was tested for partner preference before and after sexual experience. Unlike rats, sexually-inexperienced gonad-intact male hamsters preferred the receptive female to a stimulus male. However, sexual experience did not enhance preference for the stimulus female. Castration (orchx) reduced sexual motivation: OrchX males showed no significant preference for the stimulus female. Subsequently, intact males were castrated (Intact→Orchx) and OrchX males received a testosterone implant (Orchx→Orchx+T) to determine the time course of gonadal hormones on partner preference and mating behavior. Partner preference changed significantly in both groups within 6 weeks. In Intact→Orchx males, preference for the stimulus female decreased while Orchx→Orchx+T males increased their preference for the stimulus female. However, significant changes in mating behavior preceded the alterations in partner preference. Chemosensory cues are also important for partner preference. After BulbX, preference for the stimulus female significantly decreased. However, VnoX failed to block partner preference. These results show that partner preference may be even more dependent on testosterone than is sexual behavior. Furthermore, while chemosensory cues are essential for sexual motivation, the vomeronasal organ is not required for partner preference. PMID:17316716

  4. Absence of pineal-independent mediation of seasonal differences in suprachiasmatic nucleus AVP and VIP mRNA expression in Siberian hamsters.

    PubMed

    Freeman, David A; Herron, Jana M; Duncan, Marilyn J

    2002-05-30

    Assessment of seasonal variations in expression of brain neuropeptide mRNA is complicated by concurrent circadian variations. Because entrainment of suprachiasmatic nucleus (SCN) based rhythms differs in long versus short day lengths, valid seasonal comparisons must be made at equivalent circadian phases. We used a novel experimental design which permitted sampling at identical circadian phases of animals exhibiting opposite seasonal reproductive responses to the same intermediate day length. This allowed us to test whether seasonal changes in arginine vasopressin (AVP) and vasoactive intestinal peptide (VIP) mRNA expression in the SCN occur in the absence of the pineal gland. Juvenile Siberian hamsters were gestated and maintained postnatally in either a long photoperiod (16 h light/day) or short photoperiod (10 h light/day). At the time of weaning (18 days of age), the hamsters were pinealectomized and either transferred to a new photoperiod (10-, 16- or 14-h light/day) or left in the original photoperiod. Hamsters from 10L had substantially smaller and lighter testes than those from 16L. If photoperiodic modulation of AVP and VIP mRNA expression occurs in the absence of the pineal, then transfer of pinealectomized hamsters from a longer (16L) or shorter (10L) photoperiod to an intermediate photoperiod (14L) should result in a differential response with respect to SCN AVP and VIP mRNA expression but not testis size. When sampled at an identical circadian phase (3 h after lights on) in 14L there was no difference in the expression of AVP or VIP mRNA in the SCN between animals previously housed in long versus short day lengths. In contrast to a previous study that did not carefully control for circadian phase, the present findings suggest that seasonal photoperiodic control of SCN neuropeptide mRNA expression depends upon the pineal gland. In addition, the present findings demonstrate a significant, negative correlation between AVP mRNA expression in the SCN and

  5. Eosinophilic granulomatous gastroenterocolitis and hepatitis in a 1-year-old male Siberian Husky.

    PubMed

    Brellou, G D; Kleinschmidt, S; Meneses, F; Nolte, I; Hewicker-Trautwein, M

    2006-11-01

    A case of eosinophilic granulomatous gastroenterocolitis and hepatitis in a 1-year-old male Siberian Husky is described. The dog presented with a history of diarrhea, weakness, lethargy, and anorexia of several months' duration. Hematologic and biochemical examinations, abdominal ultrasonography, computer tomography, and exploratory laparotomy were performed. Histopathologic examination of full-thickness biopsies from the gastrointestinal tract and liver revealed the presence of eosinophilic granulomatous lesions in the submucosa and tunica muscularis of stomach, jejunum, ileum, colon, and liver. Infectious agents were not detected by light microscopic and electron microscopic examination or by immunohistochemistry. On the basis of the findings, it is concluded that the disease in this dog represents an unusual manifestation of chronic idiopathic inflammatory bowel disease.

  6. Influence of torpor on cardiac expression of genes involved in the circadian clock and protein turnover in the Siberian hamster (Phodopus sungorus).

    PubMed

    Crawford, Fiona I J; Hodgkinson, Cassandra L; Ivanova, Elena; Logunova, Larisa B; Evans, Gary J; Steinlechner, Stephan; Loudon, Andrew S I

    2007-11-14

    The Siberian hamster exhibits the key winter adaptive strategy of daily torpor, during which metabolism and heart rate are slowed for a few hours and body temperature declines by up to 20 degrees C, allowing substantial energetic savings. Previous studies of hibernators in which temperature drops by >30 degrees C for many days to weeks have revealed decreased transcription and translation during hypometabolism and identified several key physiological pathways involved. Here we used a cDNA microarray to define cardiac transcript changes over the course of a daily torpor bout and return to normothermia, and we show that, in common with hibernators, a relatively small proportion of the transcriptome (<5%) exhibited altered expression over a torpor bout. Pathways exhibiting significantly altered gene expression included transcriptional regulation, RNA stability and translational control, globin regulation, and cardiomyocyte function. Remarkably, gene representatives of the entire ubiquitylation pathway were significantly altered over the torpor bout, implying a key role for cardiac protein turnover and translation during a low-temperature torpor bout. The circadian clock maintained rhythmic transcription during torpor. Quantitative PCR profiling of heart, liver, and lung and in situ hybridization studies of clock genes in the hypothalamic circadian clock in the suprachiasmatic nucleus revealed that many circadian regulated transcripts exhibited synchronous alteration in expression during arousal. Our data highlight the potential importance of genes involved in protein turnover as part of the adaptive strategy of low-temperature torpor in a seasonal mammal.

  7. Dim light at night interferes with the development of the short-day phenotype and impairs cell-mediated immunity in Siberian hamsters (Phodopus sungorus).

    PubMed

    Aubrecht, Taryn G; Weil, Zachary M; Nelson, Randy J

    2014-10-01

    Winter is a challenging time to survive and breed outside of the tropics. Animals use day length (photoperiod) to regulate seasonally appropriate adaptations in anticipation of challenging winter conditions. The net result of these photoperiod-mediated adjustments is enhanced immune function and increased survival. Thus, the ability to discriminate day length information is critical for survival and reproduction in small animals. However, during the past century, urban and suburban development has rapidly expanded and filled the night sky with light from various sources, obscuring crucial light-dark signals, which alters physiological interpretation of day lengths. Furthermore, reduced space, increased proximity to people, and the presence of light at night may act as stressors for small animals. Whereas acute stressors typically enhance immune responses, chronic exposure to stressors often impairs immune responses. Therefore, we hypothesized that the combination of dim light at night and chronic stress interferes with enhanced cell-mediated immunity observed during short days. Siberian hamsters (Phodopus sungorus) were assigned to short or long days with dark nights (0 lux) or dim (5 lux) light at night for 10 weeks. Following 2 weeks of chronic restraint (6 hr/day), a model of chronic stress, delayed type hypersensitivity (DTH) responses were assessed. Both dim light at night and restraint reduced the DTH response. Dim light at night during long nights produced an intermediate short day phenotype. These results suggest the constant presence of light at night could negatively affect survival of photoperiodic rodents by disrupting the timing of breeding and immune responses.

  8. Pituitary responsiveness to LRF in castrated male hamsters exposed to different photoperiodic conditions.

    PubMed

    Turek, F W; Alvis, J D; Menaker, M

    1977-01-01

    The effect of various doses of LRF on pituitary LH and FSH release was examined in castrated adult male hamsters with different photoperiodic histories. Gonadotropin (Gn) release in response to LRF was independent of whether the animals had been exposed to a photostimulatory (LD 14:10) or a nonstimulatory (LD 6:18) light cycle for 60 days following castration. The lowest dose that caused a significant increase in serum Gns was 10 ng LRF/100 g b.w. for LH and 50 ng LRF/100 g b.w. for FSH. These results indicate that photoperiod, which is well known to exert major effects on the reproductive system of the golden hamster, does not do so by directly altering the responsiveness of the pituitary gland to hypothalamic Gn-releasing factor. PMID:345144

  9. Effects of female odors on the sexual behavior of male hamsters.

    PubMed

    Johnston, R E

    1986-09-01

    A series of experiments was undertaken to investigate the effects of removal of several scent glands and scent-producing organs of female hamsters on the copulatory performance of male hamsters. In the first experiment it was shown that males engage in less copulatory activity toward females lacking vaginal secretions than toward females with these odors. Eliminating visual cues by observing pairs under infrared illumination did not change the performance of males toward these two kinds of females. The results of Experiment 2 indicated the importance of flank, ear, and Harderian glands as well as vaginal secretions--males showed the highest levels of copulatory behavior toward females with a full complement of odors and the lowest levels toward those lacking three of four sources of scent. Similar results were obtained in the third experiment in which anesthetized females were used as stimulus animals to increase the importance of chemical cues and to reduce variability due to the behavior of females. The sexual behavior of males was greatest toward females with all sources of scent present, lower toward those lacking vaginal secretions, and still lower toward those lacking vaginal secretions and other sources of odors. In the fourth experiment we asked whether any one of the nonvaginal scent glands was particularly important in stimulating male sexual behavior, but we found no differences in male performance toward females that lacked vaginal secretions or that in addition lacked one of the other scent glands. In the fifth experiment males displayed higher levels of sexual behavior toward vaginectomized females than toward vaginectomized females that had been deodorized by a cleaning procedure, again indicating the importance of nonvaginal odors in stimulating copulatory performance. Thus these experiments demonstrate the importance of vaginal secretions in the sexual arousal of male hamsters, a role for nonvaginal odors in sexual arousal of males, and the lack of

  10. Effects of photic history and illuminance levels on male golden hamsters.

    PubMed

    Hoffman, R A; Johnson, L B

    1985-01-01

    Four-week-old male hamsters, born and raised in total darkness or in LD 14:10 (hr) were exposed to several low levels of illumination for 14 weeks. Analyses showed that testicular weights were significantly affected by both photic history and illuminance levels. Animals born in the dark possessed larger testes than those born in LD cycles and, further, displayed less responsiveness to levels of illumination below those required to suppress pineal function. While gonadal responses to photic duration may be said to be "all or none," those resulting from insufficient illuminance levels are seemingly graded. Thus, the pineal gland may act indirectly as a photodosimeter at low illuminance levels.

  11. Predator odour and its impact on male fertility and reproduction in Phodopus campbelli hamsters

    NASA Astrophysics Data System (ADS)

    Vasilieva, N. Y.; Cherepanova, E. V.; von Holst, D.; Apfelbach, R.

    This study investigated the influence of cat urine odour in suppressing development and fertility in Campbell's hamster males. Exposure to this odour from postnatal day 11 until day 45 (sexual maturation) resulted in reduced sex organ weights, reduced testosterone levels and in an increase in abnormalities of the synaptonemal complex in both sex chromosomes and autosomes. Subsequent breeding experiments revealed a significant decrease in litter size. All these data indicate a severe effect of predator odour on the breeding success of potential prey species. It is assumed that these effects are caused by the sulphurous compounds in the urine; however, the underlying mechanisms are not yet known.

  12. Influence of photoinhibition on the morphology and function of pituitary lactotropes in male golden hamsters.

    PubMed

    Cónsole, Gloria M; Jurado, Susana B; Petruccelli, Miguel; Carino, Mónica; Calandra, Ricardo S; Gómez Dumm, César L A

    2002-05-01

    Inhibition of prolactin (PRL) secretion has been previously shown in pituitaries from male and female hamsters exposed to short photoperiods. The purpose of the present study was to analyze the possible quantitative immunohistochemical and ultrastructural changes of PRL cells in male golden hamsters undergoing regression and spontaneous recrudescence, correlating the morphological findings with circulating PRL levels. Thus, adult male golden hamsters were exposed for 8, 16, 22 and 28 weeks to either short photoperiods (SP: 6 h light, 18 h darkness) or long photoperiods (LP: 14 h light, 10 h darkness). Pituitaries were processed for both light and electron microscopy, and serum levels of PRL were assessed by radioimmunoassay (RIA). Volume density (VD = cell area/reference area) and cell density (CD = number of cells/reference area) of lactotropes were measured with an image analysis system (Imaging Technology, Software Optimas 5.2). One hundred lactotropes were recorded for measuring several ultrastructural parameters. When analyzing the lactrotrope cell population from animals submitted to SP, the VD and CD were found to be significantly (p < 0.05) diminished with respect to those of the groups submitted to LP at weeks 8, 16 and 22. However, at week 28 a spontaneous recrudescence appeared. The lactotropes from animals submitted to LP for 8, 16, 22 and 28 weeks exhibited numerous large electrondense secretory granules. The rough endoplasmic reticulum (RER) presented some flat cisternae and numerous free ribosomes. Animals submitted to SP for 8 weeks showed a number of medium and large secretory granules, and the RER exhibited mainly numerous free ribosomes. In those animals submitted to SP for 16 and 22 weeks, lactotropes were found smaller and showed small and medium-sized secretory granules decreased in number. The Golgi complex exhibited some immature granules and dilated cisternae, while the RER did not present differences with respect to the 8-week SP group

  13. Elimination of short-day melatonin signaling accelerates gonadal recrudescence but does not break refractoriness in male Turkish hamsters.

    PubMed

    Jarjisian, Stephan G; Zucker, Irving

    2011-04-01

    Long days stimulate and short days (SDs) inhibit the reproductive axis of photoperiodic rodents. In long-day Turkish hamsters, unlike most other rodents, elimination of pineal melatonin secretion by constant light or pinealectomy initiates a cycle of gonadal involution and recrudescence outwardly similar to that induced by short days. The present study assessed whether short days and constant light induce the seasonal reproductive cycle via common or different interval timing mechanisms. Male hamsters that had undergone gonadal involution in SDs for 8 or 14 weeks were treated with LL for 14 and 8 weeks, respectively. If SDs and LL act via independent mechanisms, then gonadal quiescence of SD-regressed males, which normally lasts 10 weeks, might be extended by LL treatment; alternatively, if SDs and LL act on the same timer, or the timer cannot be retriggered, then LL will not extend the duration of reproductive quiescence. Neither of these outcomes materialized. Instead, male hamsters exposed to LL while reproductively quiescent exhibited accelerated gonadal recrudescence. Extended LL treatment did not restore responsiveness to SDs in photorefractory hamsters. In Turkish hamsters, photoperiodic history determines whether constant light inhibits or stimulates the hypothalamic-pituitary-testicular axis.

  14. Continuous Melatonin Attenuates the Regressing Activities of Short Photoperiod in Male Golden Hamsters

    PubMed Central

    Choi, Donchan

    2013-01-01

    Golden hamsters reproduce in a limited time of a year. Their sexual activities are active in summer but inactive in winter during which day length does not exceed night time and environmental conditions are severe to them. The reproductive activities are determined by the length of light in a day (photoperiod). Melatonin is synthesized and secreted only at night time from the pineal gland. Duration of elevated melatonin is longer in winter than summer, resulting in gonadal regression. The present study aimed at the influences of continuous melatonin treatments impinging on the gonadal function in male golden hamsters. Animals received empty or melatonin-filled capsules for 10 weeks. They were divided into long photoperiod (LP) and short photoperiod (SP). All the animals maintained in LP (either empty or melatonin-filled capsules) showed large testes, implying that melatonin had no effects on testicular functions. Animals housed in SP displayed completely regressed testes. But animals kept in SP and implanted with melatonin capsules exhibited blockage of full regression by SP. These results suggest that constant release of melatonin prohibits the regressing influence of SP. PMID:25949127

  15. Adrenal, thyroid, and testicular hormone rhythms in male golden hamsters on long and short days

    SciTech Connect

    Ottenweller, J.E.; Tapp, W.N.; Pitman, D.L.; Natelson, B.H. New Jersey Medical School, Newark )

    1987-08-01

    Plasma concentrations of adrenal, thyroid, and testicular hormones were measured at 4-h intervals around the clock in male hamsters on long (14:10-h light-dark cycle) and short (10:14-h light-dark cycle) days. Plasma corticosterone, cortisol, thyroxine (T{sub 4}), triiodothyronine (T{sub 3}), and testosterone rhythms were present on long days. The only one of these hormones to have a significant rhythm on short days was cortisol, but even its amplitude was suppressed compared with the cortisol rhythm on long days. Short days also lowered mean plasma levels of cortisol, T{sub 4}, T{sub 3}, and testosterone. Finally, short days raised the ratio of corticosterone to cortisol and lowered the ratio of T{sub 4} to T{sub 3}. Both ratios had significant rhythms on long days but not on short days. Because of the many interactions among adrenal, thyroid, and testicular hormone axes, it is unclear whether the primary effect of short days is on one of these endocrine systems or on another factor that has separate effects on each of the hormone rhythms that was measured. Nonetheless, it is clear that a major effect of short day lengths in hamsters is to suppress hormone rhythms. Explanations of photoperiodic effects that depend on endocrine mediation should take this into account.

  16. The organizational effects of pubertal testosterone on sexual proficiency in adult male Syrian hamsters.

    PubMed

    De Lorme, Kayla C; Sisk, Cheryl L

    2016-10-15

    Social proficiency requires making appropriate behavioral adaptations as a result of social experience. For example, male rodents become sexually proficient with experience as demonstrated by a reduction in ectopic (misdirected) mounts, mount-to-intromission ratio, and latency to ejaculation. We previously found that over a series of timed tests with a receptive female, male hamsters deprived of testosterone specifically during puberty (NoT@P) have overall lower levels of sexual behavior and continue to display high levels of ectopic mounts, compared with males that experienced endogenous testosterone during puberty (T@P). These results suggested that pubertal testosterone programs sexual proficiency in adulthood, but because NoT@P males engaged in less sexual behavior than T@P males in these tests, the amount of sexual experience may have been insufficient to improve sexual proficiency. To more rigorously test the hypothesis that pubertal testosterone is necessary for social proficiency in adulthood, the present study compared the behavior of NoT@P and T@P males in a series of 4 trials with a 48-h interval between each trial. Sexual experience was equated by limiting each trial to 5 intromissions. Sexually-naïve males were either gonadectomized prepubertally (NoT@P) or in adulthood (T@P) and received subcutaneous testosterone capsules four weeks later. Two weeks after testosterone replacement, these groups and a group of adult gonad-intact controls began sexual behavior testing. We found that NoT@P males had more ectopic mounts/min across all four tests compared to gonad-intact and T@P males. Moreover, both gonad-intact and T@P males, but not NoT@P males, showed an increase in the number of mounts and intromissions/min between trials 1 and 3. Unexpectedly, both gonad-intact and T@P, but not NoT@P, males showed a decrease in sexual behaviors during trial 4. Thus, T@P males display multiple behavioral adaptations to sexual experience that are not observed in No

  17. Morphological and biochemical changes of pituitary gonadotropes in male golden hamsters submitted to short and long photoperiods.

    PubMed

    Cónsole, Gloria M; Jurado, Susana B; Camihort, Gisela; Calandra, Ricardo S; Zitta, Karina; Gómez Dumm, César L A

    2002-01-01

    Golden hamsters are seasonal breeders, and a pattern of regression-recrudescence in their hypothalamic-pituitary axis is observed when adult animals are exposed to less than 12.5 h daylight for a prolonged period of time. The purpose of the present work was to investigate the possible morphological and biochemical changes of gonadotrope cell population in male golden hamsters submitted to both short (SP) and long photoperiods (LP). Thus, adult male golden hamsters were exposed to SP (6 h light, 18 h darkness) for 8, 16, 22 and 28 weeks or maintained under LP (14 h light, 10 h darkness). Pituitaries were processed using both light and electron microscopy, and serum levels of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) were assessed by heterologous radioimmunoassay. Volume density [VD = Sigma cell area/reference area (RA)] and cell density (CD = number of cells/RA) of gonadotropes were measured with an image analysis system (Imaging Technology, Software Optimas 5.2). When analyzing the gonadotrope population from animals submitted either to SP or LP, no significant differences were found. At the ultrastructural level, we found a decrease (p < 0.05) in the exocytotic profiles and the individual mean area of secretory granules of both gonadotropes in hamsters maintained under SP for 16 and 22 weeks. Exposure to short days resulted in a decline in serum levels showing a nadir after 16 weeks (p < 0.05). Gonadotropin levels of the hamsters under prolonged exposure to short cycles spontaneously returned to normal values after 22 weeks. In summary, we found a decrease in the ultrastructural and biochemical parameters suggesting an altered release of FSH and LH in male golden hamsters submitted to SP, with a spontaneous recrudescence phase appearing at the end of the study.

  18. Dorsomedial hypothalamic lesions counteract decreases in locomotor activity in male Syrian hamsters transferred from long to short day lengths.

    PubMed

    Jarjisian, Stephan G; Butler, Matthew P; Paul, Matthew J; Place, Ned J; Prendergast, Brian J; Kriegsfeld, Lance J; Zucker, Irving

    2015-02-01

    The dorsomedial nucleus (DMN) of the hypothalamus has been implicated in seasonal control of reproduction. Syrian hamsters with DMN lesions, unlike control hamsters, do not undergo testicular regression after transfer from a long day length (14 h of light per day; LD) to a short day length (8 h of light per day; SD). SDs also markedly reduce hamster locomotor activity (LMA). To assess whether the DMN is a component of the neural circuitry that mediates seasonal variation in LMA, neurologically intact males (controls) and hamsters that had sustained lesions of the DMN (DMNx) were housed in an LD or SD photoperiod for 26 weeks. DMNx that prevented testicular regression counteracted decreases in LMA during 8 to10 weeks of SD treatment; steroid-independent effects of SDs did not override high levels of LMA in DMNx males. As in previous studies, testosterone (T) restoration increased LMA in LD but not SD castrated control males. In the present study, T also failed to increase LMA in SD-DMNx hamsters. The DMN is not necessary to maintain decreased responsiveness of locomotor activity systems to T in SDs, which presumably is mediated by other central nervous system androgen target tissues. Finally, DMNx did not interfere with the spontaneous increase in LMA exhibited by photorefractory hamsters after 26 weeks of SD treatment. We propose that DMN is an essential part of the substrate that mediates seasonal decreases in LMA as day length decreases but is not required to sustain decreased SD responsiveness to T or for development of refractoriness to SDs.

  19. The circadian clock, light/dark cycle and melatonin are differentially involved in the expression of daily and photoperiodic variations in mt(1) melatonin receptors in the Siberian and Syrian hamsters.

    PubMed

    Schuster, C; Gauer, F; Malan, A; Recio, J; Pévet, P; Masson-Pévet, M

    2001-07-01

    Mechanisms underlying the daily and photoperiodic variations in mt(1) melatonin receptors were investigated in the pars tuberalis (PT) and suprachiasmatic nuclei (SCN) of Siberian and Syrian hamsters. Whatever its daily profile, melatonin receptor density was strongly increased in both structures and species after constant light exposure or pinealectomy, and decreased after a single melatonin injection, indicating melatonin involvement in the daily regulation of the receptor protein. This was confirmed by a strong inverse correlation between melatonin binding capacity and plasma melatonin concentration. In contrast, regulation of mt(1) mRNA appeared more complex. The circadian clock, the light/dark cycle and melatonin are all implicated in mt(1) gene daily fluctuations, but the extent of their involvement depends upon the structure and the species studied. The photoperiodic decrease in melatonin receptor density observed in short photoperiod (PT of the two hamster species and Syrian hamster SCN) seems to be the consequence of a long-term mt(1) gene repression induced by the lengthening of the melatonin peak. Altogether, these results show that during daily variations, mt(1) melatonin receptor mRNA and protein are differentially regulated, while at the photoperiodic level, the mt(1) protein status depends on mRNA transcription.

  20. Sex and age differences in hibernation patterns of common hamsters: adult females hibernate for shorter periods than males.

    PubMed

    Siutz, Carina; Franceschini, Claudia; Millesi, Eva

    2016-08-01

    In this study, we investigated the timing and duration of hibernation as well as body temperature patterns in free-ranging common hamsters (Cricetus cricetus) with regard to sex and age differences. Body temperature was recorded using subcutaneously implanted data loggers. The results demonstrate that although immergence and vernal emergence sequences of sex and age groups resembled those of most hibernators, particularly adult females delayed hibernation onset until up to early January. Thus, in contrast to other hibernators, female common hamsters hibernated for shorter periods than males and correspondingly spent less time in torpor. These sex differences were absent in juvenile hamsters. The period between the termination of hibernation and vernal emergence varied among individuals but did not differ between the sex and age groups. This period of preemergence euthermy was related to emergence body mass: individuals that terminated hibernation earlier in spring and had longer euthermic phases prior to emergence started the active season in a better condition. In addition, males with longer periods of preemergence euthermy had larger testes at emergence. In conclusion, females have to rely on sufficient food stores but may adjust the use of torpor in relation to the available external energy reserves, whereas males show a more pronounced energy-saving strategy by hibernating for longer periods. Nonetheless, food caches seem to be important for both males and females as indicated by the euthermic preemergence phase and the fact that some individuals, mainly yearlings, emerged with a higher body mass than shortly before immergence in autumn.

  1. Sex and age differences in hibernation patterns of common hamsters: adult females hibernate for shorter periods than males.

    PubMed

    Siutz, Carina; Franceschini, Claudia; Millesi, Eva

    2016-08-01

    In this study, we investigated the timing and duration of hibernation as well as body temperature patterns in free-ranging common hamsters (Cricetus cricetus) with regard to sex and age differences. Body temperature was recorded using subcutaneously implanted data loggers. The results demonstrate that although immergence and vernal emergence sequences of sex and age groups resembled those of most hibernators, particularly adult females delayed hibernation onset until up to early January. Thus, in contrast to other hibernators, female common hamsters hibernated for shorter periods than males and correspondingly spent less time in torpor. These sex differences were absent in juvenile hamsters. The period between the termination of hibernation and vernal emergence varied among individuals but did not differ between the sex and age groups. This period of preemergence euthermy was related to emergence body mass: individuals that terminated hibernation earlier in spring and had longer euthermic phases prior to emergence started the active season in a better condition. In addition, males with longer periods of preemergence euthermy had larger testes at emergence. In conclusion, females have to rely on sufficient food stores but may adjust the use of torpor in relation to the available external energy reserves, whereas males show a more pronounced energy-saving strategy by hibernating for longer periods. Nonetheless, food caches seem to be important for both males and females as indicated by the euthermic preemergence phase and the fact that some individuals, mainly yearlings, emerged with a higher body mass than shortly before immergence in autumn. PMID:27138337

  2. Effects of melatonin on water metabolism and renal function in male Syrian hamsters (Mesocricetus auratus).

    PubMed

    Richardson, B A; Studier, E H; Stallone, J N; Kennedy, C M

    1992-09-01

    The pineal indoleamine, melatonin, has been shown to influence many physiological systems within the mammalian body. Few studies, however, have examined the influence of melatonin on renal function. This study investigated the effects of melatonin on water metabolism and renal function. Young adult male Syrian hamsters were maintained on a long photoperiod (LD 14:10) in metabolic cages. The animals received daily (1700) injections of either control vehicle or 25 micrograms of melatonin for 85 consecutive days. Melatonin administration resulted in significant increases in water consumption and urine production. Water budgets were also significantly influenced by melatonin, as were urinary osmolality, urinary sodium, and potassium concentrations, but urinary calcium concentrations were essentially unaltered. When excretion rates for sodium, potassium, and calcium were calculated, no differences were observed between the vehicle control and melatonin-treated groups. Injections of melatonin also significantly decreased plasma antidiuretic hormone (ADH). These results demonstrate that afternoon injections of melatonin can alter renal function, which may involve direct (i.e., on ADH secretion and/or thirst mechanisms) or indirect (i.e., behavioral) effects. PMID:1453309

  3. Interaction of diet and photoperiod on growth and reproduction in male golden hamsters.

    PubMed

    Johnson, L B; Hoffman, R A

    1985-01-01

    Two basic diets (commercial rodent pellets or seeds) with or without supplements of carbohydrate were tested for growth and development, and effects on organ weights and serum calcium in male golden hamsters. The additional influence of photoperiod was measured. The data suggest that a seed diet alone is not adequate for growth. Addition of seeds and/or carbohydrate to the pellet diet increases growth rates substantially compared to the pellet diet alone. There are significant interaction effects on reproduction between diet and photoperiod indicating that diet can modify responses to short photic input. While reproduction remains essentially normal in seed-fed animals in long photoperiods, the rate of reproductive involution in short photoperiods is greatly enhanced. Added carbohydrate appears to offer some protection against the adverse effect of short photoperiods on reproduction. Even though calcium supplements to the diet increase serum calcium levels toward normal, growth rates are not improved. Addition of Tenebrio (grain beetle) larvae to the seed diet induces growth rates comparable to those of control animals, yet serum calcium levels remain significantly lower.

  4. Effects of melatonin on water metabolism and renal function in male Syrian hamsters (Mesocricetus auratus).

    PubMed

    Richardson, B A; Studier, E H; Stallone, J N; Kennedy, C M

    1992-09-01

    The pineal indoleamine, melatonin, has been shown to influence many physiological systems within the mammalian body. Few studies, however, have examined the influence of melatonin on renal function. This study investigated the effects of melatonin on water metabolism and renal function. Young adult male Syrian hamsters were maintained on a long photoperiod (LD 14:10) in metabolic cages. The animals received daily (1700) injections of either control vehicle or 25 micrograms of melatonin for 85 consecutive days. Melatonin administration resulted in significant increases in water consumption and urine production. Water budgets were also significantly influenced by melatonin, as were urinary osmolality, urinary sodium, and potassium concentrations, but urinary calcium concentrations were essentially unaltered. When excretion rates for sodium, potassium, and calcium were calculated, no differences were observed between the vehicle control and melatonin-treated groups. Injections of melatonin also significantly decreased plasma antidiuretic hormone (ADH). These results demonstrate that afternoon injections of melatonin can alter renal function, which may involve direct (i.e., on ADH secretion and/or thirst mechanisms) or indirect (i.e., behavioral) effects.

  5. Determination of Hepatotoxicity and Its Underlying Metabolic Basis of 1,2-Dichloropropane in Male Syrian Hamsters and B6C3F1 Mice.

    PubMed

    Gi, Min; Fujioka, Masaki; Yamano, Shotaro; Shimomura, Eri; Ishii, Naomi; Kakehashi, Anna; Takeshita, Masanori; Wanibuchi, Hideki

    2015-05-01

    1,2-Dichloropropane (1,2-DCP) has recently been reclassified from not classifiable as to its carcinogenicity to humans (Group 3) to carcinogenic to humans (Group 1) by the International Agency for Research on Cancer. This was based on the findings of epidemiological studies in Japan that occupational exposure to paint stripers containing 1,2-DCP was associated with increased cholangiocarcinomas. It is known that 1,2-DCP is negative for cholangiocarcinogenicity in rats and mice. However, its toxicity and carcinogenicity has not been examined in hamsters and little is known about the regulation of its metabolism in hamsters. The purpose of this study was to determine the hepatobiliary toxicity of 1,2-DCP in hamsters and to characterize and compare the altered patterns of hepatic xenometabolic enzymes in hamsters and mice. Male Syrian hamsters and male B6C3F1 mice were treated with various doses of 1,2-DCP for 4 h or 3 days or 4 weeks. These experiments demonstrated that a high dose of 1,2-DCP induced centrilobular hepatocellular necrosis in hamsters. CYP2E1 is possibly the key enzyme responsible for bioactivation and the consequent hepatocytotoxicity of 1,2-DCP, and GSH conjugation catalyzed by GST-T1 may exert a cytoprotective role in hamsters and mice. Notably, the expression pattern of GST-T1 in bile duct epithelial cells differed between hamsters and mice: GST-T1 was expressed in bile duct epithelial cells of mice but not hamsters. This indicates that responses to 1,2-DCP in the bile duct of hamsters might differ from that of mice, and suggests that long-term studies are necessary to clarify the chalangiocarcinogenicity of 1,2-DCP in hamsters, though no biliary toxicity was observed in the present short-term experiments.

  6. Determination of Hepatotoxicity and Its Underlying Metabolic Basis of 1,2-Dichloropropane in Male Syrian Hamsters and B6C3F1 Mice.

    PubMed

    Gi, Min; Fujioka, Masaki; Yamano, Shotaro; Shimomura, Eri; Ishii, Naomi; Kakehashi, Anna; Takeshita, Masanori; Wanibuchi, Hideki

    2015-05-01

    1,2-Dichloropropane (1,2-DCP) has recently been reclassified from not classifiable as to its carcinogenicity to humans (Group 3) to carcinogenic to humans (Group 1) by the International Agency for Research on Cancer. This was based on the findings of epidemiological studies in Japan that occupational exposure to paint stripers containing 1,2-DCP was associated with increased cholangiocarcinomas. It is known that 1,2-DCP is negative for cholangiocarcinogenicity in rats and mice. However, its toxicity and carcinogenicity has not been examined in hamsters and little is known about the regulation of its metabolism in hamsters. The purpose of this study was to determine the hepatobiliary toxicity of 1,2-DCP in hamsters and to characterize and compare the altered patterns of hepatic xenometabolic enzymes in hamsters and mice. Male Syrian hamsters and male B6C3F1 mice were treated with various doses of 1,2-DCP for 4 h or 3 days or 4 weeks. These experiments demonstrated that a high dose of 1,2-DCP induced centrilobular hepatocellular necrosis in hamsters. CYP2E1 is possibly the key enzyme responsible for bioactivation and the consequent hepatocytotoxicity of 1,2-DCP, and GSH conjugation catalyzed by GST-T1 may exert a cytoprotective role in hamsters and mice. Notably, the expression pattern of GST-T1 in bile duct epithelial cells differed between hamsters and mice: GST-T1 was expressed in bile duct epithelial cells of mice but not hamsters. This indicates that responses to 1,2-DCP in the bile duct of hamsters might differ from that of mice, and suggests that long-term studies are necessary to clarify the chalangiocarcinogenicity of 1,2-DCP in hamsters, though no biliary toxicity was observed in the present short-term experiments. PMID:25711234

  7. Determination of Hepatotoxicity and Its Underlying Metabolic Basis of 1,2-Dichloropropane in Male Syrian Hamsters and B6C3F1 Mice

    PubMed Central

    Gi, Min; Fujioka, Masaki; Yamano, Shotaro; Shimomura, Eri; Ishii, Naomi; Kakehashi, Anna; Takeshita, Masanori; Wanibuchi, Hideki

    2015-01-01

    1,2-Dichloropropane (1,2-DCP) has recently been reclassified from not classifiable as to its carcinogenicity to humans (Group 3) to carcinogenic to humans (Group 1) by the International Agency for Research on Cancer. This was based on the findings of epidemiological studies in Japan that occupational exposure to paint stripers containing 1,2-DCP was associated with increased cholangiocarcinomas. It is known that 1,2-DCP is negative for cholangiocarcinogenicity in rats and mice. However, its toxicity and carcinogenicity has not been examined in hamsters and little is known about the regulation of its metabolism in hamsters. The purpose of this study was to determine the hepatobiliary toxicity of 1,2-DCP in hamsters and to characterize and compare the altered patterns of hepatic xenometabolic enzymes in hamsters and mice. Male Syrian hamsters and male B6C3F1 mice were treated with various doses of 1,2-DCP for 4 h or 3 days or 4 weeks. These experiments demonstrated that a high dose of 1,2-DCP induced centrilobular hepatocellular necrosis in hamsters. CYP2E1 is possibly the key enzyme responsible for bioactivation and the consequent hepatocytotoxicity of 1,2-DCP, and GSH conjugation catalyzed by GST-T1 may exert a cytoprotective role in hamsters and mice. Notably, the expression pattern of GST-T1 in bile duct epithelial cells differed between hamsters and mice: GST-T1 was expressed in bile duct epithelial cells of mice but not hamsters. This indicates that responses to 1,2-DCP in the bile duct of hamsters might differ from that of mice, and suggests that long-term studies are necessary to clarify the chalangiocarcinogenicity of 1,2-DCP in hamsters, though no biliary toxicity was observed in the present short-term experiments. PMID:25711234

  8. A test of the coincidence and duration models of melatonin action in Siberian hamsters: the effects of 1-hr melatonin infusions on testicular development in intact and pinealectomized prepubertal Phodopus sungorus.

    PubMed

    Gündüz, B; Stetson, M H

    2001-03-01

    The pineal hormone melatonin is known to play an important role in mediating photoperiodic messages to the reproductive system in seasonal breeding animals. Our goal was to test, in a single experimental paradigm, two hypotheses that have been forwarded to describe how the circadian rhythm of pineal melatonin transmits photoperiodic information to the reproductive system: 1) induction, i.e., a short-day effect, occurs when secreted melatonin and a circadian rhythm of sensitivity to melatonin coincide in time; 2) induction occurs following exposure to elevated circulating melatonin levels for a prescribed duration. In order to determine the relative validity of these hypotheses, we investigated the testicular maturation response to 1-hr daily infusions of 10, 25, and 50 ng of melatonin in pinealectomized intact and prepubertal Siberian hamsters (Phodopus sungorus). Animals received, beginning on day 15 of life, programmed subcutaneous infusions of melatonin or vehicle at one of five time points (19:00-20:00, 20:00-21:00, 21:00-22:00, 24:00-01:00, and 03:00-04:00 hr) for 15 days. In animals gestated and raised in a long photoperiod (LD16:8 = 16L, where L is the duration of light in hours, and D that of dark), melatonin infusion right after lights off (20:00-21:00 hr) significantly retarded gonadal maturation; this dose was ineffective at other times tested. Doses of 10 and 25 ng melatonin were ineffective at all time points. Identical results were obtained in prepubertal hamsters gestated in a short photoperiod (LD10:14 = 10L) and raised in 16L; these results were independent of the presence or absence of the pineal gland. In animals gestated and raised in 10L, melatonin infusions failed to suppress testicular development beyond that induced by the photoperiod; testicular development was maximally suppressed in all groups. The results of these investigations are best explained under the experimental conditions employed here: 1) the photoperiodic gonadal response in

  9. Melatonin and 6-methoxy-2-benzoxazolinone (6-MBOA) alter the response of the male Syrian hamster to natural photoperiod

    NASA Astrophysics Data System (ADS)

    Vaughan, M. K.; Little, J. C.; Powell, D. C.; Puig-Domingo, M.; Reiter, R. J.

    1988-06-01

    Adult male hamsters bearing either a blank beeswax, 6-methoxy-2-benzoxazolinone (6-MBOA), or melatonin pellet were exposed to 8 weeks (Oct. 6 Dec. 6) of natural autumn decreasing photoperiod (<11 h light) and temperature conditions (mean 10°C for last 4 weeks) or to a 14 h light/10 h dark (14L∶10D) photoperiod and controlled temperature (20°C). Melatonin but not 6-MBOA pellets partially prevented the combined effects of short photoperiod and cold temperatures on the testes and accessory organs. However, both 6-MBOA-and melatonin-treated hamsters maintained outdoors had significantly higher pituitary follicle stimulating hormone (FSH) values compared to their respective indoor-treated controls or to the animals kept outdoors and treated with a blank beeswax pellet. When one compares the various effects of 6-MBOA and melatonin (2 mg/month) on the reproductive system of the male hamster, 6-MBOA is not as effective as melatonin in altering reproductive responses to short photoperiod and cool temperatures at the dose administered.

  10. The interaction of castration and photoperiod in the regulation of hypophyseal and serum gonadotropin levels in male golden hamsters.

    PubMed

    Turek, F W; Elliott, J A; Alvis, J D; Menaker, M

    1975-04-01

    Luteinizing hormone (LH) and follicle-stimulating hormone (FSH) were measured in intact and castrate adult male hamsters maintained on photostimulatory (LD 14:10) and non-photostimulatory (LD 6:18) light:dark cycles to assess the interaction of photic stimuli and gonadal hormones on pituitary gonadotropin release. Immunoreactive serum LH and FSH levels increased 1.6- and 8-fold respectively, within 3 days after photostimulated hamsters were castrated. In contrast, castration failed to alter serum LH concentration and had only a slight, if any, effect on FSH concentration in hamsters exposed to nonstimulatory photoperiods that induced testicular atrophy. In a second experiment, male hamsters previously maintained on LD 14:10 were castrated, transferred with intact animals to LD 6:18, and killed periodically over 60 days. In intact animals, pituitary content and serum levels of LH and FSH declined substantially during exposure to the non-stimulatory LD 6:18 cycle. In castrated animals, serum LH and FSH levels which had increased 2- and 8-fold in response to the castration eventually declined to about the levels found in the intact initial control animals. In contrast to serum gonadotropins, the increased hypophyseal content of LH and FSH following castration was not reduced during exposure to LD 6:18. Exposure to nonstimulatory photoperiods does not alter the increased hypophyseal LH and FSH content observed after castration. However, our results indicate that exposure to short days renders the hypothalamic-hypophyseal neuroendocrine system governing gonadotropin release relatively insensitive to gonadal steroid hormone feedback. PMID:1120474

  11. The influence of natural short photoperiodic and temperature conditions on plasma thyroid hormones and cholesterol in male Syrian hamsters

    NASA Astrophysics Data System (ADS)

    Vaughan, M. K.; Brainard, G. C.; Reiter, R. J.

    1984-09-01

    Adult male Syrian hamsters were subjected to 1, 3, 5, 7 or 11 weeks of either natural winter conditions or rigorously controlled laboratory conditions (LD 10∶14; 22 ± 2‡C). Although both groups of hamsters gained weight over the course of the experiment, hamsters housed indoors were significantly heavier after 5 weeks of treatment compared to their outdoors counterparts. Animals housed under natural conditions exhibited a significant decrease in circulating levels of thyroxine (T4) and a rapid rise in triiodothyronine (T3) levels; the free T4 and free T3 index (FT4I and FT3I) mirrored the changes in circulating levels of the respective hormones. Laboratory-housed animals had a slight rise in T4 and FT4I at 3 weeks followed by a slow steady decline in these values; T3 and FT3I values did not change remarkably in these animals. Plasma cholesterol declined steadily over the course of the experiment in laboratory-maintained animals but increased slightly during the first 5 weeks in animals under natural conditions. Since the photoperiodic conditions were approximately of the same duration in these 2 groups, it is concluded that the major differences in body weight, thyroid hormone values and plasma cholesterol are due to some component (possibly temperature) in the natural environment.

  12. Unrefined and refined black raspberry seed oils significantly lower triglycerides and moderately affect cholesterol metabolism in male Syrian hamsters.

    PubMed

    Ash, Mark M; Wolford, Kate A; Carden, Trevor J; Hwang, Keum Taek; Carr, Timothy P

    2011-09-01

    Unrefined and refined black raspberry seed oils (RSOs) were examined for their lipid-modulating effects in male Syrian hamsters fed high-cholesterol (0.12% g/g), high-fat (9% g/g) diets. Hamsters fed the refined and the unrefined RSO diets had equivalently lower plasma total cholesterol and high-density lipoprotein (HDL) cholesterol in comparison with the atherogenic coconut oil diet. The unrefined RSO treatment group did not differ in liver total and esterified cholesterol from the coconut oil-fed control animals, but the refined RSO resulted in significantly elevated liver total and esterified cholesterol concentrations. The unrefined RSO diets significantly lowered plasma triglycerides (46%; P=.0126) in comparison with the coconut oil diet, whereas the refined RSO only tended to lower plasma triglyceride (29%; P=.1630). Liver triglyceride concentrations were lower in the unrefined (46%; P=.0002) and refined (36%; P=.0005) RSO-fed animals than the coconut oil group, with the unrefined RSO diet eliciting a lower concentration than the soybean oil diet. Both RSOs demonstrated a null or moderate effect on cholesterol metabolism despite enrichment in linoleic acid, significantly lowering HDL cholesterol but not non-HDL cholesterol. Dramatically, both RSOs significantly reduced hypertriglyceridemia, most likely due to enrichment in α-linolenic acid. As a terrestrial source of α-linolenic acid, black RSOs, both refined and unrefined, provide a promising alternative to fish oil supplementation in management of hypertriglyceridemia, as demonstrated in hamsters fed high levels of dietary triglyceride and cholesterol.

  13. A 15-minute light pulse during darkness prevents the antigonadotrophic action of afternoon melatonin injections in male hamsters

    NASA Astrophysics Data System (ADS)

    Reiter, R. J.; Hurlbut, E. C.; King, T. S.; Richardson, B. A.; Vaughan, M. K.; Kosub, K. Y.

    1982-12-01

    When adult male Syrian hamsters were maintained under 14 h light and 10 h darkness daily (lights on from 0600-2000 h), peak pineal melatonin levels (705 pg/gland) were attained at 0500 h. When the dark phase of the light:dark cycle was interrupted with a 15 min pulse of light from 2300 2315 h (3 h after lights out), the highest melatonin levels achieved was roughly 400 pg/gland. Finally, if the 15 min pulse of light was given at 0200 0215 h (6 h after lights out) the nocturnal rise in pineal melatonin was completely abolished. Having made these observations, a second experiment was designed to determine the ability of afternoon melatonin injections to inhibit reproduction in hamsters kept under an uninterrupted 14∶10 cycle or under the same lighting regimen where the dark phase was interrupted with a 15 min pulse of light (0200 0215 h). In the uninterrupted light:dark schedule the daily afternoon injection of 25 μg melatonin caused the testes and the accessory sex organs to atrophy within 11 weeks. Conversely, if the dark phase was interrupted with light between 0200 0215 h, afternoon melatonin injections were incapable of inhibiting the growth of the reproductive organs. The findings suggest that exogenously administered melatonin normally synergizes with endogenously produced melatonin to cause gonadal involution in hamsters.

  14. Siberian Islands

    Atmospheric Science Data Center

    2013-04-16

    ... Distinguishing Clouds from Ice over the East Siberian Sea, Russia     View Larger Image ... ocean are visible. The East Siberian Sea is part of the Arctic Ocean and is ice-covered most of the year. The New Siberian Islands are ...

  15. A 1-bp deletion in Fgf5 causes male-dominant long hair in the Syrian hamster.

    PubMed

    Yoshizawa, Yasuhiro; Wada, Kenta; Shimoi, Gaku; Shiomi, Gaku; Kameyama, Yuichi; Wakabayashi, Yuichi; Fukuta, Katsuhiro; Hashizume, Ryoichi

    2015-12-01

    Hair length in mammals is generally regulated by the hair cycle, and its disruption leads to abnormal hair morphogenesis in several species. FGF5, one of the hair cycle regulators, has a role in inducing catagen, and that mutation causes abnormal hair length in both sexes in humans, mice, dogs, and cats. Male-dominant long-haired coat (MALC) is an inbred strain of Syrian hamster exhibiting spontaneous long hair in males. After castration, MALC exhibited significantly shorter hair than the control individuals, but testosterone administration to castrated MALC showed reversion to the original phenotype. Moreover, flutamide administration led to MALC phenotype repression. Histological analysis revealed that hair follicle regression was shown in the wild-type 4 weeks after depilation, but that of MALC remained in the anagen phase. We detected a c.546delG of Fgf5 in MALC (Fgf5malc) that might lead to truncation resulting from a frame shift in FGF5 (p.Arg184GlyfsX6). Additionally, homozygous Fgf5malc was only detected in long-haired (Slc:Syrian×MALC)F2 and (J-2-Nn×MALC)F2 progenies, and all homozygous wild and heterozygous Fgf5malc individuals showed normal hair length. Thus, Fgf5malc leads to male-dominant long hair via a prolonged anagen phase which is affected by testosterone in hamsters. To our knowledge, this report is the first to present the sexual dimorphism of hair length caused by the Fgf5 mutation.

  16. PC1/3 and PC2 gene expression and post-translational endoproteolytic pro-opiomelanocortin processing is regulated by photoperiod in the seasonal Siberian hamster (Phodopus sungorus).

    PubMed

    Helwig, M; Khorooshi, R M H; Tups, A; Barrett, P; Archer, Z A; Exner, C; Rozman, J; Braulke, L J; Mercer, J G; Klingenspor, M

    2006-06-01

    A remarkable feature of the seasonal adaptation displayed by the Siberian hamster (Phodopus sungorus) is the ability to decrease food intake and body weight (by up to 40%) in response to shortening photoperiod. The regulating neuroendocrine systems involved in this adaptation and their neuroanatomical and molecular bases are poorly understood. We investigated the effect of photoperiod on the expression of prohormone convertases 1 (PC1/3) and 2 (PC2) and the endoproteolytic processing of the neuropeptide precursor pro-opiomelanocortin (POMC) within key energy balance regulating centres of the hypothalamus. We compared mRNA levels and protein distribution of PC1/3, PC2, POMC, adrenocorticotrophic hormone (ACTH), alpha-melanocyte-stimulating hormone (MSH), beta-endorphin and orexin-A in selected hypothalamic areas of long day (LD, 16:8 h light:dark), short day (SD, 8:16 h light:dark) and natural-day (ND, photoperiod depending on time of the year) acclimated Siberian hamsters. The gene expression of PC2 was significantly higher within the arcuate nucleus (ARC, P < 0.01) in SD and in ND (versus LD), and is reflected in the day length profile between October and April in the latter. PC1/3 gene expression in the ARC and lateral hypothalamus was higher in ND but not in SD compared to the respective LD controls. The immunoreactivity of PC1/3 cleaved neuropeptide ACTH in the ARC and PC1/3-colocalised orexin-A in the lateral hypothalamus were not affected by photoperiod changes. However, increased levels of PC2 mRNA and protein were associated with higher abundance of the mature neuropeptides alpha-MSH and beta-endorphin (P < 0.01) in SD. This study provides a possible explanation for previous paradoxical findings showing lower food intake in SD associated with decreased POMC mRNA levels. Our results suggest that a major part of neuroendocrine body weight control in seasonal adaptation may be effected by post-translational processing mediated by the prohormone convertases PC1

  17. Maternal transfer of photoperiodic information in Siberian hamsters. vi. effects of time-dependent 1-hr melatonin infusions in the mother on photoperiod-induced testicular development of her offspring.

    PubMed

    Gündüz, Bülent; Stetson, Milton H

    2003-04-01

    We tested in Siberian hamsters the nature of the maternal signal that relays photoperiodic information to the developing fetuses. As previous investigations have identified maternal hormonal and circadian components in this process, the specific goal of this presentation is to determine quality of the signal that connotes daylength when it is imparted to the fetus. Does the function of the signal received by the fetus best support the coincidence or duration hypotheses of photoperiodic induction? Pregnant hamsters received 1 or 8 hr melatonin or vehicle infusions everyday. Juveniles of intact mothers gestated on 16 hr of light per day (16L) experienced maximal suppression of testicular development when reared on 14L. However, when intact mothers gestated on 10L received a 1-hr melatonin infusion daily at 20:00-21:00 hr, their young responded to 14L with greatly accelerated testicular development. In the absence of the maternal pineal gland (and, therefore, the maternal melatonin signal), the effects of maternal melatonin infusions were reversed. Here, only the juveniles of 16L-gestated females infused at 20:00-21:00 hr daily responded to 14L with enhanced testicular development. All other groups showed the same extent of gonadal development, independent of the time or type of infusion their mothers received. Testicular development on 14L of all juveniles from pinealectomized mothers gestated on 10L was of the same magnitude, regardless of the type and time of infusion their mothers received during pregnancy. The results suggest that the maternal signal transferred to the fetuses during gestation consists not only of the daily melatonin signal, but also some circadian-based component that greatly affects the effect of the former. The timing, and not the duration, of the maternal melatonin signal with respect to the animals' (mother and fetus) circadian day is of crucial importance in the transfer of photoperiodic information from mother to fetus.

  18. Nocturnal illumination maintains reproductive function and simulates the period-lengthening effect of constant light in the mature male Djungarian hamster (Phodopus sungorus)

    NASA Technical Reports Server (NTRS)

    Ferraro, J. S.

    1990-01-01

    Mature male Djungarian hamsters (Phodopus sungorus) were placed in individual light-tight, sound attenuated chambers and exposed to one of four lighting conditions for a duration of approximately seven weeks. The four lighting conditions were: constant light (LL); constant dark (DD); feedback lighting (LDFB; a condition that illuminates the cage in response to locomotor activity); or a feedback lighting neighbor control (LDFB NC; the animal receives the same light pattern as a paired animal in feedback lighting, but has no control over it). Exposure of hamsters to LL or LDFB produced significantly and similarly longer free-running periods of the locomotor activity rhythm than exposure of animals to DD. Hamsters exposed to LDFB NC did not free-run or entrain, but rather displayed "relative coordination". The paired testes and sex accessory glands weights suggest that in the Djungarian hamster, LL and LDFB exposed animals maintained reproductive function, whereas DD exposed animals did not. Animals exposed to LDFB NC had intermediate paired testes weights. Since several previous studies have demonstrated that short pulses of light, which are coincident with the subjective night, are photostimulatory, it is not surprising that LDFB maintained reproductive function in the mature Djungarian hamster. Feedback lighting, however, has been shown to be an insufficient stimulus to maintain reproductive function of mature male and female Syrian hamsters, and to the reproductive maturation of immature Djungarian hamsters. The results suggest that there may be slight, but significant differences in the way these two species interpret photoperiod, as well as a developmental change in the photoperiodic response of Djungarian hamsters.

  19. Mate preference for dominant vs. subordinate males in young female Syrian hamsters (Mesocricetus auratus) following chemically-accelerated ovarian follicle depletion.

    PubMed

    Roosa, Kristen A; Place, Ned J

    2015-12-01

    Life history theory predicts that selectivity for mates generally declines as females age. We previously demonstrated this phenomenon in Syrian hamsters (Mesocricetus auratus), in that older females showed reduced preference for dominant over subordinate males. To test the hypothesis that decreased reproductive quality due to aging reduces mate preference, we decoupled reproductive and chronological age by treating young female hamsters with 4-vinylcyclohexene diepoxide (VCD), which destroys ovarian follicles and functionally accelerates ovarian follicle depletion without compromising the general health of rodents. In this study, VCD effectively reduced follicle numbers in young Syrian hamsters. VCD-treated and control females were allowed to choose between a dominant and a subordinate male in a Y-maze on the day of proestrus. Both VCD-treated and control females demonstrated preference for the dominant male by leaving a greater proportion of vaginal scent marks near him, which is a behavior that females display when soliciting prospective mates. However, there was no effect of treatment on the proportion of vaginal scent marks left for the dominant male. Furthermore, ovarian follicle numbers were not significantly correlated with any behaviors in either group. We conclude that accelerated ovarian follicle depletion does not reduce mate preference in young female hamsters.

  20. HIV education in a Siberian prison colony for drug dependent males

    PubMed Central

    Dolan, Kate A; Bijl, Murdo; White, Bethany

    2004-01-01

    Aim To evaluate the effectiveness of an HIV peer training program conducted in a colony for drug dependent male prisoners in Siberia, Russia. Method Questionnaires were used to collect data pre and post peer training sessions. Three peer training sessions were conducted between questionnaires. Fifteen to twenty inmates were trained as peer educators at each week-long health education training session. Results In 2000 and 2001, 153 and 124 inmates completed the questionnaire respectively. Respondents in both years reported similar health and injecting histories and comparable levels of sexual activity. Respondents in 2001 were significantly more likely to correctly identify both how HIV can and cannot be transmitted compared to respondents in 2000. The prevalence of tattooing in prison decreased significantly between questionnaires. However, there was virtually no reported use of bleach to clean tattooing or injecting equipment in either 2000 or 2001. Access to condoms increased significantly between questionnaires. Conclusions While this training program was associated with improved HIV knowledge, the Ministry of Justice should consider improved and additional harm reduction strategies. These include increased availability of bleach and condoms and the introduction of methadone treatment and syringe exchange in prison. PMID:15207012

  1. Photoperiodic regulation of insulin receptor mRNA and intracellular insulin signaling in the arcuate nucleus of the Siberian hamster, Phodopus sungorus.

    PubMed

    Tups, Alexander; Helwig, Michael; Stöhr, Sigrid; Barrett, Perry; Mercer, Julian G; Klingenspor, Martin

    2006-09-01

    During the last 5 years it has been well established that photoperiod-induced changes in body weight in the seasonal hamster, Phodopus sungorus, are accompanied by a marked seasonal cycle in leptin sensitivity. In the present study, we investigated the possible involvement of insulin signaling in seasonal body weight regulation. We analyzed the expression pattern and relative intensity of insulin receptor (IR), phosphatidylinositol 3-kinase (PI3-kinase), and protein tyrosine phosphatase 1B (PTP1B) mRNAs by in situ hybridization in the brains of juvenile female hamsters acclimated to either long- (LD) or short-day length (SD) for 8 wk, with or without superimposed food deprivation for 48 h. Furthermore, the hypothalamic concentration and distribution of phospho-AKT, a marker of PI3-kinase activity was determined by immunoblotting and immunohistochemistry. Eight weeks of acclimation to SD led to a substantial downregulation of IR, PTP1B gene expression, and phospho-AKT concentration in this brain region, whereas PI3-kinase mRNA was unchanged. Food deprivation induced a decrease in PTP1B and a trend toward lowered IR gene expression in LD but not in SD. Additionally, a striking increase in PTP1B gene expression in the thalamus was observed after food deprivation in both photoperiods. The direction of change in neuronal insulin signaling contrasts to the central catabolic nature of this pathway described in other species. SD-induced reduction in insulin signaling may be due to decline in body fat stores mediated by enhanced central leptin sensitivity. Increased anorexigenic tone of leptin may overwrite central insulin signaling to prevent catabolic overdrive.

  2. Siberian Sediments

    NASA Technical Reports Server (NTRS)

    2002-01-01

    Today's SeaWiFS view of northern Siberia shows very turbid water along the coast in the Laptev and East Siberian Seas. The islands in the left half of the image are the New Siberian Islands. Grid lines mark one-degree intervals.

  3. The effects of feedback lighting on the circadian rhythm of locomotor activity and the reproductive maturation of the male Djungarian hamster (Phodopus sungorus)

    NASA Technical Reports Server (NTRS)

    Ferraro, J. S.

    1988-01-01

    The non-parametric model of entrainment suggests that brief pulses of light, delivered between dusk and dawn can simulate the phasing effects of full photoperiods or even constant light (LL). Feedback lighting (LDFB) is a lighting condition where individual animals, otherwise in constant darkness (DD), are exposed to light in response to a monitored behavior. The specific purpose of this type of illumination is to expose the circadian cycle to light only during the subjective night. LDFB has been used to support this hypothesis in several species of nocturnal rodents and one species of diurnal primate by producing similar free-running periods in LDFB as in LL. This lighting condition has also been used to test the hypothesis that exposing the subjective night to even short duration light pulses will maintain reproductive function in long day breeders. In the Syrian hamster (Mesocricetus auratus), however, LDFB is not as photostimulatory as LL despite extensive light exposure during the subjective night. In the experiments presented here, a group of immature male Djungarian hamsters (Phodopus sungorus) were placed in individual light-tight sound attenuated chambers where they had free access to food, water and an activity wheel. The animals were exposed to one of four lighting conditions [DD, LL, LDFB or a neighbor control of feedback lighting (LDFB NC)] for approximately 30 days shortly after weaning. LDFB NC is a lighting condition where a neighbor control hamster receives the identical lighting regime as a paired animal exposing itself to LDFB, yet the neighbor has no control over it. A fifth group was exposed to a light-dark cycle of 16 hours of light and 8 hours of dark (LD16:8). This group was housed in cages in a colony room and did not have access to a running wheel. The free-running periods of the locomotor activity rhythms for hamsters exposed to LDFB and LL were not similar, unlike the results for rats, Syrian hamsters, mice, monkeys and even mature

  4. The effects of spectral power distribution and illuminance levels on key parameters in the male golden hamster and rat with preliminary observations on the effects of pinealectomy.

    PubMed

    Hoffman, R A; Johnson, L B; Corth, R

    1985-01-01

    Three different light sources were used to determine the effects of spectral power distribution (SPD) and illuminance levels on growth and organ weights of male golden hamsters and rats. SPD had little effect on organ weights or measurements of either rats or hamsters. However, responses to illuminance levels were quite apparent, provided they were equalized for the scotopic eye sensitivity curve characteristic of nocturnal animals. Under seven illuminance levels from 0 to 3.9 scotopic fc, hamsters demonstrated graded responses in gonadal weights and presumed function from 0 to 0.02 scotopic fc. Above this level, photopic saturation was apparent. The neuroendocrine system of pinealectomized animals failed to show sensitivity to illuminance levels. The suggestion is made that the pineal gland acts to monitor illuminance levels (below about 0.02 scotopic fc) as well as photic duration. While the latter appears to be an "all or none" effect, the former appears to be graded.

  5. Photic threshold for stimulation of testicular growth and pituitary FSH release in male Djungarian hamsters.

    PubMed

    Milette, J J; Takahashi, J S; Turek, F W

    1990-04-01

    While the effects of photoperiod on neuroendocrine-gonadal activity have been extensively studied in a number of species, surprisingly little information concerning the quantitative aspects of light regulating reproductive activity is available. In the present experiment, Djungarian hamsters were exposed to two 10 min pulses of light per day and the light irradiance was systematically varied to determine the threshold for photostimulation by white light. After 10 days testes weight and serum follicle-stimulating hormone (FSH) levels were determined. The data indicate that the irradiance threshold necessary for induction of significant increases of both serum FSH levels and testes weight lies between 0.1 and 0.34 microW/cm2 for 10 min pulses of light. These results demonstrate a strong correlation between the effects of light on serum FSH levels and testes weight and provide the first quantitative assessment of the irradiance threshold for light involved in photoperiodic stimulation of the hypothalamic-pituitary gonadal axis of a mammalian species.

  6. Vomeronasal organ lesion disrupts social odor recognition, behaviors and fitness in golden hamsters.

    PubMed

    Liu, Yingjuan; Zhang, Jinhua; Liu, Dingzhen; Zhang, Jianxu

    2014-06-01

    Most studies support the viewpoint that the vomeronasal organ has a profound effect on conspecific odor recognition, scent marking and mating behavior in the golden hamster (Mesocricetus auratus). However, the role of the vomeronasal organ in social odor recognition, social interaction and fitness is not well understood. Therefore, we conducted a series of behavioral and physiological tests to examine the referred points in golden hamster. We found that male hamsters with vomeronasal organ lesion showed no preference between a predator odor (the anal gland secretion of the Siberian weasels (Mustela sibirica) and putative female pheromone components (myristic acid and palmitic acid), but were still able to discriminate between these 2 kinds of odors. In behavioral tests of anxiety, we found that vomeronasal organ removal causes female hamsters to spend much less time in center grids and to cross fewer center grids and males to make fewer crossings between light and dark boxes than sham-operated controls. This indicates that a chronic vomeronasal organ lesion induced anxious responses in females. In aggressive behavioral tests, we found that a chronic vomeronasal organ lesion decreased agonistic behavior in female hamsters but not in males. The pup growth and litter size show no differences between the 2 groups. All together, our data suggested that vomeronasal organ ablation disrupted the olfactory recognition of social chemosignals in males, and induced anxiety-like and aggressive behavior changes in females. However, a vomeronasal organ lesion did not affect the reproductive capacity and fitness of hamsters. Our studies may have important implications concerning the role of the vomeronasal organ in golden hamsters and also in rodents. PMID:24952966

  7. Vomeronasal organ lesion disrupts social odor recognition, behaviors and fitness in golden hamsters.

    PubMed

    Liu, Yingjuan; Zhang, Jinhua; Liu, Dingzhen; Zhang, Jianxu

    2014-06-01

    Most studies support the viewpoint that the vomeronasal organ has a profound effect on conspecific odor recognition, scent marking and mating behavior in the golden hamster (Mesocricetus auratus). However, the role of the vomeronasal organ in social odor recognition, social interaction and fitness is not well understood. Therefore, we conducted a series of behavioral and physiological tests to examine the referred points in golden hamster. We found that male hamsters with vomeronasal organ lesion showed no preference between a predator odor (the anal gland secretion of the Siberian weasels (Mustela sibirica) and putative female pheromone components (myristic acid and palmitic acid), but were still able to discriminate between these 2 kinds of odors. In behavioral tests of anxiety, we found that vomeronasal organ removal causes female hamsters to spend much less time in center grids and to cross fewer center grids and males to make fewer crossings between light and dark boxes than sham-operated controls. This indicates that a chronic vomeronasal organ lesion induced anxious responses in females. In aggressive behavioral tests, we found that a chronic vomeronasal organ lesion decreased agonistic behavior in female hamsters but not in males. The pup growth and litter size show no differences between the 2 groups. All together, our data suggested that vomeronasal organ ablation disrupted the olfactory recognition of social chemosignals in males, and induced anxiety-like and aggressive behavior changes in females. However, a vomeronasal organ lesion did not affect the reproductive capacity and fitness of hamsters. Our studies may have important implications concerning the role of the vomeronasal organ in golden hamsters and also in rodents.

  8. Phenotypic plasticity of male Schistosoma mansoni from the peritoneal cavity and hepatic portal system of laboratory mice and hamsters.

    PubMed

    Mati, V L T; Freitas, R M; Bicalho, R S; Melo, A L

    2015-05-01

    Morphometric analysis of Schistosoma mansoni male worms obtained from AKR/J and Swiss mice was carried out. Rodents infected by the intraperitoneal route with 80 cercariae of the schistosome (LE strain) were killed by cervical dislocation at 45 and 60 days post-infection and both peritoneal lavage and perfusion of the portal system were performed for the recovery of adult worms. Characteristics including total body length, the distance between oral and ventral suckers, extension of testicular mass and the number of testes were considered in the morphological analysis. Changes that occurred in S. mansoni recovered from the peritoneal cavity or from the portal system of AKR/J and Swiss mice included total body length and reproductive characteristics. Significant morphometric alterations were also observed when worms recovered from the portal system of both strains of mice were compared with the schistosomes obtained from hamsters (Mesocricetus auratus), the vertebrate host in which the LE strain had been adapted and maintained by successive passages for more than four decades. The present results reinforce the idea that S. mansoni has high plastic potential and adaptive capacity.

  9. Molecular and Immunological Characterization of the First Allergenic Lipocalin in Hamster

    PubMed Central

    Torres, José Alberto; de las Heras, Manuel; Maroto, Aroa Sanz; Vivanco, Fernando; Sastre, Joaquín; Pastor-Vargas, Carlos

    2014-01-01

    The most frequent pet allergy is to cat and dog, but in recent years, it has become increasingly popular to have other pets, and the risk of exposure to new allergens is more prevalent. The list of new pets includes hamsters, and one of the most popular hamsters is the Siberian hamster (Phodopus sungorus). The aim of this study was the characterization and cloning of the major allergen from this hamster. The study of its allergenicity and cross-reactivity could improve the specific diagnosis and treatment for hamster-allergic patients. Thirteen Siberian hamster-allergic patients were recruited at the outpatient clinic. Protein extracts were prepared from the hair, urine, and salivary glands of four hamster species (European, golden, Siberian, and Roborovski). IgE-binding proteins were detected by immunoblotting and identified by mass spectrometry. The recombinant protein was produced in Escherichia coli and then purified by metal chelate affinity chromatography. The allergenic properties of the recombinant protein were tested by ELISA and immunoblotting, and biological activity was tested according to capacity for basophil activation. Three IgE-binding proteins were identified in extracts obtained from Siberian hamster hair, urine, and salivary glands. All proteins corresponded to the same protein, which was identified as a lipocalin. This lipocalin had no cross-reactivity with common and golden hamsters. The recombinant allergen was cloned and purified, showing similar IgE reactivity in vitro to Siberian hamster protein extracts. Also, the recombinant allergen was capable of producing biological activation in vivo. The major Siberian hamster allergen was cloned, and allergenic properties were characterized, providing a new tool for specific diagnosis of allergy to Siberian hamster. PMID:24993820

  10. Anti-Müllerian hormone (AMH), inhibin-α, growth differentiation factor 9 (GDF9), and bone morphogenic protein-15 (BMP15) mRNA and protein are influenced by photoperiod-induced ovarian regression and recrudescence in Siberian hamster ovaries.

    PubMed

    Shahed, Asha; Young, Kelly A

    2013-11-01

    Exposure of Siberian hamsters to short photoperiod (SD) inhibits ovarian function, including folliculogenesis, whereas function is restored with their transfer to long photoperiods (LD). To investigate the mechanism of photo-stimulated recrudescence, we assessed key folliculogenic factors-anti-Müllerian hormone (AMH), inhibin-α, growth differentiation factor-9 (GDF9), and bone morphogenic protein-15 (BMP15)-across the estrus cycle and in photo-regressed and recrudescing ovaries. Adult hamsters were exposed to either LD or SD for 14 weeks, which respectively represent functional and regressed ovaries. Select regressed hamsters were transferred back to LD for 2 (post-transfer week 2; PTw2) or 8 weeks (PTw8). Ovaries were collected and fixed in formalin for immunohistochemistry or frozen in liquid nitrogen for real-time PCR. AMH, inhibin-α, GDF9, and BMP15 mRNA and protein were detected in all stages of the estrus cycle. Fourteen weeks of SD exposure increased (P < 0.05) ovarian AMH, GDF9, and BMP15, but not inhibin-α mRNA levels as compared to LD. Transfer of regressed hamsters to stimulatory long photoperiod for 8 weeks returned AMH and GDF9 mRNA levels to LD-treated levels, and further increased mRNA levels for inhibin-α and BMP15. Immunostaining for AMH, inhibin-α, GDF9, and BMP15 proteins was most intense in preantral/antral follicles and oocytes. The overall immunostaining extent for AMH and inhibin-α generally mirrored the mRNA data, though no changes were observed for GDF9 or BMP15 immunostaining. Shifts in mRNA and protein levels across photoperiod conditions suggest possible syncretic roles for these folliculogenic factors in photo-stimulated recrudescence via potential regulation of follicle recruitment, preservation, and development.

  11. Expression of vasopressin receptors in hamster hypothalamus is sexually dimorphic and dependent upon photoperiod.

    PubMed Central

    Dubois-Dauphin, M; Theler, J M; Zaganidis, N; Dominik, W; Tribollet, E; Pévet, P; Charpak, G; Dreifuss, J J

    1991-01-01

    The distribution of vasopressin receptors was studied in the brain of a photoperiodic animal, the Siberian hamster. Attention was focused on [3H]vasopressin binding sites located in the hypothalamic ventromedial nucleus, medial tuberal nucleus, and ventral premammillary nucleus in males or females kept in long or short photoperiod conditions. Displacement experiments with structural analogs suggested that vasopressin receptors in the hamster hypothalamus are of the vasopressor (V1) type. Quantitative data obtained with a gaseous detector of beta-particles indicated that in the ventromedial nucleus and in the ventral premammillary nucleus of animals in long photoperiod, the number of beta-particles emitted per unit area was significantly greater in males than in females. In the ventromedial hypothalamic nucleus, in both males and females, the number of beta-particles emitted was significantly lower in short than in long photoperiod conditions. In the ventral premammillary nucleus, shortening of the photoperiod had a significant effect in reducing the amount of [3H]vasopressin bound in females, but not in males. These data suggest that, in the hamster, the control of the expression of vasopressin receptors differs among various hypothalamic nuclei and may depend on the sex and/or on the level of circulating gonadal steroids. Images PMID:1837144

  12. [Resting metabolic rate, stress, testosterone, and induced immune response in "spring" and "fall" males of Campbell dwarf hamsters. Rearing under the long day conditions].

    PubMed

    Rogovin, K A; Bushuev, A V; Khrushchova, A M; Vasil'eva, N Iu

    2013-01-01

    We have studied morphological and physiological traits of even-young males of Campbell dwarf hamsters (Phodopus campbelli Thomas, 1905) born at the end of summer ("fall males") and at the end of winter ("spring males") in a vivarium with constant 14-hour day length (14D:10N). After removal from parental cages at the age of one month, males were kept in isolation under the same light conditions. The results obained signify the statistical difference between "fall" and "spring" males in resting metabolic rate, morphological traits associated with sexual activity, some endocrine and immunologic characteristics. Spring males had higher resting metabolic rate, higher body mass in the middle of experiment, bigger testes, seminal vesicles, higher concentration of testosterone in blood and more intensive T-cell immune response to the intracutaneous injection of phytohemagglutinin. They did not differ significantly in basal level of blood cortisole and antibodies production in response to sheep red blood cells (SRBC) antigen challenge, but possessed lower adrenocortical response to the social stressor and adrenocorticotropic hormone. GLM analysis showed that cortisol level in blood after 10 min encounter of males in the open arena, and resting metabolic rate were the only factors significantly influenced humoral immune response to SRBC. When intensity of T-cell immune response was considered as dependent variable, season turned out to be the only factor in the final model that caused a significant effect.

  13. Effect of RFRP-3 on reproduction is sex- and developmental status-dependent in the striped hamster (Cricetulus barabensis).

    PubMed

    Zhao, Lei; Zhong, Min; Xue, Hui-Liang; Ding, Ji-Shun; Wang, Shuo; Xu, Jin-Hui; Chen, Lei; Xu, Lai-Xiang

    2014-09-01

    RFamide-related peptides (RFRPs) are orthologous to gonadotropin-inhibitory hormone (GnIH) inhibiting gonadotropin release. There are only two RFRP sequences (RFRP-1 and RFRP-3) encoded in rodents. RFRP-3, which was considered as a hypothetical inhibitor on GnRH, shows a stimulatory effect on the male Syrian and male Siberian hamster in short days. As a dominant rodent pest in northern China farmland, the striped hamster (Cricetulus barabensis) has higher reproductive activities and could act as a model to study the mechanism of reproduction. However, the effect of RFRP-3 on the reproductive activity for the striped hamster is less understood. In the study, we cloned 643 bp RFRP cDNA from the striped hamster hypothalamus, which contained an ORF of 570 bp encoding two RFamide-related peptide (RFRP) sequences: SPAPANKVPHSAANLPLRF-NH2 (C. barabensis RFRP-1) and TLSRVPSLPQRF-NH2 (C. barabensis RFRP-3). We also investigated the expression variation of RFRP mRNA and GnRH mRNA in the hypothalamus from hamsters with different developmental statuses (7-week-, 13-week- and 1.5-year-olds) using FQ-PCR, in which the 13-week-old female individuals were in estrous. The striped hamsters that are 7 weeks and 1.5 years old are non-breeding individuals, and those that are 13-week hamsters have breeding phenomena. The highest hypothalamus RFRP mRNA level was found in breeding males as compared to non-breeding males. Conversely, the lowest RFRP mRNA level in the hypothalamus was observed in breeding females, with no significant level when the breeding females were compared to the 7-week-old individuals. Additionally, the investigation of GnRH expression level showed a declining expression trend across the developmental stages (7-week-, 13-week- and 1.5-year-olds) in both sexes. Significant negative and positive relationships were detected in the 13-week estrous female (r=-0.997, P=0.035) and the 13-week male (r=0.998, P=0.029) striped hamsters respectively, which suggest that RFRP-3

  14. Repeated, Intermittent Social Defeat across the Entire Juvenile Period Resulted in Behavioral, Physiological, Hormonal, Immunological, and Neurochemical Alterations in Young Adult Male Golden Hamsters

    PubMed Central

    Yu, Wei-Chun; Liu, Ching-Yi; Lai, Wen-Sung

    2016-01-01

    The developing brain is vulnerable to social defeat during the juvenile period. As complements of human studies, animal models of social defeat provide a straightforward approach to investigating the functional and neurobiological consequences of social defeats. Taking advantage of agonist behavior and social defeat in male golden hamster, a set of 6 experiments was conducted to investigate the consequences at multiple levels in young adulthood resulting from repeated, intermittent social defeats or “social threats” across the entire juvenile period. Male hamsters at postnatal day 28 (P28) were randomly assigned to either the social defeat, “social threat”, or arena control group, and they correspondingly received a series of nine social interaction trials (i.e., either social defeat, “social threat”, or arena control conditions) from P33 to P66. At the behavioral level (Experiment 1), we found that repeated social defeats (but not “social threats”) significantly impacted locomotor activity in the familiar context and social interaction in the familiar/unfamiliar social contexts. At the physiological and hormonal levels (Experiments 2 and 3), repeated social defeat significantly enhanced the cortisol and norepinephrine concentrations in blood. Enlargement of the spleen was also found in the social defeat and “social threat” groups. At the immunological level (Experiment 4), the social defeat group showed lower levels of pro-inflammatory cytokines in the hypothalamus and hippocampus but higher concentration of IL-6 in the striatum compared to the other two groups. At the neurochemical level (Experiment 5), the socially defeated hamsters mainly displayed reductions of dopamine, dopamine metabolites, and 5-HT levels in the striatum and decreased level of 5-HT in the hippocampus. In Experiment 6, an increase in the spine density of hippocampal CA1 pyramidal neurons was specifically observed in the “social threat” group. Collectively, our

  15. Repeated, Intermittent Social Defeat across the Entire Juvenile Period Resulted in Behavioral, Physiological, Hormonal, Immunological, and Neurochemical Alterations in Young Adult Male Golden Hamsters.

    PubMed

    Yu, Wei-Chun; Liu, Ching-Yi; Lai, Wen-Sung

    2016-01-01

    The developing brain is vulnerable to social defeat during the juvenile period. As complements of human studies, animal models of social defeat provide a straightforward approach to investigating the functional and neurobiological consequences of social defeats. Taking advantage of agonist behavior and social defeat in male golden hamster, a set of 6 experiments was conducted to investigate the consequences at multiple levels in young adulthood resulting from repeated, intermittent social defeats or "social threats" across the entire juvenile period. Male hamsters at postnatal day 28 (P28) were randomly assigned to either the social defeat, "social threat", or arena control group, and they correspondingly received a series of nine social interaction trials (i.e., either social defeat, "social threat", or arena control conditions) from P33 to P66. At the behavioral level (Experiment 1), we found that repeated social defeats (but not "social threats") significantly impacted locomotor activity in the familiar context and social interaction in the familiar/unfamiliar social contexts. At the physiological and hormonal levels (Experiments 2 and 3), repeated social defeat significantly enhanced the cortisol and norepinephrine concentrations in blood. Enlargement of the spleen was also found in the social defeat and "social threat" groups. At the immunological level (Experiment 4), the social defeat group showed lower levels of pro-inflammatory cytokines in the hypothalamus and hippocampus but higher concentration of IL-6 in the striatum compared to the other two groups. At the neurochemical level (Experiment 5), the socially defeated hamsters mainly displayed reductions of dopamine, dopamine metabolites, and 5-HT levels in the striatum and decreased level of 5-HT in the hippocampus. In Experiment 6, an increase in the spine density of hippocampal CA1 pyramidal neurons was specifically observed in the "social threat" group. Collectively, our findings indicate that repeated

  16. Tributyltin-mediated hepatic, renal and testicular tissue damage in male Syrian hamster (Mesocricetus auratus): a study on impact of oxidative stress.

    PubMed

    Kanimozhi, V; Palanivel, K; Akbarsha, M A; Kadalmani, B

    2016-01-01

    Organotin compounds are a versatile group of organometallic chemicals that are used in a variety of industrial and agricultural applications. Tributyltin (TBT), a common organotin, brings about severe spermatotoxic and organotoxic effects. However, information about the adverse effects of TBT on liver, kidney and testis is scanty. Hence, the present study was undertaken to elucidate the TBT-mediated oxidative stress-induced impairments in these organs. Administration of TBT through oral route at increasing doses of 50, 100 and 150 ppm for 65 days to male Syrian hamsters resulted in drastically decreased activities of antioxidant enzymes superoxide dismutase, catalase and glutathione peroxidase and decreased mean levels of non-enzymatic antioxidants (reduced glutathione, vitamin C, and vitamin E) followed by a dramatic increase in the levels of lipid peroxidation in the liver, kidney and testis as compared to the control animals. Significantly high levels of serum urea, creatinine, uric acid and bilirubin were observed in TBT-treated hamsters. Also, TBT treatment induced drastic histopathological changes in the liver, kidney and testis combined with remarkable changes in serum levels of tissue injury marker enzymes Aspartate transaminases, Alkaline phosphatase and Alanine transaminase. These data affirm that exposure to TBT can lead to oxidative stress-induced damage to liver, kidney and testis. PMID:27652096

  17. Modifying effects of 1,2-dichloropropane on N-nitrosobis(2-oxopropyl)amine-induced cholangiocarcinogenesis in male Syrian hamsters.

    PubMed

    Gi, Min; Fujioka, Masaki; Yamano, Shotaro; Shimomura, Eri; Kanki, Masayuki; Kawachi, Satoko; Tachibana, Hirokazu; Tatsumi, Kumiko; Fang, He; Ishii, Naomi; Kakehashi, Anna; Wanibuchi, Hideki

    2015-01-01

    Based on the findings of epidemiological studies in Japan that occupational exposure to 1,2-dichloropropane (1,2-DCP) was associated with increased cholangiocarcinomas, 1,2-DCP has recently been classified as being carcinogenic to humans (Group 1). However, the cholangiocarcinogenicity of 1,2-DCP has not been demonstrated experimentally, and it was negative for cholangiocarcinogenicity in rats and mice. The present study determined the effects of 1,2-DCP on N-nitrosobis(2-oxopropyl)amine (BOP)-induced cholangiocarcinogenesis in male hamsters. We found that 1,2-DCP did not enhance the development of BOP-induced atypical biliary hyperplasia and did not induce any lesions in liver bile duct when administered alone. Notably, 1,2-DCP had no effect on the proliferative activity of bile duct epithelial cells regardless of BOP-initiation. These results demonstrate that 1,2-DCP lacks promoting effects on BOP-induced cholangiocarcinogenesis and suggest the possibility that 1,2-DCP is not cholangiocarcinogenic to the hamster in the present model. In addition, 1,2-DCP also lacks promoting effects on pancreatic, lung, and renal carcinogenesis. As the occurrence of occupational cholangiocarcinomas in Japan might be attributed to exposure to multiple chemicals, the results of the present study indicate that it will be necessary to determine the cholangiocarcinogenic effects of concurrent exposure of 1,2-DCP and the other halogen solvents to which workers with cholangiocarcinomas were exposed. PMID:26354381

  18. Modifying effects of 1,2-dichloropropane on N-nitrosobis(2-oxopropyl)amine-induced cholangiocarcinogenesis in male Syrian hamsters.

    PubMed

    Gi, Min; Fujioka, Masaki; Yamano, Shotaro; Shimomura, Eri; Kanki, Masayuki; Kawachi, Satoko; Tachibana, Hirokazu; Tatsumi, Kumiko; Fang, He; Ishii, Naomi; Kakehashi, Anna; Wanibuchi, Hideki

    2015-01-01

    Based on the findings of epidemiological studies in Japan that occupational exposure to 1,2-dichloropropane (1,2-DCP) was associated with increased cholangiocarcinomas, 1,2-DCP has recently been classified as being carcinogenic to humans (Group 1). However, the cholangiocarcinogenicity of 1,2-DCP has not been demonstrated experimentally, and it was negative for cholangiocarcinogenicity in rats and mice. The present study determined the effects of 1,2-DCP on N-nitrosobis(2-oxopropyl)amine (BOP)-induced cholangiocarcinogenesis in male hamsters. We found that 1,2-DCP did not enhance the development of BOP-induced atypical biliary hyperplasia and did not induce any lesions in liver bile duct when administered alone. Notably, 1,2-DCP had no effect on the proliferative activity of bile duct epithelial cells regardless of BOP-initiation. These results demonstrate that 1,2-DCP lacks promoting effects on BOP-induced cholangiocarcinogenesis and suggest the possibility that 1,2-DCP is not cholangiocarcinogenic to the hamster in the present model. In addition, 1,2-DCP also lacks promoting effects on pancreatic, lung, and renal carcinogenesis. As the occurrence of occupational cholangiocarcinomas in Japan might be attributed to exposure to multiple chemicals, the results of the present study indicate that it will be necessary to determine the cholangiocarcinogenic effects of concurrent exposure of 1,2-DCP and the other halogen solvents to which workers with cholangiocarcinomas were exposed.

  19. Female pheromones stimulate release of luteinizing hormone and testosterone without altering GnRH mRNA in adult male Syrian hamsters (Mesocricetus auratus).

    PubMed

    Richardson, Heather N; Nelson, Aaron L A; Ahmed, Eman I; Parfitt, David B; Romeo, Russell D; Sisk, Cheryl L

    2004-09-15

    In many species chemosensory stimuli function as important signals that influence reproductive status. Neurons synthesizing the peptide gonadotropin-releasing hormone (GnRH) are critical mediators of reproductive function via their regulation of the hypothalamic-pituitary-gonadal (HPG) axis, and they are thought to be responsive to chemosensory information. In the present study, we sought to elucidate the effects of female chemosensory stimuli on the HPG axis in sexually naive adult male Syrian hamsters. In Experiment 1, serial blood samples were collected from catheterized male hamsters following exposure to female pheromones in order to characterize the luteinizing hormone (LH) response to this chemosensory stimulus. In Experiment 2, brains and terminal blood samples were collected from animals 0, 60, and 120 min following pheromone exposure. GnRH mRNA was measured in brain tissue sections using in situ hybridization, and plasma concentrations of LH and testosterone were measured using radioimmunoassay. Data from Experiment 1 indicated that female pheromones elicited a rapid rise in plasma LH that peaked at 15 min and returned to baseline 45 min after exposure. In Experiment 2, testosterone was elevated in terminal blood samples obtained 60 min, but not 120 min, after exposure to pheromones. LH levels were unaffected at both of these time points. The chemosensory-induced increases in LH and testosterone release were not accompanied by subsequent changes in GnRH mRNA over the time course studied. These data suggest that while activation of the male HPG axis by female pheromones involves release of GnRH, it does not involve increases in GnRH mRNA 1-2 h after pheromonal stimulation as a mechanism for replenishment of released peptide.

  20. MT1 receptor expression and AA-NAT activity in lymphatic tissue following melatonin administration in male golden hamster.

    PubMed

    Vishwas, Dipanshu Kumar; Haldar, Chandana

    2014-09-01

    Exogenous melatonin as a marker of the chemical expression of darkness is playing a key role in the synchronization of circadian functions and seasonal biological rhythms. Our study was designed to elucidate whether melatonin treatment can modulate the melatonin synthesis via the rate limiting enzyme arylalkylamine-N-acetyltransferase (AA-NAT) in spleen, thymus and bone marrow thereby the proliferation rate of splenocytes, thymocytes and bone marrow mononuclear cells (BM-MNCs) of golden hamsters. The AA-NAT activity in different lymphoid tissue documented the synthesis of melatonin in those organs. Exogenous melatonin treatment to hamsters enhanced the AA-NAT activity in spleen and thymus along with an increase in the inflammatory response by DTH reactions that could be related to the increased level of interleukin-2 and IFN-γ by T lymphocytes in serum/culture medium, proliferation rate and expression of melatonin membrane receptor MT(1). Thus, the relevance of melatonin synthesis by lymphatic tissues might be maintaining surveillance and local defence responses.

  1. [Immunocompetence and reproductive characteristics of male Campbell dwarf hamsters selected for low and high humoral immune response to SRBC: testing the immunocompetence handicap hypothesis].

    PubMed

    Rogovin, K A; Khrushcheva, A M; Shekarova, O N; Bushuev, A V; Sokolova, O V; Vasil'eva, N Iu

    2014-01-01

    We selected Campbell dwarf hamsters (Phodopus campbelli Thomas, 1905) for low and high humoral immune response to the sheep red blood cells (SRBC) challenge in three generations (P, F1, F2). Non-specific innate immunity and acquired T-cell immunity, resting metabolic rate, testosterone, and cortisole hormone levels, reproductive characteristics, including maturation related morphological traits, and aggressive behavior were studied within sets of males:with low (LI) and high (HI) immune response to SRBC. We found no difference between LI and HI males in cutaneous response to injection of phytohemagglutinin, (DTH test for T-cell immunity), in activity of Peroxidase - Endogenous Hydrogen Peroxide System of Neutrophils , in the white blood count, in resting metabolic rate, in body mass and ano-genital distance at the age of two months, in the blood level of testosterone before and after recurrent immunization by SRBC and in the blood level of cortisole in response to the social stressor (10 min encounter in the neutral arena). At that, LI males had significantly higher basal level of blood cortisole, were less aggressive in response to stranger male and had smaller testosterone-dependent mid-ventral specific skin gland at the age of two months. Males of two groups did not differ in the initial mating success with intact young females (time since pair formation until first litter born), although females of LI males born fewer number of pups. In fact, our results do not support the Handicap Immunocompetence Hypothesis (Folstad, Karter, 1999) which is based on the assumption of trade-off between immunocompetence and reproductive effort. PMID:25782275

  2. PSA-NCAM in the posterodorsal medial amygdala is necessary for the pubertal emergence of attraction to female odors in male hamsters.

    PubMed

    Job, Martin O; Cooke, Bradley M

    2015-09-01

    During puberty, attention turns away from same-sex socialization to focus on the opposite sex. How the brain mediates this change in perception and motivation is unknown. Polysialylated neural cell adhesion molecule (PSA-NCAM) virtually disappears from most of the central nervous system after embryogenesis, but it remains elevated in discrete regions of the adult brain. One such brain area is the posterodorsal subnucleus of the medial amygdala (MePD). The MePD has been implicated in male sexual attraction, measured here as the preference to investigate female odors. We hypothesize that PSA-NCAM gates hormone-dependent plasticity necessary for the emergence of males' attraction to females. To evaluate this idea, we first measured PSA-NCAM levels across puberty in several brain regions, and identified when female odor preference normally emerges in male Syrian hamsters. We found that MePD PSA-NCAM staining peaks shortly before the surge of pubertal androgen and the emergence of preference. To test the necessity of PSA-NCAM for female odor preference, we infused endo-neuraminidase-N into the MePD to deplete it of PSAs before female odor preference normally appears. This blocked female odor preference, which suggests that PSA-NCAM facilitates behaviorally relevant, hormone-driven plasticity. PMID:26335887

  3. Redefining gonadotropin-releasing hormone (GnRH) cell groups in the male Syrian hamster: testosterone regulates GnRH mRNA in the tenia tecta.

    PubMed

    Richardson, Heather N; Parfitt, David B; Thompson, Robert C; Sisk, Cheryl L

    2002-05-01

    Gonadotropin-releasing hormone (GnRH) regulates the production of testosterone via the hypothalamic-pituitary-gonadal axis and testosterone, in turn, regulates the GnRH system via negative feedback. We compared testosterone regulation of GnRH mRNA expression in four anatomically defined GnRH cell groups in juvenile and adult male Syrian hamsters, including a rostral population of GnRH cells in the tenia tecta. In situ hybridization histochemistry (ISHH) was used to measure GnRH mRNA in brains from castrated juveniles and adults treated with 0 mg or 2.5 mg testosterone pellets for one week. ISHH was performed on coronal sections using a 35S-cRNA probe generated from Syrian hamster GnRH cDNA. Testosterone treatment resulted in a significant reduction in mean area of GnRH neurones covered by silver grains within the tenia tecta, but only a trend toward decreased GnRH mRNA in the diagonal band of Broca/organum vasculosum of the lamina terminalis (DBB/OVLT), medial septum (MS), and caudal preoptic area (cPOA). The effects of testosterone were independent of age. Frequency distribution analyses unveiled a significant reduction in the number of heavily labelled cells following testosterone treatment within the tenia tecta and MS. Simple regression analyses revealed a significant positive correlation between plasma luteinizing hormone concentrations and GnRH mRNA only in the tenia tecta. These data indicate that, overall, GnRH mRNA is modestly reduced by testosterone, and the most robust attenuation of GnRH mRNA occurs within the tenia tecta. This is the first report to link mechanisms of steroid negative feedback with tenia tecta GnRH neurones, providing a new focus for investigating brain region-specific steroidal regulation of GnRH synthesis.

  4. Immediate post-defeat infusions of the noradrenergic receptor antagonist propranolol impair the consolidation of conditioned defeat in male Syrian hamsters.

    PubMed

    Gray, Cloe Luckett; Krebs-Kraft, Desiree L; Solomon, Matia B; Norvelle, Alisa; Parent, Marise B; Huhman, Kim L

    2015-12-01

    Social defeat occurs when an animal is attacked and subjugated by an aggressive conspecific. Following social defeat, male Syrian hamsters fail to display species-typical territorial aggression and instead exhibit submissive or defensive behaviors even when in the presence of a non-aggressive intruder. We have termed this phenomenon conditioned defeat (CD). The mechanisms underlying CD are not fully understood, but data from our lab suggest that at least some of the mechanisms are similar to those that mediate classical fear conditioning. The goal of the present experiment was to test the hypothesis that noradrenergic signaling promotes the consolidation of CD, as in classical fear conditioning, by determining whether CD is disrupted by post-training blockade of noradrenergic activity. In Experiment 1, we determined whether systemic infusions of the noradrenergic receptor antagonist propranolol (0, 1.0, 10, or 20mg/kg) given immediately after a 15 min defeat by a resident aggressor would impair CD tested 48 h later. Hamsters that were given immediate post-training infusions of propranolol (1.0, but not 10 or 20mg/kg) showed significantly less submissive behavior than did those given vehicle infusions supporting the hypothesis that there is noradrenergic modulation of the consolidation of a social defeat experience. In Experiment 2, we demonstrated that propranolol (1.0mg/kg) given immediately, but not 4 or 24h, after defeat impaired CD tested 48 h after defeat indicating that the window within which the memory for social defeat is susceptible to beta-adrenergic modulation is temporary. In Experiment 3, we examined whether central blockade of noradrenergic receptors could recapitulate the effect of systemic injections by giving an intracerebroventricular infusion of propranolol immediately after defeat and examining the effect on CD 24h later. Centrally administered propranolol (20 μg/3 μl but not 2 μg/3 μl) was also effective in dose-dependently reducing

  5. Computer-Aided Mapping of Vasopressin Neurons in the Hypothalamus of the Male Golden Hamster: Evidence of Magnocellular Neurons that do not Project to the Neurohypophysis.

    PubMed

    Mahoney, P D; Koh, E T; Irvin, R W; Ferris, C F

    1990-04-01

    total cell count of the entire vasopressin system, it was estimated that approximately 30% of all vasopressin neurons in and around the anterior hypothalamus did not project to the neurohypophysis. Based on the distribution and localization of the non-projecting perikarya, it is speculated that these neurons may provide neurotransmitter for vasopressin-dependent flank marking in the male Golden hamster.

  6. Immediate post-defeat infusions of the noradrenergic receptor antagonist propranolol impair the consolidation of conditioned defeat in male Syrian hamsters.

    PubMed

    Gray, Cloe Luckett; Krebs-Kraft, Desiree L; Solomon, Matia B; Norvelle, Alisa; Parent, Marise B; Huhman, Kim L

    2015-12-01

    Social defeat occurs when an animal is attacked and subjugated by an aggressive conspecific. Following social defeat, male Syrian hamsters fail to display species-typical territorial aggression and instead exhibit submissive or defensive behaviors even when in the presence of a non-aggressive intruder. We have termed this phenomenon conditioned defeat (CD). The mechanisms underlying CD are not fully understood, but data from our lab suggest that at least some of the mechanisms are similar to those that mediate classical fear conditioning. The goal of the present experiment was to test the hypothesis that noradrenergic signaling promotes the consolidation of CD, as in classical fear conditioning, by determining whether CD is disrupted by post-training blockade of noradrenergic activity. In Experiment 1, we determined whether systemic infusions of the noradrenergic receptor antagonist propranolol (0, 1.0, 10, or 20mg/kg) given immediately after a 15 min defeat by a resident aggressor would impair CD tested 48 h later. Hamsters that were given immediate post-training infusions of propranolol (1.0, but not 10 or 20mg/kg) showed significantly less submissive behavior than did those given vehicle infusions supporting the hypothesis that there is noradrenergic modulation of the consolidation of a social defeat experience. In Experiment 2, we demonstrated that propranolol (1.0mg/kg) given immediately, but not 4 or 24h, after defeat impaired CD tested 48 h after defeat indicating that the window within which the memory for social defeat is susceptible to beta-adrenergic modulation is temporary. In Experiment 3, we examined whether central blockade of noradrenergic receptors could recapitulate the effect of systemic injections by giving an intracerebroventricular infusion of propranolol immediately after defeat and examining the effect on CD 24h later. Centrally administered propranolol (20 μg/3 μl but not 2 μg/3 μl) was also effective in dose-dependently reducing

  7. Emphysematous cholecystitis in a Siberian husky.

    PubMed

    Armstrong, J A; Taylor, S M; Tryon, K A; Porter, C D

    2000-01-01

    A 6-year-old, intact male Siberian husky was evaluated for a 24-hour history of vomiting and lethargy. Diagnosis of emphysematous cholecystitis was achieved based on survey abdominal radiographs, a barium contrast gastrointestinal series, and abdominal ultrasound. Diagnosis and medical and surgical management of the condition are discussed.

  8. Time-dependent effects of dim light at night on re-entrainment and masking of hamster activity rhythms.

    PubMed

    Frank, David W; Evans, Jennifer A; Gorman, Michael R

    2010-04-01

    Bright light has been established as the most ubiquitous environmental cue that entrains circadian timing systems under natural conditions. Light equivalent in intensity to moonlight (<1 lux), however, also strongly modulates circadian function in a number of entrainment paradigms. For example, compared to completely dark nights, dim nighttime illumination accelerated re-entrainment of hamster activity rhythms to 4-hour phase advances and delays of an otherwise standard laboratory photocycle. The purpose of this study was to determine if a sensitive period existed in the night during which dim illumination had a robust influence on speed of re-entrainment. Male Siberian hamsters were either exposed to dim light throughout the night, for half of the night, or not at all. Compared to dark nights, dim illumination throughout the entire night decreased by 29% the time for the midpoint of the active phase to re-entrain to a 4-hour phase advance and by 26% for a 4-hour delay. Acceleration of advances and delays were also achieved with 5 hours of dim light per night, but effects depended on whether dim light was present in the first half, second half, or first and last quarters of the night. Both during phase shifting and steady-state entrainment, partially lit nights also produced strong positive and negative masking effects, as well as entrainment aftereffects in constant darkness. Thus, even in the presence of a strong zeitgeber, light that might be encountered under a natural nighttime sky potently modulates the circadian timing system of hamsters.

  9. Bioactivation of diethylstilbestrol by the Syrian hamster kidney

    SciTech Connect

    Adams, S.P.

    1987-01-01

    Male Syrian golden hamsters chronically exposed to diethylstilbestrol (DES) develop renal adenocarcinomas with an incidence approaching 100%. The ability of the hamster kidney to bioactivate DES was assessed using hamster kidney slices. The male hamster renal cortex has a 2- to 5-fold greater capacity to irreversibly bind ({sup 3}H)DES as compared with female hamster renal cortex and with male hamster renal medulla. Incubation of the tissue under anaerobic conditions inhibited the metabolism and irreversible binding of ({sup 3}H)DES. Gel electrophoresis analysis of covalently modified proteins revealed several radioactive peaks indicating that specific adduct formation had occurred. The cytochrome P-450 inhibitors SKF 525-A, metyrapone, carbon monoxide, butylated hydroxytoluene, and dicumarol decreased the irreversible binding of ({sup 3}H)DES to renal cortical protein by 38 to 72%.

  10. Complete mitochondrial genome of a wild Siberian tiger.

    PubMed

    Sun, Yujiao; Lu, Taofeng; Sun, Zhaohui; Guan, Weijun; Liu, Zhensheng; Teng, Liwei; Wang, Shuo; Ma, Yuehui

    2015-01-01

    In this study, the complete mitochondrial genome of Siberian tiger (Panthera tigris altaica) was sequenced, using muscle tissue obtained from a male wild tiger. The total length of the mitochondrial genome is 16,996 bp. The genome structure of this tiger is in accordance with other Siberian tigers and it contains 12S rRNA gene, 16S rRNA gene, 22 tRNA genes, 13 protein-coding genes, and 1 control region.

  11. Complete mitochondrial genome of a wild Siberian tiger.

    PubMed

    Sun, Yujiao; Lu, Taofeng; Sun, Zhaohui; Guan, Weijun; Liu, Zhensheng; Teng, Liwei; Wang, Shuo; Ma, Yuehui

    2015-01-01

    In this study, the complete mitochondrial genome of Siberian tiger (Panthera tigris altaica) was sequenced, using muscle tissue obtained from a male wild tiger. The total length of the mitochondrial genome is 16,996 bp. The genome structure of this tiger is in accordance with other Siberian tigers and it contains 12S rRNA gene, 16S rRNA gene, 22 tRNA genes, 13 protein-coding genes, and 1 control region. PMID:24660907

  12. Androgen metabolism in the male hamster--2. Aromatization of androstenedione in the hypothalamus and in the cerebral cortex; kinetic parameters and effect of exposure to different photoperiods.

    PubMed

    Negri-Cesi, P; Celotti, F; Martini, L

    1989-01-01

    It has been demonstrated that exposure of the hamster to a short photoperiod (light on less than 12 h/day) induces an increased sensitivity of the hypothalamic-pituitary axis to the feedback effect of testosterone. It was consequently felt of interest to investigate whether the photoperiod might act by increasing the formation of estrogens in the CNS and/or in the anterior pituitary. The aromatase activity was studied utilizing a sensitive in vitro assay that measures the amount of 3H2O formed during the conversion of [1 beta-3H]androstenedione to estrone. First of all it has been investigated whether the aromatizing enzymes, previously found in the hypothalamus, were present also in the cerebral cortex and in the anterior pituitary; secondly, the kinetic parameters of the enzyme were determined; finally, the possible variation of the central aromatase activity in hamsters exposed to a long or to a short photoperiod was investigated. The results obtained indicate that both in the hypothalamus and in the cerebral cortex the aromatization of androstenedione is linear with respect to time of incubation and tissue concentration; moreover, in the two structures, the enzyme demonstrated a similar Michaelis-Menten constant (0.03 and 0.08 microM respectively). From a quantitative point of view, the hypothalamus seems to possess an aromatizing activity higher than that of the cerebral cortex. Exposure of the hamsters to a short photostimulation for 60 days resulted in a significant regression of the reproductive system (decreased testicular weight and serum LH levels) and in a decrease of the aromatase activity of the hypothalamus. There was no effect of the photoperiod on the aromatase of the cerebral cortex. Since androgens are known to stimulate the aromatase, the present data might be tentatively interpreted by suggesting that the variation in the formation of estrogens during the short photoperiod might be the consequence of the decreased serum testosterone levels

  13. East Siberian Sea, Russia

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The winter sea ice in the east Siberian Sea is looking a bit like a cracked windshield in these true-color Moderate Resolution Imaging Spectroradiometer (MODIS) images from June 16 and 23, 2002. North of the thawing tundra, the sea ice takes on its cracked, bright blue appearance as it thins, which allows the reflection of the water to show through. Numerous still-frozen lakes dot the tundra. Credit: Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC

  14. Drinking, but not feeding, is opiate-sensitive in hamsters.

    PubMed

    Lowy, M T; Yim, G K

    1982-05-10

    The long-lasting opiate antagonist, naltrexone (NTX), was examined for its effects on various types of consummatory behavior in male golden hamsters and rats. Rat, but not hamster, 24 hr food and water intakes were significantly decreased by four daily NTX (10.0 mg/kg) injections. Hamsters displayed a minimal night to day feeding ratio compared to rats. Hamsters increased food intake following insulin (50 U/kg) administration, but not after 24 hr food deprivation (FD) or 2-deoxy-D-glucose (2-DG; 800 mg/kg) injections. NTX (1.0 and 10 mg/kg) had no effect on feeding, but markedly attenuated hamster drinking induced by 48 hr water deprivation or hypertonic saline injection. Dexamethasone (DEX), a glucocorticoid which depletes pituitary beta-endorphin and produces anorexia in rats, had no effect on daily hamster intake. Since the normal feeding profile of the hamster is similar to that of naloxone and DEX-treated rats, hamsters appear to lack an opiate-sensitive feeding system. In contrast, stimulated drinking behavior of hamsters operates through an opiate-sensitive mechanism. Thus, there are marked species differences concerning the involvement of endogenous opioids in consummatory behavior.

  15. Preference for bedding material in Syrian hamsters.

    PubMed

    Lanteigne, M; Reebs, S G

    2006-10-01

    This study aimed to determine whether Syrian (golden) hamsters, Mesocricetus auratus, prefer certain bedding materials and whether bedding material can affect paw condition, body weight gain and wheel-running activity. In a first experiment, 26 male hamsters had access to two connected cages, each cage containing a different bedding material (either pine shavings, aspen shavings, corn cob or wood pellets). In a second experiment, 14 male hamsters had access to four connected cages that contained the different bedding materials and also a piece of paper towel to serve as nest material. In a third experiment, 30 male hamsters were each placed in a single cage, 10 of them with pine shavings, 10 with aspen shavings and 10 with corn cob, and they were monitored for 50 days. Significant preferences in the first experiment were: pine shavings over aspen shavings, corn cob over wood pellets, pine shavings over corn cob and aspen shavings over wood pellets (aspen shavings versus corn cob was not tested). However, there was no significant preference expressed in the second experiment, suggesting that the general preference for shavings in the first experiment was based on bedding material suitability as a nesting material. No significant effect of bedding material on paw condition, body weight gain and wheel-running activity was detected. None of the four bedding materials tested in this study can be judged to be inappropriate in the short term if nesting material is added to the cage and if the litter is changed regularly. PMID:17018212

  16. Transmission and adaptation of chronic wasting disease to hamsters and transgenic mice: evidence for strains.

    PubMed

    Raymond, Gregory J; Raymond, Lynne D; Meade-White, Kimberly D; Hughson, Andrew G; Favara, Cynthia; Gardner, Donald; Williams, Elizabeth S; Miller, Michael W; Race, Richard E; Caughey, Byron

    2007-04-01

    In vitro screening using the cell-free prion protein conversion system indicated that certain rodents may be susceptible to chronic wasting disease (CWD). Therefore, CWD isolates from mule deer, white-tailed deer, and elk were inoculated intracerebrally into various rodent species to assess the rodents' susceptibility and to develop new rodent models of CWD. The species inoculated were Syrian golden, Djungarian, Chinese, Siberian, and Armenian hamsters, transgenic mice expressing the Syrian golden hamster prion protein, and RML Swiss and C57BL10 wild-type mice. The transgenic mice and the Syrian golden, Chinese, Siberian, and Armenian hamsters had limited susceptibility to certain of the CWD inocula, as evidenced by incomplete attack rates and long incubation periods. For serial passages of CWD isolates in Syrian golden hamsters, incubation periods rapidly stabilized, with isolates having either short (85 to 89 days) or long (408 to 544 days) mean incubation periods and distinct neuropathological patterns. In contrast, wild-type mouse strains and Djungarian hamsters were not susceptible to CWD. These results show that CWD can be transmitted and adapted to some species of rodents and suggest that the cervid-derived CWD inocula may have contained or diverged into at least two distinct transmissible spongiform encephalopathy strains.

  17. Metabolic fuel homeostasis in Syrian hamsters: nycthemeral and exercise variables.

    PubMed

    Rowland, N

    1984-08-01

    The food intake and growth of male and female golden hamsters, with and without access to running wheels, were measured under several conditions. These included different seasons, photoperiods and diets. Chow-fed males in wheels invariably had slowed weight gain and showed little hyperphagia relative to sedentary controls. One group of exercising female hamsters, fed high fat diet, grew faster than sedentary controls. The food intake of both exercising and sedentary groups was distributed evenly through the day/night cycle, but the exercising animals took smaller, more frequent meals at night. The nycthemeral variations in plasma glucose, triglycerides, free fatty acids and liver glycogen were quite small in sedentary hamsters. In exercising hamsters, however, liver glycogen was elevated in the late daytime and depleted in the mid-to-late night. In vivo lipogenesis rates in white and brown adipose and liver were elevated by day in the exercising compared to sedentary hamsters, and were lower at night in both groups. It appears that in exercising hamsters, and to a lesser extent sedentary hamsters, the day phase is one of inactivity and fuel storage, and the night phase is one of exercise and fuel mobilization.

  18. A study of the carcinogenicity of glycidol in Syrian hamsters.

    PubMed

    Lijinsky, W; Kovatch, R M

    1992-01-01

    The industrial chemical glycidol is a directly acting mutagen and a broadly acting carcinogen in rats. It was administered to Syrian golden hamsters (20 male and 20 female) by gavage of 12 mg twice a week for 60 weeks. The total dose per animal was 1.45 g or 20 mmol. Survival was not different from control hamsters treated with corn oil/ethyl acetate. Of the treated males, 9 had tumors and 13 of the treated females had tumors, some of which were adrenal cortex tumors seen in controls. More tumors were seen in the glycidol-treated hamsters than in controls, but the spleen was the only notable target organ and the number of animals with spleen hemangiosarcomas was small. Glycidol appeared to be less carcinogenic in hamsters than in rats or mice.

  19. Siberian Pine Decline and Mortality in Southern Siberian Mountains

    NASA Technical Reports Server (NTRS)

    Kharuk, V. I.; Im, S. T.; Oskorbin, P. A.; Petrov, I. A.; Ranson, K. J.

    2013-01-01

    The causes and resulting spatial patterns of Siberian pine mortality in eastern Kuznetzky Alatau Mountains, Siberia were analyzed based on satellite (Landsat, MODIS) and dendrochronology data. Climate variables studied included temperature, precipitation and Standardized Precipitation-Evapotranspiration Index (SPEI) drought index. Landsat data analysis showed that stand mortality was first detected in the year 2006 at an elevation of 650 m, and extended up to 900 m by the year 2012. Mortality was accompanied by a decrease in MODIS derived vegetation index (EVI).. The area of dead stands and the upper mortality line were correlated with increased drought. The uphill margin of mortality was limited by elevational precipitation gradients. Dead stands (i.e., >75% tree mortality) were located mainly on southern slopes. With respect to slope, mortality was observed within a 7 deg - 20 deg range with greatest mortality occurring on convex terrain. Tree radial incrementmeasurements correlate and were synchronous with SPEI (r sq = 0.37, r(sub s) = 80). Increasing synchrony between tree ring growth and SPEI indicates that drought has reduced the ecological niche of Siberian pine. The results also showed the primary role of drought stress on Siberian pine mortality. A secondary role may be played by bark beetles and root fungi attacks. The observed Siberian pine mortality is part of a broader phenomenon of "dark needle conifers" (DNC, i.e., Siberian pine, fir and spruce) decline and mortality in European Russia, Siberia, and the Russian Far East. All locations of DNC decline coincided with areas of observed drought increase. The results obtained are one of the first observations of drought-induced decline and mortality of DNC at the southern border of boreal forests. Meanwhile if model projections of increased aridity are correct DNC, within the southern part of its range may be replaced by drought-resistant Pinus silvestris and Larix sibirica.

  20. Maternal Photoperiodic History Affects Offspring Development in Syrian Hamsters

    PubMed Central

    Beery, Annaliese K.; Paul, Matthew J.; Routman, David M.; Zucker, Irving

    2009-01-01

    During the first 7 weeks of postnatal life, short day lengths inhibit the onset of puberty in many photoperiodic rodents, but not in Syrian hamsters. In this species, timing of puberty and fecundity are independent of the early postnatal photoperiod. Gestational day length affects postnatal reproductive development in several rodents; its role in Syrian hamsters has not been assessed. We tested the hypothesis that cumulative effects of pre- and postnatal short day lengths would restrain gonadal development in male Syrian hamsters. Males with prenatal short day exposure were generated by dams transferred to short day lengths 6 weeks, 3 weeks, and 0 weeks prior to mating. Additional groups were gestated in long day lengths and transferred to short days at birth, at 4 weeks of age, or not transferred (control hamsters). In pups of dams exposed to short day treatment throughout gestation, decreased testis growth was apparent by 3 weeks and persisted through 9 weeks of age, at which time maximum testis size was attained. A subset of males (14%), whose dams had been in short days for 3 to 6 weeks prior to mating displayed pronounced delays in testicular development, similar to those of other photoperiodic rodents. This treatment also increased the percentage of male offspring that underwent little or no gonadal regression postnatally (39%). By 19 weeks of age, males housed in short days completed spontaneous gonadal development. After prolonged long day treatment to break refractoriness, hamsters that initially were classified as nonregressors underwent testicular regression in response to a 2nd sequence of short day lengths. The combined action of prenatal and early postnatal short day lengths diminishes testicular growth of prepubertal Syrian hamsters no later than the 3rd week of postnatal life, albeit to a lesser extent than in other photoperiodic rodents. PMID:18838610

  1. Spontaneous nonneoplastic lesions in control Syrian hamsters in three 24-month long-term carcinogenicity studies.

    PubMed

    McInnes, Elizabeth F; Ernst, Heinrich; Germann, Paul-Georg

    2015-02-01

    Information about the incidence of spontaneously occurring, nonneoplastic background findings in Syrian hamsters is essential if Syrian hamsters are to be used for toxicity studies. Male and female Syrian hamsters of the strain Han:AURA from the Fraunhofer Institute for Toxicology and Experimental Medicine (ITEM) breeding colony were maintained as control animals for carcinogenicity studies and were examined for the presence of nonneoplastic background findings either when they died or when the study was terminated. The nonneoplastic background lesions observed at an incidence of >50% (high), >25% (moderate), and >10% (low) in either male or female animals or in both sexes in one or more long-term studies are detailed. The results are compared to previous published reports of nonneoplastic, spontaneous background lesions in Syrian hamsters. Background information about the incidence of background lesions in Syrian hamsters on short- and long-term studies is useful to both toxicologists and toxicological pathologists.

  2. 20% PARTIAL SIBERIAN SNAKE IN THE AGS.

    SciTech Connect

    Huang, H; Bai, M; Brown, K A; Glenn, W; Luccio, A U; Mackay, W W; Montag, C; Ptitsyn, V; Roser, T; Tsoupas, N; Zeno, K; Ranjbar, V; Spinka, H; Underwood, D

    2002-11-06

    An 11.4% partial Siberian snake was used to successfully accelerate polarized proton through a strong intrinsic depolarizing spin resonance in the AGS. No noticeable depolarization was observed. This opens up the possibility of using a 20% to 30% partial Siberian snake in the AGS to overcome all weak and strong depolarizing spin resonances. Some design and operation issues of the new partial Siberian snake are discussed.

  3. Food hoarding is increased by food deprivation and decreased by leptin treatment in Syrian hamsters.

    PubMed

    Buckley, Carolyn A; Schneider, Jill E

    2003-11-01

    Compensatory increases in food intake are commonly observed after a period of food deprivation in many species, including laboratory rats and mice. Thus it is interesting that Syrian hamsters fail to increase food intake after a period of food deprivation, despite a fall in plasma leptin concentrations similar to those seen in food-deprived rats and mice. In previous laboratory studies, food-deprived Syrian hamsters increased the amount of food hoarded. We hypothesized that leptin treatment during food deprivation would attenuate food-deprivation-induced increases in hoarding. Baseline levels of hoarding were bimodally distributed, with no hamsters showing intermediate levels of hoarding. Both high (HH) and low hoarding (LH) hamsters were included in each experimental group. Fifty-six male hamsters were either food deprived or given ad libitum access to food for 48 h. One-half of each group received intraperitoneal injections of leptin (4 mg/kg) or vehicle every 12 h during the food-deprivation period. Within the HH group, the hoarding score increased significantly in food-deprived but not fed hamsters (P < 0.05). Leptin treatment significantly decreased hoarding in the food-deprived HH hamsters (P < 0.05). The LH hamsters did not increase hoarding regardless of whether they were food deprived or had ad libitum access to food. These results are consistent with the idea that HH hamsters respond to energetic challenges at least in part by changing their hoarding behavior and that leptin might be one factor that mediates this response.

  4. The Hamster Cheek Pouch

    PubMed Central

    Klintworth, Gordon K.

    1973-01-01

    To gain insight into factors that might be responsible for the normal avascularity of the cornea and for its vascularization in certain pathologic states, an experimental model was designed in which corneal vascularization could be studied under controlled conditions in hamster cheek pouch chambers. Normal corneal tissue, as well as corneas that had been altered in a variety of ways (eg, boiled, autoclaved, freeze-thawed) were implanted into hamster cheek pouch chambers. The fate of the transplanted tissue was observed at regular intervals by direct visualization within the hamster cheek pouch at various magnifications and by light and electron microscopy. This report reviews observations on more than 300 such experiments. Normal and injured corneal autografts, allografts and xenografts and nonviable (autoclaved, boiled or freeze-thawed) corneas commonly became vascularized in the cheek pouch. When this occurred, a similar morphologic sequence of events preceded and accompanied the growth of blood vessels into the cornea. Vascular invasion was generally preceded by the formation of granulation tissue around the cornea. This was followed by a leukocytic, and frequently a fibroblastic, infiltration of the cornea. When cells did not invade the transplanted cornea, the cornea invariably remained avascular. In the present model, a swollen cornea was not a sufficient stimulus for corneal vascularization. The data suggest that under certain circumstances leukocytes may produce one or more factors which stimulate directional vascular growth. The findings are viewed in terms of current concepts on corneal vascularization. ImagesFig 5Fig 6Fig 7Fig 8Fig 9Fig 10Fig 11Fig 12Fig 1Fig 2Fig 3Fig 4Fig 13Fig 14 PMID:4271966

  5. Gait disturbances in dystrophic hamsters.

    PubMed

    Hampton, Thomas G; Kale, Ajit; Amende, Ivo; Tang, Wenlong; McCue, Scott; Bhagavan, Hemmi N; VanDongen, Case G

    2011-01-01

    The delta-sarcoglycan-deficient hamster is an excellent model to study muscular dystrophy. Gait disturbances, important clinically, have not been described in this animal model. We applied ventral plane videography (DigiGait) to analyze gait in BIO TO-2 dystrophic and BIO F1B control hamsters walking on a transparent treadmill belt. Stride length was ∼13% shorter (P < .05) in TO-2 hamsters at 9 months of age compared to F1B hamsters. Hindlimb propulsion duration, an indicator of muscle strength, was shorter in 9-month-old TO-2 (247 ± 8 ms) compared to F1B hamsters (272 ± 11 ms; P < .05). Braking duration, reflecting generation of ground reaction forces, was delayed in 9-month-old TO-2 (147 ± 6 ms) compared to F1B hamsters (126 ± 8 ms; P < .05). Hindpaw eversion, evidence of muscle weakness, was greater in 9-month-old TO-2 than in F1B hamsters (17.7 ± 1.2° versus 8.7 ± 1.6°; P < .05). Incline and decline walking aggravated gait disturbances in TO-2 hamsters at 3 months of age. Several gait deficits were apparent in TO-2 hamsters at 1 month of age. Quantitative gait analysis demonstrates that dystrophic TO-2 hamsters recapitulate functional aspects of human muscular dystrophy. Early detection of gait abnormalities in a convenient animal model may accelerate the development of therapies for muscular dystrophy.

  6. Copulatory and agonistic behavior in Syrian hamsters following social defeat.

    PubMed

    Jeffress, Elizabeth C; Huhman, Kim L

    2013-01-01

    Syrian hamsters are highly aggressive animals that reliably defend their home territory. After social defeat, however, hamsters no longer defend their home cage but instead display submissive and defensive behavior toward an intruder, a response that we have termed conditioned defeat. Plasma testosterone is significantly reduced in Syrian hamsters following repeated defeat suggesting that social defeat might also impair copulatory behavior. The present study aimed to determine whether copulatory behavior in male Syrian hamsters is suppressed following repeated social defeats and additionally whether exposure to a hormone-primed stimulus female after social defeat reduces the behavioral response to defeat. Hamsters were paired with an aggressive opponent for one or nine defeats using a resident-intruder model, while controls were placed into the empty cage of a resident aggressor. On the day after the last treatment, half of the hamsters were paired with a receptive female for 10 min. There were no significant differences in the copulatory behavior of defeated versus non-defeated hamsters, and the opportunity to copulate had no effect on subsequent conditioned defeat testing, as defeated animals displayed significantly more submissive behavior than did non-defeated animals. The current data suggest that conditioned defeat is not necessarily a maladaptive response to social stress, at least in terms of reproductive behavior, but may instead represent a viable behavioral strategy adopted by losing animals following social defeat. Further, these data indicate that conditioned defeat is relatively persistent and stable, as the opportunity to copulate does not reduce the subsequent display of submissive behavior.

  7. [Comparative analysis of virulence of the Siberian and Far-East subtypes of the tick-born encephalitis virus].

    PubMed

    Pogodina, V V; Bochkova, N G; Karan', L S; Frolova, M P; Trukhina, A G; Malenko, G V; Levina, L S; Platonov, A E

    2004-01-01

    The Siberian subtype of the tick-borne encephalitis virus (TEV) is different from the Far-East subtype by a moderate virulence observed in Siberian hamsters and by a low infection development rate (100 strains were compared). No differences were found in neuro-invasiveness. Clinical findings and experiments with monkeys denote the ability of the Siberian subtype to provoke severe forms of tick-borne encephalitis (TBE). The inflammation-and-degenerative changes were localized in the brain cortex, subcortical ganglions, nuclei of medulla oblongata, in the cortex and nuclei of the cerebellum as well as in the anterior horns of the spinal cord. 18 disease cases triggered by the Siberian TEV subtypes in residents of the Western and Eastern Siberia and of Central Russia (Yaroslavl Region), including 7 acute TBE cases (5 lethal outcomes), as well as 11 chronic TBE cases are analyzed. The viral RNA was found in the cortex, medulla oblongata, horn and in the cervical part of the spinal cord of those diseased of acute TBE. Sequences of genotyped strains were presented to Gen Bank, NCBI (AY363846-AY363865).

  8. Body weight as a determinant of clinical evolution in hamsters (Mesocricetus auratus) infected with Leishmania (Viannia) panamensis.

    PubMed

    Gómez-Galindo, Angela María; Delgado-Murcia, Lucy Gabriela

    2013-01-01

    The clinical outcome of infection with Leishmania species of the subgenus Viannia in hamster model (Mesocricetus auratus) has shown to be different depending on experimental protocol. Body weight has been a relevant determinant of the clinical outcome of the infection in hamsters with visceral leishmaniasis but its importance as a clinical parameter in hamsters with cutaneous leishmaniasis is not known. In this study, the clinical evolution of infection with L. (V) panamensis was evaluated in juvenile and adult male hamsters during 11 weeks by comparing clinical parameters such as attitude, temperature, respiratory rate, appearance of the stool, and body weight between infected and non-infected groups. Results showed that body weight decreased in adult hamsters after infection by L. (V) panamensis; this observation supports the use of body weight as an additional parameter to define the management or treatment of cutaneous leishmaniasis in infected adult hamsters used as an animal experimental model for leishmaniasis.

  9. [Variability and Identification Power 60 X-Cromosome in Two Native Siberian Populations].

    PubMed

    Stepanova, V A; Vagaitseva, K V; Kharkov, V N; Cherednichenko, A A; Minaicheva, L I; Bocharova, A V

    2016-04-01

    Genetic diversity of 60 X-chromosome single nucleotide polymorphisms (XSNPid panel) in populations of Siberian Tatars and Tuvinians is described. A close spectrum of allele frequencies and a low level of their genetic differentiation (Gst = 0.021) is revealed. High discriminating power of the XSNPid panel in populations under study is demonstrated. The random matching probability (MP) of multilocus genotypes in males is 1.12 x 10⁻¹⁸ in Siberian Tatars and 7.77 x 10⁻¹⁶ in Tuvans. In females, MP is several orders of magnitude lower: 1.51 x 10⁻²⁵ in Siberian Tatars and 1.83 x 10⁻²³ in Tuvinians. PMID:27529985

  10. [Interaction of the Siberian and Far Eastern subtypes of tick-borne encephalitis virus in mammals with mixed infection. Competition of the subtypes in acute and inapparent infection].

    PubMed

    Gerasimov, S G; Pogodina, V V; Koliasnikova, N M; Karan', L S; Malenko, G V; Levina, L S

    2011-01-01

    Long-term monitoring of natural tick-borne encephalitis virus (TBEV) populations could reveal the change of TBEV subtypes, the displacement of the Far Eastern (FE) subtype, and its substitution for the Siberian (Sib) subtype. Acute and inapparent mixed infections were studied in Syrian hamsters to understand this phenomenon. The animals were inoculated with the Sib subtype and then with the FE one of TBEV (JQ845440-YaroslavI-Aver-08 and Fj214132-Kemerovo-Phateev-1954 strains). The inapparent form developed more frequently in mixed infection. Viral progeny was genotyped by reverse transcription polymerase chain reaction and hybridization fluorescence detection using genotype-specific probes. Independent reproduction of strains in the brain gave way to competition. The FE subtype dominated in hamster youngsters with acute infection. The Sib subtype had selective benefits in asymptomatic infection (adult hamsters infected intracerebrally and subcutaneously and youngsters infected subcutaneously). The competition of the subtypes was imperfect.

  11. Pyometra in a Siberian Polecat (Mustela eversmanni)

    USGS Publications Warehouse

    Johnson, J.D.; Biggins, D.E.; Wrigley, R.H.; Mangone, B.A.; Wimsatt, J.

    1999-01-01

    A 2-year-old Siberian polecat (Mustela eversmanni) from a breeding colony presented for ultrasound evaluation for pregnancy. It was paired with a male for 2.75 months and had remained absent of pregnancy signs when it was anesthetized and clinically evaluated. Until this time, the animal had eaten well and shown no outward signs of debility. On palpation, the animal had a fluid-filled tubular structure in the caudal abdomen, consistent in location and size with the uterus. No sign of vaginal discharge was present. Ultrasonography revealed 10 fluid-filled evaginations (approximately 12 mm in diameter) of the uterine horns. A presumptive diagnosis of a fluid-filled reproductive tract and likely reproductive failure was made in light of the animal's history, its clinical signs, and the ultrasound findings. Euthanasia was performed because the animal was nonreproductive and might yield information relevant to the breeding colony as a whole. Necropsy of the polecat revealed a distended fluctuant uterus containing mildly odiferous, thick, yellow-green, purulent material. Histopathology confirmed the diagnosis of pyometra. A pure and heavy growth of Enterococcus fecalis was cultured from the uterine contents. In light of results from routine minimal inhibitory concentration antibiotic sensitivity screening, this isolate was resistant to all antibiotics tested in the standard teaching hospital screen.

  12. Eyelid eosinophilic granuloma in a Siberian husky.

    PubMed

    Vercelli, A; Cornegliani, L; Portigliotti, L

    2005-01-01

    Canine eosinophilic granuloma (CEG) is a rare skin disease of unknown origin. It has been reported in Siberian huskies, Cavalier King Charles spaniels and occasionally in other breeds. The lesions comprise nodules or plaques, mostly localised in the oral cavity. A case of a single cutaneous nodular lesion of CEG on the eyelid of a Siberian husky is described. Complete remission was achieved with oral glucocorticoid treatment.

  13. 40Ar/39Ar dates from the West Siberian Basin: Siberian flood basalt province doubled.

    PubMed

    Reichow, Marc K; Saunders, Andrew D; White, Rosalind V; Pringle, Malcolm S; Al'Mukhamedov, Alexander I; Medvedev, Alexander I; Kirda, Nikolay P

    2002-06-01

    Widespread basaltic volcanism occurred in the region of the West Siberian Basin in central Russia during Permo-Triassic times. New 40Ar/39Ar age determinations on plagioclase grains from deep boreholes in the basin reveal that the basalts were erupted 249.4 +/- 0.5 million years ago. This is synchronous with the bulk of the Siberian Traps, erupted further east on the Siberian Platform. The age and geochemical data confirm that the West Siberian Basin basalts are part of the Siberian Traps and at least double the confirmed area of the volcanic province as a whole. The larger area of volcanism strengthens the link between the volcanism and the end-Permian mass extinction. PMID:12052954

  14. Scatter hoarding and hippocampal cell proliferation in Siberian chipmunks.

    PubMed

    Pan, Y; Li, M; Yi, X; Zhao, Q; Lieberwirth, C; Wang, Z; Zhang, Z

    2013-01-01

    Food hoarding, especially scatter hoarding and retrieving food caches, requires spatial learning and memory and is an adaptive behavior important for an animal's survival and reproductive success. In the present study, we examined the effects of hoarding behavior on cell proliferation and survival in the hippocampus of male and female Siberian chipmunks (Tamias sibiricus). We found that chipmunks in a semi-natural enclosure displayed hoarding behavior with large individual variations. Males ate more scatter-hoarded seeds than females. In addition, the display of hoarding behavior was associated with increased cell proliferation in the hippocampus and this increase occurred in a brain region-specific manner. These data provide further evidence to support the notion that new cells in the adult hippocampus are affected by learning and memory tasks and may play an important role in adaptive behavior.

  15. [Prevention of cholelithiasis with ascorbic acid. Experimental study in hamsters].

    PubMed

    Peraza, M; Méndez, N; Lagarriga, J; Cohen, J; Alcantar, M; Chiprut, R

    1979-01-01

    Cholesterol lithogenesis is the end result of hepatic microsomal enzymatic alterations which determine an increase in cholesterol synthesis (HMG CoA reductase) and a decrease in its transformation into bile salts (7 alpha hydroxylase). Therefore biliary cholesterol excretion is increased while bile salt excretion is diminished. Ascorbic Acid (A.A.) seems capable of reversing those enzymatic derrangements in scorbutic animals. Since hamsters are able to synthesize A.A., we evaluated its effect used in high doses during diet induced lithogenesis. Two groups of 6 weeks old, male hamsters, were fed with a lithogenic diet for 30 days. Group A received the usual amount of A.A. contained in the diet (0.25 mg/day/manster) while group B had supplementary A.A. added to drinking water (5 mg/day/hamster). Thirteen out of twenty of group A (65%) and 5 out of 20 of group B (25%) developed cholesterol calculi (p 0.05). Less stones were found in the gallbladders of hamsters fed with supplementary A.A. It is concluded that A.A. in this model, has an inhibitory effect on lithogenesis. The possible mechanism seems to be related to A.A. influence on the microsomal enzymes involved in lithogenesis. These findings, plus the lack of undesirable secondary effects of supplementary A.A. suggest a potential therapeutic role in human cholelithiasis. PMID:531439

  16. Distribution of substance P and neurokinin-1 receptor immunoreactivity in the suprachiasmatic nuclei and intergeniculate leaflet of hamster, mouse, and rat.

    PubMed

    Piggins, H D; Samuels, R E; Coogan, A N; Cutler, D J

    2001-09-10

    The circadian pacemaker in the hypothalamic suprachiasmatic nuclei (SCN) receives photic information directly via the retinohypothalamic tract (RHT) and indirectly from retinally innervated cells in the thalamic intergeniculate leaflet (IGL) that project to the SCN. Using standard immunohistochemical methods, we examined the presence and distribution of substance P (SP) and the neurokinin-1 receptor (NK-1) in the SCN and IGL of rat and determined whether the patterns of immunostaining generalized to the SCN and IGL of Syrian hamster, Siberian hamster, and mouse. Terminals immunoreactive for SP were sparse within the SCN of Siberian and Syrian hamsters and mouse but were intense in the ventral, retinally innervated portion of the rat SCN. Immunostaining for the NK-1 receptor was mainly absent from the SCN of hamster and mouse. In contrast, a plexus of NK-1-ir cells and processes that was in close proximity to SP-ir terminals was found in the ventral SCN of the rat. Substance P-ir terminals were observed in the IGL of all four species, as were NK-1-ir cells and fibres. Double-labelled IGL sections of hamster or rat revealed SP-ir terminals in close apposition to NK-1-immunostained cells and/or fibres. These data indicate that SP could be a neurotransmitter of the RHT in rat, but not in hamster or in mouse, and they highlight potential species differences in the role of SP within the SCN circadian pacemaker. Such species differences do not appear to exist at the level of the IGL, where SP-ir and NK-1-ir were similar in all species studied.

  17. Plasma and hepatic cholesterol-lowering in hamsters by tomato pomace, tomato seed oil and defatted tomato seed supplemented in high fat diets

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We determined the cholesterol-lowering effects of tomato pomace (TP), a byproduct of tomato processing, and its components such as tomato seed oil (TSO) and defatted tomato seed (DTS) in hamsters, a widely used animal model for cholesterol metabolism. Male Syrian Golden hamsters were fed high-fat di...

  18. Characterization of a siberian virus isolated from a patient with progressive chronic tick-borne encephalitis.

    PubMed

    Gritsun, T S; Frolova, T V; Zhankov, A I; Armesto, M; Turner, S L; Frolova, M P; Pogodina, V V; Lashkevich, V A; Gould, E A

    2003-01-01

    A strain of Tick-borne encephalitis virus designated Zausaev (Za) was isolated in Siberia from a patient who died of a progressive (2-year) form of tick-borne encephalitis 10 years after being bitten by a tick. The complete genomic sequence of this virus was determined, and an attempt was made to correlate the sequence with the biological characteristics of the virus. Phylogenetic analysis demonstrated that this virus belongs to the Siberian subtype of Tick-borne encephalitis virus. Comparison of Za virus with two related viruses, a Far Eastern isolate, Sofjin, and a Siberian isolate, Vasilchenko, revealed differences among the three viruses in pathogenicity for Syrian hamsters, cytopathogenicity for PS cells, plaque morphology, and the electrophoretic profiles of virus-specific nonstructural proteins. Comparative amino acid alignments revealed 10 individual amino acid substitutions in the Za virus polyprotein sequence that were different from those of other tick-borne flaviviruses. Notably, the dimeric form of the Za virus NS1 protein migrated in polyacrylamide gels as a heterogeneous group of molecules with a significantly higher electrophoretic mobility than those of the Sofjin and Vasilchenko viruses. Two amino acid substitutions, T(277)-->V and E(279)-->G, within the NS1 dimerization domain are probably responsible for the altered oligomerization of Za virus NS1. These studies suggest that the patient from whom Za virus was isolated died due to increased pathogenicity of the latent virus following spontaneous mutagenesis.

  19. Effects of single and repeated inhalation exposure of Syrian hamsters to aerosols of /sup 144/CeO/sub 2/

    SciTech Connect

    Lundgren, D.L.; Hahn, F.F.; McClellan, R.O.

    1982-05-01

    Male Syrian hamsters (84 days old at the time of the initial exposure) were repeatedly exposed by inhalation at approximately 60-day intervals for 1 year (seven exposures) to aerosols of /sup 144/CeO/sub 2/ to reestablish lung burdens of 0.4, 2.0, or 10 ..mu..Ci of /sup 144/Ce. Other hamsters were exposed once when either 84, 220, or 360 days old to achieve similar initial lung burdens. Primary lung tumors were observed in 7 of 197 hamsters repeatedly exposed to /sup 144/CeO/sub 2/ that died between 177 and 685 days after the initial inhalation exposure. The cumulative adsorbed ..beta..-radiation doses to the lungs of these hamsters were 14,000 to 50,000 rad. Primary lung tumors also were observed in 6 of 153 hamsters exposed once to /sup 144/CeO/sub 2/ when 84 or 220 days old that died between 270 and 695 days after exposure. The cumulative ..beta..-radiation doses to the lungs of these hamsters were 6000 to 21,000 rad. Lung tumors were not observed in hamsters exposed when 360 days old or in control hamsters. The incidences of primary lung tumors were more dependent on the cumulative dose to the lung than the radiation dose pattern that resulted in the cumulative dose.

  20. Lack of carcinogenicity of cadmium chloride in female Syrian hamsters.

    PubMed

    Waalkes, M P; Rehm, S

    1998-04-01

    Cadmium is very effective at inducing necrosis within the ovaries of rodents, and the Syrian hamster appears particularly sensitive. The extent of cadmium-induced necrosis depends on the stage of the estrous cycle and is most pronounced when injected on the day prior to ovulation (proestrous). In male rodents cadmium induces a similar necrosis within the testes, which given sufficient time can lead to the development of testicular tumors. In this study we tested the hypothesis that cadmium-induced ovarian necrosis could eventually lead to tumor formation. In sexually mature groups of female Syrian hamsters (> 8 weeks old; n = 50-59), the estrous cycle was determined by visual inspection of vaginal discharge for four consecutive cycles. The animals were then given cadmium (0, 30, 40 and 50 micromol/kg) subcutaneously as a single injection in the dorsal thoracic midline on cycle day 4 (proestrous). Based on prior work, these doses are sufficient to induce extensive acute ovarian damage. Animals were then observed over the next 78 weeks. Although survival and body weight were reduced by cadmium, treatment with the metal did not result in an enhanced incidence of tumors at any site including the ovaries. Non-neoplastic lesions such as amyloidosis and pancreatic hepatocytes were linked to cadmium exposure. These results indicate that the association of cadmium-induced testicular necrosis with tumor development seen in males does not occur in the Syrian hamster ovaries. PMID:9674965

  1. Cystolithiasis in a Syrian hamster: a different outcome.

    PubMed

    Petrini, D; Di Giuseppe, M; Deli, G; De Caro Carella, C

    2016-01-01

    A 14-month-old intact male Syrian hamster was admitted for lethargy and hematuria. A total body radiographic image and abdominal ultrasonography showed the presence of a vesical calculus. During cystotomy, a sterile urine sample was obtained and sent to the diagnostic laboratory along with the urolith for analysis. Urine culture was found negative for bacterial growth, and the urolith was identified as a calcium-oxalate stone. Diet supplementation with palmitoylethanolamide, glucosamine and hesperidin was adopted the day after discharge. One year follow up revealed no presence of vesical calculi. Although this is the report of a single clinical case, this outcome differs from the results reported in the literature characterized by recurrences after few months. Considering the positive outcome and the beneficial properties of palmitoylethanolamide, glucosamine, and hesperidin, these nutritional elements in Syrian hamsters, are recommended to reduce recurrence after surgical treatment of urolithiasis. PMID:27540515

  2. Cystolithiasis in a Syrian hamster: a different outcome

    PubMed Central

    Petrini, D.; Di Giuseppe, M.; Deli, G.; De Caro Carella, C.

    2016-01-01

    A 14-month-old intact male Syrian hamster was admitted for lethargy and hematuria. A total body radiographic image and abdominal ultrasonography showed the presence of a vesical calculus. During cystotomy, a sterile urine sample was obtained and sent to the diagnostic laboratory along with the urolith for analysis. Urine culture was found negative for bacterial growth, and the urolith was identified as a calcium-oxalate stone. Diet supplementation with palmitoylethanolamide, glucosamine and hesperidin was adopted the day after discharge. One year follow up revealed no presence of vesical calculi. Although this is the report of a single clinical case, this outcome differs from the results reported in the literature characterized by recurrences after few months. Considering the positive outcome and the beneficial properties of palmitoylethanolamide, glucosamine, and hesperidin, these nutritional elements in Syrian hamsters, are recommended to reduce recurrence after surgical treatment of urolithiasis. PMID:27540515

  3. Androgen dependence in hamsters: overdose, tolerance, and potential opioidergic mechanisms.

    PubMed

    Peters, K D; Wood, R I

    2005-01-01

    Anabolic steroids are drugs of abuse. However, the potential for steroid reward and addiction remains largely unexplored. This study used i.c.v. testosterone self-administration and controlled infusions of testosterone or vehicle in hamsters to explore central mechanisms of androgen overdose. Forty-two hamsters used nose-pokes to self-administer 1 microg/microl testosterone i.c.v. 4 h/day in an operant chamber. During 1-56 days of androgen self-administration, 10 (24%) hamsters died. Deaths correlated with peak daily intake of testosterone. Of the hamsters that self-administered a peak intake of <20 microg/day, there was 100% survival (10/10). Survival decreased to 86% (19/22) when daily testosterone intake peaked at 20-60 microg/day. Only 30% (three of 10) survived when daily testosterone intake exceeded 60 microg/day. Deaths are not due to volume or vehicle because i.c.v. infusions of 80 mul vehicle had no effect. Testosterone overdose resembles opiate intoxication. When male hamsters received infusions of 40 microg testosterone, locomotion (25.1+/-18.8 grid-crossings/10 min), respiration (72.7+/-5.4 breaths/min) and body temperature (33.5+/-0.4 degrees C) were significantly reduced, compared with males receiving vehicle infusions (186.1+/-8.1 crossings/10 min, 117.6+/-1.0 breaths/min, 35.9+/-0.1 degrees C, P<0.05). However, males developed tolerance to continued daily testosterone infusion. After 15 days, locomotion (170.2+/-6.3 crossings), respiration (118.4+/-1.3 breaths/min), and body temperature (35.3+/-0.3 degrees C) in testosterone-infused males were equivalent to that in vehicle controls (P>0.05). The depressive effects of testosterone infusion are blocked by the opioid antagonist, naltrexone. With naltrexone pre-treatment (10 mg/kg s.c.), locomotion (183.7+/-1.8 crossings/10 min), respiration (116.9+/-0.3 breaths/min), and body temperature (36.1+/-0.4 degrees C) during testosterone infusion were equivalent to vehicle controls. Likewise, naltrexone

  4. [Interaction of the Siberian and Far Eastern subtypes of tick-borne encephalitis virus in mammals with mixed infection. I. Factors influencing the type of interaction].

    PubMed

    Gerasimov, S G; Pogodina, V V; Kolyasnikova, N M; Karan, L S; Malenko, G V; Levina, L S

    2011-01-01

    Polytypic strains containing the fragments of genes of Siberian and Far Eastern tick-borne encephalitis (TBE) virus subtypes were isolated from the brain of fatal TBE patients, the blood of TBE patients, and Ixodes persulcatus ticks in the foci of concomitant circulation of the two subtypes. The interaction of the Siberian and Far Eastern TBE virus subtypes was studied in the neural phase of the infection of albino mice and Syrian hamsters in order to understand conditions for formation of these strains and their role in the etiology of acute TBE. Their viral progeny was genotyped by reverse transcription-polymerase chain reaction and fluorescence hybridization assay with genotype-specific probes. Mixed infection showed an effect of synergism, independent reproduction of the two subtypes in the brain and spleen, competitive exclusion of one subtype from the viral population. The type of the Interaction depended on the species of animals, the properties of partner strains, and the target organ.

  5. Effect of exercise on photoperiod-regulated hypothalamic gene expression and peripheral hormones in the seasonal Dwarf Hamster Phodopus sungorus.

    PubMed

    Petri, Ines; Dumbell, Rebecca; Scherbarth, Frank; Steinlechner, Stephan; Barrett, Perry

    2014-01-01

    The Siberian hamster (Phodopus sungorus) is a seasonal mammal responding to the annual cycle in photoperiod with anticipatory physiological adaptations. This includes a reduction in food intake and body weight during the autumn in anticipation of seasonally reduced food availability. In the laboratory, short-day induction of body weight loss can be reversed or prevented by voluntary exercise undertaken when a running wheel is introduced into the home cage. The mechanism by which exercise prevents or reverses body weight reduction is unknown, but one hypothesis is a reversal of short-day photoperiod induced gene expression changes in the hypothalamus that underpin body weight regulation. Alternatively, we postulate an exercise-related anabolic effect involving the growth hormone axis. To test these hypotheses we established photoperiod-running wheel experiments of 8 to 16 weeks duration assessing body weight, food intake, organ mass, lean and fat mass by magnetic resonance, circulating hormones FGF21 and insulin and hypothalamic gene expression. In response to running wheel activity, short-day housed hamsters increased body weight. Compared to short-day housed sedentary hamsters the body weight increase was accompanied by higher food intake, maintenance of tissue mass of key organs such as the liver, maintenance of lean and fat mass and hormonal profiles indicative of long day housed hamsters but there was no overall reversal of hypothalamic gene expression regulated by photoperiod. Therefore the mechanism by which activity induces body weight gain is likely to act largely independently of photoperiod regulated gene expression in the hypothalamus.

  6. Asymptomatic anomalous pulmonary veins in a Siberian Husky.

    PubMed

    Abraham, L A; Slocombe, R F

    2003-07-01

    A 2-year-old, neutered male Siberian Husky presented with depression, weight loss and an inability to prehend food and water. Cerebrospinal fluid was collected under general anaesthesia prior to euthanasia. The elevated white cell count comprised mostly mononuclear cells. Histological changes within the brain were variable and multifocal. Non-suppurative meningitis secondary to lymphoma was diagnosed. At necropsy, abnormal venous drainage of the right cranial and middle lung lobes was found. A dilated major pulmonary vein from these lobes passed across the lateral aspect of the right caudal lung lobe prior to entering the heart, and subpleural veins from the affected lobes were enlarged and tortuous. These vascular abnormalities were considered incidental. There were no apparent congenital abnormalities of the heart and the animal's clinical signs were related to lymphoma of the brain.

  7. A Grammatical Sketch of Siberian Yupik Eskimo.

    ERIC Educational Resources Information Center

    Jacobson, Steven A.

    This is a grammatical sketch of Siberian Yupik Eskimo as spoken on St. Lawrence Island. The text is in English and is intended to be used by linguists and native speakers who wish to learn the grammatical structure of the language. It should not be used by non-speakers wishing to learn to speak the language. The book covers morphology, nominals,…

  8. Oral eosinophilic granuloma in Siberian husky dogs.

    PubMed

    Madewell, B R; Stannard, A A; Pulley, L T; Nelson, V G

    1980-10-15

    Oral eosinophilic granuloma in 6 young Siberian Husky dogs was characterized by involvement of lateral and ventral surfaces of the tongue. Histologically, the major change was degenerated (necrobiotic) collagen. Although the cause of the disease is unknown, hereditary and immunologic factors are implicated in the pathogenesis.

  9. Aneuploidy in spermatozoa detected by FISH. Comparison with sperm chromosome data obtained via hamster system

    SciTech Connect

    Estop, A.M.; Van Kirk, V.; Cieply, K.

    1994-09-01

    Fluorescence in-situ hybridization (FISH) with two-color and cocktail DNA probes was used to assess the rates of aneuploidy for the X,Y and 18 chromosomes in 3 male donors. (Experiment 1). These individuals had previously been studied with the hamster system and published. Experiment 2 was designed in order to compare aneuploidy rates for chromosome 18 in donor 2 in conjunction with chromosome 6 and 12 as an internal control. (1) Aneuploidy for the sex chromosomes in the hamster system was 0.5 for Donor 1 and 0.7 (3) which was very similar to 0.49 (1) and 0.41 (3) found in this experiment. However, Donor 2 showed a lower rate of sex non-disjunction with this system: 0.18 vs. 0.7 with the hamster system. (2) Diploidy rates are in the same ranges in experiments 1 and 2. (3) If autosome aneuploidy rates are extrapolated to 22 chromosomes, the following values are found: Donor 1:2.42 (vs. 2.0 in the hamster system); donor 3:2.2 (vs. 1.34 with the hamster system) and donor 2:1.32 which is lower than 4.32 found with the hamster system. More data needs to be collected on the use of FISH for this study of aneuploides in sperm cells and attention needs to be paid to the different types of probes used for validation of results.

  10. Autoradiographic localization of tritiated dihydrotestosterone in the flank organ of the albino hamster

    SciTech Connect

    Lucky, A.W.; Eisenfeld, A.J.; Visintin, I.

    1985-02-01

    In the hamster flank organ, the growth of hair and growth of sebaceous glands are androgen-dependent functions. Although dihydrotestosterone (DHT) is known to be a potent stimulator of flank organ growth, there is no information about localization of DHT receptor sites in this organ. The purpose of this study was to use steroid autoradiography to localize DHT receptors in the hamster flank organ. Because steroid hormones are functional when translocated to nuclear receptors, nuclear localization by autoradiography defines receptor sites. In order to be able to visualize autoradiographic grains from radiolabeled androgens around hair follicles, albino hamsters were studied to avoid confusion between the grains and pigment granules which are abundant in the more common Golden Syrian hamster. Mature male hamsters castrated 24 hours earlier were given tritium-labeled dihydrotestosterone ( (/sup 3/H)DHT). Using the technique of thaw-mount steroid autoradiography, 4-micron unfixed frozen sections were mounted in the dark onto emulsion-coated glass slides and allowed to develop for 4-6 months. (/sup 3/H)DHT was found to be concentrated over sebocyte nuclei. The label was present peripherally as well as in differentiating sebocytes. There was no nuclear localization of (/sup 3/H)DHT in animals pretreated with excessive quantities of unlabeled DHT. Steroid metabolites of (/sup 3/H) DHT were assessed by thin-layer chromatography in paired tissue samples. Most of the label remained with DHT. Uptake was inhibited in the flank organ of hamsters pretreated with unlabeled DHT.

  11. Short-day response in Djungarian hamsters of different circadian phenotypes.

    PubMed

    Schöttner, Konrad; Schmidt, Maren; Hering, Anke; Schatz, Juliane; Weinert, Dietmar

    2012-05-01

    In Djungarian hamsters (Phodopus sungorus) bred at the authors' institute, a certain number of animals show activity patterns incompatible with proper entrainment of their endogenous circadian pacemaker to the environmental light-dark (LD) cycle. Even though the activity-offset in these animals is stably coupled to "light-on," activity-onset is increasingly delayed, leading to a compression of the activity time (α). If α falls below a critical value, the circadian rhythm in these so called delayed activity-onset (DAO) hamsters starts to free-run and finally breaks down. Animals then show an arrhythmic activity pattern (AR hamsters). Previous studies revealed the mechanisms of photic entrainment have deteriorated (DAO) or the suprachiasmatic nucleus (SCN) does not generate a rhythmic signal (AR). The aim of the present study was to investigate the consequences that these deteriorations have upon photoperiodic time measurement. Animals were bred and kept under standardized housing conditions with food and water ad libitum and a 14L/10D (long day, LD) regimen. Locomotor activity was recorded continuously using passive infrared motion detectors. Body mass, testes size, and fur coloration were measured weekly or biweekly to further quantify the photoperiodic reaction. In a first experiment, adult male wild-type (WT), DAO, and AR hamsters were transferred initially to a 16L/8D cycle. After 3-4 wks, the light period was shortened symmetrically by 8 h. After 14 wks, none of the DAO and AR hamsters, and only 1 of 8 WT hamsters showed short-day (SD) traits. Therefore, in a second experiment, hamsters were transferred to SD conditions (8L/16D cycle) for 8 wks directly from standard LD conditions. In 6 of 7 WT hamsters, activity time expanded, body mass and testes size decreased, and fur coloration changed from summer to winter pelage. In contrast, none of the DAO and AR hamsters displayed an SD response. In a third experiment, DAO and AR hamsters were kept in constant

  12. Long-term carcinogenicity study in Syrian golden hamster of particulate emissions from coal- and oil-fired power plants

    SciTech Connect

    Persson, S.A.; Ahlberg, M.; Berghem, L.; Koenberg, E.N.; Nordberg, G.F.; Bergman, F.

    1988-04-01

    Male Syrian golden hamsters were given 15 weekly intratracheal instillations with suspensions of coal fly ash or oil fly ash. Controls were instilled with saline containing gelatine (0.5 g/100 mL) or to check particle effects with suspensions of hematite (Fe/sub 2/O/sub 3/). The common weekly dose was 4.5 mg/hamster. In addition, one subgroup of hamsters was treated with oil fly ash at a weekly dose of 3.0 mg/hamster and another with coal fly ash at a weekly dose of 6.0 mg/hamster. Other groups of hamsters were treated with suspensions of benzo(a)pyrene (BaP) or with suspensions on coal fly ash, oil fly ash, or Fe/sub 2/O/sub 3/ coated with BaP. The mass median aerodynamic diameters of the coal and oil fly ashes were 4.4 microns and 28 microns, respectively. Hamsters treated with oil fly ash showed a higher frequency of bronchiolar-alveolar hyperplasia than hamsters in the other treatment groups. Squamous dysplasia and squamous metaplasia were most frequent in animals treated with suspensions of BaP or BaP-coated particles. The earliest appearance of a tumor, the highest incidence of tumors, and the highest incidence of malignant tumors were observed in hamsters treated with oil fly ash coated with BaP. Squamous cell carcinoma and adenosquamous carcinoma were the most frequent malignant tumors. No malignant tumors and only few benign tumors were observed in hamsters instilled with suspensions of fly ash not coated with BaP. The present study gives no indication that coal fly ash could create more serious health problems than oil fly ash.

  13. Hamster-tropic sarcomagenic and nonsarcomagenic viruses derived from hamster tumors induced by the Gross pseudotype of Moloney sarcoma virus.

    PubMed

    Kelloff, G; Huebner, R J; Lee, Y K; Toni, R; Gilden, R

    1970-02-01

    Hamster sarcomas induced by the Gross pseudotype of Moloney sarcoma virus yielded a virus sarcomagenic for hamsters but not mice. This virus was able to produce foci on hamster embryo cells, but not on mouse embryo cells. A hamster-tropic nonfocus-forming helper virus was also found in the viral stocks. These hamster-tropic viruses are not immunologically related to the murine viruses in the original inoculum but appear to represent indigenous C-type RNA viruses of the hamster.

  14. Lifetime carcinogenesis studies of amosite asbestos (Case No. 121-72-73-5) in Syrian golden hamsters (feed studies). Technical report series

    SciTech Connect

    Not Available

    1983-11-01

    Carcinogenesis studies of amosite asbestos were conducted by administering diets containing 1% of the asbestos in pellets from the conception of the mothers through the lifetime of male and female Syrian golden hamsters. Control groups consisted of 127 male and 126 female hamsters and the amosite asbestos group consisted of 252 male and 254 female hamsters. No adverse effect on body-weight gain or survival was observed from treatment with amosite asbestos. Neither of the amosite asbestos groups showed increased neoplasia in any organ or tissue compared to the control groups. Under the conditions of these studies, the ingestion of amosite asbestos at a level of 1% in the diet for their lifetime was not toxic and did not cause a carcinogenic response in male and female Syrian golden hamsters.

  15. Hibernation patterns of Turkish hamsters: influence of sex and ambient temperature.

    PubMed

    Batavia, Mariska; Nguyen, George; Harman, Kristine; Zucker, Irving

    2013-02-01

    Turkish hamsters (Mesocricetus brandti) are a model organism for studies of hibernation, yet a detailed account of their torpor characteristics has not been undertaken. This study employed continuous telemetric monitoring of body temperature (T(b)) in hibernating male and female Turkish hamsters at ambient temperatures (T(a)s) of 5 and 13 °C to precisely characterize torpor bout depth, duration, and frequency, as well as rates of entry into and arousal from torpor. Hamsters generated brief intervals of short (<12 h), shallow test bouts (T(b) > 20 °C), followed by deep torpor bouts lasting 4-6 days at T(a) = 5 °C and 2-3 days at T(a) = 13 °C. Females at T(a) = 5 °C had longer bouts than males, but maintained higher torpor T(b); there were no sex differences at T(a) = 13 °C. Neither body mass loss nor food intake differed between the two T(a)s. Hamsters entered torpor primarily during the scotophase (subjective night), but timing of arousals was highly variable. Hamsters at both T (a)s generated short, shallow torpor bouts between deep bouts, suggesting that this species may be capable of both hibernation and daily torpor.

  16. Effects of short photoperiod on energy intake, thermogenesis, and reproduction in desert hamsters (Phodopus roborovskii).

    PubMed

    Zhang, Xueying; Zhao, Zhijun; Vasilieva, Nina; Khrushchova, Anastasia; Wang, Dehua

    2015-03-01

    Desert hamsters (Phodopus roborovskii) are the least known species in the genus Phodopus with respect to ecology and physiology, and deserve scientific attention, particularly because of their small body size. Here, the responses of energy metabolism and reproductive function to short photoperiods in desert hamsters were investigated. Male and female desert hamsters were acclimated to either long day (LD) (L:D 16:8 h) or short day (SD) photoperiods (L:D 8:16 h) for three months, and then the females were transferred back to an LD photoperiod for a further five months, while at the end of the SD acclimation the males were killed and measurements were taken for serum leptin as well as molecular markers for thermogenesis. We found that like the other two species from the genus Phodopus, the desert hamsters under SD decreased body mass, increased adaptive thermogenesis as indicated by elevated mitochondrial protein content and uncoupling protein-1 content in brown adipose tissue, and suppressed reproduction compared to those under LD. However, different from the other two species, desert hamsters did not show any differences in energy intake or serum leptin concentration between LD and SD. These data suggest that different species from the same genus respond in different ways to the environmental signals, and the desert adapted species are not as sensitive to change in photoperiod as the other two species.

  17. Evaluation of amitrole (aminotriazole) for potential carcinogenicity in orally dosed rats, mice, and golden hamsters

    SciTech Connect

    Steinhoff, D.; Weber, H.; Mohr, U.; Boehme, K.

    1983-06-30

    Amitrole was evaluated for carcinogenic potential in lifespan studies on Wistar rats, NMRI mice, and golden hamsters. At the start of the studies the animals were 6 weeks old. Amitrole was administered, mixed with pulverized chow, at dietary concentrations of 0, 1, 10, and 100 micrograms/g (ppm). Each treated group and control group consisted of 75 male and 75 female rats and mice and of 76 male and 76 female golden hamsters. Additional animals were used to evaluate the functional state of the thyroid. Somewhat lower body weights, slightly reduced survival times, and transient effects on thyroid function were observed in golden hamsters at 100 ppm. In mice, a slight increase in pituitary gland hyperemias was seen at 100 ppm; also an effect on thyroid function usually occurred at the same concentration. In rats, a very large number of cystic dilatations of follicles in the thyroid at 100 ppm and a dose-unrelated increase in hemorrhages and hyperemias in the pituitary gland were indicative of an effect of amitrole on these organs. The strongest effect of amitrole on thyroid function, as compared to golden hamsters and mice, was seen in rats at 100 ppm. At this concentration a highly increased number of thyroid and pituitary gland tumors was observed in rats. In golden hamsters and mice, no tumor induction was seen.

  18. Visual landmark-directed scatter-hoarding of Siberian chipmunks Tamias sibiricus.

    PubMed

    Zhang, Dongyuan; Li, Jia; Wang, Zhenyu; Yi, Xianfeng

    2016-05-01

    Spatial memory of cached food items plays an important role in cache recovery by scatter-hoarding animals. However, whether scatter-hoarding animals intentionally select cache sites with respect to visual landmarks in the environment and then rely on them to recover their cached seeds for later use has not been extensively explored. Furthermore, there is a lack of evidence on whether there are sex differences in visual landmark-based food-hoarding behaviors in small rodents even though male and female animals exhibit different spatial abilities. In the present study, we used a scatter-hoarding animal, the Siberian chipmunk, Tamias sibiricus to explore these questions in semi-natural enclosures. Our results showed that T. sibiricus preferred to establish caches in the shallow pits labeled with visual landmarks (branches of Pinus sylvestris, leaves of Athyrium brevifrons and PVC tubes). In addition, visual landmarks of P. sylvestris facilitated cache recovery by T. sibiricus. We also found significant sex differences in visual landmark-based food-hoarding strategies in Siberian chipmunks. Males, rather than females, chipmunks tended to establish their caches with respect to the visual landmarks. Our studies show that T. sibiricus rely on visual landmarks to establish and recover their caches, and that sex differences exist in visual landmark-based food hoarding in Siberian chipmunks. PMID:27160702

  19. Visual landmark-directed scatter-hoarding of Siberian chipmunks Tamias sibiricus.

    PubMed

    Zhang, Dongyuan; Li, Jia; Wang, Zhenyu; Yi, Xianfeng

    2016-05-01

    Spatial memory of cached food items plays an important role in cache recovery by scatter-hoarding animals. However, whether scatter-hoarding animals intentionally select cache sites with respect to visual landmarks in the environment and then rely on them to recover their cached seeds for later use has not been extensively explored. Furthermore, there is a lack of evidence on whether there are sex differences in visual landmark-based food-hoarding behaviors in small rodents even though male and female animals exhibit different spatial abilities. In the present study, we used a scatter-hoarding animal, the Siberian chipmunk, Tamias sibiricus to explore these questions in semi-natural enclosures. Our results showed that T. sibiricus preferred to establish caches in the shallow pits labeled with visual landmarks (branches of Pinus sylvestris, leaves of Athyrium brevifrons and PVC tubes). In addition, visual landmarks of P. sylvestris facilitated cache recovery by T. sibiricus. We also found significant sex differences in visual landmark-based food-hoarding strategies in Siberian chipmunks. Males, rather than females, chipmunks tended to establish their caches with respect to the visual landmarks. Our studies show that T. sibiricus rely on visual landmarks to establish and recover their caches, and that sex differences exist in visual landmark-based food hoarding in Siberian chipmunks.

  20. Novel function of lipids as a pheromone from the Harderian gland of golden hamster

    PubMed Central

    Seyama, Yousuke; Uchijima, Yasunobu

    2007-01-01

    Sexual diversity of ADG in Harderian gland of golden hamster was demonstrated on TLC. Female ADG contained iso- and anteiso-branched acyl and alkyl components, but male ADG contained only straight chain ones, which suggested the hormonal control of the expression of acyl-CoA dehydrogenases in the catabolism of BCAA. Acyl-CoA dehydrogenases were not expressed in the absence of testosterone, and then isovaleryl-CoA, 2-methylbutyryl-CoA, and isobutyryl-CoA accumulated, and acted as primers for the synthesis of iso- and anteiso-branched fatty acids. The incorporation of [U-14C] leucine into lipids was monitored by TLC. The cholesterol fraction was labeled in males but not in female, which means that cholesterol was not produced from BCAA in female gland due to the lack of expression of acyl-CoA dehydrogenases. We monitored the behavior of male hamsters toward female gland lipids, and found slightly greater attractiveness in female ones than that in male ones although the difference was not significant. Considering the lifestyle of golden hamster in nature, we propose a hypothesis that the lipids from the Harderian gland of golden hamster serve as a pheromone to declare their territory and to seek the mate with good congeniality. PMID:24019586

  1. Directed Student Inquiry: Modeling in Roborovsky Hamsters

    ERIC Educational Resources Information Center

    Elwess, Nancy L.; Bouchard, Adam

    2007-01-01

    In this inquiry-based activity, Roborovsky hamsters are used to provide students with an opportunity to develop their skills of analysis, inquiry, and design. These hamsters are easy to maintain, yet offer students a means to use conventional techniques and those of their own design to make further observations through measuring, assessing, and…

  2. Superplume Metasomatism: Evidence from Siberian mantle xenoliths

    NASA Astrophysics Data System (ADS)

    Taylor, L. A.; Howarth, G. H.; Barry, P. H.; Pernet-Fisher, J. F.; Baziotis, I. P.; Pokhilenko, L. N.; Bodnar, R. J.; Pokhilenko, N. P.

    2013-12-01

    The Siberian craton has been subjected to numerous stages of Superplume-related magmatism, including several pre- and post-temporal stages of kimberlite emplacement relative to the extrusion of the Siberian Flood basalts (SFB; 250 Ma). The primary objective of this study is to characterize the metasomatic imprints rendered on the sub-continental lithospheric mantle (SCLM) by percolating Superplume related fluids. Mantle xenoliths brought to the surface by kimberlites provide rare windows into the SCLM. Here, we present major- and trace-element mineral data for peridotite xenoliths of the Late Devonian Udachnaya (360 Ma) and Jurassic Obnazhennaya (180 Ma) kimberlites. These xenoliths were selected in order to better characterize the temporal evolution of metasomatic processes affecting the SCLM over the life cycle of the Siberian Superplume; they represent sections of SCLM that bracket the SFB climax of activity. This work presents an initial model as part of a larger study focusing on the chemical effects of Superplume related metasomatism on the Siberian SCLM, which also include; Re/Os systematics [1] and noble gas geochemistry [2]. Garnet compositions have two distinct trends in CaO-Cr2O3 space: 1) increasing CaO at constant Cr2O3 within the harzburgite field, and 2) decreasing CaO and Cr2O3 within the lherzolite field, moving from ultramafic compositions of Udachanaya toward mafic compositions of Obnazhennaya. Distinct-zoned garnet grains have sinusoidal-REE patterns within cores and display a gradational change to flat MREE-HREE profiles at the rims. Clinopyroxenes typically are LREE-enriched and have high Ti/Sr. Re-constructed melts in equilibrium with garnet REE chemistry indicate that Obnazhennaya garnets were over-printed by plume-derived basaltic fluids, whereas Udachnaya garnets were over-printed mainly by kimberlite fluids. The ubiquitous plume signatures in the younger Obnazhennaya garnets are clear evidence for extensive metasomatism by mafic fluids

  3. Effect of dexamethasone on babesiasis in hamsters.

    PubMed

    Eckblad, W P; Stiller, D; Woodard, L F; Kuttler, K L

    1984-09-01

    Three subcutaneous injections of 0.20 mg of dexamethasone/kg of body weight caused a substantial increase in Babesia microti-parasitized RBC of hamsters, indicating that this was a useful method for revealing the presence of latent infections. A relative neutrophilia, lymphocytopenia, and eosinopenia were also seen in the long-term B microti-infected carrier hamsters after 0.20 mg or 0.02 mg of dexamethasone/kg. Noninfected hamsters treated with dexamethasone had a neutrophilic leukocytosis and a transient lymphocytopenia. Spleen to body weight ratios of noninfected hamsters decreased significantly (P less than 0.02) after 4 injections with either dosage level. These ratios did not significantly (P greater than 0.05) decrease in dexamethasone-treated infected hamsters.

  4. Hydrogeology of the West Siberian Basin

    SciTech Connect

    Foley, M.G.; Bradley, D.J.; Cole, C.R.

    1996-08-01

    Nuclear fuel cycle activities of the former Soviet Union (FSU) have resulted in extensive radioactive contaminant releases to the environment in western Siberia. We are developing three-dimensional numerical models of the hydrogeology and potential contaminant migration in the West Siberian Basin. We have assumed that ground-water flow in the West Siberian Basin is topographically driven, with recharge to the basin occurring in the highlands on the west, east, and south, and internal discharge localized in numerous river valleys and lakes that ultimately discharge north to the ocean. We are modeling the regional hydrogeology as three-dimensional, steady-state, saturated flow that is recharged from above. We acquired topographic, geologic, hydrostratigraphic, hydrogeologic, and water-balance data for the West Siberian Basin and constructed a regional water table. We correlated and combined 70 different rock types derived from published descriptions of West Siberian Basin rocks into 17 rock types appropriate for assignment of hydrogeologic properties on the basis of spatial heterogeneity and constituent (i.e., sand, silt, and clay) diversity. Examination of resulting three-dimensional assemblages of rock types showed that they were consistent with published and inferred paleogeography and depositional processes. Calibrating the basin`s moisture balance (i.e., recharge and discharge) to the derived water table determined plausible input parameter values for unknowns such as hydraulic conductivities. The general directions of calculated ground-water flow suggest that major rivers act as discharge areas, with upwelling below the rivers extending down into the basement rocks, and that ground-water divides that penetrate the entire thickness of the model are evident between major rivers.

  5. Lena River Delta and East Siberian Sea

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The winter sea ice in the east Siberian Sea is looking a bit like a cracked windshield in these true-color Moderate Resolution Imaging Spectroradiometer (MODIS) images from June 16 and 23, 2002. North of the thawing tundra, the sea ice takes on its cracked, bright blue appearance as it thins, which allows the reflection of the water to show through. Numerous still-frozen lakes dot the tundra. Credit: Jacques Descloitres, MODIS Land Rapid Response Team, NASA/GSFC

  6. The emergence of obesity among indigenous Siberians.

    PubMed

    Snodgrass, J Josh; Leonard, William R; Sorensen, Mark V; Tarskaia, Larissa A; Alekseev, Vasili P; Krivoshapkin, Vadim

    2006-01-01

    Once considered a disease of affluence and confined to industrialized nations, obesity is currently emerging as a major health concern in nearly every country in the world. Available data suggest that the prevalence rate of obesity has reached unprecedented levels in most developing countries, and is increasing at a rate that far outpaces that of developed nations. This increase in obesity has also been documented among North American circumpolar populations and is associated with lifestyle changes related to economic development. While obesity has not been well studied among indigenous Siberians, recent anthropological studies indicate that obesity and its associated comorbidities are important health problems.The present study examines recent adult body composition data from four indigenous Siberian populations (Evenki, Ket, Buriat, and Yakut) with two main objectives: 1) to determine the prevalence of overweight and obesity among these groups, and 2) to assess the influence of lifestyle and socioeconomic factors on the development of excess body fat. The results of this study indicate that obesity has emerged as an important health issue among indigenous Siberians, and especially for women, whose obesity rates are considerably higher than those of men (12% vs. 7%). The present study investigated the association between lifestyle and body composition among the Yakut, and documented substantial sex differences in lifestyle correlates of obesity. Yakut men with higher incomes and who owned more luxury consumer goods were more likely to have excess body fat while, among Yakut women, affluence was not strongly associated with overweight and obesity.

  7. Anabolic-androgenic steroid exposure during adolescence and aggressive behavior in golden hamsters.

    PubMed

    Melloni, R H; Connor, D F; Hang, P T; Harrison, R J; Ferris, C F

    1997-03-01

    Anabolic androgenic steroid (AAS) abuse by adolescents represents a significant health care risk due to the potential for long-term negative physical and psychological sequelae, including increased aggressive behavior. The current experiments examined the effects of AAS use in young male adolescent hamsters (Mesocricetus auratus) and their consequences on aggressive behavior. It was hypothesized that AAS administration during adolescence predisposes hamsters to heightened levels of aggressive behavior (i.e., offensive aggression). To test this hypothesis adolescent male hamsters were administered high doses of synthetic AAS to mimic a 'heavy use' self-administration regimen used by athletes. Immediately following the exposure to AAS hamsters were tested for aggressive behavior using a resident-intruder model. Animals treated with high doses of AAS during their adolescent development showed heightened measures of offensive aggression i.e., decreased latency to bite and increased total number of attacks and bites) during the test period, while measures of total activity (total contact time) between the animals remained unchanged. AAS-treated males did not differ in body weight from controls, suggesting that the increased aggression was not due to increased body mass. The results of this study show that exposure to AAS during adolescence facilitates aggressive response patterns, but does not alter body weight.

  8. In Hamsters the D1 Receptor Antagonist SCH 23390 Depresses Ventilation during Hypoxia

    PubMed Central

    Schlenker, Evelyn H.

    2008-01-01

    During exposure of animals to hypoxia, brain and blood dopamine levels increase stimulating dopaminergic receptors which influence the integrated ventilatory response to low oxygen. The purpose of the present study is to test the hypothesis, that in conscious hamsters, systemic antagonism of D1 receptors would depress their breathing in air and in response to hypoxic and hypercapnic challenges. Nine male hamsters were treated with saline or 0.25 mg/kg SCH-23390 (SCH), a D1 receptor antagonist that crosses the blood-brain barrier. Ventilation was determined using the barometric method and oxygen consumption and CO2 production were evaluated utilizing the flow-through method. During exposure to air, SCH decreased frequency of breathing. During exposure to hypoxia (10% oxygen in nitrogen), relative to saline, SCH-treated hamsters decreased minute ventilation by decreasing tidal volume and oxygen consumption but not CO2 production. During exposure to hypercapnia (5% CO2 in 95% O2) frequency of breathing was decreased with SCH, but there was no significant effect on minute ventilation. Relative to saline treatment body temperature was lower in SCH treated hamsters by 0.6 degrees Celsius. These results demonstrate that in hamsters D1 receptors can modulate control of ventilation in air and during hypoxia and hypercapnic exposures. Whether D1 receptors located centrally or on carotid bodies modulate these effects is not clear from this study. PMID:18036574

  9. Effect of age on respiratory carcinogenesis with diethyl-nitrosamine (DEN) in hamsters

    SciTech Connect

    Stinson, S.F.; Saffiotti, U.

    1986-03-01

    Groups of male and female Syrian golden hamsters were given 12 weekly s.c. injections of 10 mg/kg DEN beginning at 1 day (85 animals) or 8 weeks (70 animals) of age, and were held for lifetime observation. In hamsters receiving DEN from birth, the first respiratory tumors were observed at 15 experimental weeks; all animals were dead by 66 weeks with a 99% respiratory tumor incidence. Of these hamster, 87% developed carcinomas or adenomas in the nasal cavities, 75% papillomas of the trachea, larynx or extrapulmonary bronchi and 7% adenomas or adenocarcinomas of the peripheral lung. Hamsters given DEN from 8 weeks of age first showed respiratory tumors after 25 weeks with a 96% incidence by 62 weeks when all had died. Of these hamsters, 24% developed carcinomas or adenomas in the nasal cavities, 91% papillomas of the trachea, larynx or bronchi, and 9% adenomas or adenocarcinomas of the peripheral lung. In comparison, the nasal tumors in the first group were more anaplastic and invaded the brain more frequently than in the second. These results indicate that the nasal mucosa of newborns is more sensitive to carcinogenesis with DEN than is that of adults, while there appears to be little age-related susceptibility of the epithelium of the airways or lung. A serial sacrifice experiment is currently under way to study the cells of origin of the various tumors using immuno-histochemical and electron microscopic techniques.

  10. Affirmative Action Education Programs for Siberian Native People.

    ERIC Educational Resources Information Center

    Bartels, Dennis; Bartels, Alice

    1984-01-01

    Describes origin and development of programs, focusing on affirmative action at the Faculty of Northern Peoples of Leningrad's Herzen Pedagogical Institute. Offers conclusions and implications for North America. Includes extensive bibliography, tables on Siberian populations and languages, and biographies of two Siberian educators and two female…

  11. Autonomic and behavioral thermoregulation in golden hamsters exposed perinatally to dioxin.

    PubMed

    Gordon, C J; Yang, Y; Gray, L E

    1996-03-01

    Perinatal exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) cause s a permanent change in thermoregulatory control of male offspring of the rat, characterized by a reduced core temperature (Tc over a wide range of ambient temperatures (Ta). To examine the similarities in this effect across species, the thermoregulatory effects of perinatal TCDD were evaluated in the golden hamster, a species which is very resistant to the lethal effects of TCDD. Adult male hamsters exposed on Gestational Day 11.5-11.75 to 2.0 microgram TCDD/kg by gavage were subjected to a variety of behavioral and autonomic thermoregulatory measurements. Nocturnal Tc of TCDD-treated animals was 0.4 to 1.0 degrees C below that of controls over a Ta range of 14 to 34 degrees C. Hypothermia persisted in spite of normal metabolic responses to cold exposure. The hypothermic effect of perinatal TCDD exposure was found to persist over a 24-hr period in unrestrained hamsters monitored by radiotelemetry. The TCDD-treated hamster offspring placed in a temperature gradient exhibited a preference for warm Ta's for 2 to 3 hr; however, when maintained over a 22-hr period in the gradient there was no effect of TCDD on behavioral thermoregulation. TCDD had no effect on motor activity measured over a 24-hr period. TCDD resulted in an approximately 30% reduction in body weight compared to controls; however, this weight loss appeared to have no bearing on the thermoregulatory deficiencies of the TCDD-treated animals. TCDD-treated hamsters displayed a normal metabolic response to cold exposure; thus, it would appear that perinatal exposure to TCDD leads to a dysfunction in the central control of body temperature. The perinatal effects of TCDD on thermoregulation in the rat and hamster appear to be similar. PMID:8607137

  12. Seasonal regulation of reproduction: altered role of melatonin under naturalistic conditions in hamsters.

    PubMed

    Butler, Matthew P; Turner, Kevin W; Park, Jin Ho; Schoomer, Elanor E; Zucker, Irving; Gorman, Michael R

    2010-09-22

    The seasonal reproductive cycle of photoperiodic rodents is conceptualized as a series of discrete melatonin-dependent neuroendocrine transitions. Least understood is the springtime restoration of responsiveness to winter-like melatonin signals (breaking of refractoriness) that enables animals to once again respond appropriately to winter photoperiods the following year. This has been posited to require many weeks of long days based on studies employing static photoperiods instead of the annual pattern of continually changing photoperiods under which these mechanisms evolved. Maintaining Siberian hamsters under simulated natural photoperiods, we demonstrate that winter refractoriness is broken within six weeks after the spring equinox. We then test whether a history of natural photoperiod exposure can eliminate the requirement for long-day melatonin signalling. Hamsters pinealectomized at the spring equinox and challenged 10 weeks later with winter melatonin infusions exhibited gonadal regression, indicating that refractoriness was broken. A photostimulatory effect on body weight is first observed in the last four weeks of winter. Thus, the seasonal transition to the summer photosensitive phenotype is triggered prior to the equinox without exposure to long days and is thereafter melatonin-independent. Distinctions between photoperiodic and circannual seasonal organization erode with the incorporation in the laboratory of ecologically relevant day length conditions. PMID:20444712

  13. Spontaneous endomyometrial neoplasms in aging Chinese hamsters

    SciTech Connect

    Brownstein, D.G.; Brooks, A.L.

    1980-05-01

    Twenty-one endomyometrial neoplasms among 93 nulliparous noninbred Chinese hamsters were evaluated. The median survival time of the 93 females was 1040 days. The median age of hamsters with endomyometrial neoplasms was 1200 days. Neoplasms were classified as carcinomas or malignant mixed muellerian tumors of the endometrium and benign or malignant myometrial neoplasms. There were 13 endometrial adenocarcinomas. Three tumors were mixed adenosquamous carcinomas, which occurred in significantly older Chinese hamsters than did adenocarcinomas. Three malignant mixed muellerian tumors consisted of 2 carcinosarcomas and 1 mixed mesodermal tumor. The 2 myometrial neoplasms were a lelomyoma and a lelomyosarcoma. The classification and relative frequency of these neoplasms were similar to endomyometrial neoplasms of women, which makes Chinese hamsters useful subjects for studies of spontaneous endomyometrial cancers.

  14. Induction of lyme arthritis in LSH hamsters

    SciTech Connect

    Schmitz, J.L.; Schell, R.F.; Hejka, A.; England, D.M.; Konick, L.

    1988-09-01

    In studies of experimental Lyme disease, a major obstacle has been the unavailability of a suitable animal model. We found that irradiated LSH/Ss Lak hamsters developed arthritis after injection of Borrelia burgdorferi in the hind paws. When nonirradiated hamsters were injected in the hind paws with B. burgdorferi, acute transient synovitis was present. A diffuse neutrophilic infiltrate involved the synovia and periarticular structures. The inflammation was associated with edema, hyperemia, and granulation tissue. Numerous spirochetes were seen in the synovial and subsynovial tissues. The histopathologic changes were enhanced in irradiated hamsters. The onset and duration of the induced swelling were dependent on the dose of radiation and the inoculum of spirochetes. Inoculation of irradiated hamsters with Formalin-killed spirochetes or medium in which B. burgdorferi had grown for 7 days failed to induce swelling. This animal model should prove useful for studies of the immune response to B. burgdorferi and the pathogenesis of Lyme arthritis.

  15. Multiple Partial Siberian Snakes in the AGS

    SciTech Connect

    Takano, J.; Ahrens, L. A.; Bai, M.; Brown, K.; Courant, E. D.; Gardner, C. J.; Glenn, J. W.; Huang, H.; Luccio, A. U.; MacKay, W. W.; Okamura, M.; Roser, T.; Tepikian, S.; Tsoupas, N.; Yip, K.; Zelenski, A.; Zeno, K.; Hattori, T.; Lin, F.

    2007-06-13

    Polarized protons are accelerated up to 24.3 GeV in the Alternating Gradient Synchrotron (AGS) at Brookhaven National Laboratory (BNL). To accelerate the beam with preserving the polarization, two different types of helical dipole partial Siberian snake have been installed to the AGS. One is a superconducting magnet (Cold Snake, CSNK), and the other is a normal conducting one (Warm Snake, WSNK). With these snake magnets, the polarization at the AGS extraction achieved 65%. However, the AGS has spin mismatches at the injection and extraction. This description shows calculated results to have better spin matching with using two or three snakes.

  16. Eye diseases in Siberian husky dogs.

    PubMed

    Stanley, R G; Blogg, J R

    1991-05-01

    A full ophthalmic examination was performed on 40 Siberian husky dogs using direct and indirect ophthalmoscopy, gonloscopy and nasolacrimal cannulation. Eight (20%) of the dogs were found to have distichia, 10 (25%) had excessive medial caruncular hairs, 8 (20%) had absence, displacement, or narrowing of the nasolacrimal puncta, 2 (5%) had bilateral corneal crystalline opacities, and 2 (5%) had unilateral areas of lateral corneal lipidosis. Fifty percent of the dogs had some abnormality of the iridocorneal (drainage) angle. However, in only one of these was the deformity severe enough to require glaucoma prophylaxis. An association between blue iris colour and malformation of the iridocorneal angle was noted.

  17. Cause and Possible Treatments of Foot Lesions in Captive Syrian Hamsters (Mesocricetus auratus)

    PubMed Central

    Veillette, Mélisa; Guitard, Julie; Reebs, Stéphan G.

    2010-01-01

    Syrian hamsters (Mesocricetus auratus) run extensively in exercise wheels. This running may cause paw lesions. Three treatments of these wounds (topical application of vitamin E, wheel blocking, and a combination of both) were compared using both sexes. A pretreatment period with or without wheels lasted 15 days and the ensuing treatment period lasted 45 days. At the end of the pre-treatment period, none of the animals without wheels had paw wounds, whereas at least 75% of the females and 100% of the males with wheels did. Females had fewer and smaller wounds than males at this point. At the end of the treatment period, no effect of vitamin E could be discerned, but significant wound healing occurred after wheel blocking in both males and females. Wheel blocking is an easy way to prevent or treat paw wounds, but it presents problems in terms of animal welfare, as wheels are an important cage enrichment for hamsters. PMID:20613965

  18. High levels of Y-chromosome differentiation among native Siberian populations and the genetic signature of a boreal hunter-gatherer way of life.

    PubMed

    Karafet, Tatiana M; Osipova, Ludmila P; Gubina, Marina A; Posukh, Olga L; Zegura, Stephen L; Hammer, Michael F

    2002-12-01

    We examined genetic variation on the nonrecombining portion of the Y chromosome (NRY) to investigate the paternal population structure of indigenous Siberian groups and to reconstruct the historical events leading to the peopling of Siberia. A set of 62 biallelic markers on the NRY were genotyped in 1432 males representing 18 Siberian populations, as well as nine populations from Central and East Asia and one from European Russia. A subset of these markers defines the 18 major NRY haplogroups (A-R) recently described by the Y Chromosome Consortium (YCC 2002). While only four of these 18 major NRY haplogroups accounted for -95% of Siberian Y-chromosome variation, native Siberian populations differed greatly in their haplogroup composition and exhibited the highest phiST value for any region of the world. When we divided our Siberian sample into four geographic regions versus five major linguistic groupings, analyses of molecular variance (AMOVA) indicated higher phiST and phiCT values for linguistic groups than for geographic groups. Mantel tests also supported the existence of NRY genetic patterns that were correlated with language, indicating that language affiliation might be a better predictor of the genetic affinity among Siberians than their present geographic position. The combined results, including those from a nested cladistic analysis, underscored the important role of directed dispersals, range expansions, and long-distance colonizations bound by common ethnic and linguistic affiliation in shaping the genetic landscape of Siberia. The Siberian pattern of reduced haplogroup diversity within populations combined with high levels of differentiation among populations may be a general feature characteristic of indigenous groups that have small effective population sizes and that have been isolated for long periods of time.

  19. SV40 lymphomagenesis in Syrian golden hamsters

    PubMed Central

    McNees, Adrienne L.; Vilchez, Regis A.; Heard, Tiffany C.; Sroller, Vojtech; Wong, Connie; Herron, Alan J.; Hamilton, Mary J.; Davis, William C.; Butel, Janet S.

    2013-01-01

    Simian virus 40 (SV40) isolates differ in oncogenic potential in Syrian golden hamsters following intraperitoneal inoculation. Here we describe the effect of intravenous exposure on tumor induction by SV40. Strains SVCPC (simple regulatory region) and VA45-54(2E) (complex regulatory region) were highly oncogenic following intravenous inoculation, producing a spectrum of tumor types. Three lymphoma cell lines were established; all expressed SV40 T-antigen, were immortalized for growth in culture, and were tumorigenic following transplantation in vivo. New monoclonal antibodies directed against hamster lymphocyte surface antigens are described. The cell lines expressed MHC class II and macrophage markers and were highly phagocytic, indicating a histiocytic origin. Many hamsters that remained tumor-free developed SV40 T-antigen antibodies, suggesting that viral replication occurred. This study shows that route of exposure influences the pathogenesis of SV40-mediated carcinogenesis, that SV40 strain VA45-54(2E) is lymphomagenic in hamsters, that hamster lymphoid cells of histiocytic origin can be transformed in vivo and established in culture, and that reagents to hamster leukocyte differentiation molecules are now available. PMID:19038412

  20. Metabolic activation by hamster and rat hepatocytes in the Salmonella mutagenicity assay.

    PubMed

    Poiley, J A; Raineri, R; Andrews, A W; Cavanaugh, D M; Pienta, R J

    1980-12-01

    Intact and homogenized hepatocytes from untreated or Aroclor 1254-treated male and female noninbred Sprague-Dawley rats and noninbred Syrian golden hamsters were compared for their ability to metabolize chemicals in the Salmonella-mammalian microsome mutagenesis assay. The following chemicals were used: two aromatic amines, 2-amino-anthracene and N-2-fluorenylacetamide; two polycyclic aromatic hydrocarbons, 3-methylcholanthrene and benzo[a]pyrene (BP); and one nitrosamine, diethylnitrosamine (DENA). With one exception, hepatocytes from hamsters were more active than were hepatocytes from rats in the activation of these mutagens. The homogenized preparations from Aroclor 1254-treated rats were slightly more active with BP than was the equivalent hamster preparation. Intact hepatocytes from Aroclor 1254-treated hamsters were more efficient at metabolizing the aromatic amines and DENA, whereas homogenates were more effective with the hydrocarbons. Results were similar with the rat preparations, except that only large quantities of Aroclor 1254-treated intact male rat hepatocytes appeared to activate DENA. These results suggest that, in the choice of an activation system, the kind of chemical being evaluated should be considered.

  1. Pentalogy of Fallot in a captive Siberian tiger (Panthera tigris altaica).

    PubMed

    Scaglione, Frine E; Tursi, Massimiliano; Chiappino, Laura; Schröder, Cathrin; Triberti, Orfeo; Bollo, Enrico

    2012-12-01

    A 2-yr-old male Siberian Tiger (Panthera tigris altaica) died during a fight with a conspecific. At necropsy, significant abnormalities included severe cardiomegaly with cardiac malformations consisting of a large atrial septal defect, a membranous ventricular septal defect, overriding aorta, and stenosis of the pulmonary valve with secondary concentric hypertrophy of the right ventricle. Endocardiosis of the mitral valve was also noted. To the authors' knowledge, this is the first report of a pentalogy of Fallot in a large felid that resulted in sudden death. PMID:23272365

  2. Iliopsoas abscess with iliac and femoral vein thrombosis in an adult Siberian husky.

    PubMed

    Grösslinger, K; Lorinson, D; Hittmair, K; Konar, M; Weissenböck, H

    2004-02-01

    A nine-year-old, male Siberian husky was presented with fever, decreased appetite and activity, non-weightbearing lameness, and oedematous swelling of the right inguinal and preputial area and the right hindlimb. An abscess within the right iliopsoas muscle, with severe thrombosis of the iliac and femoral vein, was diagnosed by haematology and diagnostic imaging. The abscess and adjoining lymph node were removed surgically through a median coellotomy. The isolated pathogen was Staphylococcus intermedius. Clinical signs resolved completely after surgery. Antimicrobial therapy was continued for four weeks. Within the follow-up period of six months, no recurrence of the clinical signs was detected.

  3. Induction of Spermatogenesis by Bone Marrow-derived Mesenchymal Stem Cells in Busulfan-induced Azoospermia in Hamster

    PubMed Central

    Tamadon, Amin; Mehrabani, Davood; Rahmanifar, Farhad; Jahromi, Alireza Raayat; Panahi, Mohadeseh; Zare, Shahrokh; Khodabandeh, Zahra; Jahromi, Iman Razeghian; Tanideh, Nader; Dianatpour, Mehdi; Ramzi, Mani; Koohi-Hoseinabadi, Omid

    2015-01-01

    Background Bone marrow-derived mesenchymal stem cells (BM-MSCs) have potential of differentiation and they secrete anti-inflammatory cytokines and growth factors which make them appropriate for cell therapy. Aim of the Work Were to evaluate the healing effect of BM-MSCs transplantation on germinal cells of busulfan-induced azoospermic hamsters. Material and Methods In the present experimental case control study, BM-MSCs were isolated from bone marrow of donor albino hamsters. Five mature male recipient hamsters received two doses of 10 mg/kg of busulfan with 21 days interval to stop endogenous spermatogenesis. After induction of azoospermia, right testis of hamsters was injected with 106 BM-MSCs via efferent duct and the left one remained as azoospermia control testis. Five normal mature hamsters were selected as normal intact control. After 35 days, testes and epididymis of three groups were removed for histological evaluation. Results Histomorphological analyses of BM-MSCs treated testes and epididymis showed the epithelial tissue of seminiferous tubules had normal morphology and spermatozoa were present in epididymis tubes. Spermatogenesis was observed in most cell-treated seminiferous tubules. The untreated seminiferous tubules were empty. Conclusion Transplanted BM-MSCs could successfully induce spermatogenesis in seminiferous tubules of azoospermic hamster. Therefore, BM-MSCs can be an attractive candidate in cell transplantation of azoospermia. PMID:26634062

  4. Siberian Platform: Geology and Natural Bitumen Resources

    USGS Publications Warehouse

    Meyer, Richard F.; Freeman, P.A.

    2006-01-01

    Summary: The Siberian platform is located between the Yenisey River on the west and the Lena River on the south and east. The Siberian platform is vast in size and inhospitable in its climate. This report is concerned principally with the setting, formation, and potential volumes of natural bitumen. In this report the volumes of maltha and asphalt referred to in the Russian literature are combined to represent natural bitumen. The generation of hydrocarbons and formation of hydrocarbon accumulations are discussed. The sedimentary basins of the Platform are described in terms of the Klemme basin classification system and the conditions controlling formation of natural bitumen. Estimates of in-place bitumen resources are reviewed and evaluated. If the bitumen volume estimate is confined to parts of identified deposits where field observations have verified rock and bitumen grades values, the bitumen resource amounts to about 62 billion barrels of oil in-place. However, estimates of an order of magnitude larger can be obtained if additional speculative and unverified rock volumes and grade measures are included.

  5. Hydrogen gas attenuates embryonic gene expression and prevents left ventricular remodeling induced by intermittent hypoxia in cardiomyopathic hamsters.

    PubMed

    Kato, Ryuji; Nomura, Atsuo; Sakamoto, Aiji; Yasuda, Yuki; Amatani, Koyuha; Nagai, Sayuri; Sen, Yoko; Ijiri, Yoshio; Okada, Yoshikatsu; Yamaguchi, Takehiro; Izumi, Yasukatsu; Yoshiyama, Minoru; Tanaka, Kazuhiko; Hayashi, Tetsuya

    2014-12-01

    The prevalence of sleep apnea is very high in patients with heart failure (HF). The aims of this study were to investigate the influence of intermittent hypoxia (IH) on the failing heart and to evaluate the antioxidant effect of hydrogen gas. Normal male Syrian hamsters (n = 22) and cardiomyopathic (CM) hamsters (n = 33) were exposed to IH (repeated cycles of 1.5 min of 5% oxygen and 5 min of 21% oxygen for 8 h during the daytime) or normoxia for 14 days. Hydrogen gas (3.05 vol/100 vol) was inhaled by some CM hamsters during hypoxia. IH increased the ratio of early diastolic mitral inflow velocity to mitral annulus velocity (E/e', 21.8 vs. 16.9) but did not affect the LV ejection fraction (EF) in normal Syrian hamsters. However, IH increased E/e' (29.4 vs. 21.5) and significantly decreased the EF (37.2 vs. 47.2%) in CM hamsters. IH also increased the cardiomyocyte cross-sectional area (672 vs. 443 μm(2)) and interstitial fibrosis (29.9 vs. 9.6%), along with elevation of oxidative stress and superoxide production in the left ventricular (LV) myocardium. Furthermore, IH significantly increased the expression of brain natriuretic peptide, β-myosin heavy chain, c-fos, and c-jun mRNA in CM hamsters. Hydrogen gas inhalation significantly decreased both oxidative stress and embryonic gene expression, thus preserving cardiac function in CM hamsters. In conclusion, IH accelerated LV remodeling in CM hamsters, at least partly by increasing oxidative stress in the failing heart. These findings might explain the poor prognosis of patients with HF and sleep apnea.

  6. A comparison of liver protein changes in mice and hamsters treated with the peroxisome proliferator Wy-14,643.

    SciTech Connect

    Giometti, C. S.; Tollaksen, S. L.; Cunningham, M. L.; Center for Mechanistic Biology and Biotechnology; National Inst. of Environmental Health Sciences

    1998-01-01

    Interspecies differences in the liver response to Wy-14,643, a potent peroxisome proliferator in rats and mice, have been demonstrated. While both rats and mice show dramatic increases in the number of peroxisomes, the activity of peroxisomal enzymes involved in the {beta}-oxidation of fatty acids, and heptocyte replication, Syrian hamsters have a more moderate peroxisome proliferation response and no sustained increase in cell replication. Rats and mice, but not hamsters, develop hepatocellular carcinoma after prolonged exposure to Wy-14,643. To further characterize this species difference, two-dimensional gel electrophoresis (2-DE) has been used to compare the effect of 14-day exposure to various dietary concentrations of Wy-14,643 on liver protein expression in male mice and hamsters. Digitized images of the 2-DE protein maps were searched for significant changes. The peroxisome bifunctional enzyme (PBE) enoyl CoA hydratase/3-hydroxyacyl dehydrogenase, which migrates to the same position in mouse and hamster liver protein 2-DE patterns, increased in abundance by more than three times the control level in both mice and hamsters. In addition to the quantitative change in PBE, significant quantitative changes (P < 0.001) were found in 49 mouse liver proteins (47 decreasing and 2 increasing) and in 35 hamster liver proteins (27 decreasing and 8 increasing). There was little overlap in the mouse and hamster proteins showing quantitative changes in response to Wy-14,643, with the exception of PBE and one unidentified liver protein with an approximate molecular weight of 50 000. These results show that although peroxisome proliferation occurs in the livers of both mice and hamsters exposed to Wy-14,643, other species-specific changes in proteins occur that are independent of the peroxisome proliferation response and that could be related to species-specific susceptibility or resistance to liver tumor induction.

  7. Comparative Metabolism of Carbon Tetrachloride in Rats, Mice and Hamsters Using Gas Uptake and PBPK Modeling

    SciTech Connect

    Thrall, Karla D. ); Vucelick, Mark E.; Gies, Richard A. ); Zangar, Richard C. ); Weitz, Karl K. ); Poet, Torka S. ); Springer, David L. ); Grant, Donna M. ); Benson, Janet M.

    2000-08-25

    No study has comprehensively compared the rate of metabolism of carbon tetrachloride (CCl4) across species. Therefore, the in vivo metabolism of CCl4 was evaluated using groups of male animals (F344 rats, B6C3F1 mice, and Syrian hamsters) exposed to 40-1800 ppm CCl4 in a closed, recirculating gas-uptake system. For each species, an optimal fit of the family of uptake curves was obtained by adjusting Michaelis-Menten metabolic constants Km (affinity) and Vmax (capacity) using a physiologically based pharmacokinetic (PBPK) model. The results show that the mouse has a slightly higher capacity and lower affinity for metabolizing CCl4 compared to the rat, while the hamster has a higher capacity and lower affinity than either rat or mouse. A comparison of the Vmax to Km ratio, normalized for mg of liver protein (L/hr/mg) across species indicates that hamsters metabolize more CCl4 than either rats or mice, and should be more susceptible to CCl4-induced hepatotoxicity. These species comparisons were evaluated against toxicokinetic studies conducted in animals exposed by nose-only inhalation to 20 ppm 14C-labeled CCl4 for 4 hours. The toxicokinetic study results are consistent with the in vivo rates of metabolism, with rats eliminating less radioactivity associated with metabolism (14CO2 and urine/feces) and more radioactivity associated with the parent compound (radioactivity trapped on charcoal) compared to either hamsters or mice. The in vivo metabolic constants determined here, together with in vitro constants determined using rat, mouse, hamster and human liver microsomes, were used to estimate human in vivo metabolic rates of 1.49 mg/hr/kg body weight and 0.25 mg/L for Vmax and Km, respectively. Normalizing the rate of metabolism (Vmax/Km) by mg liver protein, the rate of metabolism of CCl4 differs across species, with hamster > mouse& > rat > human.

  8. Arrhythmogenic right ventricular dysplasia/cardiomyopathy in a Siberian husky.

    PubMed

    Fernández del Palacio, M J; Bernal, L J; Bayón, A; Bernabé, A; Montes de Oca, R; Seva, J

    2001-03-01

    A seven-month-old male Siberian husky was presented with a recent history of anorexia, hindlimb weakness and syncope. Physical examination revealed severe tachycardia, tachypnoea and dyspnoea. Mucous membranes were pale and femoral pulses were weak. An electrocardiogram showed sustained ventricular tachycardia with a left bundle branch block configuration. Thoracic radiographs revealed slight right ventricular enlargement and two-dimensional echocardiography revealed mild right ventricular dilation at the cardiac apex and some hyperechogenic areas on the right side of the interventricular septum. Administration of intravenous lignocaine converted the ventricular tachycardia to sinus rhythm. The maintenance antiarrhythmic therapy consisted of oral procainamide and propranolol. Three weeks later the dog died suddenly. On postmortem examination, the right ventricular free wall was very thin at the apex, infundibulum and caudal aspect of the right ventricular parietal wall, similar to the 'triangle of dysplasia' of human patients. Histopathological examination revealed replacement of several areas of right ventricular free wall myocardium with connective tissue and fat. The right atrium and left ventricle were less severely affected by the same lesions. The clinical and pathological findings are similar to those reported in young people with arrhythmogenic right ventricular dysplasia/cardiomyopathy.

  9. Effect of Exercise on Photoperiod-Regulated Hypothalamic Gene Expression and Peripheral Hormones in the Seasonal Dwarf Hamster Phodopus sungorus

    PubMed Central

    Petri, Ines; Dumbell, Rebecca; Scherbarth, Frank; Steinlechner, Stephan; Barrett, Perry

    2014-01-01

    The Siberian hamster (Phodopus sungorus) is a seasonal mammal responding to the annual cycle in photoperiod with anticipatory physiological adaptations. This includes a reduction in food intake and body weight during the autumn in anticipation of seasonally reduced food availability. In the laboratory, short-day induction of body weight loss can be reversed or prevented by voluntary exercise undertaken when a running wheel is introduced into the home cage. The mechanism by which exercise prevents or reverses body weight reduction is unknown, but one hypothesis is a reversal of short-day photoperiod induced gene expression changes in the hypothalamus that underpin body weight regulation. Alternatively, we postulate an exercise-related anabolic effect involving the growth hormone axis. To test these hypotheses we established photoperiod-running wheel experiments of 8 to 16 weeks duration assessing body weight, food intake, organ mass, lean and fat mass by magnetic resonance, circulating hormones FGF21 and insulin and hypothalamic gene expression. In response to running wheel activity, short-day housed hamsters increased body weight. Compared to short-day housed sedentary hamsters the body weight increase was accompanied by higher food intake, maintenance of tissue mass of key organs such as the liver, maintenance of lean and fat mass and hormonal profiles indicative of long day housed hamsters but there was no overall reversal of hypothalamic gene expression regulated by photoperiod. Therefore the mechanism by which activity induces body weight gain is likely to act largely independently of photoperiod regulated gene expression in the hypothalamus. PMID:24603871

  10. Polypeptide heterogeneity of hamster and calf fibronectins.

    PubMed Central

    Pena, S D; Mills, G; Hughes, R C; Aplin, J D

    1980-01-01

    The adhesive glycoprotein fibronectin has been isolated from fresh hamster plasma by affinity chromatography on gelatin coupled to Sepharose beads by the method of Engvall & Ruoslahti [Int. J. Cancer (1979) 20, 1-5]. Polyacrylamide-gel electrophoresis of material heated in sodium dodecyl sulphate and 2-mercaptoethanol shows two prominent polypeptide subunits of approx. mol.wts. 215 000 and 200 000, with variable amounts of lower-molecular-weight fragments. The unexpected polypeptide heterogeneity of different preparations of hamster fibronectins and bovine serum fibronectin is shown to be partly an artefact and is generated during isolation and storage of purified fibronectin. Treatment of each hamster fibronectin subunit or a smaller fragment of approx. mol.wt. 140 000 with thermolysin or trypsin after radioiodination produces similar patterns of tyrpsine-containing peptides, indicating similar primary amino-acid sequences. Antibodies raised against the major subunits of hamster plasma fibronectin were coupled to Sepharose beads and used in conjunction with gelatin affinity chromatography to isolate fibronectins extracted with urea from baby-hamster kidney (BHK) cells and present in the long-term culture medium of these cells. The cell and medium fibronectins are similar to hamster plasma fibronectin in amino-acid and carbohydrate composition and also produce very similar peptide 'maps'. We conclude that the various forms of hamster fibronectins are structurally analogous in agreement with indistinguishable biological properties in mediating the substance adhesion of BKH cells [Pena & Hughes (1978) Cell Biol. Int. Rep. 3, 339-344]. Images Fig. 1. Fig. 2. Fig. 3. Fig. 4. Fig. 6. Fig. 7. PMID:7458916

  11. Epidermal growth factor advances some aspects of development but retards others in both rats and hamsters.

    PubMed

    Smart, J L; da Silva, V A; Malheiros, L R; Paumgartten, F J; Massey, R F

    1989-03-01

    The present experiments were undertaken to confirm the recent suggestion that epidermal growth factor (EGF) can have both retarding and accelerating effects on development, using a greater number of developmental indices than hitherto; to extend such studies to another species, the golden hamster, and to compare the responses of males and females. On each of days 0-3, one male and one female rat pup from each of 16 litters of 6 pups were injected subcutaneously with human EGF (0.5 micrograms/g body weight), one male and one female with vehicle, and the remaining two pups were not injected. As expected, EGF accelerated incisor eruption and eye-opening. However, EGF retarded the detachment of the pinna and the appearance of the auditory startle response. Free-fall righting was little affected. Hamster litters were left undisturbed till day 7 to minimise infanticide. Thereafter, experimental design was as far as possible the same as for the rats. Pups from 18 litters were injected on days 7-10. EGF advanced eye-opening, but retarded auditory startling, vaginal opening and the weaning growth spurt. Free-fall righting was unaffected. Hence, EGF had similar accelerating and retarding effects on development in both rats and hamsters. Also, these effects were the same in males and females for most indices. PMID:2809131

  12. Social forces can impact the circadian clocks of cohabiting hamsters

    PubMed Central

    Paul, Matthew J.; Indic, Premananda; Schwartz, William J.

    2014-01-01

    A number of field and laboratory studies have shown that the social environment influences daily rhythms in numerous species. However, underlying mechanisms, including the circadian system's role, are not known. Obstacles to this research have been the inability to track and objectively analyse rhythms of individual animals housed together. Here, we employed temperature dataloggers to track individual body temperature rhythms of pairs of cohabiting male Syrian hamsters (Mesocricetus auratus) in constant darkness and applied a continuous wavelet transform to determine the phase of rhythm onset before, during, and after cohabitation. Cohabitation altered the predicted trajectory of rhythm onsets in 34% of individuals, representing 58% of pairs, compared to 12% of hamsters single-housed as ‘virtual pair’ controls. Deviation from the predicted trajectory was by a change in circadian period (τ), which tended to be asymmetric—affecting one individual of the pair in nine of 11 affected pairs—with hints that dominance might play a role. These data implicate a change in the speed of the circadian clock as one mechanism whereby social factors can alter daily rhythms. Miniature dataloggers coupled with wavelet analyses should provide powerful tools for future studies investigating the principles and mechanisms mediating social influences on daily timing. PMID:24500164

  13. [Fleas (Siphonaptera) infesting birds of West Siberian plain].

    PubMed

    Sapegina, V F; Ravkin, Iu S

    2003-01-01

    The four species of fleas associated with birds in West Siberian Plain have been recorded. Ceratophyllus styx is a specific parasite of Riparia riparia. Ceratophyllus garei, C. gallinae, and C. tribulis parasitize various setting of birds.

  14. The Effects of Vaccinium myrtillus Extract on Hamster Pial Microcirculation during Hypoperfusion-Reperfusion Injury

    PubMed Central

    Mastantuono, Teresa; Starita, Noemy; Sapio, Daniela; D’Avanzo, Sabato Andrea; Di Maro, Martina; Muscariello, Espedita; Paterni, Marco; Colantuoni, Antonio; Lapi, Dominga

    2016-01-01

    Introduction The present study was aimed to assess the in vivo hamster pial microvessel alterations due to 30 min transient bilateral common carotid artery occlusion (BCCAO) and reperfusion (60 min); moreover, the neuroprotective effects of Vaccinium myrtillus extract, containing 34.7% of anthocyanins, were investigated. Materials and Methods Two groups of male hamsters were used: the first fed with control diet and the other with Vaccinium myrtillus supplemented diet. Hamster pial microcirculation was visualized by fluorescence microscopy through an open cranial window. Pial arterioles were classified according to Strahler’s method. Results In age-matched control diet-fed hamsters, BCCAO caused a decrease in diameter of all arterioles. At the end of reperfusion, the reduction of diameter in order 3 arterioles was by 8.4 ± 3.1%, 10.8 ± 2.3% and 12.1 ± 1.1% of baseline in the 2, 4 and 6 month control diet-fed hamsters, respectively. Microvascular permeability and leukocyte adhesion were markedly enhanced, while perfused capillary length (PCL) decreased. The response to acetylcholine and papaverine topical application was impaired; 2’-7’-dichlorofluoresceine-diacetate assay demonstrated a significant ROS production. At the end of BCCAO, in age-matched Vaccinium myrtillussupplemented diet-fed hamsters, the arteriolar diameter did not significantly change compared to baseline. After 60 min reperfusion, order 3 arterioles dilated by 9.3 ± 2.4%, 10.6 ± 3.1% and 11.8 ± 2.7% of baseline in the 2, 4 and 6 month Vaccinium myrtillus supplemented diet-fed hamsters, respectively. Microvascular leakage and leukocyte adhesion were significantly reduced in all groups according to the time-dependent treatment, when compared with the age-matched control diet-fed hamsters. Similarly, the reduction in PCL was progressively prevented. Finally, the response to acetylcholine and papaverine topical application was preserved and there was no significant increase in ROS

  15. New geological data of New Siberian Archipelago

    NASA Astrophysics Data System (ADS)

    Sobolev, Nikolay; Petrov, Evgeniy

    2014-05-01

    The area of New Siberian Archipelago (NSA) encompasses different tectonic blocks is a clue for reconstruction of geological structure and geodynamic evolution of East Arctic. According to palaeomagnetic study two parts of the archipelago - Bennett and Anjou Islands formed a single continental block at least from the Early Palaeozoic. Isotope dating of De Long Islands igneous and sedimentary rocks suggests Neoproterozoic (Baikalian) age of its basement. The De Long platform sedimentary cover may be subdivided into two complexes: (1) intermediate of PZ-J variously deformed and metamorphosed rocks and (2) K-KZ of weakly lithified sediments. The former complex comprises the Cambrian riftogenic volcanic-clastic member which overlain by Cambrian-Ordovician turbiditic sequence, deposited on a continental margin. This Lower Palaeozoic complex is unconformably overlain by Early Cretaceous (K-Ar age of c.120 Ma) basalts with HALIP petrochemical affinities. In Anjou Islands the intermediate sedimentary complex encompasses the lower Ordovician -Lower Carboniferous sequence of shallow-marine limestone and subordinate dolomite, mudstone and sandstone that bear fossils characteristic of the Siberian biogeographic province. The upper Mid Carboniferous - Jurassic part is dominated by shallow-marine clastic sediments, mainly clays. The K-KZ complex rests upon the lower one with angular unconformity and consists mainly of coal-bearing clastic sediments with rhyolite lavas and tuffs in the bottom (117-110 Ma by K-Ar) while the complexe's upper part contains intraplate alkalic basalt and Neogene-Quaternary limburgite. The De-Long-Anjou block's features of geology and evolution resemble those of Wrangel Island located some 1000 km eastward. The Laptev Sea shelf outcrops in intrashelf rises (Belkovsky and Stolbovoy Islands) where its geology and structure may be observed directly. On Belkovsky Island non-dislocated Oligocene-Miocene sedimentary cover of littoral-marine coal

  16. Crystalline corneal opacities in the Siberian Husky.

    PubMed

    MacMillan, A D; Waring, G O; Spangler, W L; Roth, A M

    1979-10-15

    Bilaterally symmetric opacities were detected in the corneal stroma of 78 (14%) of 560 Siberian Huskies, aged 7 months to 12 years, examined in ophthalmology screening clinics. The opacities were round or horizontally oval and consisted of a diffuse gray homogeneous haze in the anterior stroma or an array of fine polychromatic crystals in the posterior stroma, or both. The corneas were not inflamed. The frequency of occurrence and density of the opacities increased with age. Several affected dogs were closely related, but a specific inheritance pattern could not be established. Light and electron microscopy disclosed clusters of extracellular, thin, needle-shaped, crystalline clefts. Histochemical stains on frozen sections identified neutral fats, phospholipids, and cholesterol as components of the crystals.

  17. Field of a helical Siberian Snake

    SciTech Connect

    Luccio, A.

    1995-02-01

    To preserve the spin polarization of a beam of high energy protons in a circular accelerator, magnets with periodic magnetic field, called Siberian Snakes are being used. Recently, it was proposed to build Siberian Snakes with superconducting helical dipoles. In a helical, or twisted dipole, the magnetic field is perpendicular to the axis of the helix and rotates around it as one proceeds along the magnet. In an engineering study of a 4 Tesla helical snake, the coil geometry is derived, by twisting, from the geometry of a cosine superconducting dipole. While waiting for magnetic measurement data on such a prototype, an analytical expression for the field of the helice is important, to calculate the particle trajectories and the spin precession in the helix. This model will also allow to determine the optical characteristics of the snake, as an insertion in the lattice of the accelerator. In particular, one can calculate the integrated multipoles through the magnet and the equivalent transfer matrix. An expression for the field in the helix body, i.e., excluding the fringe field was given in a classical paper. An alternate expression can be found by elaborating on the treatment of the field of a transverse wiggler obtained under the rather general conditions that the variables are separable. This expression exactly satisfies Maxwell`s div and curl equations for a stationary field, {del} {center_dot} B = 0, {del} x B = 0. This approach is useful in that it will allow one to use much of the work already done on the problem of inserting wigglers and undulators in the lattice of a circular accelerator.

  18. The susceptibility of the hamster to mouse encephalomyelitis virus.

    PubMed

    DEAN, D J; DALLDORF, G

    1948-12-01

    The OT strain of mouse encephalomyelitis virus induces an inapparent infection in suckling hamsters associated with lesions of the central nervous system and skeletal muscles. The virus increases in pathogenicity after alternating mouse-hamster transfers and then induces both paralysis and encephalitis. Pathogenicity is lost through serial hamster passages but is restored by a single mouse transfer.

  19. Subcutaneous Angiolipoma of Abdomen in a Golden Hamster (Mesocrietus auratus).

    PubMed

    Kondo, H; Sato, T; Shibuya, H; Onuma, M

    2005-10-01

    This is a single case report of an angiolipoma located in the subcutis of a 2-year-old golden hamster. The histological appearance of the tumour resembled that described in other species. The hamster died 1 month following removal of tumour and a necropsy was not performed. This is apparently the first recorded case of angiolipoma in a hamster.

  20. Ascarid infestation in captive Siberian tigers in China.

    PubMed

    Peng, Zhiwei; Liu, Shijie; Hou, Zhijun; Xing, Mingwei

    2016-08-15

    The Siberian tiger is endangered and is listed by the International Union for the Conservation of Nature; the captive environment is utilized to maintain Siberian tiger numbers. Little information regarding the prevalence of parasites in Siberian tigers is available. A total of 277 fecal samples of Siberian tigers were analyzed in this study. The microscopic analysis indicated the presence of ascarid eggs of Toxascaris leonina and Toxocara cati. The ascarid infection rate was 67.5% in Siberian tigers. The internal transcribed spacer-1 (ITS-1) phylogenetic analysis indicated that T. leonina belonged to Toxascaris and that Toxo. cati belonged to Toxocara. The infestation rate and intensity of T. leonina were higher than those of Toxo. cati. One-way analysis of variance showed that the presence of T. leonina was significantly associated with age (P<0.05). Temperature changes also influenced T. leonina and Toxo. cati infestation, and a rise in temperature caused an increase in the number of T. leonina and Toxo. cati eggs. This study provides a better understanding of ascarid infestation among the captive Siberian tigers and is helpful for the prevention of the spread of infectious parasitic diseases among other tigers in the zoo.

  1. Ascarid infestation in captive Siberian tigers in China.

    PubMed

    Peng, Zhiwei; Liu, Shijie; Hou, Zhijun; Xing, Mingwei

    2016-08-15

    The Siberian tiger is endangered and is listed by the International Union for the Conservation of Nature; the captive environment is utilized to maintain Siberian tiger numbers. Little information regarding the prevalence of parasites in Siberian tigers is available. A total of 277 fecal samples of Siberian tigers were analyzed in this study. The microscopic analysis indicated the presence of ascarid eggs of Toxascaris leonina and Toxocara cati. The ascarid infection rate was 67.5% in Siberian tigers. The internal transcribed spacer-1 (ITS-1) phylogenetic analysis indicated that T. leonina belonged to Toxascaris and that Toxo. cati belonged to Toxocara. The infestation rate and intensity of T. leonina were higher than those of Toxo. cati. One-way analysis of variance showed that the presence of T. leonina was significantly associated with age (P<0.05). Temperature changes also influenced T. leonina and Toxo. cati infestation, and a rise in temperature caused an increase in the number of T. leonina and Toxo. cati eggs. This study provides a better understanding of ascarid infestation among the captive Siberian tigers and is helpful for the prevention of the spread of infectious parasitic diseases among other tigers in the zoo. PMID:27514888

  2. Histopathology of Lyme arthritis in LSH hamsters

    SciTech Connect

    Hejka, A.; Schmitz, J.L.; England, D.M.; Callister, S.M.; Schell, R.F.

    1989-05-01

    The authors studied the histopathologic evolution of arthritis in nonirradiated and irradiated hamsters infected with Borrelia burgdorferi. Nonirradiated hamsters injected in the hind paws with B. burgdorferi developed an acute inflammatory reaction involving the synovium, periarticular soft tissues, and dermis. This acute inflammatory reaction was short-lived and was replaced by a mild chronic synovitis as the number of detectable spirochetes in the synovium, periarticular soft tissues, and perineurovascular areas diminished. Exposing hamsters to radiation before inoculation with B. burgdorferi exacerbated and prolonged the acute inflammatory phase. Spirochetes also persisted longer in the periarticular soft tissues. A major histopathologic finding was destructive and erosive bone changes of the hind paws, which resulted in deformation of the joints. These studies should be helpful in defining the immune mechanism participating in the onset, progression, and resolution of Lyme arthritis.

  3. A neuroethological approach to hamster vision.

    PubMed

    Finlay, B L; Sengelaub, D R; Berg, A T; Cairns, S J

    1980-12-01

    The contributions of the midbrain optic tectum to visuomotor behaviors likely to be important to hamsters in the wild were studied, including aperture detection, insect catching, and barrier avoidance. Following tectal undercuts, hamsters ceased to make direct approaches to apertures in the posterior 180 degrees of the visual field; this appeared to be mediated by a loss of exploratory or scanning head movements. Reorientation to and pursuit of crickets jumping out of grasp into the visual periphery was impaired, though initial approach to them was not. Barrier avoidance was unaffected by tectal undercuts. This pattern is similar to the contribution of the frog and toad optic tectum to analogous visuomotor tasks. The contribution of the tectum to searching and scanning in the hamster is an extension of the basic orienting capabilities dependent on optic tectum in anurans.

  4. Decreased adult neurogenesis in hibernating Syrian hamster.

    PubMed

    León-Espinosa, Gonzalo; García, Esther; Gómez-Pinedo, Ulises; Hernández, Félix; DeFelipe, Javier; Ávila, Jesús

    2016-10-01

    Generation of new neurons from adult neural stem cells occurs in the dentate gyrus (DG) of the hippocampus and the lateral walls of the lateral ventricles. In this article, we study the neurogenesis that takes place during the hibernation of the Syrian hamster (Mesocricetus auratus). Using a variety of standard neurogenesis markers and 5-bromo-2-deoxyuridine (BrdU) incorporation, we describe a preferential decrease in the proliferation of newborn neurons in the subventricular zone (SVZ) of the hibernating hamsters (torpor) rather than in the hippocampus. Furthermore, we demonstrate that the proliferative capacity is recovered after 3-4days of torpor when arousal is triggered under natural conditions (i.e., not artificially provoked). In addition, we show that tau3R, a tau isoform with three microtubule-binding domains, is a suitable marker to study neurogenesis both in the SVZ and subgranular zone (SGZ) of the Syrian hamster brain. PMID:27436535

  5. Increases in plasma pool size of lipoprotein components in copper-deficient hamsters

    SciTech Connect

    Al-Othman, A.A.; Rosenstein, F.; Lei, K.Y. )

    1991-03-15

    Twenty-four male Golden Syrian hamsters, were randomly assigned to 2 dietary copper (Cu) treatments; deficient and adequate. Reductions in weight gain, hematocrit and liver Cu as well as increases in heart weight and plasma volume were observed in CD hamsters after 7 weeks of treatment. Plasma very low (VLDL), low (LDL) and high (HDL) density lipoproteins were isolated by ultracentrifugation and Sepharose column chromatography. The percentage of total plasma cholesterol carried by LDL was increased from 20 to 24% but was reduced from 71 to 68% for HDL as a result of Cu deficiency. In LDL the % composition of triglycerides (TG) and phospholipids (PL) was increased by 25% but that of cholesterol was reduced by 13%. The % composition of protein was reduced 24% but that of TG was increased 18% in VLDL by Cu deficiency. Since plasma volume was increased 50% in CD hamsters, the data were expressed as the amount present in the plasma pool corrected for body weight. With the exceptions of smaller increased in VLDL protein and PL as well as the more than threefold increases in LDL TG and PL plasma pool size, the pool size for the rest of the lipoprotein components were increased about twofold in CD hamsters. The lipoprotein data further indicate that Cu deficiency increased the particle number of VLDL, LDL and HDL but enlarged the size of only VLDL and LDL.

  6. Aortic ER stress in streptozotocin-induced diabetes mellitus in APA hamsters.

    PubMed

    Kurokawa, Masaki; Hideshima, Makoto; Ishii, Yoshiyuki; Kyuwa, Shigeru; Yoshikawa, Yasuhiro

    2009-04-01

    Atherosclerosis is thought to be associated with endoplasmic reticulum (ER) dysfunction and the accumulation of unfolded proteins. In this study, we examined the relationship between atherosclerosis and ER stress and the effect of sodium 4-phenylbutyrate (4-PBA), a kind of chemical chaperone, on atherosclerosis in streptozotocin-induced diabetic APA hamsters. Male, 8-week-old, APA hamsters were injected with streptozotocin (30 mg/kg body weight) to induce diabetes mellitus, and ER stress was evaluated immunohistochemically or by semi-quantitative RT-PCR analysis using ER stress markers such as calreticulin and GPR78. Control hamsters were injected with citrate buffer and were similarly analyzed. In the aorta of control animals, a weak ER stress was detected, and 4-PBA treatment decreased the calreticulin- and GRP78-positive areas and also reduced the mRNA levels of calreticulin and GRP78. On the other hand, strong ER stress was detected at the lesser curvature of the aortic arch of streptozotocin-induced diabetic APA hamsters. However, 4-PBA treatment failed to lessen the ER stress in the aorta and had no effect on improvement of the atherosclerotic lesions. These results may provide an explanation for the complex etiology of atherosclerosis accompanied by diabetes mellitus and various other clinical phenotypes of atherosclerosis.

  7. Nuciferine Prevents Hepatic Steatosis and Injury Induced by a High-Fat Diet in Hamsters

    PubMed Central

    Li, Xiaoxia; Feng, Rennan; Guan, Chunmei; Wang, Yanwen; Li, Ying; Sun, Changhao

    2013-01-01

    Background Nuciferine is a major active aporphine alkaloid from the leaves of N. nucifera Gaertn that possesses anti-hyperlipidemia, anti-hypotensive, anti-arrhythmic, and insulin secretagogue activities. However, it is currently unknown whether nuciferine can benefit hepatic lipid metabolism. Methodology/Principal Findings In the current study, male golden hamsters were randomly divided into four groups fed a normal diet, a high-fat diet (HFD), or a HFD supplemented with nuciferine (10 and 15 mg/kg·BW/day). After 8 weeks of intervention, HFD-induced increases in liver and visceral adipose tissue weight, dyslipidemia, liver steatosis, and mild necroinflammation in hamsters were analyzed. Nuciferine supplementation protected against HFD-induced changes, alleviated necroinflammation, and reversed serum markers of metabolic syndrome in hamsters fed a HFD. RT-PCR and western blot analyses revealed that hamsters fed a HFD had up-regulated levels of genes related to lipogenesis, increased free fatty acid infiltration, and down-regulated genes involved in lipolysis and very low density lipoprotein secretion. In addition, gene expression of cytochrome P4502E1 and tumor necrosis factor-α were also increased in the HFD group. Nuciferine supplementation clearly suppressed HFD-induced alterations in the expression of genes involved in lipid metabolism. Conclusions/Significance Nuciferine supplementation ameliorated HFD-induced dyslipidemia as well as liver steatosis and injury. The beneficial effects of nuciferine were associated with altered expression of hepatic genes involved in lipid metabolism. PMID:23691094

  8. Altered cytokeratin expression during chemoprevention of hamster buccal pouch carcinogenesis by S-allylcysteine.

    PubMed

    Balasenthil, Seetharaman; Rao, Kunchala S; Nagini, Siddavaram

    2003-01-01

    We examined the effect of S-allylcysteine (SAC), a water-soluble garlic constituent, on cytokeratin expression, a sensitive and specific marker for differentiation status during 7,12-dimethylbenz[a]anthracene (DMBA)-induced hamster buccal pouch (HBP) carcinogenesis in male Syrian hamsters. Hamsters were divided into four groups of six animals each. Animals in group 1 were painted with a 0.5% solution of DMBA in liquid paraffin on the right buccal pouches three times a week for 14 weeks. Group 2 animals were painted with DMBA as in group I, and in addition they received orally 200 mg/kg of SAC on days alternate to DMBA application. Group 3 animals received SAC as in group 2. Group 4 animals received neither DMBA nor SAC and served as the control. The hamsters were killed after an experimental period of 14 weeks. Cytokeratin expression was detected by Western blot analysis using monoclonal antibodies AE1 and AE3. In DMBA-induced HBP tumors, the decreased expression of high molecular weight cytokeratins of molecular mass between 55-70 kDa was observed. Administration of SAC (200 mg/kg) to animals painted with DMBA suppressed the incidence of DMBA-induced carcinomas and was associated with restoration of normal cytokeratin expression. The results of the present study suggest that inhibition of HBP tumorigenesis by SAC may be due to its regulatory effects on differentiation, tumor invasiveness, and its ability to migrate and form metastases. PMID:14704476

  9. Chronic effects of dietary exposure to amosite and chrysotile asbestos in Syrian golden hamsters.

    PubMed Central

    McConnell, E E; Shefner, A M; Rust, J H; Moore, J A

    1983-01-01

    Bioassays of amosite, short-range (SR), intermediate-range (IR) or intermediate-range chrysotile asbestos in combination with the intestinal carcinogen 1,2-dimethylhydrazine dihydrochloride (DMH) were conducted with male and female Syrian golden hamsters. Amosite and both forms of chrysotile asbestos were administered at a concentration of 1% in pelleted diet for the entire lifetime of the hamsters starting with mothers of the test animals. Group sizes varied from 125-254. There was no adverse effect on body weight gain or survival by either type of asbestos or by IR chrysotile asbestos in combination with DMH. A significant increase (p less than 0.05) in adrenal cortical tumors was observed in male hamsters exposed to SR and IR chrysotile asbestos and in females treated with IR chrysotile asbestos when compared to the pooled control groups. However, statistical significance (p less than 0.05) was lost when these dosed groups were compared with temporal control groups. Neither of the male or female amosite asbestos groups showed increased neoplasia in any tissue or organ compared to the control groups. The cocarcinogen studies using IR chrysotile asbestos and 1,2-dimethylhydrazine dihydrochloride were considered inadequate because there was no increase in intestinal neoplasia in the DMH group. PMID:6319115

  10. Thyroid function and cold acclimation in the hamster, Mesocricetus auratus

    SciTech Connect

    Tomasi, T.E.; Horwitz, B.A.

    1987-02-01

    Basal metabolic rate (BMR), thyroxine utilization rate (T4U), and triiodothyronine utilization rate (T3U) were measured in cold-acclimated (CA) and room temperature-acclimated (RA) male golden hamsters, Mesocricetus auratus. Hormone utilization rates were calculated via the plasma disappearance technique using SVI-labeled hormones and measuring serum hormone levels via radioimmunoassay. BMR showed a significant 28% increase with cold acclimation. The same cold exposure also produced a 32% increase in T4U, and a 204% increase in T3U. The much greater increase in T3U implies that previous assessments of the relationship between cold acclimation and thyroid function may have been underestimated and that cold exposure induces both quantitative and qualitative changes in thyroid function. It is concluded that in the cold-acclimated state, T3U more accurately reflects thyroid function than does T4U. A mechanism for the cold-induced change in BMR is proposed.

  11. Soy protein with or without isoflavones, soy germ and soy germ extract, and daidzein lessen plasma cholesterol levels in golden Syrian hamsters.

    PubMed

    Song, Tongtong; Lee, Sun-Ok; Murphy, Patricia A; Hendrich, Suzanne

    2003-10-01

    Dietary isolated soy protein (ISP, containing approximately equal amounts of daidzein and genistein), ethanol-extracted ISP (ISP (-)), soygerm or soygerm extract (containing large amounts of daidzein and glycitein and little genistein) and the isoflavone, daidzein, were hypothesized to lessen plasma cholesterol in comparison with casein. Sixty male and 60 female golden Syrian hamsters (6-8 weeks of age) were randomly assigned to six treatments fed for 10 weeks. Four of the experimental diets (ISP, daidzein, soygerm, and soygerm extract) contained 1.3 mmol total isoflavones/kg. The ISP (-) diet contained 0.013 mmol isoflavone/kg, whereas the casein diet contained no isoflavones. Hamsters fed ISP, ISP (-), daidzein, soygerm, and soygerm extract had significantly less plasma total cholesterol (by 16%-28%), less non-HDL cholesterol (by 15%-50%) and less non-HDL/HDL cholesterol ratios compared with hamsters fed casein (P < 0.01). For male hamsters, there were no differences among treatments in plasma HDL concentrations. Female hamsters fed ISP (-) had significantly greater HDL levels (P < 0.01) than females fed casein or daidzein. Triglyceride concentration was significantly less in hamsters fed ISP (-) compared with the casein-fed females. Because soy protein with or without isoflavones, soygerm and soygerm extract, and daidzein lessened plasma cholesterol to an approximately equal extent, soy protein alone, varying mixtures of isoflavones, and other extractable components of soy are responsible for cholesterol-lessening effects of soy foods, mainly due to their effects to lessen LDL cholesterol.

  12. The tectonic evolution of the New Siberian Islands

    NASA Astrophysics Data System (ADS)

    Piepjohn, K.; Brandes, C.; Gaedicke, C.; Franke, D.; Mrugalla, S.; Sobolev, N.; Tolmacheva, T.

    2012-04-01

    The New Siberian Islands are located on the wide arctic shelf between the Laptev Sea in the west and the East-Siberian Sea in the east and represent the westernmost part of the Chuchotka-Alaska Terrane. Geologically, they are bounded by the Laptev Sea Rift in the west, the passive continental margin towards the Arctic Ocean in the north and the South Anyui Suture Zone in the south. Two scenarios are discussed: (1) the New Siberian Islands were situated at the North American margin before the start of the break-up of Laurasia in Jurassic times, and (2) the New Siberian Islands are part of the Siberian platform since at least Palaeozoic times. Compared with the structural evolution of Severnaya Semlya, Franz Joseph Land and Svalbard, the sedimentary succession of the New Siberian Islands is only very little affected by tectonicdeformation. There is no evidence for the Caledonian and Ellesmerian orogeny on the New Siberian Islands. Although there are some Late Ordovician volcanics exposed on the DeLong Islands, the stratigraphic succession continues without important breaks from Cambrian to Middle Carboniferous, a time span which includes both orogenies. Furthermore, the Paleozoic evolution of the sedimentary basin on the New Siberian Islands has more affinities to the Siberian platform than to Severnaya Semlya, Franz Joseph Land and Svalbard. The only observed deformation on the New Siberian Islands is related to the plate tectonic re-organisation of the recent Arctic during the break-up of the Arctic Ocean in probably Early Tertiary times. The deformation on the Anyui Islands is characterized by mostly gentle, open synclines and anticlines with NW-SE trending axis. The deformation increases westwards towards the Laptev Sea, and is dominated by tight folding, thrusting and partly cleavage-development at the west coast of Koteĺny Island and on Beĺkovski Island. The fold-vergencies and the cross-cutting relationships of bedding and cleavage indicate NE

  13. Congenital Transmission of Experimental Leishmaniasis in a Hamster Model

    PubMed Central

    Osorio, Yaneth; Rodriguez, Luz D.; Bonilla, Diana L.; Peniche, Alex G.; Henao, Hector; Saldarriaga, Omar; Travi, Bruno L.

    2012-01-01

    Little information is available on transplacental transmission of Leishmania spp. We determined the frequency and impact of congenital infection caused by Leishmania panamensis or L. donovani in experimentally infected hamsters. A polymerase chain reaction showed that congenital transmission occurred in 25.8% (24 of 93) of offspring born to L. panamensis-infected hamsters and 14.6% (11 of 75) offspring born to L. donovani-infected hamsters. Mortality during lactation was higher in offspring born to L. panamensis-infected hamsters and offspring born to L. donovani-infected hamsters than controls, and lymphoproliferation to Leishmania was more frequent in offspring born to L. panamensis-infected hamsters (17.4%, 11 of 63) than in offspring born to L. donovani-infected hamsters (8.5%, 3 of 35). After weaning, only offspring born to L. donovani-infected hamsters had lower weight gain (P < 0.001) and hematocrit levels (P = 0.0045) than controls. Challenge of offspring born to L. panamensis-infected hamsters with L. panamensis showed no differences in lesion evolution, and offspring born to L. donovani-infected hamsters were more susceptible to L. donovani challenge than controls. Consequently, prenatal exposure of hamsters to L. donovani significantly increased the mortality risk and susceptibility to secondary homologous infection. PMID:22556079

  14. Light pulses do not induce c-fos or per1 in the SCN of hamsters that fail to reentrain to the photocycle.

    PubMed

    Barakat, Monique T; O'Hara, Bruce F; Cao, Vinh H; Larkin, Jennie E; Heller, H Craig; Ruby, Norman F

    2004-08-01

    Circadian activity rhythms of most Siberian hamsters (Phodopus sungorus sungorus) fail to reentrain to a 5-h phase shift of the light-dark (LD) cycle. Instead, their rhythms free-run at periods close to 25 h despite the continued presence of the LD cycle. This lack of behavioral reentrainment necessarily means that molecular oscillators in the master circadian pacemaker, the SCN, were unable to reentrain as well. The authors tested the hypothesis that a phase shift of the LD cycle rendered the SCN incapable of responding to photic input. Animals were exposed to a 5-h phase delay of the photocycle, and activity rhythms were monitored until a lack of reentrainment was confirmed. Hamsters were then housed in constant darkness for 24 h and administered a 30-min light pulse 2 circadian hours after activity onset. Brains were then removed, and tissue sections containing the SCN were processed for in situ hybridization. Sections were probed with Siberian hamster c-fos and per1 mRNA probes because light rapidly induces these 2 genes in the SCN during subjective night but not at other circadian phases. Light pulses induced robust expression of both genes in all animals that reentrained to the LD cycle, but no expression was observed in any animal that failed to reentrain. None of the animals exhibited an intermediate response. This finding is the first report of acute shift in a photocycle eliminating photosensitivity in the SCN and suggests that a specific pattern of light exposure may desensitize the SCN to subsequent photic input.

  15. An assessment of anti-Müllerian hormone in predicting mating outcomes in female hamsters that have undergone natural and chemically-accelerated reproductive aging.

    PubMed

    Roosa, Kristen A; Zysling, Devin A; Place, Ned J

    2015-04-01

    In mammals, female fertility declines with age due in part to a progressive loss of ovarian follicles. The rate of follicle decline varies among individuals making it difficult to predict the age of onset of reproductive senescence. Serum anti-Müllerian hormone (AMH) concentrations correlate with the numbers of ovarian follicles, and therefore, AMH could be a useful predictor of female fertility. In women and some production animals, AMH is used to identify which individuals will respond best to ovarian stimulation for assisted reproductive technologies. However, few studies have evaluated AMH's predictive value in unassisted reproduction, and they have yielded conflicting results. To assess the predictive value of AMH in the context of reproductive aging, we prospectively measured serum AMH in 9-month-old Siberian hamsters shortly before breeding them. Female Siberian hamsters experience substantial declines in fertility and fecundity by 9months of age. We also measured serum AMH in 5-month-old females treated with 4-vinylcyclohexene diepoxide (VCD), which selectively destroys ovarian follicles and functionally accelerates ovarian aging. Vehicle-treated 5-month-old females served as controls. AMH concentrations were significantly reduced in VCD-treated females yet many females with low AMH reproduced successfully. On average, both young and old hamsters that littered had higher AMH concentrations than females that did not. However, some females with relatively high AMH concentrations failed to litter, whereas several with low AMH succeeded. Our results suggest that mean AMH concentration can predict mating outcomes on a population or group level, but on an individual basis, a single AMH determination is less informative.

  16. Lifetime carcinogenesis studies of chrysotile asbestos (CAS No. 12001-29-5) in syrian golden hamsters (feed studies). Technical report series

    SciTech Connect

    Not Available

    1990-07-01

    Carcinogenesis studies of short range (SR), intermediate range (IR) or intermediate range chrysotile asbestos in combination with the intestinal carcinogen 1,2-dimethylhydrazine dihydrochloride (DMH) were conducted with male and female Syrian golden hamsters. Both forms of chrysotile asbestos were administered at a concentration of 1% in pelleted diet for the entire lifetime of the hamsters, starting with mothers of the test animals. Group sizes varied from 125 to 253. Starting at 6 weeks of age, male and female hamsters in the intermediate range chrysotile/DMH study were given oral doses of DMH (4 mg/kg) every other week for a total of 5 doses. There was no adverse effect on body weight gain or survival by either form of asbestos or by asbestos in combination with DMH. Under the conditions of these studies, neither short range chrysotile nor intermediate range chrysotile asbestos was carcinogenic when ingested at 1% levels in the diet by male and female Syrian golden hamsters. While there were increases in the rates of adrenal cortical adenomas in male and female hamsters exposed to intermediate range chrysotile asbestos compared with pooled control groups, these incidence rates were not different when compared with the concurrent control groups. Additionally, the biologic importance of adrenal tumors in the absence of target organ (gastrointestinal tract) neoplasia is questionable.

  17. The Environmental Impact of Siberian Traps Volcanism

    NASA Astrophysics Data System (ADS)

    Saunders, A. D.; Reichow, M. K.

    2008-12-01

    New high-precision 40Ar/39Ar data confirm that the Siberian Traps extend as far west as the Ural Mountains, and from the Kuznetsk Basin in the south to the Taimyr Peninsula in the north; an area encompassing some 5 million km2. The bulk of this volcanism occurred at about 250 Ma (Ar-Ar time). These data, plus new and published Ar/Ar data from the P-Tr section at Meishan, China, confirm that volcanism and the mass extinction were synchronous. Here, we explore the causal link between volcanism and extinction. The volcanism is associated with global super-greenhouse conditions and widespread shallow oceanic anoxia - perhaps the sine qua non of the marine mass extinctions. Injection of isotopically 'light' carbon is required to explain the characteristic and dramatic negative carbon isotope excursion preserved in ocean water proxies, but because the CIE occurs after the mass extinction, this suggests that the carbon pulse (from breakdown of methane hydrates, or magmatic burning of coal or other hydrocarbons) was not the fundamental cause of the extinction. Rather, we suggest that magmatic CO2 released during the eruptions (complemented by pyrogenetic CO2 and methane) led to progressive CO2 accumulation in the atmosphere-ocean system (rates of long-term removal of carbon by geological processes are significantly lower than volcanic injection). Atmospheric accumulation may have been amplified by short-term sulphate-induced volcanic winters that caused collapse of photosynthetic cycles by atmospheric temperature fluctuations and sunlight attenuation, thus inhibiting carbon draw-down. Subsequent warming of the deep ocean may have triggered the methane pulse, leading to the main CIE. What lessons can we take away for present climate change? Unlike in the Cenozoic, when atmospheric CO2 progressively decreased to low pre-industrial levels, throughout the Permian atmospheric CO2 levels fluctuated strongly, and may have been as much as 10x present-day by the time that Siberian

  18. Hypolipidemic and antioxidative effects of noni (Morinda citrifolia L.) juice on high- fat/cholesterol-dietary hamsters.

    PubMed

    Lin, Yi-Ling; Chou, Chung-Hsi; Yang, Deng-Jye; Chen, Jr-Wei; Tzang, Bor-Show; Chen, Yi-Chen

    2012-09-01

    Noni juice (NJ) is rich in phytochemicals and polysaccharides. Lipid-lowering and antioxidative effects of NJ were investigated in this study. Fifty male hamsters were assigned randomly to one of the following groups: (1) normal diet and distilled water (LFCD); (2) high-fat/cholesterol diet and distilled water (HFCD); (3) HFCD and 3 ml NJ (including 0.20 g solids)/kg BW (NJ_L); (4) HFCD and 6 mL NJ (including 0.40 g solids)/kg BW (NJ_M); (5) HFCD and 9 ml NJ (including 0.60 g solids)/kg BW (NJ_H) for six weeks. NJ supplementation decreased (p < 0.05) serum triacylglycerol, cholesterol, atherogenic index, malondialdehyde levels, and hepatic lipids in HFCD hamsters, whereas serum trolox equivalent antioxidant capacity, glutathione, and fecal lipids in HFCD hamsters were increased (p < 0.05) by NJ supplementation. Although NJ supplementation downregulated (p < 0.05) sterol regulator element binding protein-1c in HFCD hamsters, it upregulated (p < 0.05) hepatic peroxisome proliferator-activated receptor-alpha and uncoupling protein 2 gene expressions in HFCD hamsters. Results demonstrate that NJ promotes cardioprotection in a high-fat/cholesterol diet.

  19. Pathology of acute inhalation exposure to 3-methylfuran in the rat and hamster

    SciTech Connect

    Haschek, W.M.; Morse, C.C.; Boyd, M.R.; Hakkinen, P.J.; Witschi, H.P.

    1983-12-01

    The acute inhalation toxicity of 3-methylfuran (3MF) was investigated in SPF Fischer-derived and CD/CR rats, and golden Syrian hamsters by determination of the 2-week LC50, and by histologic examination of animals killed 1, 3, and 14 days following a 1-hr exposure to 148 and 322 mumole 3MF/liter for CD/CR rats and hamsters, respectively. The Fischer-derived rat was more sensitive to 3MF-induced lethality than the CD/CR rat with an LC50 in the male rat of 81 mumole/liter-1 hr as compared to 222 mumole/liter-1 hr. No sex difference was found. The hamster was relatively resistant with no lethality at 322 mumole 3MF/liter-2 hr. Pulmonary damage was present in both species. In the hamster, selective necrosis of nonciliated bronchiolar epithelial (Clara) cells was seen at 1 day with virtually complete regeneration by 14 days whereas in the rat the bronchiolar epithelial damage was more extensive and was followed by scattered peribronchiolar fibrosis and epithelial mucous metaplasia suggestive of ''small airway disease'' of man. Relatively selective 3MF-induced necrosis of olfactory epithelium occurred in the nasal mucosa of both species. Resolution of this lesion was seen by 14 days in the hamster. In the rat, however, the necrosis was much more extensive and was followed by partially occlusive fibrosis of the nasal cavity as seen at 14 days. 3MF also induced centrilobular hepatic necrosis in both species. In the rat, lymphocyte necrosis in the thymus and spleen, and esophageal necrosis was also seen.

  20. Testicular function and pelage color have different critical daylengths in the Djungarian hamster, Phodopus sungorus sungorus.

    PubMed

    Duncan, M J; Goldman, B D; Di Pinto, M N; Stetson, M H

    1985-01-01

    Testicular function and pelage color are regulated by photoperiod in the Djungarian hamster. To investigate the critical daylengths of these functions, adult male hamsters were exposed to one of four photoperiods: 16 h of light, 8 h of darkness (16L:8D), 14L:10D, 12L:12D, or 10L:14D. 10L:14D and 12L:12D induced the winter molt and testicular regression, in contrast to 14L:10D which induced only the latter response, and 16L:8D which maintained the summer pelage and large testes. Melatonin injections administered 4, 2, or 0 h before lights-off to hamsters exposed to 16L:8D mimicked the effects in hamsters exposed to 10:14D, 12L:12D or 14L:10D, respectively, on pelage color and testicular weight. Based on previous observations, the elevated circulating melatonin levels resulting from these injections were expected to extend the endogenous melatonin peak. Thus, this finding suggests that the duration of circadian melatonin elevation is the critical parameter determining its effect not only on the gonads, but also on the pelage. Since 14L:10D induced testicular regression but not the winter molt, this study also investigated whether circulating FSH levels, known to affect testicular function, and PRL levels, which have been shown to affect pelage color, might be affected differently by 14L:10D. Both FSH and PRL levels were found to be suppressed in 14L:10D hamsters compared to those in 16L:8D hamsters, although the interval between the initial decrease and eventual recovery was less than that in 10L:14D hamsters. Thus, the differential responses of the pelage and gonads to 14L:10D do not appear to be based on selective suppression of FSH in this photoperiod. However, different responses to 14L:10D compared to 10L:14D may be related to the shorter period of suppression of both PRL and FSH by the 14L:10D daylengths. PMID:3917252

  1. Acute hematologic, hepatologic, and nephrologic changes after intraperitoneal injections of 18 nm gold nanoparticles in hamsters

    PubMed Central

    Saleh, Hazem Mohamed; Soliman, Omar A; Elshazly, Mohamed Osama; Raafat, Alaa; Gohar, Adel K; Salaheldin, Taher A

    2016-01-01

    In vivo responses to gold nanoparticles (GNPs) vary not only according to the size, shape, surface charge, and capping agent of GNPs but also according to the animal model, the route of administration, and the exposure frequency and duration. We illustrate here the changes in some hematologic parameters, in the hepatic and renal functions, and in the histopathology of solid organs after multiple intraperitoneal injections of 18 nm GNPs in adult male Syrian golden hamsters. We scored the histopathological changes in the liver and kidneys to grade the deleterious effects. Multiple intraperitoneal injections of 18 nm GNPs in hamsters were nonlethal in the short term but resulted in macrocytosis and hypochromasia, leukocytosis, neutrophilia, lymphocytosis, and monocytosis. The hepatic and renal functions showed nonsignificant changes; however, histopathological examination showed hepatic and renal alterations ranging from mild to marked degeneration, with occasional necrosis of hepatocytes and tubular epithelium. PMID:27354788

  2. Acute hematologic, hepatologic, and nephrologic changes after intraperitoneal injections of 18 nm gold nanoparticles in hamsters.

    PubMed

    Saleh, Hazem Mohamed; Soliman, Omar A; Elshazly, Mohamed Osama; Raafat, Alaa; Gohar, Adel K; Salaheldin, Taher A

    2016-01-01

    In vivo responses to gold nanoparticles (GNPs) vary not only according to the size, shape, surface charge, and capping agent of GNPs but also according to the animal model, the route of administration, and the exposure frequency and duration. We illustrate here the changes in some hematologic parameters, in the hepatic and renal functions, and in the histopathology of solid organs after multiple intraperitoneal injections of 18 nm GNPs in adult male Syrian golden hamsters. We scored the histopathological changes in the liver and kidneys to grade the deleterious effects. Multiple intraperitoneal injections of 18 nm GNPs in hamsters were nonlethal in the short term but resulted in macrocytosis and hypochromasia, leukocytosis, neutrophilia, lymphocytosis, and monocytosis. The hepatic and renal functions showed nonsignificant changes; however, histopathological examination showed hepatic and renal alterations ranging from mild to marked degeneration, with occasional necrosis of hepatocytes and tubular epithelium. PMID:27354788

  3. Spermatids as male gametes.

    PubMed

    Ogura, A; Yanagimachi, R

    1995-01-01

    Intracytoplasmic sperm injection (ICSI) is becoming increasingly popular in human infertility clinics as an efficient method for the treatment of male infertility. It is proposed that spermatids can be used as substitutes for spermatozoa if men are unable to produce sperm in their testes. At least in the hamster and mouse, the nuclei of round spermatids were capable of participating in syngamy when incorporated into homologous mature oocytes either by microsurgical ICSI or electrofusion. Normal mouse offspring were born after after electrofusion of oocytes with round spermatids. When culture in vitro of spermatogonia and spermatocytes is perfected, then spermatids, transforming spermatids and spermatozoa will all be able to be used as male gametes. PMID:7480833

  4. East Siberian Shelf Study Alleviates Scarcity of Observations

    NASA Astrophysics Data System (ADS)

    Semiletov, Igor; Gustafsson, Örjan

    2009-04-01

    The East Siberian Arctic Shelf (ESAS) is the world's largest continental shelf and also the most understudied part of the Arctic Ocean. Composed of the Laptev Sea, the East Siberian Sea, and the Russian section of the Chukchi Sea, the ESAS is characterized by tundra discharge through the Lena, Indigirka, and Kolyma rivers; coastal erosion; methane seeps from subsea permafrost reservoirs; and the formation of water masses that spread throughout the Arctic Ocean. The region, which has experienced a 4°C springtime positive air temperature anomaly for 2000-2005 compared with preceding decades, is also of particular interest for its carbon-climate couplings.

  5. The hypocholesterolemic and antiatherogenic effects of Cholazol H, a chemically functionalized insoluble fiber with bile acid sequestrant properties in hamsters.

    PubMed

    Wilson, T A; Romano, C; Liang, J; Nicolosi, R J

    1998-08-01

    Cholazol H (Alpha-Beta Technology, Worcester, MA), a chemically functionalized, insoluble dietary fiber with bile acid sequestrant properties, was studied in 30 male F1 B Golden Syrian hamsters for its effect on plasma lipid concentrations and early atherogenesis in experiment 1. In experiment 2, 30 male Golden Syrian hamsters were studied for the effects on plasma lipids and fecal excretion of bile acids. In experiment 1, three groups of 10 hamsters each were fed a chow-based hypercholesterolemic diet supplemented with 5% coconut oil and 0.1% cholesterol for 6 weeks. After 6 weeks, hamsters were continued on the diet with either 0% drug (hypercholesterolemic diet [HCD]), 0.5% cholestyramine (CSTY), or 0.5% Cholazol H for 8 weeks. Fasting plasma lipids were measured at weeks 6, 10, and 14, and early atherosclerosis (fatty streak formation) was measured at week 14. Relative to HCD, CSTY and Cholazol H significantly lowered plasma total cholesterol (TC) (-37%, P < .03, and -30%, P < .04, respectively) and plasma very-low and low-density lipoprotein-cholesterol (nonHDL-C) (-45%, P < .02, and -36%, P < .03, respectively) with no significant effects on plasma HDL-C or triglycerides (TG). Despite similar reductions in nonHDL-C, only Cholazol H significantly prevented early atherosclerosis (-38%, P < .02) relative to HCD. In experiment 2, three groups of 10 hamsters each were fed a chow-based hypercholesterolemic diet supplemented with 10% coconut oil and 0.05% cholesterol and either 0% drug HCD, 0.5% CSTY, or 0.5% Cholazol H for 4 weeks. Fasting plasma lipids were measured at weeks 2 and 4, and fecal bile acids were measured at week 4. Both Cholazol H and CSTY were equally effective in significantly lowering plasma TC (-16%, P < .003, and -13%, P < .01, respectively) and nonHDL-C (-22%, P < .004, and -18%, P < .02, respectively), with no significant effect on HDL-C and TG relative to HCD. Cholazol H and CSTY produced a significantly greater concentration of fecal total

  6. Siberian Apparent Polar Wander Path for the Phanerozoic Eon: towards finding Siberian place on Earth

    NASA Astrophysics Data System (ADS)

    Blanco, D.; Kravchinsky, V. A.; Kabin, K.

    2011-12-01

    The existence of Siberia as an independent stable platform can be traced back with accuracy from the breakup of Rodinia (~800 Ma) until the end of the Paleozoic Eon when it became part of Eurasia. Different continental blocks accreted to Siberia since Precambrian forming one of the largest tectonic structures on Earth - Siberian continent. At the same time Siberian apparent polar wander path (APWP), which is crucial for global tectonic reconstructions, still contain long unresolved segments. Cocks and Torsvik (2007) compiled the available paleomagnetic poles from Siberia and applied smoothing methods to construct the APWP. We updated the available paleomagnetic pole list with recently published poles for the Paleozoic and Mesozoic Eras. In order to ensure the reliability of the data, we considered only poles available in international journals and followed the Van der Voo's (1993) selection criteria. We excluded the poles that did not have well described age constrains or acceptable experimental procedures. In terms of the APWP construction, we applied several techniques that enabled us to reconstruct the APWP segments where paleomagnetic poles were absent from the database. As a first approach, we approximated APWP using a least-squares fit computed through singular value decomposition. The advantage of the method was in its numerical stability and ease of application to either dense or sparse data sets. The second technique we used was based on smoothing techniques, similar to those by Cocks and Torsvik (2007). However, the large number of degrees of freedom for the smoothing method might lead to excessively effective approximation and thus transcribe the noise (De Boor, 2001). The effectiveness of both approaches was demonstrated by excellent comparison with very well resolved APWP for Europe (Torsvik et al., 2001). Subsequently we reconstructed the APWP for Siberia applying and comparing both of our techniques for the Phanerozoic Eon. Two sets of

  7. Comparative study of the toxic effects of gallium arsenide, indium arsenide and arsenic trioxide following intratracheal instillations to the lung of Syrian golden hamsters.

    PubMed

    Tanaka, A; Hirata, M; Omura, M; Zhao, M; Makita, Y; Yamazaki, K; Inoue, N; Gotoh, K

    2000-01-01

    Toxic effects of gallium arsenide (GaAs), indium arsenide (InAs) and arsenic trioxide (As2O3) were studied in male Syrian golden hamsters. GaAs (7.7 mg/kg) and As2O3 (1.3 mg/kg) particles were instilled intratracheally twice a week a total of 16 times, while InAs (7.7 mg/kg) was instilled a total of 14 times. As a control, hamsters were treated with the vehicle, phosphate buffer solution. During the instillation period, the cumulative body weight gain of the InAs-, but not the GaAs- or As2O3-treated hamsters was suppressed significantly, when compared with the control group. Slight to severe inflammatory responses were observed in the lung for all treatment groups. The most severe inflammatory change, characterized by an accumulation of neutrophils and macrophages, exudation, thickness of the pleura and fibrotic proliferation was found in the InAs-treated hamsters. Extensive alveolar or bronchiolar cell hyperplasia with or without keratinizing squamous cell metaplasia was observed in almost all the InAs-treated hamsters. Furthermore, squamous cell metaplasia or squamous cell hyperplasia developed in some of the InAs-treated hamsters, but not in the GaAs- or As2O3-treated hamsters. Slight to mild lesions were found in the convoluted tubules of the kidney in both the GaAs and InAs groups. From the present study, the toxic potency of these particles was provisionally estimated to be in the following order: InAs > GaAs > As2O3, at the dosage level used in this study. Furthermore, there was evidence that InAs particles could induce pulmonary, renal or systemic toxicity, and as such, InAs particles may produce pulmonary precancerous change when instilled intratracheally into hamsters.

  8. SV40 induces mesotheliomas in hamsters.

    PubMed Central

    Cicala, C.; Pompetti, F.; Carbone, M.

    1993-01-01

    In the course of studies to elucidate the relative contribution of simian virus 40 (SV40) large T and small t proteins during oncogenesis, we observed the appearance of pericardial and pleural tumors in 100% of Syrian hamsters injected in the pleural space with wild type SV40. When SV40 was injected via the intracardiac or intraperitoneal routes, more than 50% of hamsters developed mesothelial tumors. Macroscopic, microscopic, ultramicroscopic, and histochemical characteristics identify these neoplasms and derived cell lines as mesotheliomas and mesothelioma-derived cell lines. The SV40 genome was integrated and expressed in the mesotheliomas and derived cell lines. The absence of mesotheliomas in hamsters injected with SV40 small t deletion mutants indicates that the small t protein plays an important role in the development of SV40-induced mesotheliomas. To the best of our knowledge, this is the first definitive report of virus-induced mesotheliomas in mammals. Images Figure 1 Figure 2 Figure 3 Figure 4 PMID:8388174

  9. The effect of escapable versus inescapable social defeat on conditioned defeat and social recognition in Syrian hamsters.

    PubMed

    McCann, Katharine E; Huhman, Kim L

    2012-01-18

    Male Syrian hamsters are naturally aggressive animals that reliably defend their home territory against intruding conspecifics. Hamsters that lose agonistic encounters subsequently exhibit a striking change in their agonistic behavior, however, expressing no aggression and instead becoming highly submissive, a behavioral change that we have termed conditioned defeat. We have generally employed an inescapable defeat training protocol when studying conditioned defeat. The purpose of the present study was to determine if conditioned defeat is an epiphenomenon of the inescapable defeat experience by comparing the behavior of hamsters exposed to inescapable versus escapable defeat. In the conditioned defeat model, defeated hamsters subsequently generalize their submission and social avoidance to a novel, non-aggressive opponent, suggesting that hamsters subjected to inescapable defeat may not form a specific memory of their aggressive opponent. Thus, a secondary purpose of the present study was to determine whether hamsters subjected to our defeat protocol have the ability to recognize a familiar opponent following defeat. Our results provide evidence that conditioned defeat is not solely a by-product of inescapable defeat because all experimental animals, regardless of the type of defeat, expressed conditioned defeat during testing. We also found that animals experiencing an inescapable defeat avoided a familiar aggressor significantly more than they did an unfamiliar aggressor, demonstrating that these animals have the ability to recognize their previous attacker. Thus, we maintain that a variety of social defeat models, and conditioned defeat in particular, represent generalizable and ethologically valid models with which to study the effects of social stress on physiology and behavior.

  10. Topical photosan-mediated photodynamic therapy for DMBA-induced hamster buccal pouch premaligant lesions: an in vivo study

    NASA Astrophysics Data System (ADS)

    Hsu, Yih-Chih; Chiang, Chun-Pin; Chen, Jian Wen; Chen, Ying-Ru; Lee, Jeng-Woei

    2010-02-01

    One of the best strategies to prevent the occurrence of oral cancer is to eliminate oral precancers and block their further malignant transformation. Previous studies showed that photosan-mediated photodynamic therapy (photosan-PDT) is very effective for human head and neck cancers. To avoid the systemic photodynamic toxicity of photosan, this study was designed to use a topical photosan-PDT for treatment of DMBA-induced hamster buccal pouch precancerous lesions. Twelve 10-week-old male Syrian golden hamsters were used in this study. DMBA was applied to the left buccal pouches thrice a week for 8 to 10 weeks and mineral oil was painted on the right buccal pouches thrice a week for 8 to 10 weeks as the normal controls. Six hamsters were euthanized for tissue harvest. Precancerous lesions of moderate to severe dysplasia were consistently induced and proven by histological examination. These induced precancerous lesions in the remaining 6 hamsters were used for testing the efficacy of topical photosan-PDT. Before PDT, fluorescence spectroscopy was used to determine when protoporphyrine IX (PpIX) reached its peak level in the lesional epithelial cells after topical application of photosan-gel. We found that PpIX reached its peak level in precancerous lesions about 13.5 min after topical application of photosan-gel. The precancerous lesions in 4 hamsters were treated with topical photosan-PDT using the 635-nm LED light once or twice a week. Complete regression of the precancerous lesions was found after 2-4 PDT treatments by visual and histological examination. Our findings indicate that topical photosan-PDT is a very effective treatment modality for DMBA-induced hamster buccal pouch precancerous lesions.

  11. The Effect of Escapable Versus Inescapable Social Defeat on Conditioned Defeat and Social Recognition in Syrian Hamsters

    PubMed Central

    McCann, Katharine E.; Huhman, Kim L.

    2011-01-01

    Male Syrian hamsters are naturally aggressive animals that reliably defend their home territory against intruding conspecifics. Hamsters that lose agonistic encounters subsequently exhibit a striking change in their agonistic behavior, however, expressing no aggression and instead becoming highly submissive, a behavioral change that we have termed conditioned defeat. We have generally employed an inescapable defeat training protocol when studying conditioned defeat. The purpose of the present study was to determine if conditioned defeat is an epiphenomenon of the inescapable defeat experience by comparing the behavior of hamsters exposed to inescapable versus escapable defeat. In the conditioned defeat model, defeated hamsters subsequently generalize their submission and social avoidance to a novel, non-aggressive opponent, suggesting that hamsters subjected to inescapable defeat may not form a specific memory of their aggressive opponent. Thus, a secondary purpose of the present study was to determine whether hamsters subjected to our defeat protocol have the ability to recognize a familiar opponent following defeat. Our results provide evidence that conditioned defeat is not solely a by-product of inescapable defeat because all experimental animals, regardless of the type of defeat, expressed conditioned defeat during testing. We also found that animals experiencing an inescapable defeat avoided a familiar aggressor significantly more than they did an unfamiliar aggressor, demonstrating that these animals have the ability to recognize their previous attacker. Thus, we maintain that a variety of social defeat models, and conditioned defeat in particular, represent generalizable and ethologically valid models with which to study the effects of social stress on physiology and behavior. PMID:21945371

  12. T-lymphocyte-rich thymoma and myasthenia gravis in a Siberian tiger (Panthera tigris altaica).

    PubMed

    Allan, K; Masters, N; Rivers, S; Berry, K; Routh, A; Lamm, C

    2014-01-01

    A 10-year-old captive male Siberian tiger (Panthera tigris altaica) presented with acute onset collapse, vomiting and dyspnoea, preceded by a 6-month period of progressive muscle wasting. Following humane destruction, post-mortem examination revealed a large multilobulated mass in the cranial mediastinum, which was diagnosed as a T-lymphocyte-rich thymoma with the aid of immunohistochemistry. Retrospective serology for acetylcholine receptor antibodies (titre 3.90 nmol/l) confirmed a diagnosis of thymoma-associated myasthenia gravis. Thymomas are reported rarely in wild carnivores, but when detected they appear to be similar in morphology to those seen in domestic carnivores and may also be accompanied by paraneoplastic syndromes. The clinical signs of myasthenia gravis in the tiger were consistent with those reported in cats and dogs and the condition is proposed as an important differential diagnosis for generalized weakness in captive Felidae.

  13. T-lymphocyte-rich thymoma and myasthenia gravis in a Siberian tiger (Panthera tigris altaica).

    PubMed

    Allan, K; Masters, N; Rivers, S; Berry, K; Routh, A; Lamm, C

    2014-01-01

    A 10-year-old captive male Siberian tiger (Panthera tigris altaica) presented with acute onset collapse, vomiting and dyspnoea, preceded by a 6-month period of progressive muscle wasting. Following humane destruction, post-mortem examination revealed a large multilobulated mass in the cranial mediastinum, which was diagnosed as a T-lymphocyte-rich thymoma with the aid of immunohistochemistry. Retrospective serology for acetylcholine receptor antibodies (titre 3.90 nmol/l) confirmed a diagnosis of thymoma-associated myasthenia gravis. Thymomas are reported rarely in wild carnivores, but when detected they appear to be similar in morphology to those seen in domestic carnivores and may also be accompanied by paraneoplastic syndromes. The clinical signs of myasthenia gravis in the tiger were consistent with those reported in cats and dogs and the condition is proposed as an important differential diagnosis for generalized weakness in captive Felidae. PMID:24444818

  14. Portal vein and aortic thromboses in a Siberian husky with ehrlichiosis and hypothyroidism.

    PubMed

    Bressler, C; Himes, L C; Moreau, R E

    2003-09-01

    A six-year-old, neutered male Siberian husky was presented for euthanasia for end-stage liver disease. Examination of the dog raised questions regarding the severity of the condition. It had presented to the referring veterinarian with polyuria, polydipsia and weight loss. Blood tests at that time revealed elevated liver enzymes and hypoalbuminaemia. Cirrhosis was presumptively diagnosed, based on an ultrasound examination, which showed ascites with a normal liver. The dog had a history of hypothyroidism, which was controlled with levothyroxine. Physical examination revealed cachexia. A second abdominal ultrasound examination was performed and revealed portal vein and aortic thromboses. Tick titres showed a positive Ehrlichia canis titre of 1:640. Skin biopsies showed lymphoplasmacytic vasculitis. Doxycycline and aspirin treatment was initiated, and the clinical signs resolved. The authors concluded that the thrombi were primarily caused by chronic ehrlichiosis, based on the clinical findings and the response to treatment.

  15. Oil and Gas Resources of the West Siberian Basin, Russia

    EIA Publications

    1997-01-01

    Provides an assessment of the oil and gas potential of the West Siberian Basin of Russia. The report was prepared in cooperation with the U. S. Geological Survey (USGS) and is part of the Energy Information Administration's (EIA) Foreign Energy Supply Assessment Program (FESAP).

  16. Biodiesel from Siberian apricot (Prunus sibirica L.) seed kernel oil.

    PubMed

    Wang, Libing; Yu, Haiyan

    2012-05-01

    In this paper, Siberian apricot (Prunus sibirica L.) seed kernel oil was investigated for the first time as a promising non-conventional feedstock for preparation of biodiesel. Siberian apricot seed kernel has high oil content (50.18 ± 3.92%), and the oil has low acid value (0.46 mg g(-1)) and low water content (0.17%). The fatty acid composition of the Siberian apricot seed kernel oil includes a high percentage of oleic acid (65.23 ± 4.97%) and linoleic acid (28.92 ± 4.62%). The measured fuel properties of the Siberian apricot biodiesel, except cetane number and oxidative stability, were conformed to EN 14214-08, ASTM D6751-10 and GB/T 20828-07 standards, especially the cold flow properties were excellent (Cold filter plugging point -14°C). The addition of 500 ppm tert-butylhydroquinone (TBHQ) resulted in a higher induction period (7.7h) compliant with all the three biodiesel standards. PMID:22440572

  17. Improved Establishment Characteristics of 'Vavilov II' Siberian Wheatgrass

    Technology Transfer Automated Retrieval System (TEKTRAN)

    'Vavilov II' Siberian wheatgrass (Agropyron fragile (Roth) Candargy) was developed for reseeding disturbed rangelands dominated by annual weeds as a result of severe disturbance, frequent fires, and soil erosion. Selection emphasis in Vavilov II was on seedling establishment and plant persistence. ...

  18. The Value Priorities of Young People in the Siberian Region

    ERIC Educational Resources Information Center

    Orlova, V. V.

    2010-01-01

    This article discusses the implications of the survey results involving young people in the Siberian Region on their value priorities. In the process of their socialization, special importance attaches to the problem of the value priorities of young people. Among these, in the authors opinion, it is possible to single out both spiritual and moral…

  19. Aminostratigraphy of Organisms in Antarctic and Siberian Permafrost Cores

    NASA Technical Reports Server (NTRS)

    Brinton, K. L. F.; Tsapin, A. I.; McDonald, G. D.; Gilichinsky, D.

    1999-01-01

    Amino acid racemization dating (or aminostratigraphy) in Antarctic and Siberian permafrost core samples can be used to evaluate the age of organisms in frozen environments. The potential for subsurface permafrost on Mars makes terrestrial permafrost an important source of information regarding the preservation of both living organisms and their remains. Additional information is contained in the original extended abstract.

  20. Siberian Yupik Eskimo: The Language and Its Contacts with Chukchi.

    ERIC Educational Resources Information Center

    de Reuse, Willem Joseph

    The study provides a description of the verbal derivational suffixation, postinflectional derivation, enclitics, and particles of the Central Siberian Yupik Eskimo language as spoken on St. Lawrence Island, Alaska and on the coast of Chukotka, in the Soviet Union. It also shows how these elements participate in a network of four tightly-knit…

  1. Effectiveness of Science Tasks and Plans for Siberian Scholars.

    ERIC Educational Resources Information Center

    Marchuk, G. I.

    1972-01-01

    Science and Technology research plans formulated for the Siberian Department of the U.S.S.R. Academy of Sciences are analyzed in this article to illustrate the tasks of scholars, workers, and engineering and technical personnel in the fulfillment of the 24th party congress resolutions The hypothesis of developing Siberia and the Far East up to the…

  2. Aging in the Soviet Union: A West Siberian Perspective.

    ERIC Educational Resources Information Center

    Demitri, Shimkin

    1989-01-01

    Presents ethnographic observations on the aged and aging from six months' residence in Siberian industrial city. Describes interactions with medical personnel and reviews scanty literature in Soviet Union. Notes integration of aged in families and respect given to older persons. Discusses problems of elderly caused by hard living conditions,…

  3. Volatile Release From The Siberian Traps Inferred From Melt Inclusions

    NASA Astrophysics Data System (ADS)

    Black, Benjamin A.; Elkins-Tanton, Linda T.; Rowe, Michael C.; Ukstins Peate, Ingrid

    2010-05-01

    The Siberian Traps Large Igneous Province is one of the largest known continental flood volcanic provinces in the Phanerozoic. The quantification of volatile degassing is particularly important because the Siberian Traps have often been invoked as a possible trigger for the end-Permian mass extinction (e.g. Campbell et al., 1992; Wignall, 2001). Volatile degassing provides a crucial mechanism to link mafic volcanic eruption with global environmental change. Mafic flood basalt magmas are expected to have low volatile contents (similar to mid-ocean ridge basalts). However, Siberian Traps magmas were chambered in and erupted through a thick sedimentary basin and may have interacted with, and obtained volatiles from, sedimentary lithologies such as limestone, coal, and evaporite. Melt inclusions from the Siberian Traps provide insight into the potential total volatile budget throughout the evolution of the large igneous province. These droplets of trapped melt may preserve volatile species that would otherwise have degassed at the time of eruption. We present data from the analysis of more than 100 melt inclusions, including both homogenized inclusions and rare glassy inclusions with low crystallinity. Many melt inclusions from tuffs and flows near the base of the Siberian Traps sequence are substantially enriched in chlorine and fluorine compared to Deccan Traps and Laki melt inclusions (Self et al., 2008; Thordarson et al., 1996). These inclusions record chlorine concentrations up to ~1400 ppm, and fluorine concentrations up to ~5000 ppm. Olivines from the Maymechinsky suite, recognized as the last extrusive products of Siberian Traps volcanism, contain melt inclusions with maximum sulfur concentrations in the range of ~5000 ppm and substantial concentrations of chlorine. Intrusive igneous rocks from the province also display significant volatile contents. A sill from the Ust-Ilimsk region yielded plagioclase-hosted melt inclusions which contain chlorine and fluorine

  4. Volatile Release from the Siberian Traps Inferred from Melt Inclusions

    NASA Astrophysics Data System (ADS)

    Black, B. A.; Elkins-Tanton, L. T.; Rowe, M. C.; Ukstins Peate, I.

    2009-12-01

    The Siberian Traps Large Igneous Province is one of the largest known continental flood volcanic provinces in the Phanerozoic. The quantification of volatile degassing is particularly important because the Siberian Traps have often been invoked as a possible trigger for the end-Permian mass extinction (e.g. Campbell et al., 1992; Wignall, 2001). Volatile degassing provides a crucial mechanism to link mafic volcanic eruption to global environmental change. Mafic flood basalt magmas are expected to have low volatile contents (similar to mid-ocean ridge basalts). However, Siberian Traps magmas were chambered in and erupted through a thick sedimentary basin and may have interacted with, and obtained volatiles from, sedimentary lithologies such as limestone, coal, and evaporite. Melt inclusions from the Siberian Traps provide insight into the potential total volatile budget throughout the evolution of the large igneous province. These droplets of trapped melt may preserve volatile species that would otherwise have degassed at the time of eruption (Thordarson et al., 1996). Mafic pyroclastic deposits from the lowermost Arydzhangsky suite (basal Siberian Traps) contain clinopyroxene phenocrysts hosting melt inclusions. Electron microprobe analysis of clinopyroxene-hosted re-homogenized melt inclusions indicates maximum measured concentrations of up to 1500 - 2000 ppm sulfur, 500 - 760 ppm chlorine, and 1900 - 2400 ppm fluorine. Olivines from the Maymechinsky suite, recognized as the last extrusive products of Siberian Traps volcanism, contain melt inclusions with maximum sulfur concentrations in the range of 5000 ppm, and less substantial concentrations of chlorine and fluorine. Intrusive igneous rocks from the province also display significant volatile contents. A sill from the Ust-Ilimsk region yielded plagioclase-hosted melt inclusions which contain chlorine and fluorine concentrations nearing one weight percent. Visscher et al. (2004) proposed that chlorofluorocarbon

  5. Parent-of-origin growth effects and the evolution of hybrid inviability in dwarf hamsters.

    PubMed

    Brekke, Thomas D; Good, Jeffrey M

    2014-11-01

    Mammalian hybrids often show abnormal growth, indicating that developmental inviability may play an important role in mammalian speciation. Yet, it is unclear if this recurrent phenotype reflects a common genetic basis. Here, we describe extreme parent-of-origin-dependent growth in hybrids from crosses between two species of dwarf hamsters, Phodopus campbelli and Phodopus sungorus. One cross type resulted in massive placental and embryonic overgrowth, severe developmental defects, and maternal death. Embryos from the reciprocal cross were viable and normal sized, but adult hybrid males were relatively small. These effects are strikingly similar to patterns from several other mammalian hybrids. Using comparative sequence data from dwarf hamsters and several other hybridizing mammals, we argue that extreme hybrid growth can contribute to reproductive isolation during the early stages of species divergence. Next, we tested if abnormal growth in hybrid hamsters was associated with disrupted genomic imprinting. We found no association between imprinting status at several candidate genes and hybrid growth, though two interacting genes involved in embryonic growth did show reduced expression in overgrown hybrids. Collectively, our study indicates that growth-related hybrid inviability may play an important role in mammalian speciation but that the genetic underpinnings of these phenotypes remain unresolved.

  6. Human sperm chromosome analysis after subzonal sperm insemination of hamster oocytes

    SciTech Connect

    Cozzi, J.

    1994-09-01

    Sperm microinjection techniques, subzonal sperm insemination (SUZI) and intracytoplasmic sperm injection (ICSI), have achieved a wide spread clinical application for the treatment of male infertility. To date, only one study has focused on sperm karyotypes after microinjection. Martin et al. reported a very high incidence of abnormal human sperm complements after ICSI into hamster oocytes. In the present study, are reported the first human sperm karyotypes after SUZI of hamster oocytes. Spermatozoa from two control donors were treated by calcium ionophore A23187 and injected under the zona of hamster eggs. The microinjected eggs were then cultured for cytogenetic analysis of the pronuclei. Out of 47 analyzed sperm chromosome metaphases, 5 (10.6%) were abnormal, 4 (8.5%) were hypohaploid and 1 (2.1%) had a structural abnormality. The sex ratio was not significantly different from the expected 1:1 ratio. Rates of chromosomal abnormalities in microinjected spermatozoa were similar to those observed in spermatozoa inseminated with zona free eggs, suggesting that SUZI procedure per se does not increase sperm chromosomal abnormalities.

  7. PARENT-OF-ORIGIN GROWTH EFFECTS AND THE EVOLUTION OF HYBRID INVIABILITY IN DWARF HAMSTERS

    PubMed Central

    Brekke, Thomas D.; Good, Jeffrey M.

    2015-01-01

    Mammalian hybrids often show abnormal growth, indicating that developmental inviability may play an important role in mammalian speciation. Yet it is unclear if this recurrent phenotype reflects a common genetic basis. Here we describe extreme parent-of-origin dependent growth in hybrids from crosses between two species of dwarf hamsters, Phodopus campbelli and P. sungorus. One cross type resulted in massive placental and embryonic overgrowth, severe developmental defects, and maternal death. Embryos from the reciprocal cross were viable and normal sized but adult hybrid males were relatively small. These effects are strikingly similar to patterns from several other mammalian hybrids. Using comparative sequence data from dwarf hamsters and several other hybridizing mammals, we argue that extreme hybrid growth can contribute to reproductive isolation during the early stages of species divergence. Next we tested if abnormal growth in hybrid hamsters was associated with disrupted genomic imprinting. We found no association between imprinting status at several candidate genes and hybrid growth, though two interacting genes involved in embryonic growth did show reduced expression in overgrown hybrids. Collectively, our study indicates that growth-related hybrid inviability may play an important role in mammalian speciation but that the genetic underpinnings of these phenotypes remain unresolved. PMID:25130206

  8. Hypolipidemic and Antioxidative Effects of Glossogyne tenuifolia in Hamsters Fed an Atherogenic Diet.

    PubMed

    Lee, Yi-Ning; Hsu, Guoo-Shyng Wang; Lin, Wan-Teng; Lu, Yi-Fa

    2016-05-01

    Glossogyne tenuifolia (GT) Cassini is a special herbal tea in the Penghu Islands, Taiwan, and has a long history of being used as an antipyretic, detoxifying, and anti-inflammatory remedy in folk medicine among local residents. The aim of this study was to investigate the effect of hot water extracts from GT on oxidative stress and lipid metabolism in animals. Five- to 6-week-old male Syrian hamsters were divided into four groups (n = 14) for different treatments, that is: control group (C), high-fat/cholesterol (HF) group, HF diet containing 0.5% (GT0.5) and 1.5% (GT1.5) GT extracts for 4 weeks. Hamsters fed with 0.5% GT powder as well as 1.5% GT powder exhibited reduced serum total cholesterol (TC), conjugated diene of low-density lipoprotein (LDL), and increased serum antioxidant capacity, but 1.5% GT powder was more potent at lowering serum LDL cholesterol and thiobarbituric acid reactive substance concentrations than 0.5% GT. GT extracts significantly lowered liver triacylglycerol (TG) concentration by diminishing activities of fatty acid synthase (FAS) and glucose-6-phosphate dehydrogenase (G-6-PDH). In addition, fecal excretion of cholesterol and bile acids were increased in GT extract groups. In conclusion, GT extracts increase the antioxidative capacity, decrease serum TC, inhibit the activities of FAS and G-6-PDH, and further reduce liver TG accumulation in hamster fed on atherogenic diets. PMID:27152981

  9. Dietary supplementation of Chardonnay grape seed flour reduces plasma cholesterol concentration, hepatic steatosis, and abdominal fat content in high-fat diet-induced obese hamsters

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The mechanisms for the hypocholesterolemic and anti-obesity effects of grape seed flours derived from white and red winemaking processing were investigated. Male Golden Syrian hamsters were fed high-fat (HF) diets supplemented with 10% partially defatted grape seed flours from Chardonnay (ChrSd), Ca...

  10. Lower weight gain and hepatic lipid content in hamsters fed high fat diets supplemented with white rice protein, brown rice protein, and soy protein and their hydrolysates

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The physiological effects of the hydrolysates from white rice, brown rice, and soy isolate were compared to the original protein source. White rice, brown rice, and soy protein were hydrolyzed with the food grade enzyme, alcalase2.4 L®. Male Syrian hamsters were fed high-fat diets containing eithe...

  11. Identification of liver CYP51 as a gene responsive to circulating cholesterol in a hamster model.

    PubMed

    Huang, Haiqiu; Xie, Zhuohong; Yokoyama, Wallace; Yu, Liangli; Wang, Thomas T Y

    2016-01-01

    Hypercholesterolaemia is a risk factor for CVD, which is a leading cause of death in industrialised societies. The biosynthetic pathways for cholesterol metabolism are well understood; however, the regulation of circulating cholesterol by diet is still not fully elucidated. The present study aimed to gain more comprehensive understanding of the relationship between circulating cholesterol levels and molecular effects in target tissues using the hamster model. Male golden Syrian hamsters were fed with chow or diets containing 36 % energy from fat with or without 1 % cholesteyramine (CA) as a modulator of circulating cholesterol levels for 35 d. It was revealed that the expression of lanosterol 14α-demethylase (CYP51) instead of 3-hydroxy-3-methyl-glutaryl (HMG)-CoA reductase mRNA expression was responsive to circulating cholesterol in hamsters fed hypercholesterolaemic diets. The high-fat diet increased circulating cholesterol and down-regulated CYP51, but not HMG-CoA reductase. The CA diet decreased cholesterol and increased CYP51 expression, but HMG-CoA reductase expression was not affected. The high-fat diet and CA diet altered the expression level of cholesterol, bile acids and lipid metabolism-associated genes (LDL receptor, cholesterol 7α-hydroxylase (CYP7A1), liver X receptor (LXR) α, and ATP-binding cassette subfamily G member 5/8 (ABCG5/8)) in the liver, which were significantly correlated with circulating cholesterol levels. Correlation analysis also showed that circulating cholesterol levels were regulated by LXR/retinoid X receptor and PPAR pathways in the liver. Using the hamster model, the present study provided additional molecular insights into the influence of circulating cholesterol on hepatic cholesterol metabolism pathways during hypercholesterolaemia. PMID:27110359

  12. Roborovskin, a lipocalin in the urine of the Roborovski hamster, Phodopus roborovskii.

    PubMed

    Turton, Michael J; Robertson, Duncan H L; Smith, Julia R; Hurst, Jane L; Beynon, Robert J

    2010-10-01

    Many rodents are now known to exhibit an obligate proteinuria that delivers urine-mediated chemosignals. In this paper, we explore the urinary proteins of the Roborovski hamster (Phodopus roborovskii). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis of urine from individual male and female Roborovski hamsters revealed 2 proteins, with approximate masses of 6 and 17 kDa, the expression pattern of which showed little variation between individuals or between sexes. Peptide mass fingerprints obtained from these 2 proteins revealed a number of features: 1) the proteins of a given mass were the same in all individuals regardless of sex, 2) the 6 kDa protein was not a fragment of the 21 kDa protein, and 3) neither protein was a fragment of a larger, conserved protein such as serum albumin. Electrospray mass spectrometry of purified protein preparations established the mass of the larger protein as invariant, at 17144 ± 2 Da in all samples. This protein has been termed roborovskin. The primary structure of roborovskin was determined by tandem mass spectrometry of peptides derived from independent and overlapping digestion with 3 proteases, supported by Edman degradation of the protein N-terminus. Roborovskin shared significant homology with olfactory-binding proteins from Myodes glareolus (bank vole) and with aphrodisin and submandibular protein from the golden hamster Mesocricetus auratus, all of which belong to the lipocalin superfamily. Lower levels of homology were also indicated between a variety of other lipocalins including the major urinary proteins from house mice and Norway rats. A model of the tertiary structure of roborovskin was constructed from the primary sequence by homology modeling. This model structure resembled other 8-stranded beta barrel lipocalins. Thus, the Roborovski hamster may demonstrate another variant of urinary lipocalin expression, as for the animals studied here, there appears to be no polymorphism in expression either

  13. Transformation of Hamster Embryo Cells and Tumor Induction in Newborn Hamsters by Simian Adenovirus SV11

    PubMed Central

    Casto, Bruce C.

    1969-01-01

    Simian adenovirus, SV11, readily transformed hamster embryo cell cultures in vitro and produced tumors in vivo when inoculated into newborn hamsters. Foci consisting of small, loosely attached, rounded cells could be seen as early as 7 days postinoculation. Many of these cells contained several nuclei or the nucleus was multilobed. The cells grew without extensive cell to cell contact or formed small chains or clusters when passaged in vitro. This pattern of cell morphology and growth has not been reported with other simian or human adenovirus-transformed cells. Linearity of foci formation with virus dilution was observed when the virus multiplicity was less than 3 plaque-forming units (PFU)/cell. The PFU to focus-forming units ratio for SV11 was found to be 2 × 104 to 4 × 104, which is approximately 5- to 10-fold and 50- to 100-fold lower than those reported for simian adenovirus, SA7, and human adenovirus type 12, respectively. Cells transformed by SV11: (i) produced tumors when inoculated into young hamsters, (ii) contained tumor antigen which reacts with serum obtained from hamsters bearing SV11 passaged tumors, and (iii) could be propagated in vitro through an indefinite number of generations. Images PMID:5786181

  14. Thermostability of sperm nuclei assessed by microinjection into hamster oocytes

    EPA Science Inventory

    Nuclei isolated from spermatozoa of various species (golden hamster, mouse, human, rooster, and the fish tilapia) were heated at 60 degrees-125 degrees C for 20-120 min and then microinjected into hamster oocytes to determine whether they could decondense and develop into pronucl...

  15. Characteristics of 263K Scrapie Agent in Multiple Hamster Species

    PubMed Central

    Barbian, Kent D.; Race, Brent; Favara, Cynthia; Gardner, Don; Taubner, Lara; Porcella, Stephen; Race, Richard

    2009-01-01

    Transmissible spongiform encephalopathy (TSE) diseases are known to cross species barriers, but the pathologic and biochemical changes that occur during transmission are not well understood. To better understand these changes, we infected 6 hamster species with 263K hamster scrapie strain and, after each of 3 successive passages in the new species, analyzed abnormal proteinase K (PK)–resistant prion protein (PrPres) glycoform ratios, PrPres PK sensitivity, incubation periods, and lesion profiles. Unique 263K molecular and biochemical profiles evolved in each of the infected hamster species. Characteristics of 263K in the new hamster species seemed to correlate best with host factors rather than agent strain. Furthermore, 2 polymorphic regions of the prion protein amino acid sequence correlated with profile differences in these TSE-infected hamster species. PMID:19193264

  16. Effect of geraniol, a plant derived monoterpene on lipids and lipid metabolizing enzymes in experimental hyperlipidemic hamsters.

    PubMed

    Jayachandran, Muthukumaran; Chandrasekaran, Balaji; Namasivayam, Nalini

    2015-01-01

    Hyperlipidemia is a major, modifiable risk factor for atherosclerosis and cardiovascular disease. In the present study, we have focused on the effect of different doses of geraniol (GOH) on the lipid profile and lipid metabolizing enzymes in atherogenic diet (AD) fed hamsters. Male Syrian hamsters were grouped into seven: group 1 were control animals; group 2 were animals fed GOH alone (200 mg/kg b.w); group 3 were animals fed AD (10 % coconut oil, 0.25 % cholesterol, and 0.25 % cholic acid); group 4 were animals fed AD + corn oil (2.5 ml/kg b.w); and groups 5, 6, and 7 were fed AD as in group 3 + different doses of GOH (50, 100, and 200 mg/kg b.w), respectively, for 12 weeks. At the end of the experimental period, animals were sacrificed by cervical dislocation and various assays were performed in the plasma and tissues. The AD hamsters showed marked changes in lipid profile and lipid metabolizing enzymes. However, supplementation with GOH counteracted the hyperlipidemia by inhibiting HMG CoA reductase and suppressing lipogenesis. The antihyperlipidemic efficacy of GOH was found to be effective at the dose of 100 mg/kg b.w. This study illustrates that GOH is effective in lowering the risk of hyperlipidemia in AD fed hamsters.

  17. Combination therapies in adjuvant with topical ALA-mediated photodynamic therapy for DMBA-induced hamster buccal pouch premalignant lesions

    NASA Astrophysics Data System (ADS)

    Yang, Deng-Fu; Hsu, Yih-Chih

    2012-03-01

    In Taiwan, oral cancer has becomes the fastest growth male cancer disease due to the betel nut chewing habit combing with smoking and alcohol-drinking lifestyle of people. In order to eliminate the systemic phototoxic effect of 5-aminolevulinic acid (ALA), this study was designed to use a topical ALA-mediated PDT for treatment of DMBA-induced hamster buccal pouch precancerous lesions. DMBA was applied to one of the buccal pouches of hamsters thrice a week for 10 to 12 weeks. Cancerous lesions were induced and proven by histological examination. These DMBA-induced cancerous lesions were used for testing the efficacy of topical ALA-mediated PDT. Before PDT, fluorescence spectroscopy was used to determine when ALA reached its peak level in the lesional epithelial cells after topical application of ALA gel. We found that ALA reached its peak level in precancerous lesions about 2.5 hrs after topical application of ALA gel. The cancerous lesions in hamsters were then treated with topical ALA -mediated PDT with light exposure dose of 150 J/cm2 using LED 635 nm fiber-guided light device. Visual examination demonstrated that adjuvant topical ALA -mediated PDT group has shown better therapeutic results in compared to those of non-adjuvant topical ALA-mediated PDT group for DMBA-induced hamster buccal pouch precancerous lesions.

  18. A 13-week toxicity study of acrylamide administered in drinking water to hamsters.

    PubMed

    Imai, Toshio; Kitahashi, Tsukasa

    2014-01-01

    Acrylamide (AA) is known to induce tumors in various organs/tissues in rats and mice. Epidemiological studies of oral exposure have generated controversial results but mortality studies of people who work with AA have indicated increased rates of pancreatic cancer. In the present study, for dose selection for chronic toxicity/carcinogenicity studies, 13-week toxicity of AA was evaluated in Syrian hamsters, which are sensitive to induction of pancreatic ductal carcinogenesis, at concentrations required to provide doses of 0 (control), 20, 30 and 50 mg kg(-1) body weight in drinking water. Treatment with AA caused abnormal gait advancing to hind limb paralysis in all males and females at 50 mg kg(-1). Body weights in 30 and 50 mg kg(-1) males and 50 mg kg(-1) females were lower than in the controls. At termination of the study, red blood cells (RBC) and hemoglobin (Hb) were decreased or showed a tendency for a decrease at 20 and 30 mg kg(-1) in females. Microscopically, axonal/myelin degeneration of sciatic nerves was observed in all AA-treated groups with dose dependence. No obvious changes were found in pancreatic ducts/ductules in any groups of animal. These results indicated the maximum tolerated dose for long-term studies of AA to be 20 mg kg(-1) or less in both male and female Syrian hamsters.

  19. Hydrological modelling for siberian crane Grus Leucogeranus stopover sites in northeast China.

    PubMed

    Jiang, Haibo; He, Chunguang; Sheng, Lianxi; Tang, Zhanhui; Wen, Yang; Yan, Tingting; Zou, Changlin

    2015-01-01

    Habitat loss is one of the key factors underlying the decline of many waterbird species, including Siberian Crane (Grus leucogeranus), a threatened species worldwide. Wetlands are the primary stopover for many waterbirds and restoration of these wetlands involves both hydrological restoration and water resource management. To protect the stopover sites of Siberian Cranes, we collected Siberian Crane stopover numbers, meteorological and hydrological data, and remote sensing data from 2008 to 2011 in Momoge National Nature Reserve, one of the largest wetlands in northeastern China. A model was developed to estimate the suitability of Siberian Crane stopover sites. According to our results, the most suitable daily water level for Siberian Cranes between 2008 and 2012 occurred in the spring of 2008 and in the Scirpus planiculmis growing season and autumn of 2010. We suggest a season-dependent water management strategy in order to provide suitable conditions at Siberian Crane stopover sites.

  20. Hydrological Modelling for Siberian Crane Grus Leucogeranus Stopover Sites in Northeast China

    PubMed Central

    Jiang, Haibo; He, Chunguang; Sheng, Lianxi; Tang, Zhanhui; Wen, Yang; Yan, Tingting; Zou, Changlin

    2015-01-01

    Habitat loss is one of the key factors underlying the decline of many waterbird species, including Siberian Crane (Grus leucogeranus), a threatened species worldwide. Wetlands are the primary stopover for many waterbirds and restoration of these wetlands involves both hydrological restoration and water resource management. To protect the stopover sites of Siberian Cranes, we collected Siberian Crane stopover numbers, meteorological and hydrological data, and remote sensing data from 2008 to 2011 in Momoge National Nature Reserve, one of the largest wetlands in northeastern China. A model was developed to estimate the suitability of Siberian Crane stopover sites. According to our results, the most suitable daily water level for Siberian Cranes between 2008 and 2012 occurred in the spring of 2008 and in the Scirpus planiculmis growing season and autumn of 2010. We suggest a season-dependent water management strategy in order to provide suitable conditions at Siberian Crane stopover sites. PMID:25874552

  1. Hydrological modelling for siberian crane Grus Leucogeranus stopover sites in northeast China.

    PubMed

    Jiang, Haibo; He, Chunguang; Sheng, Lianxi; Tang, Zhanhui; Wen, Yang; Yan, Tingting; Zou, Changlin

    2015-01-01

    Habitat loss is one of the key factors underlying the decline of many waterbird species, including Siberian Crane (Grus leucogeranus), a threatened species worldwide. Wetlands are the primary stopover for many waterbirds and restoration of these wetlands involves both hydrological restoration and water resource management. To protect the stopover sites of Siberian Cranes, we collected Siberian Crane stopover numbers, meteorological and hydrological data, and remote sensing data from 2008 to 2011 in Momoge National Nature Reserve, one of the largest wetlands in northeastern China. A model was developed to estimate the suitability of Siberian Crane stopover sites. According to our results, the most suitable daily water level for Siberian Cranes between 2008 and 2012 occurred in the spring of 2008 and in the Scirpus planiculmis growing season and autumn of 2010. We suggest a season-dependent water management strategy in order to provide suitable conditions at Siberian Crane stopover sites. PMID:25874552

  2. Schistosoma japonicum-infected hamsters (Mesocricetus auratus) used as a model in experimental chemotherapy with praziquantel, artemether, and OZ compounds.

    PubMed

    Xiao, Shu-hua; Mei, Jing-yan; Jiao, Pei-ying

    2011-02-01

    The purpose of the study is to better understand the antischistosomal properties of artemether, praziquantel, and ozonide (OZ) compounds (synthetic trioxolanes, secondary ozonides) in hamster (Mesocricetus auratus) model. A total of 230 male hamsters infected each with 100 Schistosoma japonicum cercariae were used in the study. Groups of five to ten hamsters were treated orally with artemether, praziquantel, and OZ78 or OZ277 7-35 days post-infection at single doses of 50, 100, 150, or 200 mg/kg. Untreated but infected hamsters in each batch of test served as the control. All treated hamsters were sacrificed 4 weeks post-treatment for collection of residual worms using perfusion technique. Nonparametric method (Mann-Whitney test) was used to analyze the data. In groups of five hamsters treated with artemether 7, 14, 21, 28, and 35 days post-infection at single doses of 150 and 200 mg/kg, the difference of mean worm burden between each treated group and control group was statistically significant (P<0.01). Apart from individual group, no difference in mean worm burden between each two groups of them was seen (P>0.05). Further test with various single doses of 50-200 mg/kg confirmed the similar susceptibility of 7-day-old juvenile and 35-day-old adult schistosomes to artemether. After administration of praziquantel 100 mg/kg to groups of five hamsters 7, 21, and 35 days post-infection, higher worm burden reduction of 95.5% was seen in the group with 35-day-old adult schistosomes while in the groups with 7- and 21-day-old juvenile schistosomes, poor efficacy was seen with mean worm burden reductions of 36.6% and 35.6%. In the same batch of hamster treated with praziquantel 200 mg/kg, the moderate effect of the drug against 7- and 21-day-old worms was seen, but their mean worm burden was significantly higher than that of the group with adult schistosomes. In comparison of artemether and praziquantel against various stages of schistosomes, the results further

  3. SPOT-VEG Based Analysis of Siberian Silkmoth Outbreak

    NASA Technical Reports Server (NTRS)

    Kharuk, Viatcheslav I.; Ranson, K. Jon; Im. Sergey T.

    2007-01-01

    The spatial and temporal dynamics of an outbreak of the Siberian silkmoth were correlated with topographic features of the affected area using SPOT-VEG data and a high resolution digital elevation model (DEM). In 2002-2003 an outbreak affected approximately 20,000 ha in the South Siberian mountains of Russia. The outbreak began between the elevations of approximately 430- 480 m and on southwest slopes with steepness < 5 degrees. As the pest searched for food it moved up and down slope, resulting in an elevation distribution split within a range of approximately 390-540 m and slope steepness up to 15 degrees. In the final phase the azimuth distribution of damaged stands became even. The correlation between the initial phase and topographic features can be used to prioritize monitoring forest areas most vulnerable to destruction by pests.

  4. Overcoming depolarizing resonances with dual helical partial Siberian snakes.

    PubMed

    Huang, H; Ahrens, L A; Bai, M; Brown, K; Courant, E D; Gardner, C; Glenn, J W; Lin, F; Luccio, A U; Mackay, W W; Okamura, M; Ptitsyn, V; Roser, T; Takano, J; Tepikian, S; Tsoupas, N; Zelenski, A; Zeno, K

    2007-10-12

    Acceleration of polarized protons in the energy range of 5 to 25 GeV is challenging. In a medium energy accelerator, the depolarizing spin resonances are strong enough to cause significant polarization loss but full Siberian snakes cause intolerably large orbit excursions and are also not feasible since straight sections usually are too short. Recently, two helical partial Siberian snakes with double pitch design have been installed in the Brookhaven Alternating Gradient Synchrotron (AGS). With a careful setup of optics at injection and along the energy ramp, this combination can eliminate the intrinsic and imperfection depolarizing resonances otherwise encountered during acceleration to maintain a high intensity polarized beam in medium energy synchrotrons. The observation of partial snake resonances of higher than second order will also be described.

  5. Vertical plate motions in the West Siberian Basin

    NASA Astrophysics Data System (ADS)

    Vibe, Yulia

    2014-05-01

    The West Siberian Basin is a sedimentary basin situated between the Ural Mountains and the Siberian Craton. The Basin has experienced several periods of subsidence and uplift since the arrival of the Siberian Traps c. 250 Ma. Although the Basin is extensively explored and hosts large reserves of Oil and Gas, the forces driving the vertical motions are poorly understood. In this work we attempt to analyse the amount, timing and location of subsidence and uplift in the Basin to shed light on the possible causes of these motions. A detailed description of sedimentary layers is published in a number of Soviet-era books and articles and serves as a basis for our research. This data is first converted into sediment grids through time. Subsequently, the sediments, the sediment load and the compaction are taken into account ('backstripping') to produce the depth of the Basin at respective time steps. With this technique we calculate the tectonic component of subsidence. Uncertainties related to uplift events are estimated by the unconformities in the stratigraphic charts. One of the possible driving forces of vertical motions is a change of force balance arising at plate boundaries. Since active plate tectonics have been absent from West Siberia since the formation of the Urengoy and Khodosey Rifts, c. 250Ma, we study the far-field tectonic effects as a potential driving mechanism. Indeed, some of the significant vertical events in the West Siberian Basin coincide with the major tectonic events around Siberia. An example is the spreading in the Arctic (Eurasian Basin) in the Eocene (56 Ma) which was synchronous with initiation of uplift events in the northern part of West Siberia. In the middle Oligocene (33 Ma), the northern and eastern parts of the basin were subjected to uplift as subsidence migrated southwards and the Basin rose above the sea level. This was coincident with the changes of plate motions in the northern North Atlantic and Indo-European collision.

  6. Pulmonary function in normal and elastase-treated hamsters exposed to a complex mixture of olefin-ozone-sulfur dioxide reaction products

    SciTech Connect

    Raub, J.A.; Miller, F.J.; Graham, J.A.; Gardner, D.E.; O'Neil, J.J.

    1983-01-01

    An elastase-induced emphysema model was utilized to determine if hamsters with preexisting lung disease were more susceptible to lung damage from air-pollutant exposure. Male golden hamsters, divided into two treatment groups, were given a single intratracheal injection of either 6 units of porcine pancreatic elastase (EMP) or buffer (CNT). After a 4-week recovery period, equal numbers of each group were exposed 23 hr/day x 28 day to filtered air (AIR) or to the complex by-products from a dark-phase-reaction mixture of trans-2-butene, ozone, and sulfur dioxide (MIX). Lung-function measurements on the elastase-treated groups showed changes consistent with mild emphysema. There were no significant differences in lung volumes or lung compliance between the AIR- and MIX-exposed animals. However, the nitrogen washout slope decreased and the diffusing capacity for carbon monoxide increased in both the CNT and EMP hamsters exposed to the MIX. The change in diffusing capacity was greater in normal hamsters than in hamsters with emphysema, and it is hypothesized that animals with impaired lung function had a decreased ability to respond to a pulmonary insult from the mix.

  7. S-allylcysteine, a garlic constituent, inhibits 7,12-dimethylbenz[a]anthracene-induced hamster buccal pouch carcinogenesis.

    PubMed

    Balasenthil, S; Ramachandran, C R; Nagini, S

    2001-01-01

    The effect of S-allylcysteine (SAC), a water-soluble garlic constituent, on 7,12-dimethylbenz[a]anthracene (DMBA)-induced hamster buccal pouch (HBP) carcinogenesis was investigated in male Syrian hamstes. Forty hamsters were divided into 4 groups of 10 animals. The right buccal pouches of the animals in Group I were painted with a 0.5% solution of DMBA in liquid paraffin three times a week. The animals in Group II were painted with DMBA as in Group I and, in addition, received 200 mg/kg body wt p.o. SAC three times a week on days alternate to DMBA application. Group III animals received SAC as in Group II. Group IV animals received neither DMBA nor SAC and served as the control. The hamsters were killed after an experimental period of 14 wk. Measurement of lipid peroxidation, the antioxidant enzymes superoxide dismutase (SOD) and catalase, in the buccal pouch mucosa, liver, and circulation was used to monitor the chemopreventive potential of SAC. All hamsters painted with DMBA alone developed tumors identified histologically as well-differentiated squamous cell carcinomas. In hamsters bearing DMBA-induced buccal pouch tumors, diminished lipid peroxidation in the tumor tissue was accompanied by decreased activities of SOD and catalase, whereas in the liver and circulation, enhanced lipid peroxidation was associated with compromised antioxidant defenses. Administration of SAC suppressed the incidence of DMBA-induced HBP tumors as revealed by the absence of carcinomas. Histologically, only keratosis was observed. SAC modulated DMBA-induced decreased susceptibility of the HBP to lipid peroxidation while simultaneously enhancing SOD and catalase activities, whereas in the liver and circulation, SAC decreased the extent of lipid peroxidation and significantly enhanced antioxidant activities. We suggest that SAC exerts its chemopreventive effects by modulating lipid peroxidation and enhancing antioxidant activities in the target organ as well as in the liver and

  8. Distinguishing Clouds from Ice over the East Siberian Sea, Russia

    NASA Technical Reports Server (NTRS)

    2002-01-01

    As a consequence of its capability to retrieve cloud-top elevations, stereoscopic observations from the Multi-angle Imaging SpectroRadiometer (MISR) can discriminate clouds from snow and ice. The central portion of Russia's East Siberian Sea, including one of the New Siberian Islands, Novaya Sibir, are portrayed in these views from data acquired on May 28, 2002.

    The left-hand image is a natural color view from MISR's nadir camera. On the right is a height field retrieved using automated computer processing of data from multiple MISR cameras. Although both clouds and ice appear white in the natural color view, the stereoscopic retrievals are able to identify elevated clouds based on the geometric parallax which results when they are observed from different angles. Owing to their elevation above sea level, clouds are mapped as green and yellow areas, whereas land, sea ice, and very low clouds appear blue and purple. Purple, in particular, denotes elevations very close to sea level. The island of Novaya Sibir is located in the lower left of the images. It can be identified in the natural color view as the dark area surrounded by an expanse of fast ice. In the stereo map the island appears as a blue region indicating its elevation of less than 100 meters above sea level. Areas where the automated stereo processing failed due to lack of sufficient spatial contrast are shown in dark gray. The northern edge of the Siberian mainland can be found at the very bottom of the panels, and is located a little over 250 kilometers south of Novaya Sibir. Pack ice containing numerous fragmented ice floes surrounds the fast ice, and narrow areas of open ocean are visible.

    The East Siberian Sea is part of the Arctic Ocean and is ice-covered most of the year. The New Siberian Islands are almost always covered by snow and ice, and tundra vegetation is very scant. Despite continuous sunlight from the end of April until the middle of August, the ice between the island and the

  9. Chemical characteristics of Siberian boreal forest fire emissions

    NASA Astrophysics Data System (ADS)

    Engling, G.; Popovicheva, O.; Fan, T. S.; Eleftheriadis, K.; Diapouli, E.; Kozlov, V.

    2014-12-01

    Smoke emissions from Siberian boreal forest fires exert critical impacts on the aerosol/climate system of subarctic regions and the Arctic. It is, therefore, crucial to assess the ability of such particles to absorb/scatter incoming solar radiation as well as act as cloud condensation nuclei, which is closely linked to the physical and chemical aerosol properties. However, observations of Siberian wildfire emissions are limited, and no systematic database of smoke particle properties is available for this region to date. As part of this study, ambient aerosol samples were collected during two smoke episodes in Tomsk, Siberia, in the summers of 2012 and 2013. In addition, the chemical composition and optical properties of smoke particles derived from the combustion of typical Siberian fuels, including pine wood and debris, were determined during chamber burn experiments in a large aerosol/combustion chamber under controlled combustion conditions representative of wildfires and prescribed burns. Detailed multi-component characterization of individual particles and bulk properties was accomplished with a suite of techniques, including various types of chromatography, microscopy, spectroscopy, and thermo-optical analysis. Individual particle analysis by SEM-EDX combined with cluster analysis revealed characteristic smoke structural components and major types of particles, which allowed to discriminate between flaming and smoldering regimes, reflected in specific morphological and chemical microstructure. The physicochemical properties representing the combustion phase (smoldering versus flaming) and the degree of processing (fresh versus aged) were assessed in the ambient aerosol based on the chamber burn results. For instance, some chemical transformation (aging of smoke particles) was noticed over a period of two days in the absence of sun light in the combustion chamber for certain chemical species, while the molecular tracer levoglucosan appeared to be rather

  10. Subsidence of the West Siberian Basin: Geophysical evidence for eclogitization

    NASA Astrophysics Data System (ADS)

    Cherepanova, Yulia; Artemieva, Irina M.

    2013-04-01

    The West Siberian basin is the world's largest intracratonic sedimentary basin. The basin basement consists of complexes of island arcs, terranes, micro-continents, and relict ocean basins which amalgamated during late Proterozoic-Paleozoic orogenic events up to the formation of the Pangea super-continent. The basin was affected by rifting and flood basalt eruption in the Permian-early Triassic (ca 250 Ma), which was floowed by rapid late Triassic (190 Ma) subsidence, as observed in borehole data from the axial part of the Ob rift (Saunders, 2005). Widely distributed subsidence of the north and central parts of the basin took place in the Jurassic with accumulation of 1,5- 3 km sediments. Two other subsidence episodes in the early Cretaceous and in the Late Cretaceous to Cenozoic led to deposition of 2-3 km of sediment in the north-eastern and axial parts. (Rudkevich, 1976). Most of the present-day West Siberian basin lacks surface topography, whereas the reliefs of the Moho and the top of the basement have amplitudes of ca. 20 km and 15 km, respectively (Cherepanova et al., 2012). Modeling suggests that the thermal lithosphere is 130km thick in the West Siberian basin, up-to 260 km in the Siberian craton further east, and 90 km in the axial part of the basin under the Ob rift (Artemieva and Mooney, 2001). Assuming local isostatic equilibrium and no effect of dynamic topography (which probably is a valid approximation for most of the region, except for the southern margin and the Urals), we examine the relative contributions of the crust and the lithospheric mantle to maintaining the surface topography. Lithosphere buoyancy is controlled by thicknesses and densities of the crust and the lithospheric mantle, and therefore by composition, metamorphic state, and temperature. Crustal thickness and density are constrained by our new regional crustal model, which is based on a quality-controlled compilation of all seismic models published in international and Russian

  11. A role for glucose in hypothermic hamsters

    NASA Technical Reports Server (NTRS)

    Resch, G. E.; Musacchia, X. J.

    1976-01-01

    Hypothermic hamsters at a rectal temperature of 7 C showed a fivefold increase in survival times from 20 to 100.5 hr when infused with glucose which maintained a blood level at about 45 mg/100 ml. A potential role for osmotic effects of the infusion was tested and eliminated. There was no improvement in survival of 3-O-methylglucose or dextran 40-infused animals. The fact that death eventually occurs even in the glucose-infused animal after about 4 days and that oxygen consumption undergoes a slow decrement in that period suggests that hypothermic survival is not wholly substrate limited. Radioactive tracer showed that localization of the C-14 was greatest in brain tissue and diaphragm, intermediate in heart and kidney, and lowest in skeletal muscle and liver. The significance of the label at sites important to respiration and circulation was presented.

  12. The facial levels of the melting of the Permian - Triassic trap basalts of West Siberian plate and Siberian platform.

    NASA Astrophysics Data System (ADS)

    Sharapov, Victor; Vasiliev, Yury

    2014-05-01

    Statistical processing of numerical information allow to indicate the following regional petro- geochemical characteristics of Permo-Triassic trap magmatism in West Siberian plate WSP: 1) Examined regional petrochemical trend of major element chemistry variation of trap magmatism from north to the south is appeared in increase of the acidity, a decrease of Mg and alumina and potassium of the igneous rocks, for other components existing data do not allow to determine regularities; 2) According to (La/Yb)n, (Gd/Yb)n and(Tb/Yb)n ratios all basic melts belong to the spinel facie. In general the trap basalts of Siberian Platform reveal the following structural facial features are characteristic: 1) From west and east the region of the basalt effusions practically coincides with the area of Devonian sea depressions, 2) from the west to east lava shields are framed by the zones of the variously differentiated intrusive basic bodies grouped within the zones of arched and linear faults; 3) the region of effusive volcanics appearance has the zone - distributed structural - material areas, the tholeitic "super-shield" (plateau Putorana) occupyingthe center part of the Tunguska syneclise), framed from the West, and NW by the local lava shields located in rounded depressions( mulda) in which the lavas are more magnesian, titaniferrous and alkaline. 4) examined overall petrochemical zonation of basic rocks in Siberian platform reveal general decrease from the Norilsk mulda to Angara- Ilim iron-ore deposit region, with the growth of Ti02 and alkalinity of the basic rocks. The statistical wavelet analysis of the cyclic recurrence of the effusive rock sections along the eastern board of Khatanga rift show substantially different characteristics of the spectra of time series, in Norilsk -Kharaelakh depression the low-frequency modules predominate, whereas for The Meimecha-Kotuy effusion section the high frequency values are characteristic. The comparison of the possible facial

  13. Localization of gamma-glutamyl transpeptidase in hamster buccal pouch epithelium treated with 7,12-dimethylbenz(a)anthracene

    SciTech Connect

    Solt, D.B.

    1981-07-01

    The utility of gamma-glutamyl transpeptidase (GGT) was explored as a histochemical marker for chemical carcinogenesis in hamster buccal pouch mucosa. One or both buccal pouches of 18 noninbred male Syrian golden hamsters were treated topically with 0.5% 7,12-dimethylbenz(a)anthracene (DMBA) in mineral oil over 16 weeks to produce numerous epithelial lesions at various stages of neoplastic development. Both buccal pouches of 4 control animals were similarly treated with mineral oil alone. GGT activity was not detectable in untreated pouches or pouches treated with mineral oil alone. With this technique, multiple discrete GGT-stained areas were visible in wholemounts prepared at 1 and 6 weeks after the final application of DMBA. The experimental results were consistent with the hypothesis that the early GGT-stained cell populations are preneoplastic in nature.

  14. A Practical Grammar of the St. Lawrence Island/Siberian Yupik Eskimo Language. Preliminary Edition.

    ERIC Educational Resources Information Center

    Jacobson, Steven A.

    The grammar of the St. Lawrence Island/Siberian Yupik Eskimo language was written for college-level classes containing a mixture of Yupik speakers and non-speakers, and for students learning the language on their own. It uses only the Central Siberian Yupik dialect spoken on St. Lawrence Island (Alaska) and on a small portion of the Asian…

  15. Ungipaghaghlanga: Quutmiit Yupigita Ungipaghaatangit = Let Me Tell a Story: Legends of the Siberian Eskimos.

    ERIC Educational Resources Information Center

    Koonooka, Christopher

    The language of these stories, Siberian Yupik, in this book were first written down by Russian educator and linguist, Gregoriy A. Menovshchikov, during his 30 years of teaching and working with Eskimo languages in Chukotka, Russian, beginning in the 1930s. Siberian Yupik is the ancestral language of more than 2,000 people equally divided between…

  16. Some Contact Languages and Pidgin and Creole Languages in the Siberian Region.

    ERIC Educational Resources Information Center

    Wurm, Stephen A.

    1992-01-01

    Discusses the role of Russian colonization of the Siberian region and the impact of demographic changes on languages in the region. Topics addressed include intercommunication through contact languages based on one-way bilingualism, pidgin and creole languages in the Siberian region, and Eskimo Pidgin. (33 references) (Author/JP)

  17. Evidence for a metabolic limitation of survival in hypothermic hamsters.

    NASA Technical Reports Server (NTRS)

    Prewitt, R. L.; Anderson, G. L.; Musacchia, X. J.

    1972-01-01

    The underlying factors limiting survival in the hypothermic state are studied. Hamsters of both sexes, clipped and unclipped, were inducted into profound hypothermia by the helium cold method until they reached a temperature between 7 and 10 C. It appears that the primary cause of death is failure of respiration due to the depletion of carbohydrate energy supplies and may explain why survival time in hypothermia is shorter than the normal hibernation time of the hamster.

  18. Fasting-induced daily torpor in desert hamsters (Phodopus roborovskii).

    PubMed

    Chi, Qing-Sheng; Wan, Xin-Rong; Geiser, Fritz; Wang, De-Hua

    2016-09-01

    Daily torpor is frequently expressed in small rodents when facing energetically unfavorable ambient conditions. Desert hamsters (Phodopus roborovskii, ~20g) appear to be an exception as they have been described as homeothermic. However, we hypothesized that they can use torpor because we observed reversible decreases of body temperature (Tb) in fasted hamsters. To test this hypothesis we (i) randomly exposed fasted summer-acclimated hamsters to ambient temperatures (Tas) ranging from 5 to 30°C or (ii) supplied them with different rations of food at Ta 23°C. All desert hamsters showed heterothermy with the lowest mean Tb of 31.4±1.9°C (minimum, 29.0°C) and 31.8±2.0°C (minimum, 29.0°C) when fasted at Ta of 23°C and 19°C, respectively. Below Ta 19°C, the lowest Tb and metabolic rate increased and the proportion of hamsters using heterothermy declined. At Ta 5°C, nearly all hamsters remained normothermic by increasing heat production, suggesting that the heterothermy only occurs in moderately cold conditions, perhaps to avoid freezing at extremely low Tas. During heterothermy, Tbs below 31°C with metabolic rates below 25% of those during normothermia were detected in four individuals at Ta of 19°C and 23°C. Consequently, by definition, our observations confirm that fasted desert hamsters are capable of shallow daily torpor. The negative correlation between the lowest Tbs and amount of food supply shows that heterothermy was mainly triggered by food shortage. Our data indicate that summer-acclimated desert hamsters can express fasting-induced shallow daily torpor, which may be of significance for energy conservation and survival in the wild.

  19. Fasting-induced daily torpor in desert hamsters (Phodopus roborovskii).

    PubMed

    Chi, Qing-Sheng; Wan, Xin-Rong; Geiser, Fritz; Wang, De-Hua

    2016-09-01

    Daily torpor is frequently expressed in small rodents when facing energetically unfavorable ambient conditions. Desert hamsters (Phodopus roborovskii, ~20g) appear to be an exception as they have been described as homeothermic. However, we hypothesized that they can use torpor because we observed reversible decreases of body temperature (Tb) in fasted hamsters. To test this hypothesis we (i) randomly exposed fasted summer-acclimated hamsters to ambient temperatures (Tas) ranging from 5 to 30°C or (ii) supplied them with different rations of food at Ta 23°C. All desert hamsters showed heterothermy with the lowest mean Tb of 31.4±1.9°C (minimum, 29.0°C) and 31.8±2.0°C (minimum, 29.0°C) when fasted at Ta of 23°C and 19°C, respectively. Below Ta 19°C, the lowest Tb and metabolic rate increased and the proportion of hamsters using heterothermy declined. At Ta 5°C, nearly all hamsters remained normothermic by increasing heat production, suggesting that the heterothermy only occurs in moderately cold conditions, perhaps to avoid freezing at extremely low Tas. During heterothermy, Tbs below 31°C with metabolic rates below 25% of those during normothermia were detected in four individuals at Ta of 19°C and 23°C. Consequently, by definition, our observations confirm that fasted desert hamsters are capable of shallow daily torpor. The negative correlation between the lowest Tbs and amount of food supply shows that heterothermy was mainly triggered by food shortage. Our data indicate that summer-acclimated desert hamsters can express fasting-induced shallow daily torpor, which may be of significance for energy conservation and survival in the wild. PMID:27215346

  20. Cardiac dynamics during daily torpor in the Djungarian hamster (Phodopus sungorus).

    PubMed

    Mertens, Alexander; Stiedl, Oliver; Steinlechner, Stephan; Meyer, Michael

    2008-02-01

    Djungarian or Siberian hamsters (Phodopus sungorus) acclimated to short photoperiod display episodes of spontaneous daily torpor with metabolic rate depressed by approximately 70% and body temperature (T(b)) reduced by approximately 20 degrees C. To study the cardiovascular adjustment to daily torpor in Phodopus, electrocardiogram (ECG) and T(b) were continuously recorded by telemetry during entrance into torpor, in deep torpor, and during arousal from torpor. Minimum T(b) during torpor bouts was approximately 21 degrees C, and heart rate, approximately 349 beats/min at euthermy, displayed marked sinus bradyarrhythmia at approximately 70 beats/min. Arousal was typically completed within approximately 40 min, followed by a sustained post-torpor inactivity tachycardia ( approximately 540 beats/min). The absence of episodes of conduction block, tachyarrhythmia, or other forms of ectopy throughout the torpor cycle demonstrates a remarkable resistance to arrhythmogenesis. The ECG morphology lacks a distinct isoelectric interval following the QRS complex, and the ST segment resembles the ECG pattern in mice, with a prominent fast transient outward K(+) current (I(to,f)) determining the early phase of ventricular repolarization. During low-temperature torpor, the amplitudes of the QRS complex substantially increased, suggesting that in the euthermic state the terminal portion of ventricular depolarization is fused with the beginning of repolarization, low T(b) acting to decorrelate the superposition between depolarization and repolarization by delaying the repolarization onset. Atrioventricular and ventricular conduction times were prolonged as function of T(b). In contrast, the QT vs. T(b) relationship showed marked hysteresis indicating the operation of nonlinear control mechanisms whereby the rapid QT shortening during arousal results from additional mechanisms (probably sympathetic stimulation) other than temperature alone.

  1. Regulation of tonic gonadotropin release in prepubertal female hamsters

    SciTech Connect

    Smith, S.G.; Matt, K.S.; Prestowitz, W.F.; Stetson, M.H.

    1982-04-01

    Basal serum gonadotropin levels were monitored weekly in female hamsters from birth to 10 weeks of age. Hamsters raised on three different photoperiods presented uniform pre- and postpubertal patterns of serum LH and FSH, suggesting that gonadotropin release in the young hamster occurs independently of ambient photoperiod. In all groups, serum LH levels increased gradually in animals up to 4 weeks of age, after which levels plateaued at 50--100 ng/ml. Serum FSH was markedly elevated in 2- and 3-week-old hamsters (800--1200 ng/ml), but remained at 200--400 ng/ml in all other groups. We next examined the change in the responsiveness of the pituitary to exogenous gonadotropin-releasing hormone (GnRH) challenge. Female hamsters 2 days of age failed to respond to any dose (0.025--1000 ng) of GnRH, while 10-day old females responded in typical dose-dependent fashion. GnRH-stimulated LH release first occurred in 6-day-old hamsters and was maximal by day 9, whereas FSH release first occurred on day 8 and was maximal by day 9. The prepubertal pattern of gonadotropin release can, in part, be explained on the basis of the development of pituitary GnRH sensitivity, which occurs independently of photoperiod.

  2. Regulation of hamster splenocyte reactivity to concanavalin A during pregnancy

    SciTech Connect

    Weppner, W.A.; Coggin, J.H. Jr.

    1980-08-15

    The survival to term of mammalian fetuses regardless of their expression of paternal or embryonic developmental antigens suggests that some alteration in the immune capabilities of a female occur during pregnancy. The immunocompetence of female Syrian golden hamsters during pregnancy was investigated with respect to the blastogenic response of spleen cells to the T-cell mitogen concanavalin A (Con A). The blastogenic response of spleen cells from pregnant hamsters during mid- or late gestation is 10% of that observed for spleen cells from age-matched, virgin female animals. The spleen cells from pregnant hamsters are not capable of suppressing the proliferative response of spleen cells from virgin females to Con A. However, the serum from pregnant hamsters, in comparison with serum from virgin female animals, is capable of reducing this mitogenic response. Extensive washing of the splenocytes from pregnant hamsters does reduce the degree of suppression. These results suggest that the hamster is an excellent animal model for the investigation of the mechanism(s) of immune regulation that operate during pregnancy.

  3. Weather entrainment and multispectral diel activity rhythm of desert hamsters.

    PubMed

    Wan, Xinrong; Zhang, Xinjie; Huo, Yingjun; Wang, Guiming

    2013-10-01

    The circadian rhythm of animals is an adaptation to predictable variation in environmental conditions. Multiple internal oscillators may allow animals to cope with environmental oscillations in different frequencies. Heat stress and dramatic differences between night and day temperatures are the main selective pressures of the diel activity of desert mammals, particularly small-sized rodents. We tested the hypotheses that the diel activities of desert hamsters (Phodopus roborovskii) would be entrained by ambient humidity and temperature. We predicted that increases in night temperature and humidity would improve the propensity to perform activities of the hamster. We observed hourly activities of desert hamsters under semi natural conditions for 24 consecutive hours, with seven replicates in 7 different days. We fit generalized linear mixed models to observed proportions of active hamsters, temperatures, and relative humidity. Observed diel activities of desert hamsters consisted of three harmonic oscillations in the periodicities of 24 h, 12 h, and 6 h, respectively. Furthermore, probabilities to perform activities were positively related to night temperature and humidity. Therefore, the diel activities of desert hamsters are synchronized by atmospheric humidity, temperatures, and environmental cues of ultradian fluctuations.

  4. [Genetic passportization and identification of Siberian cranes (Grus leucogeranus Pallas) in captivity].

    PubMed

    Mudrik, E A; Kashentseva, T A; Gamburg, E A; Politov, D V

    2014-01-01

    The genetic diversity of the founders of an artificial population of the Siberian crane Grus leucogeranus Pallas (rare species of cranes) was characterized using 10 microsatellite loci. It was established that the allelic diversity (on average, 5.9 alleles per locus) and genic (H(o) = 0.739) diversity of the Siberian crane is rather high and comparable with the estimations for natural populations of different crane species. Genetic passportization of the birds (119 individuals) from the register of the Siberian crane International Studbook was carried out at the initial stage. The efficiency of genetic passportization for individual identification, identification of the origin, paternity analysis, and exclusion of inbreeding was demonstrated in Siberian cranes under natural mating and artificial insemination. Cases of natural reproduction in pairs of Siberian cranes imprinted to the human and continuous storage of spermatozoa in the female reproductive ducts were registered. PMID:25731031

  5. [Genetic passportization and identification of Siberian cranes (Grus leucogeranus Pallas) in captivity].

    PubMed

    Mudrik, E A; Kashentseva, T A; Gamburg, E A; Politov, D V

    2014-01-01

    The genetic diversity of the founders of an artificial population of the Siberian crane Grus leucogeranus Pallas (rare species of cranes) was characterized using 10 microsatellite loci. It was established that the allelic diversity (on average, 5.9 alleles per locus) and genic (H(o) = 0.739) diversity of the Siberian crane is rather high and comparable with the estimations for natural populations of different crane species. Genetic passportization of the birds (119 individuals) from the register of the Siberian crane International Studbook was carried out at the initial stage. The efficiency of genetic passportization for individual identification, identification of the origin, paternity analysis, and exclusion of inbreeding was demonstrated in Siberian cranes under natural mating and artificial insemination. Cases of natural reproduction in pairs of Siberian cranes imprinted to the human and continuous storage of spermatozoa in the female reproductive ducts were registered.

  6. Inhibition of melanin production by a combination of Siberian larch and pomegranate fruit extracts.

    PubMed

    Diwakar, Ganesh; Rana, Jatinder; Scholten, Jeffrey D

    2012-09-01

    In an effort to find botanicals containing polyphenolic compounds with the capacity to inhibit melanin biosynthesis, we identified a novel combination of Siberian larch (Larix sibirica) extract, standardized to 80% taxifolin, and pomegranate fruit (Punica granatum) extract, containing 20% punicalagins, that demonstrates a synergistic reduction of melanin biosynthesis in Melan-a cells. The combination of Siberian larch and pomegranate extracts (1:1) produced a 2-fold reduction in melanin content compared to Siberian larch or pomegranate extracts alone with no corresponding effect on cell viability. Siberian larch and pomegranate fruit extracts inhibited expression of melanocyte specific genes, tyrosinase (Tyr), microphthalmia transcription factor (Mitf), and melanosome structural proteins (Pmel17 and Mart1) but did not inhibit tyrosinase enzyme activity. These results suggest that the mechanism of inhibition of melanin biosynthesis by Siberian larch and pomegranate extracts, alone and in combination, is through downregulation of melanocyte specific genes and not due to inhibition of tyrosinase enzyme activity.

  7. Suppression of hamster lymphocyte reactivity to simian virus 40 tumor surface antigens by spleen cells from pregnant hamsters

    SciTech Connect

    Weppner, W.A.; Adkinson, L.R.; Coggin, J.H.Jr

    1980-09-01

    SV40-transformed tumor cells in hamsters have been found to have cell surface antigens cross-reactive with antigens temporally expressed on fetal tissues. Using a lymphocyte transformation assay, spleen cells from pregnant hamsters were found to be incapable of responding to preparations of either hamster fetal tissue or SV40-transformed cells. However, a suppressor component can be demonstrated in spleen cell populations of both primi-and multiparous hamsters during pregnancy that is capable of reducing the response of lymphocytes sensitized against SV40 tumor-associated antigens. The degree of suppression is proportional to the ratio of responder cells to spleen cells from pregnant animals. These results suggest there is a subpopulation of spleen cells involved in immunoregulation during pregnancy that has the ability to suppress the reactivity of lymphocytes sensitized against SV40-associated oncofetal antigens.

  8. Influence of photoperiod on pineal melatonin synthesis, fur color, body weight, and reproductive function in the female Djungarian hamster, Phodopus sungorus.

    PubMed

    Lerchl, A; Schlatt, S

    1993-01-01

    In order to investigate female Djungarian hamsters' reactions to changes of the photoperiod, the following two experiments were performed. Experiment I: Age-matched female hamsters were exposed to either short (8L:16D) or long days (16L:8D) for 38 weeks. Initially, the short-day group showed a decline in body weight, associated with changes in gonadal function and fur color. This was not maintained by the short-day group which returned, on the most part, to long-day levels, thus becoming insensitive to this regressive lighting regimen. The time courses of these events compare well with those observed in males, which suggests a common mechanism. Experiment II: Two groups of female hamsters were exposed for 8 weeks to either long days or short days. At the end of the test period, the diurnal variations in pineal content of melatonin, serotonin, hydroxyindole acetic acid, and serum melatonin were estimated, revealing marked differences between the two groups. Not only was there a prolongation of melatonin synthesis observed in the short-day animals, but there was also a significant elevation of the melatonin levels when compared to the long-day animals. Together with recent findings in males, these findings lend support to the hypothesis that, in the Djungarian hamster, the elevation of nocturnal melatonin levels may be of additional significance, with respect to the physiological changes induced by short-day photoperiods. PMID:7685505

  9. Helium isotope evidence for plume metasomatism of Siberian continental lithosphere

    NASA Astrophysics Data System (ADS)

    Barry, P. H.; Hilton, D. R.; Howarth, G. H.; Pernet-Fisher, J. F.; Day, J. M.; Taylor, L. A.

    2013-12-01

    The Siberian craton contains more than 1000 kimberlite intrusions of various ages (Silurian to Jurassic), making it an ideal setting for understanding temporal and spatial variations in subcontinental lithospheric mantle (SCLM) composition and metasomatism. This region also experienced one of the largest flood basalt events in the geologic record. The Permo-Triassic Siberian Flood Basalts (SFB) are considered to have erupted in response to plume-head impingement under the Siberian SCLM. Here we present new He-isotope data for a suite of peridotitic xenoliths (n=19) from two temporally and petrologically-distinct kimberlite pipes (i.e., Late-Devonian Udachnaya and Jurassic Obnazhennaya) in Siberia that span the age of eruption of the SFB. All samples have previously been well-characterized, mineralogically, petrographically, and for major- and trace-element abundance geochemistry. He-isotope ratios (3He/4He) of garnet, pyroxene and olivine separates from 2.7-3.1 Ga Siberian peridotites range from 0.11 to 8.4 RA, displaying both strongly radiogenic (i.e., low 3He/4He) and mantle-like (i.e., SCLM = 6.1 × 0.9 RA; MORB = 8 × 1 RA) values. In contrast, SFB values extend up to ~13 RA [1]. Helium concentrations span ~ five orders of magnitude from 0.05 to 350 [4He]C (×10-6) cm3STP/g. These findings are consistent with previous studies [2], which suggested that the SCLM is heterogeneous with respect to He and that this heterogeneity is strongly dependent on lithospheric age. Notably, all but one Obnazhennaya sample displays 3He/4He values in the mantle range and are He depleted. In contrast, all but one Udachnaya samples are radiogenic and have higher He contents. Previous studies have suggested that partially-melted subducted ocean crust amalgamated to form the Siberian craton at ~3 Ga [3], followed by a complex history of metasomatism until eruption of xenolith samples within kimberlites [4]. For example, during the main stage of SFB emplacement (i.e., Siberian plume

  10. Northern and eastern margins of the Siberian continent in Triassic

    SciTech Connect

    Egorov, A.Yu. )

    1993-09-01

    Siliciclastic sedimentation has been predominant on the northern and eastern margins of the Siberian continent since the Triassic period. Seven transgression-regression cycles can be recognized in the Triassic succession: Griesbachien-Dienerian, Smithian-Low Spathian, Upper Spathian, Anissian (with subcycles), Ladian, Carnian, and Norlan (with subcycles). All zonal units were distinguished within transgressive portions of the cycles. Regressive portions of the cycles formed practically instantaneously. Very high sedimentation rate (300-3000 mm/1000 yr), specific structures of sedimentary rocks, and distribution of unconformities led to the conclusion that active avalanche sedimentation at the basin margins was of major significance. six facies regions are recognized in the sedimentation area: Taimyr, Kotuy-Anabar, Leno-Anabar, Bur-Olenek, Verkhoyansk, and Novosibirsk (New Siberian Islands). The main source areas were located at the Patoma Mountains for the eastern margin and at the Anabar anticline and Olenek uplift for the northern margin. Most sediments were transported to the eastern margin by a large river with a huge delta which was similar in size to the modern Lena's delta. Sediments were further distributed by contour streams. Local synsedimentary structures controlled the paleogeography of the entire area. The paleogeographical evolution of the eastern margin is the history of this delta development. The rifting activities with the trappean magmatism were the main events at the northern margin, especially in the Talmyr area. The pelagic sedimentation has been predominant in the New Siberian Islands area and most of the Laptev Sea aquatoria. The organic-rich sediments have been distinguished in Low Olenekian (Smithian), Low Anissian, Low Ladinian, and Low Carnian substages. Most of them could be hydrocarbon source rocks. Triassic oil and gas seeps have been discovered at the northern portion of the Vilyui syncline, near the Lena's delta and the Nordvic Bay.

  11. Supertoxic Flood Basalts: The CAMP - Siberian Trap Connection

    NASA Astrophysics Data System (ADS)

    Puffer, J. H.

    2007-12-01

    Several diverse magma types are represented throughout the CAMP and Siberian Trap LIPs, however, the main extrusive phase of each province is highly unusual among continental flood basalts. The most widespread extrusions were intermediate titanium (ITi-type) CAMP basalt and the lower portion of the Upper Sequence of Siberian Trap. New and recently published data indicate that the geochemistry and petrology of these basalt suites closely resemble each other and infer similar origins. The basalts are characterized by strong negative Nb- Ta anomalies and unusual island arc-like depletion in high field strength elements, particularly Ti, plotted on spider diagrams. The geochemical data is consistent with significant contributions from subducted slabs into the magma source regions. If contaminated, volatile enriched mantle wedges were trapped beneath thick continental plates during the assembly of Pangea, fertile magma sources would have remained dormant until decompression melting was triggered during failed rift, then early rift stages of continental plate disassembly. The combination of volatile enriched sources and highly extensional tectonism would create rare perfect storms of toxicity. Calculated low viscosities assuming negligible carbon dioxide are consistent with rapid crustal penetration. Resulting aphyric melts extruded at enormous effusive rates as thick sub-parallel flows across wide subareal terrains through fissures extending several hundred km in length. High fountain heights would afford ample opportunity for efficient degassing, perhaps into the stratosphere. When the supply of volatile flux was exhausted magmatism ceased. The mass extinctions that coincide with CAMP and Siberian volcanism contrast with some large plume and superplume events that correlate with expansions of biodiversity. This may be due in part to contrasting magma access to sources of toxic volatiles, particularly sulfur concentrations in anoxic subducted sediments.

  12. North Siberian lakes: A methane source fueled by Pleistocene carbon

    SciTech Connect

    Zimov, S.A.; Davidov, S.P.; Prosiannikov, S.F.; Trumbore, S.

    1997-08-08

    The sizes of major sources and sinks of atmospheric methane (CH{sub 4}), an important greenhouse gas, are poorly known. CH{sub 4} from north Siberian lakes contributes {approximately}1.5 teragrams CH{sub 4} year{sup -1} to observed winter increases in atmospheric CH{sub 4} concentration at high northern latitudes. CH{sub 4} emitted from these lakes in winter had a radiocarbon age of 27,200 years and was derived largely from Pleistocene-aged carbon.

  13. Degenerative myelopathy in a family of Siberian Husky dogs.

    PubMed

    Bichsel, P; Vandevelde, M; Lang, J; Kull-Hächler, S

    1983-11-01

    Three closely related, Siberian Husky dogs had chronic progressive paresis and ataxia with muscle atrophy in the hindlimbs. Radiologic and myelographic examination of the spine revealed no abnormalities. On histologic examination, disseminated degeneration of the white matter, particularly in the thoracic segments, was seen. The clinical and pathological findings were similar to those described in aging large dogs with so-called degenerative myelopathy. The cause of this disease is unknown but the fact that these 3 Huskies were closely related suggest that hereditary factors may play a role.

  14. Targeted delivery of anticancer drugs with intravenously administered magnetic liposomes in osteosarcoma-bearing hamsters.

    PubMed

    Kubo, T; Sugita, T; Shimose, S; Nitta, Y; Ikuta, Y; Murakami, T

    2000-08-01

    Although active targeting of anticancer drugs using magnetically responsive carriers is a very attractive treatment approach for solid tumors, successful results are limited. In particular, the therapeutic utility of intravenously administered magnetically responsive carriers has to date not been clearly established. The present study investigates magnetic liposomes designed to act as anticancer drug carriers, which can be effectively delivered to solid tumors via intravenous administration. Magnetic liposomes with incorporated adriamycin (magnetic ADR liposomes) were prepared by the reverse-phase evaporation method, and an in vivo study was carried out to assess the magnetic targeting of these liposomes to hamster osteosarcoma. The average diameter of liposomes thus prepared was 146 nm. Syrian male hamsters inoculated with osteosarcoma, Os515, in the right hind limb were studied 7 days after inoculation. After the hamsters had received an intravenous administration of either magnetic ADR liposomes or ADR solution (corresponding to 5 mg ADR/kg), the ADR concentrations in plasma, tumor, liver, lung, heart, and kidney were determined at designated time intervals. Administration of magnetic ADR liposomes under magnetic force using a permanent magnet (0.4 tesla) implanted in solid tumor produced an approximately 4-fold higher maximum ADR concentration in the tumor than did administration of ADR solution. The former administration modality induced an increase in ADR concentration in the liver and lung and a decrease in the heart compared with concentrations produced by the latter. The present results indicated that intravenously administered magnetic ADR liposomes can be used to effectively deliver ADR to osteosarcoma implanted with a magnet, as well as to the lung, a common site of metastases for osteosarcoma. Our results also suggest that this new treatment approach, which involves a combination of magnet implantation at the target site and intravenous administration

  15. Effect of selenium supplementation on histopathology of vitamin E deficiency in the syrian golden hamster

    SciTech Connect

    Hinton, D.E.; Banks, M.A.; Martin, W.G.

    1986-03-01

    Male hamsters (N-40) were placed on a semi-purified torula yeast diet (< 0.05 ppm Se) containing 0.1 ppm added Se (as Na/sub 2/SeO/sub 3/) at age 6-8 weeks, then assigned to either vitamin E deficient (< 1 I.U./100 g, DS) or sufficient (1.5 I.U./100 g CS) diets and pair-fed. Body weights were recorded at 3 week intervals. At 65, 92, 120 and 180 days on diet (dod) two pairs of hamsters were sacrificed by injection of 10 cc/kg Brevital sodium. Blood samples were obtained from the inferior vena cava. Organs were removed, weighted, fixed, routinely processed and stained with hematoxylin and eosin. DS began to lose weight relative to CS at 75 dod. At 92 dod DS plasma ..cap alpha..-tocopherol decreased (DS = 4.3 +/- 1.2, CS = 36.7 +/- 4.4 ..mu..g/ml, p < 0.01), while at 180 dod, RBC hemolysis did not significantly differ (DS = 19.2 +/- 11.3, CS = 3.9 +/-2.7%, p < 0.10). A previous study indicated that dietary vitamin E plus Se deficiencies resulted in depressed growth (70 dod), increased RBC hemolysis (90 dod), muscle degeneration (120 dod), hepatocellular hypertrophy (180 dod) and acinar cell atrophy of the pancreas (170 dod). At 180 dod, Se-supplemented vitamin E deficient hamsters did not display muscle degeneration, hypertrophy of the liver or atrophy of the pancreas, but did have testicular atrophy. None of the DS animals died.

  16. Hypolipidemic Effect of Tomato Juice in Hamsters in High Cholesterol Diet-Induced Hyperlipidemia.

    PubMed

    Lee, Li-Chen; Wei, Li; Huang, Wen-Ching; Hsu, Yi-Ju; Chen, Yi-Ming; Huang, Chi-Chang

    2015-12-17

    Tomato is a globally famous food and contains several phytonutrients including lycopene, β-carotene, anthocyanin, and flavonoids. The increased temperature used to produce tomato juice, ketchup, tomato paste and canned tomato enhances the bioactive composition. We aimed to verify the beneficial effects of processed tomato juice from Kagome Ltd. (KOT) on hypolipidemic action in hamsters with hyperlipidemia induced by a 0.2% cholesterol and 10% lard diet (i.e., high-cholesterol diet (HCD)). Male Golden Syrian hamsters were randomly divided into two groups for treatment: normal (n = 8), standard diet (control); and experimental (n = 32), HCD. The 32 hamsters were further divided into four groups (n = 8 per group) to receive vehicle or KOT by oral gavage at 2787, 5573, or 13,934 mg/kg/day for six weeks, designated the HCD-1X, -2X and -5X groups, respectively. The efficacy and safety of KOT supplementation was evaluated by lipid profiles of serum, liver and feces and by clinical biochemistry and histopathology. HCD significantly increased serum levels of total cholesterol (TC), triacylglycerol (TG), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C), LDL-C/HDL-C ratio, hepatic and fetal TC and TG levels, and degree of fatty liver as compared with controls. KOT supplementation dose-dependently decreased serum TC, TG, LDL-C levels, LDL-C/HDL-C ratio, hepatic TC and TG levels, and fecal TG level. Our study provides experiment-based evidence to support that KOT may be useful in treating or preventing the onset of hyperlipidemia.

  17. Hypolipidemic Effect of Tomato Juice in Hamsters in High Cholesterol Diet-Induced Hyperlipidemia

    PubMed Central

    Lee, Li-Chen; Wei, Li; Huang, Wen-Ching; Hsu, Yi-Ju; Chen, Yi-Ming; Huang, Chi-Chang

    2015-01-01

    Tomato is a globally famous food and contains several phytonutrients including lycopene, β-carotene, anthocyanin, and flavonoids. The increased temperature used to produce tomato juice, ketchup, tomato paste and canned tomato enhances the bioactive composition. We aimed to verify the beneficial effects of processed tomato juice from Kagome Ltd. (KOT) on hypolipidemic action in hamsters with hyperlipidemia induced by a 0.2% cholesterol and 10% lard diet (i.e., high-cholesterol diet (HCD)). Male Golden Syrian hamsters were randomly divided into two groups for treatment: normal (n = 8), standard diet (control); and experimental (n = 32), HCD. The 32 hamsters were further divided into four groups (n = 8 per group) to receive vehicle or KOT by oral gavage at 2787, 5573, or 13,934 mg/kg/day for six weeks, designated the HCD-1X, -2X and -5X groups, respectively. The efficacy and safety of KOT supplementation was evaluated by lipid profiles of serum, liver and feces and by clinical biochemistry and histopathology. HCD significantly increased serum levels of total cholesterol (TC), triacylglycerol (TG), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C), LDL-C/HDL-C ratio, hepatic and fetal TC and TG levels, and degree of fatty liver as compared with controls. KOT supplementation dose-dependently decreased serum TC, TG, LDL-C levels, LDL-C/HDL-C ratio, hepatic TC and TG levels, and fecal TG level. Our study provides experiment-based evidence to support that KOT may be useful in treating or preventing the onset of hyperlipidemia. PMID:26694461

  18. Hypolipidemic Effect of Tomato Juice in Hamsters in High Cholesterol Diet-Induced Hyperlipidemia.

    PubMed

    Lee, Li-Chen; Wei, Li; Huang, Wen-Ching; Hsu, Yi-Ju; Chen, Yi-Ming; Huang, Chi-Chang

    2015-12-01

    Tomato is a globally famous food and contains several phytonutrients including lycopene, β-carotene, anthocyanin, and flavonoids. The increased temperature used to produce tomato juice, ketchup, tomato paste and canned tomato enhances the bioactive composition. We aimed to verify the beneficial effects of processed tomato juice from Kagome Ltd. (KOT) on hypolipidemic action in hamsters with hyperlipidemia induced by a 0.2% cholesterol and 10% lard diet (i.e., high-cholesterol diet (HCD)). Male Golden Syrian hamsters were randomly divided into two groups for treatment: normal (n = 8), standard diet (control); and experimental (n = 32), HCD. The 32 hamsters were further divided into four groups (n = 8 per group) to receive vehicle or KOT by oral gavage at 2787, 5573, or 13,934 mg/kg/day for six weeks, designated the HCD-1X, -2X and -5X groups, respectively. The efficacy and safety of KOT supplementation was evaluated by lipid profiles of serum, liver and feces and by clinical biochemistry and histopathology. HCD significantly increased serum levels of total cholesterol (TC), triacylglycerol (TG), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C), LDL-C/HDL-C ratio, hepatic and fetal TC and TG levels, and degree of fatty liver as compared with controls. KOT supplementation dose-dependently decreased serum TC, TG, LDL-C levels, LDL-C/HDL-C ratio, hepatic TC and TG levels, and fecal TG level. Our study provides experiment-based evidence to support that KOT may be useful in treating or preventing the onset of hyperlipidemia. PMID:26694461

  19. Hypolipidemic Effects and Safety of Lactobacillus Reuteri 263 in a Hamster Model of Hyperlipidemia

    PubMed Central

    Huang, Wen-Ching; Chen, Yi-Ming; Kan, Nai-Wen; Ho, Chun-Sheng; Wei, Li; Chan, Ching-Hung; Huang, Hui-Yu; Huang, Chi-Chang

    2015-01-01

    We aimed to verify the beneficial effects of probiotic strain Lactobacillus reuteri 263 (Lr263) on hypolipidemic action in hamsters with hyperlipidemia induced by a 0.2% cholesterol and 10% lard diet (i.e., high-cholesterol diet (HCD)). Male Golden Syrian hamsters were randomly divided into two groups: normal (n = 8), standard diet (control), and experimental (n = 32), a HCD. After a two-week induction followed by a six-week supplementation with Lr263, the 32 hyperlipidemic hamsters were divided into four groups (n = 8 per group) to receive vehicle or Lr263 by oral gavage at 2.1, 4.2, or 10.5 × 109 cells/kg/day for 6 weeks, designated the HCD, 1X, 2X and 5X groups, respectively. The efficacy and safety of Lr263 supplementation were evaluated by lipid profiles of serum, liver and feces and by clinical biochemistry and histopathology. HCD significantly increased serum levels of total cholesterol (TC), triacylglycerol (TG) cholesterol, high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C), LDL-C/HDL-C ratio, hepatic and fetal TC and TG levels, and degree of fatty liver as compared with controls. Lr263 supplementation dose dependently increased serum HDL-C level and decreased serum TC, TG, LDL-C levels, LDL-C/HDL-C ratio, hepatic TC and TG levels, and fecal TG level. In addition, Lr263 supplementation had few subchronic toxic effects. Lr263 could be a potential agent with a hypolipidemic pharmacological effect. PMID:25988768

  20. Curcuma oil ameliorates hyperlipidaemia and associated deleterious effects in golden Syrian hamsters.

    PubMed

    Singh, Vishal; Jain, Manish; Misra, Ankita; Khanna, Vivek; Rana, Minakshi; Prakash, Prem; Malasoni, Richa; Dwivedi, Anil Kumar; Dikshit, Madhu; Barthwal, Manoj Kumar

    2013-08-28

    Essential oil components from turmeric (Curcuma longa L.) are documented for neuroprotective, anti-cancer, anti-thrombotic and antioxidant effects. The present study aimed to investigate the disease-modifying potential of curcuma oil (C. oil), a lipophilic component from C. longa L., in hyperlipidaemic hamsters. Male golden Syrian hamsters were fed a chow or high-cholesterol (HC) and fat-rich diet with or without C. oil (30, 100 and 300 mg/kg) for 28 d. In HC diet-fed hamsters, C. oil significantly reduced plasma total cholesterol, LDL-cholesterol and TAG, and increased HDL-cholesterol when compared with the HC group. Similar group comparisons showed that C. oil treatment reduced hepatic cholesterol and oxidative stress, and improved liver function. Hyperlipidaemia-induced platelet activation, vascular dysfunction and repressed eNOS mRNA expression were restored by the C. oil treatment. Furthermore, aortic cholesterol accumulation and CD68 expression were also reduced in the C. oil-treated group. The effect of C. oil at 300 mg/kg was comparable with the standard drug ezetimibe. Delving into the probable anti-hyperlipidaemic mechanism at the transcript level, the C. oil-treated groups fed the chow and HC diets were compared with the chow diet-fed group. The C. oil treatment significantly increased the hepatic expression of PPARa, LXRa, CYP7A1, ABCA1, ABCG5, ABCG8 and LPL accompanied b