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Sample records for alters dentate granule

  1. Altered morphology of hippocampal dentate granule cell presynaptic and postsynaptic terminals following conditional deletion of TrkB.

    PubMed

    Danzer, Steve C; Kotloski, Robert J; Walter, Cynthia; Hughes, Maya; McNamara, James O

    2008-01-01

    Dentate granule cells play a critical role in the function of the entorhinal-hippocampal circuitry in health and disease. Dentate granule cells are situated to regulate the flow of information into the hippocampus, a structure required for normal learning and memory. Correspondingly, impaired granule cell function leads to memory deficits, and, interestingly, altered granule cell connectivity may contribute to the hyperexcitability of limbic epilepsy. It is important, therefore, to understand the molecular determinants of synaptic connectivity of these neurons. Brain-derived neurotrophic factor and its receptor TrkB are expressed at high levels in the dentate gyrus (DG) of the hippocampus, and are implicated in regulating neuronal development, neuronal plasticity, learning, and the development of epilepsy. Whether and how TrkB regulates granule cell structure, however, is incompletely understood. To begin to elucidate the role of TrkB in regulating granule cell morphology, here we examine conditional TrkB knockout mice crossed to mice expressing green fluorescent protein in subsets of dentate granule cells. In stratum lucidum, where granule cell mossy fiber axons project, the density of giant mossy fiber boutons was unchanged, suggesting similar output to CA3 pyramidal cell targets. However, filopodial extensions of giant boutons, which contact inhibitory interneurons, were increased in number in TrkB knockout mice relative to wildtype controls, predicting enhanced feedforward inhibition of CA3 pyramidal cells. In knockout animals, dentate granule cells possessed fewer primary dendrites and enlarged dendritic spines, indicative of disrupted excitatory synaptic input to the granule cells. Together, these findings demonstrate that TrkB is required for development and/or maintenance of normal synaptic connectivity of the granule cells, thereby implying an important role for TrkB in the function of the granule cells and hippocampal circuitry.

  2. Effects of prenatal protein malnutrition on kindling-induced alterations in dentate granule cell excitability. II. Paired-pulse measures.

    PubMed

    Bronzino, J D; Austin-LaFrance, R J; Morgane, P J; Galler, J R

    1991-05-01

    The effects of prenatal protein malnutrition on kindling-induced changes in inhibitory modulation of dentate granule cell activity were examined by analysis of extracellular field potentials recorded from the granule cell layer of the dentate gyrus in response to paired-pulse stimulation of the perforant pathway in freely-moving rats. Since we have shown that kindling results in enhanced synaptic transmission at the level of the perforant path/granule cell synapse (see preceding paper), we sought to determine if the kindling process might induce changes in inhibitory modulation of granule cell excitability which could be involved in the slower acquisition of the kindled state we have previously reported in malnourished animals. Beginning at 120-150 days of age, the response of dentate granule cells to paired-pulse stimulation of the perforant path was examined at interpulse intervals (IPIs) ranging from 20-1000 ms. A paired-pulse index (PPI) was constructed based on the mean percent change in population spike amplitudes of the two responses resulting from application of the pulse pair. PPI measures obtained during the kindling process were compared with individual prekindling measures to determine the mean percent change in excitatory/inhibitory modulation of granule cell activity. Significant inhibition of the second population response was apparent at all IPIs tested for both diet groups following the first kindled afterdischarge.(ABSTRACT TRUNCATED AT 250 WORDS)

  3. Altered patterning of dentate granule cell mossy fiber inputs onto CA3 pyramidal cells in limbic epilepsy

    PubMed Central

    McAuliffe, John J.; Bronson, Stefanie L.; Hester, Michael S.; Murphy, Brian L.; Dahlquist-Topalá, Renée; Richards, David A.; Danzer, Steve C.

    2009-01-01

    Impaired gating by hippocampal dentate granule cells may promote the development of limbic epilepsy by facilitating seizure spread through the hippocampal trisynaptic circuit. The second synapse in this circuit, the dentate granule cell≫CA3 pyramidal cell connection, may be of particular importance because pathological changes occurring within the dentate likely exert their principal effect on downstream CA3 pyramids. Here, we utilized GFP-expressing mice and immunolabeling for the zinc transporter ZnT-3 to reveal the pre- and postsynaptic components of granule cell≫CA3 pyramidal cell synapses following pilocarpine-epileptogenesis. Confocal analyses of these terminals revealed that while granule cell presynaptic giant boutons increased in size and complexity one month after status epilepticus, individual thorns making up the postsynaptic thorny excrescences of the CA3 pyramidal cells were reduced in number. This reduction, however, was transient, and three months after status, thorn density recovered. This recovery was accompanied by a significant change in the distribution of thorns along pyramidal cells dendrites. While thorns in control animals tended to be tightly clustered, thorns in epileptic animals were more evenly distributed. Computational modeling of thorn distributions predicted an increase in the number of boutons required to cover equivalent numbers of thorns in epileptic vs. control mice. Confirming this prediction, ZnT-3 labeling of presynaptic giant boutons apposed to GFP-expressing thorns revealed a near doubling in bouton density, while the number of individual thorns per bouton was reduced by half. Together, these data provide clear evidence of novel plastic changes occurring within the epileptic hippocampus. PMID:20014385

  4. GSK-3β Overexpression Alters the Dendritic Spines of Developmentally Generated Granule Neurons in the Mouse Hippocampal Dentate Gyrus

    PubMed Central

    Pallas-Bazarra, Noemí; Kastanauskaite, Asta; Avila, Jesús; DeFelipe, Javier; Llorens-Martín, María

    2017-01-01

    The dentate gyrus (DG) plays a crucial role in hippocampal-related memory. The most abundant cellular type in the DG, namely granule neurons, are developmentally generated around postnatal day P6 in mice. Moreover, a unique feature of the DG is the occurrence of adult hippocampal neurogenesis, a process that gives rise to newborn granule neurons throughout life. Adult-born and developmentally generated granule neurons share some maturational aspects but differ in others, such as in their positioning within the granule cell layer. Adult hippocampal neurogenesis encompasses a series of plastic changes that modify the function of the hippocampal trisynaptic network. In this regard, it is known that glycogen synthase kinase 3β (GSK-3β) regulates both synaptic plasticity and memory. By using a transgenic mouse overexpressing GSK-3β in hippocampal neurons, we previously demonstrated that the overexpression of this kinase has deleterious effects on the maturation of newborn granule neurons. In the present study, we addressed the effects of GSK-3β overexpression on the morphology and number of dendritic spines of developmentally generated granule neurons. To this end, we performed intracellular injections of Lucifer Yellow in developmentally generated granule neurons of wild-type and GSK-3β-overexpressing mice and analyzed the number and morphologies of dendritic spines (namely, stubby, thin and mushroom). GSK-3β overexpression led to a general reduction in the number of dendritic spines. In addition, it caused a slight reduction in the percentage, head diameter and length of thin spines, whereas the head diameter of mushroom spines was increased. PMID:28344548

  5. Effects of prenatal protein malnutrition on kindling-induced alterations in dentate granule cell excitability. I. Synaptic transmission measures.

    PubMed

    Bronzino, J D; Austin-LaFrance, R J; Morgane, P J; Galler, J R

    1991-05-01

    The effects of prenatal protein malnutrition upon the efficacy of excitatory synaptic transmission at the level of the perforant path/dentate granule cell synapse were examined during development of perforant path kindling in chronically implanted adults rats. Rats born to dams fed a low protein (6% casein) or control protein (25% casein) diet were fostered to lactating dams fed the 25% casein diet 24 h after birth and were maintained on this diet throughout life following weaning. Beginning at 90-120 days of age, animals received daily kindling stimulations applied to the perforant path. Extracellular field potentials recorded from the granule cell layer of the dentate gyrus in response to single-pulse stimulation of the perforant path were analyzed to determine the effects of prenatal protein malnutrition on the efficacy of synaptic transmission during the kindling process. Measures used for these analyses included the EPSP slope, an indicator of the level of synaptic drive, the population spike amplitude which is a measure of postsynaptic activation and cellular firing, and the ratio of the population spike amplitude relative to the corresponding EPSP slope value, which was used to evaluate the overall efficacy of synaptic transmission. animals of the 6%/25% diet group were found to have significantly lower afterdischarge thresholds, yet required significantly more daily kindling stimulations to develop generalized motor convulsions (stage 5 seizure) than control animals. Examination of dentate field potentials obtained prior to kindling revealed no significant between group differences in measures of EPSP slope or population spike amplitude. Statistically significant increases in measures of both the population EPSP slope and population spike amplitude were observed in both diet groups 24 h after the first kindled afterdischarge. The degree of increase in both of these measures was significantly greater in animals of the 6%/25% group. Evaluation of input

  6. Preventing Effect of L-Type Calcium Channel Blockade on Electrophysiological Alterations in Dentate Gyrus Granule Cells Induced by Entorhinal Amyloid Pathology

    PubMed Central

    Pourbadie, Hamid Gholami; Naderi, Nima; Mehranfard, Nasrin; Janahmadi, Mahyar; Khodagholi, Fariba; Motamedi, Fereshteh

    2015-01-01

    The entorhinal cortex (EC) is one of the earliest affected brain regions in Alzheimer’s disease (AD). EC-amyloid pathology induces synaptic failure in the dentate gyrus (DG) with resultant behavioral impairment, but there is little known about its impact on neuronal properties in the DG. It is believed that calcium dyshomeostasis plays a pivotal role in the etiology of AD. Here, the effect of the EC amyloid pathogenesis on cellular properties of DG granule cells and also possible neuroprotective role of L-type calcium channel blockers (CCBs), nimodipine and isradipine, were investigated. The amyloid beta (Aβ) 1–42 was injected bilaterally into the EC of male rats and one week later, electrophysiological properties of DG granule cells were assessed. Voltage clamp recording revealed appearance of giant sIPSC in combination with a decrease in sEPSC frequency which was partially reversed by CCBs in granule cells from Aβ treated rats. EC amyloid pathogenesis induced a significant reduction of input resistance (Rin) accompanied by a profound decreased excitability in the DG granule cells. However, daily administration of CCBs, isradipine or nimodipine (i.c.v. for 6 days), almost preserved the normal excitability against Aβ. In conclusion, lower tendency to fire AP along with reduced Rin suggest that DG granule cells might undergo an alteration in the membrane ion channel activities which finally lead to the behavioral deficits observed in animal models and patients with early-stage Alzheimer’s disease. PMID:25689857

  7. Ectopic Granule Cells of the Rat Dentate Gyrus

    PubMed Central

    Scharfman, Helen; Goodman, Jeffrey; McCloskey, Daniel

    2007-01-01

    Granule cells of the mammalian dentate gyrus normally form a discrete layer, and virtually all granule cells migrate to this location. Exceptional granule cells that are positioned incorrectly, in ‘ectopic’ locations, are rare. Although the characteristics of such ectopic granule cells appear similar in many respects to granule cells located in the granule cell layer, their rare occurrence has limited a full evaluation of their structure and function. More information about ectopic granule cells has been obtained by studying those that develop after experimental manipulations that increase their number. For example, after severe seizures, the number of ectopic granule cells located in the hilus increases dramatically. These experimentally induced ectopic granule cells may not be equivalent to normal ectopic granule cells necessarily, but the vastly increased numbers have allowed much more information to be obtained. Remarkably, the granule cells that are positioned ectopically develop intrinsic properties and an axonal projection that are similar to granule cells that are located normally, i.e., in the granule cell layer. However, dendritic structure and synaptic structure/function appear to differ. These studies have provided new insight into a rare type of granule cell in the dentate gyrus, and the plastic characteristics of dentate granule cells that appear to depend on the location of the cell body. PMID:17148946

  8. Massively augmented hippocampal dentate granule cell activation accompanies epilepsy development.

    PubMed

    Dengler, Christopher G; Yue, Cuiyong; Takano, Hajime; Coulter, Douglas A

    2017-02-20

    In a mouse model of temporal lobe epilepsy, multicellular calcium imaging revealed that disease emergence was accompanied by massive amplification in the normally sparse, afferent stimulation-induced activation of hippocampal dentate granule cells. Patch recordings demonstrated reductions in local inhibitory function within the dentate gyrus at time points where sparse activation was compromised. Mimicking changes in inhibitory synaptic function and transmembrane chloride regulation was sufficient to elicit the dentate gyrus circuit collapse evident during epilepsy development. Pharmacological blockade of outward chloride transport had no effect during epilepsy development, and significantly increased granule cell activation in both control and chronically epileptic animals. This apparent occlusion effect implicates reduction in chloride extrusion as a mechanism contributing to granule cell hyperactivation specifically during early epilepsy development. Glutamine plays a significant role in local synthesis of GABA in synapses. In epileptic mice, sparse granule cell activation could be restored by glutamine application, implicating compromised GABA synthesis. Glutamine had no effect on granule cell activation earlier, during epilepsy development. We conclude that compromised feedforward inhibition within the local circuit generates the massive dentate gyrus circuit hyperactivation evident in animals during and following epilepsy development. However, the mechanisms underlying this disinhibition diverge significantly as epilepsy progresses.

  9. Massively augmented hippocampal dentate granule cell activation accompanies epilepsy development

    PubMed Central

    Dengler, Christopher G.; Yue, Cuiyong; Takano, Hajime; Coulter, Douglas A.

    2017-01-01

    In a mouse model of temporal lobe epilepsy, multicellular calcium imaging revealed that disease emergence was accompanied by massive amplification in the normally sparse, afferent stimulation-induced activation of hippocampal dentate granule cells. Patch recordings demonstrated reductions in local inhibitory function within the dentate gyrus at time points where sparse activation was compromised. Mimicking changes in inhibitory synaptic function and transmembrane chloride regulation was sufficient to elicit the dentate gyrus circuit collapse evident during epilepsy development. Pharmacological blockade of outward chloride transport had no effect during epilepsy development, and significantly increased granule cell activation in both control and chronically epileptic animals. This apparent occlusion effect implicates reduction in chloride extrusion as a mechanism contributing to granule cell hyperactivation specifically during early epilepsy development. Glutamine plays a significant role in local synthesis of GABA in synapses. In epileptic mice, sparse granule cell activation could be restored by glutamine application, implicating compromised GABA synthesis. Glutamine had no effect on granule cell activation earlier, during epilepsy development. We conclude that compromised feedforward inhibition within the local circuit generates the massive dentate gyrus circuit hyperactivation evident in animals during and following epilepsy development. However, the mechanisms underlying this disinhibition diverge significantly as epilepsy progresses. PMID:28218241

  10. Disrupted Dentate Granule Cell Chloride Regulation Enhances Synaptic Excitability during Development of Temporal Lobe Epilepsy

    PubMed Central

    Pathak, Hemal R.; Weissinger, Florian; Terunuma, Miho; Carlson, Gregory C.; Hsu, Fu-Chun; Moss, Stephen J.; Coulter, Douglas A.

    2008-01-01

    GABAA receptor-mediated inhibition depends on the maintenance of intracellular Cl− concentration ([Cl−]in ) at low levels. In neurons in the developing CNS, [Cl−]in is elevated, EGABA is depolarizing, and GABA consequently is excitatory. Depolarizing GABAergic synaptic responses may be recapitulated in various neuropathological conditions, including epilepsy. In the present study, rat hippocampal dentate granule cells were recorded using gramicidin perforated patch techniques at varying times (1–60 d) after an epileptogenic injury, pilocarpine-induced status epilepticus (STEP). In normal, non-epileptic animals, these strongly inhibited dentate granule cells act as a gate, regulating hippocampal excitation, controlling seizure initiation and/or propagation. For 2 weeks after STEP, we found that EGABA was positively shifted in granule cells. This shift in EGABA altered synaptic integration, increased granule cell excitability, and resulted in compromised “gate” function of the dentate gyrus. EGABA recovered to control values at longer latencies post-STEP (2–8 weeks), when animals had developed epilepsy. During this period of shifted EGABA, expression of the Cl− extruding K+/Cl− cotransporter, KCC2 was decreased. Application of the KCC2 blocker, furosemide, to control neurons mimicked EGABA shifts evident in granule cells post-STEP. Furthermore, post-STEP and furosemide effects interacted occlusively, both on EGABA in granule cells, and on gatekeeper function of the dentate gyrus. This suggests a shared mechanism, reduced KCC2 function. These findings demonstrate that decreased expression of KCC2 persists for weeks after an epileptogenic injury, reducing inhibitory efficacy and enhancing dentate granule cell excitability. This pathophysiological process may constitute a significant mechanism linking injury to the subsequent development of epilepsy. PMID:18094240

  11. Newborn granule cells in the ageing dentate gyrus

    PubMed Central

    Morgenstern, Nicolás A; Lombardi, Gabriela; Schinder, Alejandro F

    2008-01-01

    The dentate gyrus of the hippocampus generates neurons throughout life, but adult neurogenesis exhibits a marked age-dependent decline. Although the decrease in the rate of neurogenesis has been extensively documented in the ageing hippocampus, the specific characteristics of dentate granule cells born in such a continuously changing environment have received little attention. We have used retroviral labelling of neural progenitor cells of the adult mouse dentate gyrus to study morphological properties of neurons born at different ages. Dendritic spine density was measured to estimate glutamatergic afferent connectivity. Fully mature neurons born at the age of 2 months display ∼2.3 spines μm−1 and maintain their overall morphology and spine density in 1-year-old mice. Surprisingly, granule cells born in 10-month-old mice, at which time the rate of neurogenesis has decreased by ∼40-fold, reach a density of dendritic spines similar to that of neurons born in young adulthood. Therefore, in spite of the sharp decline in cell proliferation, differentiation and overall neuronal number, the ageing hippocampus presents a suitable environment for new surviving neurons to reach a high level of complexity, comparable to that of all other dentate granule cells. PMID:18565998

  12. Dentate granule cell modulation in freely moving rats: vigilance state effects.

    PubMed

    Bronzino, J D; Blaise, J H; Mokler, D J; Morgane, P J

    1999-04-12

    Dentate granule cell population responses to paired-pulse stimulation applied to the perforant pathway across a range of interpulse intervals (IPIs) were examined during different vigilance states-quiet waking (QW), slow-wave sleep (SWS), and rapid-eye movement (REM) sleep-in freely moving rats at 15, 30 and 90 days of age. Using these evoked field potentials, the paired-pulse index (PPI), a measure of the type and degree of modulation of dentate granule cell excitability, was computed and shown to be altered as a function of age. Animals, 15 days old, showed significantly lower levels of early inhibition (20-40 ms IPIs), i.e., greater PPI values, during all three vigilance states when compared to both the 30- and 90-day old animals. Adult, i.e, 90-day old animals, on the other hand, showed significantly greater levels of late inhibition (300-1000 ms IPIs), i.e., lower PPI values, than the younger animals (15- and 30-day old) during QW and SWS. These results indicate that as the dentate field of the hippocampal formation matures there are significant alterations in the modulation of dentate granule cell activity.

  13. How to make a hippocampal dentate gyrus granule neuron.

    PubMed

    Yu, Diana X; Marchetto, Maria C; Gage, Fred H

    2014-06-01

    Granule neurons in the hippocampal dentate gyrus (DG) receive their primary inputs from the cortex and are known to be continuously generated throughout adult life. Ongoing integration of newborn neurons into the existing hippocampal neural circuitry provides enhanced neuroplasticity, which plays a crucial role in learning and memory; deficits in this process have been associated with cognitive decline under neuropathological conditions. In this Primer, we summarize the developmental principles that regulate the process of DG neurogenesis and discuss recent advances in harnessing these developmental cues to generate DG granule neurons from human pluripotent stem cells.

  14. Sparse activity of identified dentate granule cells during spatial exploration

    PubMed Central

    Diamantaki, Maria; Frey, Markus; Berens, Philipp; Preston-Ferrer, Patricia; Burgalossi, Andrea

    2016-01-01

    In the dentate gyrus – a key component of spatial memory circuits – granule cells (GCs) are known to be morphologically diverse and to display heterogeneous activity profiles during behavior. To resolve structure–function relationships, we juxtacellularly recorded and labeled single GCs in freely moving rats. We found that the vast majority of neurons were silent during exploration. Most active GCs displayed a characteristic spike waveform, fired at low rates and showed spatial activity. Primary dendritic parameters were sufficient for classifying neurons as active or silent with high accuracy. Our data thus support a sparse coding scheme in the dentate gyrus and provide a possible link between structural and functional heterogeneity among the GC population. DOI: http://dx.doi.org/10.7554/eLife.20252.001 PMID:27692065

  15. PTEN deletion from adult-generated dentate granule cells disrupts granule cell mossy fiber axon structure

    PubMed Central

    LaSarge, Candi L.; Santos, Victor R; Danzer, Steve C.

    2015-01-01

    Dysregulation of the mTOR-signaling pathway is implicated in the development of temporal lobe epilepsy. In mice, deletion of PTEN from hippocampal dentate granule cells leads to mTOR hyperactivation and promotes the rapid onset of spontaneous seizures. The mechanism by which these abnormal cells initiate epileptogenesis, however, is unclear. PTEN-knockout granule cells develop abnormally, exhibiting morphological features indicative of increased excitatory input. If these cells are directly responsible for seizure genesis, it follows that they should also possess increased output. To test this prediction, dentate granule cell axon morphology was quantified in control and PTEN-knockout mice. Unexpectedly, PTEN deletion increased giant mossy fiber bouton spacing along the axon length, suggesting reduced innervation of CA3. Increased width of the mossy fiber axon pathway in stratum lucidum, however, which likely reflects an unusual increase in mossy fiber axon collateralization in this region, offset the reduction in boutons per axon length. These morphological changes predicts a net increase in granule cell >> CA3 innervation. Increased diameter of axons from PTEN-knockout cells would further enhance granule cell >> CA3 communication. Altogether, these findings suggest that amplified information flow through the hippocampal circuit contributes to seizure occurrence in the PTEN-knockout mouse model of temporal lobe epilepsy. PMID:25600212

  16. Potassium currents in acutely isolated human hippocampal dentate granule cells.

    PubMed Central

    Beck, H; Clusmann, H; Kral, T; Schramm, J; Heinemann, U; Elger, C E

    1997-01-01

    1. Properties of voltage- and Ca(2+)-dependent K+ currents were investigated in thirty-four dentate granule cells acutely isolated from the resected hippocampus of eleven patients with therapy-refractory temporal lobe epilepsy (TLE). 2. When intracellular Ca2+ was strongly buffered with 11.5 mM EGTA-1 mM Ca2+ in the recording pipette, K+ currents (IK) with a slow activation and biexponential time-dependent decay could be elicited, which showed a threshold for activation around -30 mV. 3. A contribution of Ca(2+)-dependent K+ currents became apparent with intracellular solution containing 1 mM BAPTA-0.1 mM Ca2+. Superfusion of low-Ca2+ extracellular solution blocked 43% of outward currents in this recording configuration. Outward current components could also be blocked by substituting 5 mM Ba2+ for extracellular Ca2+ (78%), or by application of 100 microM Cd2+ (25%). 4. The Ca(2+)-dependent K+ currents could be pharmacologically subdivided into two components. One component was sensitive to 500 microM tetraethylammmonium (TEA; 41%) and 10 nM charybdotoxin (CTX; 47.2%). The blocking effects of 10 nM CTX and 500 microM TEA were not additive, suggesting that both agents block the same conductance. A second, smaller outward current component was blocked by 50 nM apamin (13%). 5. A transient A-type K+ current could be observed in six neurones and showed a fast monoexponential time-dependent inactivation with a steady-state voltage dependence that was distinct from that of IK. The A-type current was blocked by 4-aminopyridine (4-AP) but not by TEA or low-Ca2+ solution. 6. We conclude that outward currents in human hippocampal dentate granule cells can be separated into at least four types by their kinetic and pharmacological properties. These include at least one voltage-dependent current similar to those observed in mammalian hippocampal neurones, and two Ca(2+)-dependent K+ currents that most probably correspond to SK- and BK-type currents. A classical A-type current

  17. Granule cell hyperexcitability in the early post-traumatic rat dentate gyrus: the ‘irritable mossy cell’ hypothesis

    PubMed Central

    Santhakumar, Vijayalakshmi; Bender, Roland; Frotscher, Michael; Ross, Stephen T; Hollrigel, Greg S; Toth, Zsolt; Soltesz, Ivan

    2000-01-01

    Cytochemical and in vitro whole-cell patch clamp techniques were used to investigate granule cell hyperexcitability in the dentate gyrus 1 week after fluid percussion head trauma. The percentage decrease in the number of hilar interneurones labelled with either GAD67 or parvalbumin mRNA probes following trauma was not different from the decrease in the total population of hilar cells, indicating no preferential survival of interneurones with respect to the non-GABAergic hilar cells, i.e. the mossy cells. Dentate granule cells following trauma showed enhanced action potential discharges, and longer-lasting depolarizations, in response to perforant path stimulation, in the presence of the GABAA receptor antagonist bicuculline. There was no post-traumatic alteration in the perforant path-evoked monosynaptic excitatory postsynaptic currents (EPSCs), or in the intrinsic properties of granule cells. However, after trauma, the monosynaptic EPSC was followed by late, polysynaptic EPSCs, which were not present in controls. The late EPSCs in granule cells from fluid percussion-injured rats were not blocked by the NMDA receptor antagonist 2-amino-5-phosphonovaleric acid (APV), but were eliminated by both the non-NMDA glutamate receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) and the AMPA receptor antagonist GYKI 53655. In addition, the late EPSCs were not present in low (0·5 mM) extracellular calcium, and they were also eliminated by the removal of the dentate hilus from the slice. Mossy hilar cells in the traumatic dentate gyrus responded with significantly enhanced, prolonged trains of action potential discharges to perforant path stimulation. These data indicate that surviving mossy cells play a crucial role in the hyperexcitable responses of the post-traumatic dentate gyrus. PMID:10747187

  18. Granule cell hyperexcitability in the early post-traumatic rat dentate gyrus: the 'irritable mossy cell' hypothesis.

    PubMed

    Santhakumar, V; Bender, R; Frotscher, M; Ross, S T; Hollrigel, G S; Toth, Z; Soltesz, I

    2000-04-01

    1. Cytochemical and in vitro whole-cell patch clamp techniques were used to investigate granule cell hyperexcitability in the dentate gyrus 1 week after fluid percussion head trauma. 2. The percentage decrease in the number of hilar interneurones labelled with either GAD67 or parvalbumin mRNA probes following trauma was not different from the decrease in the total population of hilar cells, indicating no preferential survival of interneurones with respect to the non-GABAergic hilar cells, i.e. the mossy cells. 3. Dentate granule cells following trauma showed enhanced action potential discharges, and longer-lasting depolarizations, in response to perforant path stimulation, in the presence of the GABAA receptor antagonist bicuculline. 4. There was no post-traumatic alteration in the perforant path-evoked monosynaptic excitatory postsynaptic currents (EPSCs), or in the intrinsic properties of granule cells. However, after trauma, the monosynaptic EPSC was followed by late, polysynaptic EPSCs, which were not present in controls. 5. The late EPSCs in granule cells from fluid percussion-injured rats were not blocked by the NMDA receptor antagonist 2-amino-5-phosphonovaleric acid (APV), but were eliminated by both the non-NMDA glutamate receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) and the AMPA receptor antagonist GYKI 53655. 6. In addition, the late EPSCs were not present in low (0.5 mM) extracellular calcium, and they were also eliminated by the removal of the dentate hilus from the slice. 7. Mossy hilar cells in the traumatic dentate gyrus responded with significantly enhanced, prolonged trains of action potential discharges to perforant path stimulation. 8. These data indicate that surviving mossy cells play a crucial role in the hyperexcitable responses of the post-traumatic dentate gyrus.

  19. Spatial Representations of Granule Cells and Mossy Cells of the Dentate Gyrus.

    PubMed

    GoodSmith, Douglas; Chen, Xiaojing; Wang, Cheng; Kim, Sang Hoon; Song, Hongjun; Burgalossi, Andrea; Christian, Kimberly M; Knierim, James J

    2017-02-08

    Granule cells in the dentate gyrus of the hippocampus are thought to be essential to memory function by decorrelating overlapping input patterns (pattern separation). A second excitatory cell type in the dentate gyrus, the mossy cell, forms an intricate circuit with granule cells, CA3c pyramidal cells, and local interneurons, but the influence of mossy cells on dentate function is often overlooked. Multiple tetrode recordings, supported by juxtacellular recording techniques, showed that granule cells fired very sparsely, whereas mossy cells in the hilus fired promiscuously in multiple locations and in multiple environments. The activity patterns of these cell types thus represent different environments through distinct computational mechanisms: sparse coding in granule cells and changes in firing field locations in mossy cells.

  20. Depletion of primary cilia from mature dentate granule cells impairs hippocampus-dependent contextual memory

    PubMed Central

    Rhee, Soyoung; Kirschen, Gregory W.; Gu, Yan; Ge, Shaoyu

    2016-01-01

    The primary cilium, a sensory organelle, regulates cell proliferation and neuronal development of dentate granule cells in the hippocampus. However, its role in the function of mature dentate granule cells remains unknown. Here we specifically depleted and disrupted ciliary proteins IFT20 and Kif3A (respectively) in mature dentate granule cells and investigated hippocampus-dependent contextual memory and long-term plasticity at mossy fiber synapses. We found that depletion of IFT20 in these cells significantly impaired context-dependent fear-related memory. Furthermore, we tested synaptic plasticity of mossy fiber synapses in area CA3 and found increased long-term potentiation upon depletion of IFT20 or disruption of Kif3A. Our findings suggest a role of primary cilia in the memory function of mature dentate granule cells, which may result from abnormal mossy fiber synaptic plasticity. A direct link between the primary cilia of mature dentate granule cells and behavior will require further investigation using independent approaches to manipulate primary cilia. PMID:27678193

  1. Activation of protease activated receptor 1 increases the excitability of the dentate granule neurons of hippocampus

    PubMed Central

    2011-01-01

    Protease activated receptor-1 (PAR1) is expressed in multiple cell types in the CNS, with the most prominent expression in glial cells. PAR1 activation enhances excitatory synaptic transmission secondary to the release of glutamate from astrocytes following activation of astrocytically-expressed PAR1. In addition, PAR1 activation exacerbates neuronal damage in multiple in vivo models of brain injury in a manner that is dependent on NMDA receptors. In the hippocampal formation, PAR1 mRNA appears to be expressed by a subset of neurons, including granule cells in the dentate gyrus. In this study we investigate the role of PAR activation in controlling neuronal excitability of dentate granule cells. We confirm that PAR1 protein is expressed in neurons of the dentate cell body layer as well as in astrocytes throughout the dentate. Activation of PAR1 receptors by the selective peptide agonist TFLLR increased the intracellular Ca2+ concentration in a subset of acutely dissociated dentate neurons as well as non-neuronal cells. Bath application of TFLLR in acute hippocampal slices depolarized the dentate gyrus, including the hilar region in wild type but not in the PAR1-/- mice. PAR1 activation increased the frequency of action potential generation in a subset of dentate granule neurons; cells in which PAR1 activation triggered action potentials showed a significant depolarization. The activation of PAR1 by thrombin increased the amplitude of NMDA receptor-mediated component of EPSPs. These data suggest that activation of PAR1 during normal function or pathological conditions, such as during ischemia or hemorrhage, can increase the excitability of dentate granule cells. PMID:21827709

  2. An LRRTM4-HSPG complex mediates excitatory synapse development on dentate gyrus granule cells.

    PubMed

    Siddiqui, Tabrez J; Tari, Parisa Karimi; Connor, Steven A; Zhang, Peng; Dobie, Frederick A; She, Kevin; Kawabe, Hiroshi; Wang, Yu Tian; Brose, Nils; Craig, Ann Marie

    2013-08-21

    Selective synapse development determines how complex neuronal networks in the brain are formed. Complexes of postsynaptic neuroligins and LRRTMs with presynaptic neurexins contribute widely to excitatory synapse development, and mutations in these gene families increase the risk of developing psychiatric disorders. We find that LRRTM4 has distinct presynaptic binding partners, heparan sulfate proteoglycans (HSPGs). HSPGs are required to mediate the synaptogenic activity of LRRTM4. LRRTM4 shows highly selective expression in the brain. Within the hippocampus, we detected LRRTM4 specifically at excitatory postsynaptic sites on dentate gyrus granule cells. LRRTM4(-/-) dentate gyrus granule cells, but not CA1 pyramidal cells, exhibit reductions in excitatory synapse density and function. Furthermore, LRRTM4(-/-) dentate gyrus granule cells show impaired activity-regulated AMPA receptor trafficking. These results identifying cell-type-specific functions and multiple presynaptic binding partners for different LRRTM family members reveal an unexpected complexity in the design and function of synapse-organizing proteins.

  3. Functional alpha7 nicotinic receptors are expressed on immature granule cells of the postnatal dentate gyrus.

    PubMed

    John, Danielle; Shelukhina, Irina; Yanagawa, Yuchio; Deuchars, Jim; Henderson, Zaineb

    2015-03-19

    Neurogenesis occurs throughout life in the subgranular zone of the dentate gyrus, and postnatal-born granule cells migrate into the granule cell layer and extend axons to their target areas. The α7*nicotinic receptor has been implicated in neuronal maturation during development of the brain and is abundant in interneurons of the hippocampal formation of the adult brain. Signalling through these same receptors is believed also to promote maturation and integration of adult-born granule cells in the hippocampal formation. We therefore aimed to determine whether functional α7*nicotinic receptors are expressed in developing granule cells of the postnatal dentate gyrus. For these experiments we used 2-3 week-old Wistar rats, and 2-9 week old transgenic mice in which GABAergic interneurons were marked by expression of green fluorescent protein. Immunohistochemistry indicated the presence of α7*nicotinic receptor subunits around granule cells close around the subgranular zone which correlated with the distribution of developmental markers for immature granule cells. Whole-cell patch clamp recording showed that a proportion of granule cells responded to puffed ACh in the presence of atropine, and that these cells possessed electrophysiological properties found in immature granule cells. The nicotinic responses were potentiated by an allosteric α7*nicotinic receptor modulator, which were blocked by a specific α7*nicotinic receptor antagonist and were not affected by ionotropic glutamate or GABA receptor antagonists. These results suggest the presence of functional somato-dendritic α7*nicotinic receptors on immature granule cells of the postnatal dentate gyrus, consistent with studies implicating α7*nicotinic receptors in dendritic maturation of dentate gyrus neurons in adult brain.

  4. Functional alpha7 nicotinic receptors are expressed on immature granule cells of the postnatal dentate gyrus

    PubMed Central

    John, Danielle; Shelukhina, Irina; Yanagawa, Yuchio; Deuchars, Jim; Henderson, Zaineb

    2015-01-01

    Neurogenesis occurs throughout life in the subgranular zone of the dentate gyrus, and postnatal-born granule cells migrate into the granule cell layer and extend axons to their target areas. The α7⁎nicotinic receptor has been implicated in neuronal maturation during development of the brain and is abundant in interneurons of the hippocampal formation of the adult brain. Signalling through these same receptors is believed also to promote maturation and integration of adult-born granule cells in the hippocampal formation. We therefore aimed to determine whether functional α7⁎nicotinic receptors are expressed in developing granule cells of the postnatal dentate gyrus. For these experiments we used 2–3 week-old Wistar rats, and 2–9 week old transgenic mice in which GABAergic interneurons were marked by expression of green fluorescent protein. Immunohistochemistry indicated the presence of α7⁎nicotinic receptor subunits around granule cells close around the subgranular zone which correlated with the distribution of developmental markers for immature granule cells. Whole-cell patch clamp recording showed that a proportion of granule cells responded to puffed ACh in the presence of atropine, and that these cells possessed electrophysiological properties found in immature granule cells. The nicotinic responses were potentiated by an allosteric α7⁎nicotinic receptor modulator, which were blocked by a specific α7⁎nicotinic receptor antagonist and were not affected by ionotropic glutamate or GABA receptor antagonists. These results suggest the presence of functional somato-dendritic α7⁎nicotinic receptors on immature granule cells of the postnatal dentate gyrus, consistent with studies implicating α7⁎nicotinic receptors in dendritic maturation of dentate gyrus neurons in adult brain. PMID:25553616

  5. Active dentate granule cells encode experience to promote the addition of adult-born hippocampal neurons.

    PubMed

    Kirschen, Gregory W; Shen, Jia; Tian, Mu; Schroeder, Bryce; Wang, Jia; Man, Guoming; Wu, Song; Ge, Shaoyu

    2017-04-03

    The continuous addition of new dentate granule cells, exquisitely regulated by brain activity, renders the hippocampus plastic. However, how neural circuits encode experiences to impact the addition of adult-born neurons remains unknown. Here, we used endoscopic Ca(2+) imaging to track the real-time activity of individual dentate granule cells in freely-behaving mice. For the first time, we found that active dentate granule cells responded to a novel experience by preferentially increasing their Ca(2+) event frequency. This elevated activity, which we found to be associated with object exploration, returned to baseline by one hour in the same environment, but could be dishabituated via introduction to a novel environment. To seamlessly transition between environments, we next established a freely-controllable virtual reality system for unrestrained mice. We again observed increased firing of active neurons in a virtual enriched environment. Interestingly, multiple novel virtual experiences accumulatively increased the number of newborn neurons when compared to a single experience. Finally, optogenetic silencing of existing dentate granule cells during novel environmental exploration perturbed experience-induced neuronal addition. Together, our study shows that the adult brain conveys novel, enriched experiences to increase the addition of adult-born hippocampal neurons by increasing the firing of active dentate granule cells.SIGNIFICANCE STATEMENTAdult brains are constantly reshaping themselves from synapses to circuits as we encounter novel experiences from moment to moment. Importantly, this reshaping includes the addition of newborn hippocampal neurons. However, it remains largely unknown how our circuits encode experience-induced brain activity to govern the addition of new hippocampal neurons. By coupling in vivo Ca(2+) imaging of dentate granule neurons with a novel unrestrained virtual reality system for rodents, we discovered that a new experience rapidly

  6. Rapid erasure of hippocampal memory following inhibition of dentate gyrus granule cells

    PubMed Central

    Madroñal, Noelia; Delgado-García, José M.; Fernández-Guizán, Azahara; Chatterjee, Jayanta; Köhn, Maja; Mattucci, Camilla; Jain, Apar; Tsetsenis, Theodoros; Illarionova, Anna; Grinevich, Valery; Gross, Cornelius T.; Gruart, Agnès

    2016-01-01

    The hippocampus is critical for the acquisition and retrieval of episodic and contextual memories. Lesions of the dentate gyrus, a principal input of the hippocampus, block memory acquisition, but it remains unclear whether this region also plays a role in memory retrieval. Here we combine cell-type specific neural inhibition with electrophysiological measurements of learning-associated plasticity in behaving mice to demonstrate that dentate gyrus granule cells are not required for memory retrieval, but instead have an unexpected role in memory maintenance. Furthermore, we demonstrate the translational potential of our findings by showing that pharmacological activation of an endogenous inhibitory receptor expressed selectively in dentate gyrus granule cells can induce a rapid loss of hippocampal memory. These findings open a new avenue for the targeted erasure of episodic and contextual memories. PMID:26988806

  7. Reduced inhibition of dentate granule cells in a model of temporal lobe epilepsy.

    PubMed

    Kobayashi, Masayuki; Buckmaster, Paul S

    2003-03-15

    Patients and models of temporal lobe epilepsy have fewer inhibitory interneurons in the dentate gyrus than controls, but it is unclear whether granule cell inhibition is reduced. We report the loss of GABAergic inhibition of granule cells in the temporal dentate gyrus of pilocarpine-induced epileptic rats. In situ hybridization for GAD65 mRNA and immunocytochemistry for parvalbumin and somatostatin confirmed the loss of inhibitory interneurons. In epileptic rats, granule cells had prolonged EPSPs, and they discharged more action potentials than controls. Although the conductances of evoked IPSPs recorded in normal ACSF were not significantly reduced and paired-pulse responses showed enhanced inhibition of granule cells from epileptic rats, more direct measures of granule cell inhibition revealed significant deficiencies. In granule cells from epileptic rats, evoked monosynaptic IPSP conductances were <40% of controls, and the frequency of GABA(A) receptor-mediated spontaneous and miniature IPSCs (mIPSCs) was <50% of controls. Within 3-7 d after pilocarpine-induced status epilepticus, miniature IPSC frequency had decreased, and it remained low, without functional evidence of compensatory synaptogenesis by GABAergic axons in chronically epileptic rats. Both parvalbumin- and somatostatin-immunoreactive interneuron numbers and the frequency of both fast- and slow-rising GABA(A) receptor-mediated mIPSCs were reduced, suggesting that loss of inhibitory synaptic input to granule cells occurred at both proximal/somatic and distal/dendritic sites. Reduced granule cell inhibition in the temporal dentate gyrus preceded the onset of spontaneous recurrent seizures by days to weeks, so it may contribute, but is insufficient, to cause epilepsy.

  8. Synaptosomal-associated protein 25 mutation induces immaturity of the dentate granule cells of adult mice

    PubMed Central

    2013-01-01

    Background Synaptosomal-associated protein, 25 kDa (SNAP-25) regulates the exocytosis of neurotransmitters. Growing evidence suggests that SNAP-25 is involved in neuropsychiatric disorders, such as schizophrenia, attention-deficit/hyperactivity disorder, and epilepsy. Recently, increases in anxiety-related behaviors and epilepsy have been observed in SNAP-25 knock-in (KI) mice, which have a single amino acid substitution of Ala for Ser187. However, the molecular and cellular mechanisms underlying the abnormalities in this mutant remain unknown. Results In this study, we found that a significant number of dentate gyrus (DG) granule cells was histologically and electrophysiologically similar to immature DG neurons in the dentate gyrus of the adult mutants, a phenomenon termed the “immature DG” (iDG). SNAP-25 KI mice and other mice possessing the iDG phenotype, i.e., alpha-calcium/calmodulin-dependent protein kinase II heterozygous mice, Schnurri-2 knockout mice, and mice treated with the antidepressant fluoxetine, showed similar molecular expression patterns, with over 100 genes similarly altered. A working memory deficit was also identified in mutant mice during a spontaneous forced alternation task using a modified T-maze, a behavioral task known to be dependent on hippocampal function. Chronic treatments with the antiepileptic drug valproate abolished the iDG phenotype and the working memory deficit in mutants. Conclusions These findings suggest that the substitution of Ala for Ser187 in SNAP-25 induces the iDG phenotype, which can also be caused by epilepsy, and led to a severe working memory deficit. In addition, the iDG phenotype in adulthood is likely an endophenotype for at least a part of some common psychiatric disorders. PMID:23497716

  9. Ontogeny of calbindin immunoreactivity in the human hippocampal formation with a special emphasis on granule cells of the dentate gyrus.

    PubMed

    Abrahám, Hajnalka; Veszprémi, Béla; Kravják, András; Kovács, Krisztina; Gömöri, Eva; Seress, László

    2009-04-01

    rodents, migration of postmitotic human hippocampal pyramidal cells follows the inside-out gradient; (iii) CB was expressed transiently in pyramidal cells of the CA3 area of the human hippocampus; (iv) granule cells of the dentate gyrus start to express CB as early as midgestation; (v) maturation and migration of human granule cells follow the outside-in migrational gradient described in rodents and non-human primates; (vi) CB-immunoreactivity in the axon terminals of granule cells could be observed a few weeks before birth with a long-lasting increase in staining intensity postnatally; (vii) the maturation pattern of the CB-positive mossy fiber system suggests that the development of connectivity and the mature topographical termination pattern between dentate gyrus and the CA3 area of Ammon's horn in humans resembles that previously described for rodents; (viii) the dorsal-ventral delay in development may explain the topography of neuropathologic alterations of the granule cell layer found in temporal lobe epilepsy related to febrile seizures.

  10. Cerebellar dentate nuclei lesions alter prefrontal cortex dendritic spine morphology.

    PubMed

    Bauer, David J; Peterson, Todd C; Swain, Rodney A

    2014-01-28

    Anatomical tracing studies in primates have revealed neural tracts from the cerebellar dentate nuclei to prefrontal cortex, implicating a cerebellar role in nonmotor processes. Experiments in rats examining the functional role of this cerebellothalamocortical pathway have demonstrated the development of visuospatial and motivational deficits following lesions of the dentate nuclei, in the absence of motor impairment. These behavioral deficits possibly occur due to structural modifications of the cerebral cortex secondary to loss of cerebellar input. The current study characterized morphological alterations in prefrontal cortex important for visuospatial and motivational processes following bilateral cerebellar dentate nuclei lesions. Rats received either bilateral electrolytic cerebellar dentate nuclei lesions or sham surgery followed by a 30-day recovery. Randomly selected Golgi-impregnated neurons in prefrontal cortex were examined for analysis. Measures of branch length and spine density revealed no differences between lesioned and sham rats in either apical or basilar arbors; however, the proportion of immature to mature spines significantly decreased in lesioned rats as compared to sham controls, with reductions of 33% in the basilar arbor and 28% in the apical arbor. Although expected pruning of branches and spines did not occur, the results are consistent with the hypothesis that cerebellar lesions influence prefrontal morphology and support the possibility that functional deficits following cerebellar dentate nuclei lesions are related to prefrontal morphological alteration.

  11. Studies of dentate granule cell modulation: paired-pulse responses in freely moving rats at three ages.

    PubMed

    Bronzino, J D; Blaise, J H; Austin-LaFrance, R J; Morgane, P J

    1996-10-23

    Dentate granule cell population responses to paired-pulse stimulations applied to the perforant pathway across a range of interpulse intervals (IPI) were examined in freely moving rats at 15, 30, and 90 days of age. The profile of the paired-pulse index (PPI), a measure of the type and degree of modulation of dentate granule cell excitability, was shown to change significantly as a function of age.

  12. Preservation of perisomatic inhibitory input of granule cells in the epileptic human dentate gyrus.

    PubMed

    Wittner, L; Maglóczky, Z; Borhegyi, Z; Halász, P; Tóth, S; Eross, L; Szabó, Z; Freund, T F

    2001-01-01

    Temporal lobe epilepsy is known to be associated with hyperactivity that is likely to be generated or amplified in the hippocampal formation. The majority of granule cells, the principal cells of the dentate gyrus, are found to be resistant to damage in epilepsy, and may serve as generators of seizures if their inhibition is impaired. Therefore, the parvalbumin-containing subset of interneurons, known to provide the most powerful inhibitory input to granule cell somata and axon initial segments, were examined in human control and epileptic dentate gyrus. A strong reduction in the number of parvalbumin-containing cells was found in the epileptic samples especially in the hilar region, although in some patches of the granule cell layer parvalbumin-positive terminals that form vertical clusters characteristic of axo-axonic cells were more numerous than in controls. Analysis of the postsynaptic target elements of parvalbumin-positive axon terminals showed that they form symmetric synapses with somata, dendrites, axon initial segments and spines as in the control, but the ratio of axon initial segment synapses was increased in the epileptic tissue (control: 15.9%, epileptic: 31.3%). Furthermore, the synaptic coverage of granule cell axon initial segments increased more than three times (control: 0.52, epileptic: 2.10 microm synaptic length/100 microm axon initial segment membrane) in the epileptic samples, whereas the amount of somatic symmetric synapses did not change significantly. Although the number of parvalbumin-positive interneurons is decreased, the perisomatic inhibitory input of dentate granule cells is preserved in temporal lobe epilepsy. Basket and axo-axonic cell terminals - whether positive or negative for parvalbumin - are present, moreover, the axon collaterals targeting axon initial segments sprout in the epileptic dentate gyrus. We suggest that perisomatic inhibitory interneurons survive in epilepsy, but their somadendritic compartment and partly the

  13. Seizure-Induced Motility of Differentiated Dentate Granule Cells Is Prevented by the Central Reelin Fragment

    PubMed Central

    Orcinha, Catarina; Münzner, Gert; Gerlach, Johannes; Kilias, Antje; Follo, Marie; Egert, Ulrich; Haas, Carola A.

    2016-01-01

    Granule cell dispersion (GCD) represents a pathological widening of the granule cell layer in the dentate gyrus and it is frequently observed in patients with mesial temporal lobe epilepsy (MTLE). Recent studies in human MTLE specimens and in animal epilepsy models have shown that a decreased expression and functional inactivation of the extracellular matrix protein Reelin correlates with GCD formation, but causal evidence is still lacking. Here, we used unilateral kainate (KA) injection into the mouse hippocampus, an established MTLE animal model, to precisely map the loss of reelin mRNA-synthesizing neurons in relation to GCD along the septotemporal axis of the epileptic hippocampus. We show that reelin mRNA-producing neurons are mainly lost in the hilus and that this loss precisely correlates with the occurrence of GCD. To monitor GCD formation in real time, we used organotypic hippocampal slice cultures (OHSCs) prepared from mice which express enhanced green fluorescent protein (eGFP) primarily in differentiated dentate granule cells. Using life cell microscopy we observed that increasing doses of KA resulted in an enhanced motility of eGFP-positive granule cells. Moreover, KA treatment of OHSC resulted in a rapid loss of Reelin-producing interneurons mainly in the hilus, as observed in vivo. A detailed analysis of the migration behavior of individual eGFP-positive granule cells revealed that the majority of these neurons actively migrate toward the hilar region, where Reelin-producing neurons are lost. Treatment with KA and subsequent addition of the recombinant R3–6 Reelin fragment significantly prevented the movement of eGFP-positive granule cells. Together, these findings suggest that GCD formation is indeed triggered by a loss of Reelin in hilar interneurons. PMID:27516734

  14. Targeted deletion of AKAP7 in dentate granule cells impairs spatial discrimination

    PubMed Central

    Weisenhaus, Michael; Sanford, Christina A; Slack, Margaret C; Chin, Jenesa; Nachmanson, Daniela; McKennon, Alex; Castillo, Pablo E; McKnight, G Stanley

    2016-01-01

    Protein Kinase A (PKA) mediates synaptic plasticity and is widely implicated in learning and memory. The hippocampal dentate gyrus (DG) is thought to be responsible for processing and encoding distinct contextual associations in response to highly similar inputs. The mossy fiber (MF) axons of the dentate granule cells convey strong excitatory drive to CA3 pyramidal neurons and express presynaptic, PKA-dependent forms of plasticity. Here, we demonstrate an essential role for the PKA anchoring protein, AKAP7, in mouse MF axons and terminals. Genetic ablation of AKAP7 specifically from dentate granule cells results in disruption of MF-CA3 LTP directly initiated by cAMP, and the AKAP7 mutant mice are selectively deficient in pattern separation behaviors. Our results suggest that the AKAP7/PKA complex in the MF projections plays an essential role in synaptic plasticity and contextual memory formation. DOI: http://dx.doi.org/10.7554/eLife.20695.001 PMID:27911261

  15. Increased expression of BDNF and proliferation of dentate granule cells after bacterial meningitis.

    PubMed

    Tauber, Simone C; Stadelmann, Christine; Spreer, Annette; Brück, Wolfgang; Nau, Roland; Gerber, Joachim

    2005-09-01

    Proliferation and differentiation of neural progenitor cells is increased after bacterial meningitis. To identify endogenous factors involved in neurogenesis, expression of brain-derived neurotrophic factor (BDNF), TrkB, nerve growth factor (NGF), and glial cell line-derived neurotrophic factor (GDNF) was investigated. C57BL/6 mice were infected by intracerebral injection of Streptococcus pneumoniae. Mice were killed 30 hours later or treated with ceftriaxone and killed 4 days after infection. Hippocampal BDNF mRNA levels were increased 2.4-fold 4 days after infection (p = 0.026). Similarly, BDNF protein levels in the hippocampal formation were higher in infected mice than in control animals (p = 0.0003). This was accompanied by an elevated proliferation of dentate granule cells (p = 0.0002). BDNF protein was located predominantly in the hippocampal CA3/4 area and the hilus of the dentate gyrus. The density of dentate granule cells expressing the BDNF receptor TrkB as well as mRNA levels of TrkB in the hippocampal formation were increased 4 days after infection (p = 0.027 and 0.0048, respectively). Conversely, NGF mRNA levels at 30 hours after infection were reduced by approximately 50% (p = 0.004). No significant changes in GDNF expression were observed. In conclusion, increased synthesis of BDNF and TrkB suggests a contribution of this neurotrophic factor to neurogenesis after bacterial meningitis.

  16. Electrophysiological characterization of granule cells in the dentate gyrus immediately after birth

    PubMed Central

    Pedroni, Andrea; Minh, Do Duc; Mallamaci, Antonello; Cherubini, Enrico

    2014-01-01

    Granule cells (GCs) in the dentate gyrus are generated mainly postnatally. Between embryonic day 10 and 14, neural precursors migrate from the primary dentate matrix to the dentate gyrus where they differentiate into neurons. Neurogenesis reaches a peak at the end of the first postnatal week and it is completed at the end of the first postnatal month. This process continues at a reduced rate throughout life. Interestingly, immediately after birth, GCs exhibit a clear GABAergic phenotype. Only later they integrate the classical glutamatergic trisynaptic hippocampal circuit. Here, whole cell patch clamp recordings, in current clamp mode, were performed from immature GCs, intracellularly loaded with biocytin (in hippocampal slices from P0 to P3 old rats) in order to compare their morphological characteristics with their electrophysiological properties. The vast majority of GCs were very immature with small somata, few dendritic branches terminating with small varicosities and growth cones. In spite of their immaturity their axons reached often the cornu ammonis 3 area. Immature GCs generated, upon membrane depolarization, either rudimentary sodium spikes or more clear overshooting action potentials that fired repetitively. They exhibited also low threshold calcium spikes. In addition, most spiking neurons showed spontaneous synchronized network activity, reminiscent of giant depolarizing potentials (GDPs) generated in the hippocampus by the synergistic action of glutamate and GABA, both depolarizing and excitatory. This early synchronized activity, absent during adult neurogenesis, may play a crucial role in the refinement of local neuronal circuits within the developing dentate gyrus. PMID:24592213

  17. The paired-pulse index: a measure of hippocampal dentate granule cell modulation.

    PubMed

    Bronzino, J D; Blaise, J H; Morgane, P J

    1997-01-01

    This study was undertaken to assess whether the paired-pulse index (PPI) is an effective measure of the modulation of dentate granule cell excitability during normal development. Paired-pulse stimulations of the perforant path were, therefore, used to construct a PPI for 15-, 30-, and 90-day old, freely moving male rats. Significant age-dependent differences in the PPI were obtained. Fifteen-day old rats showed significantly less inhibition at short interpulse intervals [interpulse interval (IPI): 20 to 30 msec), a lack of facilitation at intermediate IPIs (50 to 150 msec), and significantly less inhibition at longer IPIs (300 to 1,000 msec) than adults.

  18. Corruption of the Dentate Gyrus by “Dominant” Granule cells: Implications for Dentate Gyrus Function in Health and Disease

    PubMed Central

    Scharfman, Helen E.; Myers, Catherine E.

    2015-01-01

    The dentate gyrus (DG) and area CA3 of the hippocampus are highly organized lamellar structures which have been implicated in specific cognitive functions such as pattern separation and pattern completion. Here we describe how the anatomical organization and physiology of the DG and CA3 are consistent with structures that perform pattern separation and completion. We then raise a new idea related to the complex circuitry of the DG and CA3 where CA3 pyramidal cell ‘backprojections’ play a potentially important role in the sparse firing of granule cells (GCs), considered important in pattern separation. We also propose that GC axons, the mossy fibers, already known for their highly specialized structure, have a dynamic function that imparts variance – ‘mossy fiber variance’ – which is important to pattern separation and completion. Computational modeling is used to show that when a subset of GCs become ‘dominant,’ one consequence is loss of variance in the activity of mossy fiber axons and a reduction in pattern separation and completion in the model. Empirical data are then provided using an example of ‘dominant’ GCs – subsets of GCs that develop abnormally and have increased excitability. Notably, these abnormal GCs have been identified in animal models of disease where DG-dependent behaviors are impaired. Together these data provide insight into pattern separation and completion, and suggest that behavioral impairment could arise from dominance of a subset of GCs in the DG-CA3 network. PMID:26391451

  19. Corruption of the dentate gyrus by "dominant" granule cells: Implications for dentate gyrus function in health and disease.

    PubMed

    Scharfman, Helen E; Myers, Catherine E

    2016-03-01

    The dentate gyrus (DG) and area CA3 of the hippocampus are highly organized lamellar structures which have been implicated in specific cognitive functions such as pattern separation and pattern completion. Here we describe how the anatomical organization and physiology of the DG and CA3 are consistent with structures that perform pattern separation and completion. We then raise a new idea related to the complex circuitry of the DG and CA3 where CA3 pyramidal cell 'backprojections' play a potentially important role in the sparse firing of granule cells (GCs), considered important in pattern separation. We also propose that GC axons, the mossy fibers, already known for their highly specialized structure, have a dynamic function that imparts variance--'mossy fiber variance'--which is important to pattern separation and completion. Computational modeling is used to show that when a subset of GCs become 'dominant,' one consequence is loss of variance in the activity of mossy fiber axons and a reduction in pattern separation and completion in the model. Empirical data are then provided using an example of 'dominant' GCs--subsets of GCs that develop abnormally and have increased excitability. Notably, these abnormal GCs have been identified in animal models of disease where DG-dependent behaviors are impaired. Together these data provide insight into pattern separation and completion, and suggest that behavioral impairment could arise from dominance of a subset of GCs in the DG-CA3 network.

  20. Endogenous zinc depresses GABAergic transmission via T-type Ca2+ channels and broadens the time window for integration of glutamatergic inputs in dentate granule cells

    PubMed Central

    Grauert, Antonia; Engel, Dominique; Ruiz, Arnaud J

    2014-01-01

    Abstract Zinc actions on synaptic transmission span the modulation of neurotransmitter receptors, transporters, activation of intracellular cascades and alterations in gene expression. Whether and how zinc affects inhibitory synaptic signalling in the dentate gyrus remains largely unexplored. We found that mono- and di-synaptic GABAergic inputs onto dentate granule cells were reversibly depressed by exogenous zinc application and enhanced by zinc chelation. Blocking T-type Ca2+ channels prevented the effect of zinc chelation. When recording from dentate fast-spiking interneurones, zinc chelation facilitated T-type Ca2+ currents, increased action potential half-width and decreased spike threshold. It also increased the offset of the input–output relation in a manner consistent with enhanced excitability. In granule cells, chelation of zinc reduced the time window for the integration of glutamatergic inputs originating from perforant path synapses, resulting in reduced spike transfer. Thus, zinc-mediated modulation of dentate interneurone excitability and GABA release regulates information flow to local targets and hippocampal networks. PMID:24081159

  1. Endogenous zinc depresses GABAergic transmission via T-type Ca(2+) channels and broadens the time window for integration of glutamatergic inputs in dentate granule cells.

    PubMed

    Grauert, Antonia; Engel, Dominique; Ruiz, Arnaud J

    2014-01-01

    Zinc actions on synaptic transmission span the modulation of neurotransmitter receptors, transporters, activation of intracellular cascades and alterations in gene expression. Whether and how zinc affects inhibitory synaptic signalling in the dentate gyrus remains largely unexplored. We found that mono- and di-synaptic GABAergic inputs onto dentate granule cells were reversibly depressed by exogenous zinc application and enhanced by zinc chelation. Blocking T-type Ca(2+) channels prevented the effect of zinc chelation. When recording from dentate fast-spiking interneurones, zinc chelation facilitated T-type Ca(2+) currents, increased action potential half-width and decreased spike threshold. It also increased the offset of the input-output relation in a manner consistent with enhanced excitability. In granule cells, chelation of zinc reduced the time window for the integration of glutamatergic inputs originating from perforant path synapses, resulting in reduced spike transfer. Thus, zinc-mediated modulation of dentate interneurone excitability and GABA release regulates information flow to local targets and hippocampal networks.

  2. Cancer metastasis-suppressing peptide metastin upregulates excitatory synaptic transmission in hippocampal dentate granule cells.

    PubMed

    Arai, Amy C; Xia, Yan-Fang; Suzuki, Erika; Kessler, Markus; Civelli, Olivier; Nothacker, Hans-Peter

    2005-11-01

    Metastin is an antimetastatic peptide encoded by the KiSS-1 gene in cancer cells. Recent studies found that metastin is a ligand for the orphan G-protein-coupled receptor GPR54, which is highly expressed in specific brain regions such as the hypothalamus and parts of the hippocampus. This study shows that activation of GPR54 by submicromolar concentrations of metastin reversibly enhances excitatory synaptic transmission in hippocampal dentate granule cells in a mitogen-activated protein (MAP) kinase-dependent manner. Synaptic enhancement by metastin was suppressed by intracellular application of the G-protein inhibitor GDP-beta-S and the calcium chelator BAPTA. Analysis of miniature excitatory postsynaptic currents (mEPSCs) revealed an increase in the mean amplitude but no change in event frequency. This indicates that GPR54 and the mechanism responsible for the increase in EPSCs are postsynaptic. Metastin-induced synaptic potentiation was abolished by 50 microM PD98059 and 20 microM U0126, two inhibitors of the MAP kinases ERK1 and ERK2. The effect was also blocked by inhibitors of calcium/calmodulin-dependent kinases and tyrosine kinases. RT-PCR experiments showed that both KiSS-1 and GPR54 are expressed in the hippocampal dentate gyrus. Metastin is thus a novel endogenous factor that modulates synaptic excitability in the dentate gyrus through mechanisms involving MAP kinases, which in turn may be controlled upstream by calcium-activated kinases and tyrosine kinases.

  3. Interleukin-1 mediates long-term hippocampal dentate granule cell loss following postnatal viral infection.

    PubMed

    Orr, Anna G; Sharma, Anup; Binder, Nikolaus B; Miller, Andrew H; Pearce, Bradley D

    2010-05-01

    Viral infections of the developing CNS can cause long-term neuropathological sequela through undefined mechanisms. Proinflammatory cytokines such as IL-1beta have gained attention in mediating neurodegeneration in corticohippocampal structures due to a variety of insults in adults, though there is less information on the developing brain. Little is known concerning the spatial-temporal pattern of IL-1beta induction in the developing hippocampus following live virus infection, and there are few studies addressing the long-term consequences of this cytokine induction. We report that infection of rats with lymphocytic choriomeningitis virus on postnatal day 4 induces IL-1beta protein in select regions of the hippocampus on 6, 15, 21, and 45 days after infection. This infection resulted in a 71% reduction of dentate granule cell neurons by the time the rats reached mid-adulthood. We further investigated the causative role of IL-1 in this dentate granule cell loss by blocking IL-1 activity using an IL-1ra-expressing adenoviral vector administered at the time of infection. Blockade of IL-1 abrogated the infection-associated neuron loss in this vivo model. Considering that IL-1 can be triggered by multiple perinatal insults, our findings suggest that early therapy with anti-inflammatory agents that block IL-1 may be effective for reducing adulthood neuropathology.

  4. Dentate granule neuron apoptosis and glia activation in murine hippocampus induced by trimethyltin exposure.

    PubMed

    Fiedorowicz, A; Figiel, I; Kamińska, B; Zaremba, M; Wilk, S; Oderfeld-Nowak, B

    2001-09-07

    We investigated the effect of trimethyltin (TMT), a well-known neurotoxicant, on murine hippocampal neurons and glial cells. Three days following intraperitoneal (i.p.) injection of TMT into 1-month-old Balb/c mice at a dose of 2.5 mg/kg body weight we detected damage of the dentate gyrus granular neurons. The dying cells displayed chromatin condensation and internucleosomal DNA fragmentation, which are the most characteristic features of apoptosis. To study, if prolyl oligopeptidase is engaged in neuronal apoptosis following TMT administration, we pretreated mice with the specific inhibitor--Fmoc-Pro-ProCN in doses of 5 and 10 mg/kg body weight (i.p. injection). Three days following injection we did not observe any attenuation of neurotoxic damage, regardless of inhibitor dose, indicating the lack of prolyl oligopeptidase contribution to neuronal injury caused by TMT. The neurodegeneration was associated with reactive astrogliosis in whole hippocampus, but particularly in injured dentate gyrus. The reactive astrocytes showed an increased nerve growth factor (NGF) expression in ventral as well as dorsal hippocampal parts. NGF immunoreactivity was also augmented in neurons of CA3/CA4 areas, which were almost totally spared after TMT intoxication. It suggested a role for this neurotrophin in protection of pyramidal cells from loss of connection between CA3/CA4 and dentate gyrus fields. The granule neurons' death was accompanied by increased histochemical staining with isolectin B4, a marker of microglia, in the region of neurodegeneration. The microglial cells displayed ramified and ameboid morphology, characteristic of their reactive forms. Activated microglia were the main source of interleukin 1beta (IL-1beta). It is possible that this cytokine may participate in neurodegeneration of granule cells. Alternatively, IL-1beta elaborated by microglia could play a role in increasing NGF expression, both in astroglia and in CA3/CA4 neurons.

  5. Recurrent mossy fibers preferentially innervate parvalbumin-immunoreactive interneurons in the granule cell layer of the rat dentate gyrus.

    PubMed

    Blasco-Ibáñez, J M; Martínez-Guijarro, F J; Freund, T F

    2000-09-28

    Detection of vesicular zinc and immunohistochemistry against markers for different interneuron subsets were combined to study the postsynaptic target selection of zinc-containing recurrent mossy fiber collaterals in the dentate gyrus. Mossy fiber collaterals in the granule cell layer selectively innervated parvalbumin-containing cells, with numerous contacts per cell, whereas the granule cells were avoided. Under the electron microscope, those boutons made asymmetrical contacts on dendrites and somata. These findings suggest that, in addition to the hilar perforant path-associated (HIPP) interneurons, the basket and chandelier cells also receive a powerful feed-back drive from the granule cells, and thereby are able to control population synchrony in the dentate gyrus. On the other hand, the amount of monosynaptic excitatory feed-back among granule cells is shown to be negligible.

  6. Morphological changes among hippocampal dentate granule cells exposed to early kindling-epileptogenesis

    PubMed Central

    Singh, Shatrunjai P.; He, Xiaoping; McNamara, James O.; Danzer, Steve C.

    2013-01-01

    Temporal lobe epilepsy is associated with changes in the morphology of hippocampal dentate granule cells. These changes are evident in numerous models that are associated with substantial neuron loss and spontaneous recurrent seizures. By contrast, previous studies have shown that in the kindling model, it is possible to administer a limited number of stimulations sufficient to produce a lifelong enhanced sensitivity to stimulus evoked seizures without associated spontaneous seizures and minimal neuronal loss. Here we examined whether stimulation of the amygdala sufficient to evoke five convulsive seizures (class IV or greater on Racine’s scale) produce morphological changes similar to those observed in models of epilepsy associated with substantial cell loss. The morphology of GFP-expressing granule cells from Thy-1 GFP mice was examined either one day or one month after the last evoked seizure. Interestingly, significant reductions in dendritic spine density were evident one day after the last seizure, the magnitude of which had diminished by one month. Further, there was an increase in the thickness of the granule cell layer one day after the last evoked seizure, which was absent a month later. We also observed an increase in the area of the proximal axon, which again returned to control levels a month later. No differences in the number of basal dendrites were detected at either time point. These findings demonstrate that the early stages of kindling epileptogenesis produce transient changes in the granule cell body layer thickness, molecular layer spine density and axon proximal area, but do not produce striking rearrangements of granule cell structure. PMID:23893783

  7. Excitability changes within transverse lamellae of dentate granule cells and their longitudinal spread following orthodromic or antidromic activation.

    PubMed

    Lømo, Terje

    2009-07-01

    The functional organization of the perforant path input to the dentate gyrus of the exposed hippocampus was studied in adult rabbits anesthetized with urethane and chloralose. Electrical stimulation of perforant path fibers caused excitation of granule cells along narrow, nearly transverse strips (lamellae) of tissue. Stimulation of granule cell axons (mossy fibers) in CA3 caused antidromic activation of granule cells along similar strips. Paired-pulse stimulation revealed marked changes in granule cell excitability both within a lamella (on-line) and for several mm off-line along the septo-temporal axis of the dentate gyrus. After the first pulse, granule cells were inhibited for up to about 100 ms and then facilitated for up to hundreds of ms. Feedback activity along mossy fiber collaterals exciting local inhibitory and excitatory neurons appeared to dominate in producing on- and off-line inhibition and facilitation. Neurons mediating these effects could be inhibitory basket cells and other inhibitory interneurons targeting granule cells on- and off-line. In addition, excitatory mossy cells with far reaching, longitudinally running axons could affect off-line granule cells by exciting them directly or inhibit them indirectly by exciting local inhibitory interneurons. A scheme for dentate gyrus function is proposed whereby information to the dentate gyrus becomes split into interacting transverse strips of neuronal assemblies along which temporal processing occurs. A matrix of neuronal assemblies thus arises within which fragments of events and experiences is stored through the plasticity of synapses within and between the assemblies. Similar fragments may then be recognized at later times allowing memories of the whole to be created by pattern completion at subsequent computational stages in the hippocampus.

  8. Dendrites of dentate gyrus granule cells contribute to pattern separation by controlling sparsity

    PubMed Central

    Chavlis, Spyridon; Petrantonakis, Panagiotis C.

    2016-01-01

    ABSTRACT The hippocampus plays a key role in pattern separation, the process of transforming similar incoming information to highly dissimilar, nonverlapping representations. Sparse firing granule cells (GCs) in the dentate gyrus (DG) have been proposed to undertake this computation, but little is known about which of their properties influence pattern separation. Dendritic atrophy has been reported in diseases associated with pattern separation deficits, suggesting a possible role for dendrites in this phenomenon. To investigate whether and how the dendrites of GCs contribute to pattern separation, we build a simplified, biologically relevant, computational model of the DG. Our model suggests that the presence of GC dendrites is associated with high pattern separation efficiency while their atrophy leads to increased excitability and performance impairments. These impairments can be rescued by restoring GC sparsity to control levels through various manipulations. We predict that dendrites contribute to pattern separation as a mechanism for controlling sparsity. © 2016 The Authors Hippocampus Published by Wiley Periodicals, Inc. PMID:27784124

  9. Delayed dendritic development in newly generated dentate granule cells by cell-autonomous expression of the amyloid precursor protein.

    PubMed

    Morgenstern, Nicolás A; Giacomini, Damiana; Lombardi, Gabriela; Castaño, Eduardo M; Schinder, Alejandro F

    2013-09-01

    Neuronal connectivity and synaptic remodeling are fundamental substrates for higher brain functions. Understanding their dynamics in the mammalian allocortex emerges as a critical step to tackle the cellular basis of cognitive decline that occurs during normal aging and in neurodegenerative disorders. In this work we have designed a novel approach to assess alterations in the dynamics of functional and structural connectivity elicited by chronic cell-autonomous overexpression of the human amyloid precursor protein (hAPP). We have taken advantage of the fact that the hippocampus continuously generates new dentate granule cells (GCs) to probe morphofunctional development of GCs expressing different variants of hAPP in a healthy background. hAPP was expressed together with a fluorescent reporter in neural progenitor cells of the dentate gyrus of juvenile mice by retroviral delivery. Neuronal progeny was analyzed several days post infection (dpi). Amyloidogenic cleavage products of hAPP such as the β-C terminal fragment (β-CTF) induced a substantial reduction in glutamatergic connectivity at 21 dpi, at which time new GCs undergo active growth and synaptogenesis. Interestingly, this effect was transient, since the strength of glutamatergic inputs was normal by 35 dpi. This delay in glutamatergic synaptogenesis was paralleled by a decrease in dendritic length with no changes in spine density, consistent with a protracted dendritic development without alterations in synapse formation. Finally, similar defects in newborn GC development were observed by overexpression of α-CTF, a non-amyloidogenic cleavage product of hAPP. These results indicate that hAPP can elicit protracted dendritic development independently of the amyloidogenic processing pathway.

  10. Enhanced CREB phosphorylation in immature dentate gyrus granule cells precedes neurotrophin expression and indicates a specific role of CREB in granule cell differentiation

    PubMed Central

    Bender, R. A.; Lauterborn, J. C.; Gall, C. M.; Cariaga, W.; Baram, T. Z.

    2011-01-01

    Differentiation and maturation of dentate gyrus granule cells requires coordinated interactions of numerous processes. These must be regulated by protein factors capable of integrating signals mediated through diverse signalling pathways. Such integrators of inter and intracellular physiological stimuli include the cAMP-response element binding protein (CREB), a leucine-zipper class transcription factor that is activated through phosphorylation. Neuronal activity and neurotrophic factors, known to be involved in granule cell differentiation, are major physiologic regulators of CREB function. To examine whether CREB may play a role in governing coordinated gene transcription during granule cell differentiation, we determined the spatial and temporal profiles of phosphorylated (activated) CREB throughout postnatal development in immature rat hippocampus. We demonstrate that CREB activation is confined to discrete, early stages of granule cell differentiation. In addition, CREB phosphorylation occurs prior to expression of the neurotrophins BDNF and NT-3. These data indicate that in a signal transduction cascade connecting CREB and neurotrophins in the process of granule cell maturation, CREB is located upstream of neurotrophins. Importantly, CREB may be a critical component of the machinery regulating the coordinated transcription of genes contributing to the differentiation of granule cells and their integration into the dentate gyrus network. PMID:11207803

  11. Activation of κ opioid receptors increases intrinsic excitability of dentate gyrus granule cells

    PubMed Central

    McDermott, Carmel M; Schrader, Laura A

    2011-01-01

    Abstract The dentate gyrus of the hippocampus is thought to control information flow into the rest of the hippocampus. Under pathological conditions, such as epilepsy, this protective feature is circumvented and uninhibited activity flows throughout the hippocampus. Many factors can modulate excitability of the dentate gyrus and ultimately, the hippocampus. It is therefore of critical importance to understand the mechanisms involved in regulating excitability in the dentate gyrus. Dynorphin, the endogenous ligand for the kappa (κ) opioid receptor (KOR), is thought to be involved in neuromodulation in the dentate gyrus. Both dynorphin and its receptor are widely expressed in the dentate gyrus and have been implicated in epilepsy and other complex behaviours such as stress-induced deficits in learning and stress-induced depression-like behaviours. Administration of KOR agonists can prevent both the behavioural and electroencephalographic measures of seizures in several different models of epilepsy. Antagonism of the KORs also prevents stress-induced behaviours. This evidence suggests the KORs as possible therapeutic targets for various pathological conditions. In addition, KOR agonists prevent the induction of LTP. Although there are several mechanisms through which dynorphin could mediate these effects, no studies to date investigated the effects of KOR activation on intrinsic membrane properties and cell excitability. We used whole-cell, patch-clamp recordings from acute mouse hippocampus slices to investigate the effect of KOR activation on dentate gyrus granule cell excitability. The agonist U69,593 (U6, 1 μm) resulted in a lower spike threshold, a decreased latency to first spike, an increased spike half-width, and an overall increase in spike number with current injections ranging from 15 to 45 pA. There was also a reduction in the interspike interval (ISI) both early and late in the spike train, with no change in membrane potential or input resistance

  12. Axonal plasticity of age-defined dentate granule cells in a rat model of mesial temporal lobe epilepsy.

    PubMed

    Althaus, A L; Zhang, H; Parent, J M

    2016-02-01

    Dentate granule cell (DGC) mossy fiber sprouting (MFS) in mesial temporal lobe epilepsy (mTLE) is thought to underlie the creation of aberrant circuitry which promotes the generation or spread of spontaneous seizure activity. Understanding the extent to which populations of DGCs participate in this circuitry could help determine how it develops and potentially identify therapeutic targets for regulating aberrant network activity. In this study, we investigated how DGC birthdate influences participation in MFS and other aspects of axonal plasticity using the rat pilocarpine-induced status epilepticus (SE) model of mTLE. We injected a retrovirus (RV) carrying a synaptophysin-yellow fluorescent protein (syp-YFP) fusion construct to birthdate DGCs and brightly label their axon terminals, and compared DGCs born during the neonatal period with those generated in adulthood. We found that both neonatal and adult-born DGC populations participate, to a similar extent, in SE-induced MFS within the dentate gyrus inner molecular layer (IML). SE did not alter hilar MF bouton density compared to sham-treated controls, but adult-born DGC bouton density was greater in the IML than in the hilus after SE. Interestingly, we also observed MF axonal reorganization in area CA2 in epileptic rats, and these changes arose from DGCs generated both neonatally and in adulthood. These data indicate that both neonatal and adult-generated DGCs contribute to axonal reorganization in the rat pilocarpine mTLE model, and indicate a more complex relationship between DGC age and participation in seizure-related plasticity than was previously thought.

  13. AXONAL PLASTICITY OF AGE-DEFINED DENTATE GRANULE CELLS IN A RAT MODEL OF MESIAL TEMPORAL LOBE EPILEPSY

    PubMed Central

    Althaus, AL; Zhang, H; Parent, JM

    2016-01-01

    Dentate granule cell (DGC) mossy fiber sprouting (MFS) in mesial temporal lobe epilepsy (mTLE) is thought to underlie the creation of aberrant circuitry which promotes the generation or spread of spontaneous seizure activity. Understanding the extent to which populations of DGCs participate in this circuitry could help determine how it develops and potentially identify therapeutic targets for regulating aberrant network activity. In this study, we investigated how DGC birthdate influences participation in MFS and other aspects of axonal plasticity using the rat pilocarpine-induced status epilepticus (SE) model of mTLE. We injected a retrovirus (RV) carrying a synaptophysin-yellow fluorescent protein (syp-YFP) fusion construct to birthdate DGCs and brightly label their axon terminals, and compared DGCs born during the neonatal period with those generated in adulthood. We found that both neonatal and adult-born DGC populations participate, to a similar extent, in SE-induced MFS within the dentate gyrus inner molecular layer (IML). SE did not alter hilar MF bouton density compared to sham-treated controls, but adult-born DGC bouton density was greater in the IML than in the hilus after SE. Interestingly, we also observed MF axonal reorganization in area CA2 in epileptic rats, and these changes arose from DGCs generated both neonatally and in adulthood. These data indicate that both neonatal and adult-generated DGCs contribute to axonal reorganization in the rat pilocarpine mTLE model, and indicate a more complex relationship between DGC age and participation in seizure-related plasticity than was previously thought. PMID:26644085

  14. Abnormal UP/DOWN Membrane Potential Dynamics Coupled with the Neocortical Slow Oscillation in Dentate Granule Cells during the Latent Phase of Temporal Lobe Epilepsy123

    PubMed Central

    Ouedraogo, David W.; Lenck-Santini, Pierre-Pascal; Marti, Geoffrey; Robbe, David; Crépel, Valérie

    2016-01-01

    The dentate gyrus, a major entry point to the hippocampus, gates (or filters) incoming information from the cortex. During sleep or anesthesia, the slow-wave oscillation (SWO) orchestrates hippocampus–neocortex communication, which is important for memory formation. The dentate gate is altered in temporal lobe epilepsy (TLE) early during epileptogenesis, which favors the propagation of pathological activities. Yet, whether the gating of physiological SWO by dentate granule cells (DGCs) is altered in TLE has remained unexplored. We combined intracellular recordings of membrane potential (Vm) of DGCs and local field potential recordings of the SWO in parietal cortex in anesthetized rats early during epileptogenesis [post-status epilepticus (SE) rats]. As expected, in control rats, the Vm of DGCs weakly and rarely oscillated in the SWO frequency range. In contrast, in post-SE rats, the Vm of DGCs displayed strong and long-lasting SWO. In these cells, clear UP and DOWN states, in phase with the neocortical SWO, led to a bimodal Vm distribution. In post-SE rats, the firing of DGCs was increased and more temporally modulated by the neocortical SWO. We conclude that UP/DOWN state dynamics dominate the Vm of DGCs and firing early during epileptogenesis. This abnormally strong neocortical influence on the dynamics of DGCs may profoundly modify the hippocampus–neocortex dialogue during sleep and associated cognitive functions. PMID:27257629

  15. Chronic pregabalin treatment decreases excitability of dentate gyrus and accelerates maturation of adult-born granule cells.

    PubMed

    Lempel, Augusto Abel; Coll, Lucia; Schinder, Alejandro F; Uchitel, Osvaldo Daniel; Piriz, Joaquin

    2017-01-01

    Pregabalin (PGB) is extensively prescribed to treat neurological and neuropsychiatrical conditions such as neuropathic pain, anxiety disorders, and epilepsy. Although PGB is known to bind selectively to the α2δ subunit of voltage-gated calcium channels, there is little understanding about how it exerts its therapeutic effects. In this article, we analyzed the effects of an in vivo chronic treatment with PGB over the physiology of dentate gyrus granule cells (DGGCs) using ex vivo electrophysiological and morphological analysis in adult mice. We found that PGB decreases neuronal excitability of DGGCs. In addition, PGB accelerates maturation of adult-born DGGCs, an effect that would modify dentate gyrus plasticity. Together, these findings suggest that PGB reduces activity in the dentate gyrus and modulates overall network plasticity, which might contribute to its therapeutic effects. Cover Image for this issue: doi: 10.1111/jnc.13783.

  16. Palmitoylethanolamide protects dentate gyrus granule cells via peroxisome proliferator-activated receptor-α.

    PubMed

    Koch, Marco; Kreutz, Susanne; Böttger, Charlotte; Benz, Alexander; Maronde, Erik; Ghadban, Chalid; Korf, Horst-Werner; Dehghani, Faramarz

    2011-02-01

    Endocannabinoids like 2-arachidonoylglycerol strongly modulate the complex machinery of secondary neuronal damage and are shown to improve neuronal survival after excitotoxic lesion. Palmitoylethanolamide (PEA), the naturally occurring fatty acid amide of ethanolamine and palmitic acid, is an endogenous lipid known to mimic several effects of endocannabinoids even without binding to cannabinoid receptors. Here we show that PEA (0.001-1 μM) and the synthetic peroxisome proliferator-activated receptor (PPAR)-alpha agonist 4-chloro-6-(2,3-xylidino)-2-pyrimidinylthio acetic acid (Wy-14,643; 0.1-1 μM) reduced the number of microglial cells and protected dentate gyrus granule cells in excitotoxically lesioned organotypic hippocampal slice cultures (OHSCs). Treatment with the PPAR-alpha antagonist N-((2S)-2-(((1Z)-1-Methyl-3-oxo-3-(4-(trifluoromethyl)phenyl)prop-1-enyl)amino)-3-(4-(2-(5-methyl-2-phenyl-1,3-oxazol-4-yl)ethoxy)phenyl)propyl)propanamide (GW6471; 0.05-5 μM) blocked PEA-mediated neuroprotection and reduction of microglial cell numbers whereas the PPAR-gamma antagonist 2-chloro-5-nitro-N-phenyl-benzamide (GW9662; 0.01-1 μM) showed no effects. Immunocytochemistry and Western blot analyses revealed a strong PPAR-alpha immunoreaction in BV-2 microglial cells and in HT22 hippocampal cells. Intensity and location of PPAR-alpha immunoreaction remained constant during stimulation with PEA (0.01 μM; 1-36 h). In conclusion our data provide evidence that (1) PEA counteracted excitotoxically induced secondary neuronal damage of dentate gyrus granule cells, (2) PPAR-alpha but not PPAR-gamma is the endogenous binding site for PEA-mediated neuroprotection, and (3) PEA may activate PPAR-alpha in microglial cells and hippocampal neurons to exert its neuroprotective effects. In addition to classical endocannabinoids, PEA-mediated PPAR-alpha activation represents a possible target for therapeutic interventions to mitigate symptoms of secondary neuronal damage.

  17. The Possible Roles of the Dentate Granule Cell’s Leptin and Other Ciliary Receptors in Alzheimer’s Neuropathology

    PubMed Central

    Whitfield, James F.; Chiarini, Anna; Dal Prà, Ilaria; Armato, Ubaldo; Chakravarthy, Balu

    2015-01-01

    Dentate-gyral granule cells in the hippocampus plus dentate gyrus memory-recording/retrieving machine, unlike most other neurons in the brain, are continuously being generated in the adult brain with the important task of separating overlapping patterns of data streaming in from the outside world via the entorhinal cortex. This “adult neurogenesis” is driven by tools in the mature granule cell’s cilium. Here we report our discovery of leptin’s LepRb receptor in this cilium. In addition, we discuss how ciliary LepRb signaling might be involved with ciliary p75NTR and SSTR3 receptors in adult neurogenesis and memory formation as well as attenuation of Alzheimer’s neuropathology by reducing the production of its toxic amyloid-β-derived drivers. PMID:26184316

  18. Inhibition of Protease-Activated Receptor 1 Does not Affect Dendritic Homeostasis of Cultured Mouse Dentate Granule Cells

    PubMed Central

    Schuldt, Gerlind; Galanis, Christos; Strehl, Andreas; Hick, Meike; Schiener, Sabine; Lenz, Maximilian; Deller, Thomas; Maggio, Nicola; Vlachos, Andreas

    2016-01-01

    Protease-activated receptors (PARs) are widely expressed in the central nervous system (CNS). While a firm link between PAR1-activation and functional synaptic and intrinsic neuronal properties exists, studies on the role of PAR1 in neural structural plasticity are scarce. The physiological function of PAR1 in the brain remains not well understood. We here sought to determine whether prolonged pharmacologic PAR1-inhibition affects dendritic morphologies of hippocampal neurons. To address this question we employed live-cell microscopy of mouse dentate granule cell dendrites in 3-week old entorhino-hippocampal slice cultures prepared from Thy1-GFP mice. A subset of cultures were treated with the PAR1-inhibitor SCH79797 (1 μM; up to 3 weeks). No major effects of PAR1-inhibition on static and dynamic parameters of dentate granule cell dendrites were detected under control conditions. Granule cells of PAR1-deficient slice cultures showed unaltered dendritic morphologies, dendritic spine densities and excitatory synaptic strength. Furthermore, we report that PAR1-inhibition does not prevent dendritic retraction following partial deafferentation in vitro. Consistent with this finding, no major changes in PAR1-mRNA levels were detected in the denervated dentate gyrus (DG). We conclude that neural PAR1 is not involved in regulating the steady-state dynamics or deafferentation-induced adaptive changes of cultured dentate granule cell dendrites. These results indicate that drugs targeting neural PAR1-signals may not affect the stability and structural integrity of neuronal networks in healthy brain regions. PMID:27378862

  19. Semaphorin 5A inhibits synaptogenesis in early postnatal- and adult-born hippocampal dentate granule cells

    PubMed Central

    Duan, Yuntao; Wang, Shih-Hsiu; Song, Juan; Mironova, Yevgeniya; Ming, Guo-li; Kolodkin, Alex L; Giger, Roman J

    2014-01-01

    Human SEMAPHORIN 5A (SEMA5A) is an autism susceptibility gene; however, its function in brain development is unknown. In this study, we show that mouse Sema5A negatively regulates synaptogenesis in early, developmentally born, hippocampal dentate granule cells (GCs). Sema5A is strongly expressed by GCs and regulates dendritic spine density in a cell-autonomous manner. In the adult mouse brain, newly born Sema5A−/− GCs show an increase in dendritic spine density and increased AMPA-type synaptic responses. Sema5A signals through PlexinA2 co-expressed by GCs, and the PlexinA2-RasGAP activity is necessary to suppress spinogenesis. Like Sema5A−/− mutants, PlexinA2−/− mice show an increase in GC glutamatergic synapses, and we show that Sema5A and PlexinA2 genetically interact with respect to GC spine phenotypes. Sema5A−/− mice display deficits in social interaction, a hallmark of autism-spectrum-disorders. These experiments identify novel intra-dendritic Sema5A/PlexinA2 interactions that inhibit excitatory synapse formation in developmentally born and adult-born GCs, and they provide support for SEMA5A contributions to autism-spectrum-disorders. DOI: http://dx.doi.org/10.7554/eLife.04390.001 PMID:25313870

  20. Structural Plasticity of Dentate Granule Cell Mossy Fibers During the Development of Limbic Epilepsy

    PubMed Central

    Danzer, Steve C.; He, Xiaoping; Loepke, Andreas W.; McNamara, James O.

    2009-01-01

    Altered granule cell≫CA3 pyramidal cell synaptic connectivity may contribute to the development of limbic epilepsy. To explore this possibility, granule cell giant mossy fiber bouton plasticity was examined in the kindling and pilocarpine models of epilepsy using green fluorescent protein-expressing transgenic mice. These studies revealed significant increases in the frequency of giant boutons with satellite boutons 2 days and 1 month after pilocarpine status epilepticus, and increases in giant bouton area at 1 month. Similar increases in giant bouton area were observed shortly after kindling. Finally, both models exhibited plasticity of mossy fiber giant bouton filopodia, which contact GABAergic interneurons mediating feedforward inhibition of CA3 pyramids. In the kindling model, however, all changes were fleeting, having resolved by 1 month after the last evoked seizure. Together, these findings demonstrate striking structural plasticity of granule cell mossy fiber synaptic terminal structure in two distinct models of adult limbic epileptogenesis. We suggest that these plasticities modify local connectivities between individual mossy fiber terminals and their targets, inhibitory interneurons, and CA3 pyramidal cells potentially altering the balance of excitation and inhibition during the development of epilepsy. PMID:19294647

  1. Expression of the AMPA Receptor Subunits GluR1 and GluR2 is Associated with Granule Cell Maturation in the Dentate Gyrus

    PubMed Central

    Hagihara, Hideo; Ohira, Koji; Toyama, Keiko; Miyakawa, Tsuyoshi

    2011-01-01

    The dentate gyrus produces new granule neurons throughout adulthood in mammals from rodents to humans. During granule cell maturation, defined markers are expressed in a highly regulated sequential process, which is necessary for directed neuronal differentiation. In the present study, we show that α-amino-3-hydroxy-5-methy-4-isoxazole propionate (AMPA) receptor subunits GluR1 and GluR2 are expressed in differentiated granule cells, but not in stem cells, in neonatal, and adult dentate gyrus. Using markers for neural progenitors, immature and mature granule cells, we found that GluR1 and GluR2 were expressed mainly in mature cells and in some immature cells. A time-course analysis of 5-bromo-2′-deoxyuridine staining revealed that granule cells express GluR1 around 3 weeks after being generated. In mice heterozygous for the alpha-isoform of calcium/calmodulin-dependent protein kinase II, a putative animal model of schizophrenia and bipolar disorder in which dentate gyrus granule cells fail to mature normally, GluR1 and GluR2 immunoreactivities were substantially downregulated in the dentate gyrus granule cells. In the granule cells of mutant mice, the expression of both presynaptic and postsynaptic markers was decreased, suggesting that GluR1 and GluR2 are also associated with synaptic maturation. Moreover, GluR1 and GluR2 were also expressed in mature granule cells of the neonatal dentate gyrus. Taken together, these findings indicate that GluR1 and GluR2 expression closely correlates with the neuronal maturation state, and that GluR1 and GluR2 are useful markers for mature granule cells in the dentate gyrus. PMID:21927594

  2. The type 1 Interleukin 1 receptor is not required for the death of murine hippocampal dentate granule cells and microglia activation

    PubMed Central

    Harry, G. Jean; Funk, Jason; Lefebvre d’Hellencourt, Christian; Aoyama, Mineyoshi

    2008-01-01

    Alterations in the inflammatory process, neuronal death, and glia response have been observed under manipulation of the interleukin-1 (IL-1) cytokine and subsequent signaling through the type 1 IL-1 receptor (IL-1R1). To investigate the influence of IL-1R1 activation in the pathophysiology of a chemical-induced injury to the murine hippocampus, we examined the level and pattern of neuronal death and neuroinflammation in 25-day-old male mice exposed to trimethyltin hydroxide (2.0 mg/kg, i.p.). In IL-1R1 null (IL-1R1−/−) mice, the pattern and severity of dentate granule cell death was similar as compared to wild type mice. In both groups of mice, mRNA levels for TNFα and MIP-1α were elevated and the early activation of microglia, including their ability to progress to a phagocytic phenotype, was maintained. Compared to WT mice, IL-1R1−/− mice displayed a limited glial fibrillary acidic protein (GFAP) astrocytic response, as well as a preferential induction in mRNA levels of Fas signaling components. Cumulatively, these results indicate that IL-1R1 activation is not necessary for TMT-induced death of dentate granule neurons or local activation of microglia; however, IL-1R1 signaling is involved in mediating the structural response of astrocytes to injury and may also regulate apoptotic mechanisms by influencing Fas signaling components. PMID:18191113

  3. DAG-sensitive and Ca2+ permeable TRPC6 channels are expressed in dentate granule cells and interneurons in the hippocampal formation

    PubMed Central

    Nagy, Gergő A.; Botond, Gergő; Borhegyi, Zsolt; Plummer, Nicholas W.; Freund, Tamás F.; Hájos, Norbert

    2012-01-01

    Members of the transient receptor potential (TRP) cation channel family play important roles in several neuronal functions. To understand the precise role of these channels in information processing, their presence on neuronal elements must be revealed. In this study we investigated the localization of TRPC6 channels in the adult hippocampal formation. Immunostainings with a specific antibody, which was validated in Trpc6 knockout mice, showed that in the dentate gyrus, TRPC6 channels are strongly expressed in granule cells. Immunogold staining revealing the subcellular localization of TRPC6 channels clarified that these proteins were predominantly present on the membrane surface of the dendritic shafts of dentate granule cells, and also in their axons, often associated with intracellular membrane cisternae. In addition, TRPC6 channels could be observed in the dendrites of some interneurons. Double immunofluorescent staining showed that TRPC6 channels were present in the dendrites of hilar interneurons and hippocampal interneurons with horizontal dendrites in the stratum oriens expressing mGlu1a receptors, whereas parvalbumin immunoreactivity was revealed in TRPC6-expressing dendrites with radial appearance in the stratum radiatum. Electron microscopy showed that the immunogold particles depicting TRPC6 channels were located on the surface membranes of the interneuron dendrites. Our results suggest that TRPC6 channels are in a key position to alter the information entry into the trisynaptic loop of the hippocampal formation from the entorhinal cortex, and to control the function of both feed-forward and feed-back inhibitory circuits in this brain region. PMID:23193081

  4. Differential expression of cytoskeletal proteins in the dendrites of parvalbumin-positive interneurons versus granule cells in the adult rat dentate gyrus.

    PubMed

    de Haas Ratzliff, A; Soltesz, I

    2000-01-01

    Parvalbumin-positive interneurons and granule cells of the dentate gyrus exhibit characteristic differences in morphological, cytochemical, physiological, and pathophysiological properties. Several of these defining features, including dendritic morphology, spine density, and sensitivity to insults, are likely to be influenced by the neuronal cytoskeleton. The data in this paper demonstrate striking differences in the expression levels of all three neurofilament triplet proteins, as well as alpha-internexin and beta-tubulin III, between the parvalbumin-positive interneurons and dentate granule cells. Therefore, the molecular composition of intermediate filaments and microtubules in the dendritic domain of parvalbumin-positive dentate interneurons is distinct from the cytoskeleton of neighboring granule cells, indicating the existence of highly cell type-specific cytoskeletal architecture within the dentate gyrus.

  5. Tonic Inhibitory Control of Dentate Gyrus Granule Cells by α5-Containing GABAA Receptors Reduces Memory Interference

    PubMed Central

    Zarnowska, Ewa D.; Benke, Dietmar; Tsvetkov, Evgeny; Sigal, Maksim; Keist, Ruth; Bolshakov, Vadim Y.; Pearce, Robert A.; Rudolph, Uwe

    2015-01-01

    Interference between similar or overlapping memories formed at different times poses an important challenge on the hippocampal declarative memory system. Difficulties in managing interference are at the core of disabling cognitive deficits in neuropsychiatric disorders. Computational models have suggested that, in the normal brain, the sparse activation of the dentate gyrus granule cells maintained by tonic inhibitory control enables pattern separation, an orthogonalization process that allows distinct representations of memories despite interference. To test this mechanistic hypothesis, we generated mice with significantly reduced expression of the α5-containing GABAA (α5-GABAARs) receptors selectively in the granule cells of the dentate gyrus (α5DGKO mice). α5DGKO mice had reduced tonic inhibition of the granule cells without any change in fast phasic inhibition and showed increased activation in the dentate gyrus when presented with novel stimuli. α5DGKO mice showed impairments in cognitive tasks characterized by high interference, without any deficiencies in low-interference tasks, suggesting specific impairment of pattern separation. Reduction of fast phasic inhibition in the dentate gyrus through granule cell-selective knock-out of α2-GABAARs or the knock-out of the α5-GABAARs in the downstream CA3 area did not detract from pattern separation abilities, which confirms the anatomical and molecular specificity of the findings. In addition to lending empirical support to computational hypotheses, our findings have implications for the treatment of interference-related cognitive symptoms in neuropsychiatric disorders, particularly considering the availability of pharmacological agents selectively targeting α5-GABAARs. SIGNIFICANCE STATEMENT Interference between similar memories poses a significant limitation on the hippocampal declarative memory system, and impaired interference management is a cognitive symptom in many disorders. Thus, understanding

  6. In vivo 7 Tesla imaging of the dentate granule cell layer in Schizophrenia

    PubMed Central

    Kirov, Ivan I.; Hardy, Caitlin J.; Matsuda, Kant; Messinger, Julie; Cankurtaran, Ceylan Z.; Warren, Melina; Wiggins, Graham C.; Perry, Nissa N.; Babb, James S.; Goetz, Raymond R.; George, Ajax; Malaspina, Dolores; Gonen, Oded

    2013-01-01

    PURPOSE The hippocampus is central to the pathophysiology of schizophrenia. Histology shows abnormalities in the dentate granule cell layer (DGCL), but its small size (~100 micron thickness) has precluded in vivo human studies. We used ultra high field magnetic resonance imaging (MRI) to compare DGCL morphology of schizophrenic patients to matched controls’. METHOD Bilateral hippocampi of 16 schizophrenia patients (10 male) 40.7±10.6 years old (mean ±standard deviation) were imaged at 7 Tesla MRI with heavily T2*-weighted gradient-echo sequence at 232 micron in-plane resolution (0.08 μL image voxels). Fifteen matched controls (8 male, 35.6±9.4 years old) and one ex vivo post mortem hippocampus (that also underwent histopathology) were scanned with same protocol. Three blinded neuroradiologists rated each DGCL on a qualitative scale of 1 to 6 (from “not discernible” to “easily visible, appearing dark gray or black”) and mean left and right DGCL scores were compared using a non-parametric Mann-Whitney test. RESULTS MRI identification of the DGCL was validated with histopathology. Mean right and left DGCL ratings in patients (3.2±1.0 and 3.5±1.2) were not statistically different from controls’ (3.9±1.1 and 3.8±0.8), but patients’ had a trend for lower right DGCL score (p=0.07), which was significantly associated with patient diagnosis (p=0.05). The optimal 48% sensitivity and 80% specificity for schizophrenia was achieved with a DGCL rating of ≤2. CONCLUSION Decreased contrast in the right DGCL in schizophrenia was predictive of schizophrenia diagnosis. Better utility of this metric as a schizophrenia biomarker may be achieved in future studies of patients with homogeneous disease subtypes and progression rates. PMID:23664589

  7. Influence of brain-derived neurotrophic factor on pathfinding of dentate granule cell axons, the hippocampal mossy fibers.

    PubMed

    Tamura, Makoto; Tamura, Naohiro; Ikeda, Takamitsu; Koyama, Ryuta; Ikegaya, Yuji; Matsuki, Norio; Yamada, Maki K

    2009-01-31

    Mossy fibers, the dentate granule cell axons, are generated throughout an animal's lifetime. Mossy fiber paths and synapses are primarily restricted to the stratum lucidum within the CA3 region. Brain-derived neurotrophic factor (BDNF), a neurotrophin family protein that activates Trk neurotrophin receptors, is highly expressed in the stratum lucidum in an activity-dependent manner. The addition of a Trk neurotrophin receptor inhibitor, K252a, to cultured hippocampal slices induced aberrant extension of mossy fibers into ectopic regions. BDNF overexpression in granule cells ameliorated the mossy fiber pathway abnormalities caused by a submaximal dose of K252a. A similar rescue was observed when BDNF was expressed in CA3 pyramidal cells, most notably in mossy fibers distal to the expression site. These findings are the first to clarify the role of BDNF in mossy fiber pathfinding, not as an attractant cue but as a regulator, possibly acting in a paracrine manner. This effect of BDNF may be as a signal for new fibers to fasciculate and extend further to form synapses with neurons that are far from active BDNF-expressing synapses. This mechanism would ensure the emergence of new independent dentate gyrus-CA3 circuits by the axons of new-born granule cells.

  8. Developmental changes in membrane properties and postsynaptic currents of granule cells in rat dentate gyrus.

    PubMed

    Liu, Y B; Lio, P A; Pasternak, J F; Trommer, B L

    1996-08-01

    1. Whole cell patch-clamp recordings were used to study dentate gyrus granule cells in hippocampal slices from juvenile rats (postnatal days 8-32). Membrane properties were measured with the use of current-clamp recordings and were correlated with the morphology of a subgroup of neurons filled with biocytin. The components of the postsynaptic currents (PSCs) induced by medial perforant path stimulation were characterized with the use of specific receptor antagonists in voltage-clamp recordings. 2. Granule cells located in the middle third of the superior blade of stratum granulosum from the rostral third of hippocampus were divided into three groups according to their input resistance (IR). Neurons with low IR (206 +/- 182 M omega, mean +/- SD) had hyperpolarized resting membrane potentials (-82 +/- 7 mV) and high-amplitude action potentials (108 +/- 23 mV). Neurons were high IR (1,259 +/- 204 M omega) had more depolarized resting membrane potentials (-54 +/- 6 mV) and lower-amplitude action potentials (71 +/- 10 mV). Neurons with intermediate IR (619 +/- 166 M omega) also had intermediate resting membrane potentials (-63 +/- 7 mV) and action potential amplitudes (86 +/- 14 mV). Low-IR neurons became increasingly prevalent with advancing postnatal age, but neurons from each group could be found throughout the entire period under study. 3. Morphological studies of low-IR neurons revealed an extensive dendritic arborization that traversed the entire molecular layer and was characteristic of mature granule cells. High-IR cells had smaller somata and short, simple dendritic arborization that incompletely penetrated the molecular layer and were classified as immature. Intermediate-IR cells had morphological features of intermediate maturity. 4. The initial phase of the PSC evoked at -80 mV was a fast inward current that was comparable with respect to latency to peak, latency to onset, and 10-90% rise time in neurons of all maturities held at -80 mV. This current was 6

  9. Differential gene expression in dentate granule cells in mesial temporal lobe epilepsy with and without hippocampal sclerosis

    PubMed Central

    Griffin, Nicole G.; Wang, Yu; Hulette, Christine M.; Halvorsen, Matt; Cronin, Kenneth D.; Walley, Nicole M.; Haglund, Michael M.; Radtke, Rodney A.; Pate Skene, J. H.; Sinha, Saurabh R.; Heinzen, Erin L.

    2015-01-01

    Summary Objective Hippocampal sclerosis is the most common neuropathological finding in medically intractable cases of mesial temporal lobe epilepsy. In this study, we analyzed the gene expression profiles of dentate granule cells of mesial temporal lobe epilepsy patients with and without hippocampal sclerosis to show that next-generation sequencing methods can produce interpretable genomic data from RNA collected from small homogenous cell populations and to shed light on the transcriptional changes associated with hippocampal sclerosis. Methods RNA was extracted, and complementary DNA (cDNA) was prepared and amplified from dentate granule cells that had been harvested by laser capture microdissection from surgically resected hippocampi from mesial temporal lobe epilepsy patients with and without hippocampal sclerosis. Sequencing libraries were sequenced, and the resulting sequencing reads were aligned to the reference genome. Differential expression analysis was used to ascertain expression differences between patients with and without hippocampal sclerosis. Results Greater than 90% of the RNA-Seq reads aligned to the reference. There was high concordance between transcriptional profiles obtained for duplicate samples. Principal component analysis revealed that the presence or absence of hippocampal sclerosis was the main determinant of the variance within the data. Among the genes upregulated in the hippocampal sclerosis samples, there was significant enrichment for genes involved in oxidative phosphorylation. Significance By analyzing the gene expression profiles of dentate granule cells from surgically resected hippocampal specimens from mesial temporal lobe epilepsy patients with and without hippocampal sclerosis, we have demonstrated the utility of next-generation sequencing methods for producing biologically relevant results from small populations of homogeneous cells, and have provided insight on the transcriptional changes associated with this pathology

  10. Differential effects of rapamycin treatment on tonic and phasic GABAergic inhibition in dentate granule cells after focal brain injury in mice.

    PubMed

    Butler, Corwin R; Boychuk, Jeffery A; Smith, Bret N

    2016-06-01

    The cascade of events leading to post-traumatic epilepsy (PTE) after traumatic brain injury (TBI) remains unclear. Altered inhibition in the hippocampal formation and dentate gyrus is a hallmark of several neurological disorders, including TBI and PTE. Inhibitory synaptic signaling in the hippocampus is predominately driven by γ-aminobutyric acid (GABA) neurotransmission, and is prominently mediated by postsynaptic type A GABA receptors (GABAAR's). Subsets of these receptors involved in tonic inhibition of neuronal membranes serve a fundamental role in maintenance of inhibitory state, and GABAAR-mediated tonic inhibition is altered functionally in animal models of both TBI and epilepsy. In this study, we assessed the effect of mTOR inhibition on hippocampal hilar inhibitory interneuron loss and synaptic and tonic GABAergic inhibition of dentate gyrus granule cells (DGCs) after controlled cortical impact (CCI) to determine if mTOR activation after TBI modulates GABAAR function. Hilar inhibitory interneuron density was significantly reduced 72h after CCI injury in the dorsal two-thirds of the hemisphere ipsilateral to injury compared with the contralateral hemisphere and sham controls. Rapamycin treatment did not alter this reduction in cell density. Synaptic and tonic current measurements made in DGCs at both 1-2 and 8-13weeks post-injury indicated reduced synaptic inhibition and THIP-induced tonic current density in DGCs ipsilateral to CCI injury at both time points post-injury, with no change in resting tonic GABAAR-mediated currents. Rapamycin treatment did not alter the reduced synaptic inhibition observed in ipsilateral DGCs 1-2weeks post-CCI injury, but further reduced synaptic inhibition of ipsilateral DGCs at 8-13weeks post-injury. The reduction in THIP-induced tonic current after injury, however, was prevented by rapamycin treatment at both time points. Rapamycin treatment thus differentially modifies CCI-induced changes in synaptic and tonic GABAAR

  11. The granule cell density of the dentate gyrus following administration of Urtica dioica extract to young diabetic rats.

    PubMed

    Fazeli, S A; Gharravi, A M; Ghafari, S; Jahanshahi, M; Golalipour, M J

    2008-08-01

    Urtica dioica L. Stinging nettle has long been known worldwide as a medicinal plant. To study the benefits of the nettle in diabetic encephalopathy, the granule cell density of the dentate gyrus of diabetic rats was studied following administration of Urtica dioica extract. A total of 24 male albino Wistar rats were allocated equally to normal, diabetic, preventive and treatment groups. Hyperglycaemia was induced by streptozotocin (80 mg/kg) in the animals of the diabetic and treatment groups. One week after injection of the streptozotocin the animals in the treatment group received a hydroalcoholic extract of Urtica dioica (100 mg/kg/day) for 4 weeks intraperitoneally. The rats of the preventive group received hydroalcoholic extract of U. dioica (100 mg/kg/day) IP for the first 5 days and an injection of streptozotocin (80 mg/kg) on the 6th day. After 5 weeks of study all the rats were sacrificed and coronal sections were taken from the dorsal hippocampal formation of the right cerebral hemispheres and stained with cresyl violet. The area densities of the granule cells were measured and compared in the four groups. The density was lower in the diabetic rats compared with the controls (p > 0.05). The preventive group showed lower cell density than the controls (p > 0.05). The densities in the treated rats were higher than in the diabetic rats (p > 0.05). Furthermore, the control and treated rats showed similar densities (p > 0.05). It seems that U. dioica extract can help compensate for granule cell loss in the diabetic rat dentate gyrus, which can ameliorate cognitive impairment in diabetes. However, preventive use of the extract showed no significant benefit.

  12. Impaired firing properties of dentate granule neurons in an Alzheimer's disease animal model are rescued by PPARγ agonism

    PubMed Central

    Nenov, Miroslav N.; Denner, Larry; Dineley, Kelly T.

    2014-01-01

    Early cognitive impairment in Alzheimer's disease (AD) correlates with medial temporal lobe dysfunction, including two areas essential for memory formation: the entorhinal cortex and dentate gyrus (DG). In the Tg2576 animal model for AD amyloidosis, activation of the peroxisome proliferator-activated receptor-gamma (PPARγ) with rosiglitazone (RSG) ameliorates hippocampus-dependent cognitive impairment and restores aberrant synaptic activity at the entorhinal cortex to DG granule neuron inputs. It is unknown, however, whether intrinsic firing properties of DG granule neurons in these animals are affected by amyloid-β pathology and if they are sensitive to RSG treatment. Here, we report that granule neurons from 9-mo-old wild-type and Tg2576 animals can be segregated into two cell types with distinct firing properties and input resistance that correlate with less mature type I and more mature type II neurons. The DG type I cell population was greater than type II in wild-type littermates. In the Tg2576 animals, the type I and type II cell populations were nearly equal but could be restored to wild-type levels through cognitive enhancement with RSG. Furthermore, Tg2576 cell firing frequency and spike after depolarization were decreased in type I and increased in type II cells, both of which could also be restored to wild-type levels upon RSG treatment. That these parameters were restored by PPARγ activation emphasizes the therapeutic value of RSG against early AD cognitive impairment. PMID:25540218

  13. New insights into the role of hilar ectopic granule cells in the dentate gyrus based on quantitative anatomic analysis and three-dimensional reconstruction

    PubMed Central

    Scharfman, Helen E.; Pierce, Joseph P.

    2014-01-01

    SUMMARY The dentate gyrus is one of two main areas of the mammalian brain where neurons are born throughout adulthood, a phenomenon called postnatal neurogenesis. Most of the neurons that are generated are granule cells (GCs), the major principal cell type in the dentate gyrus. Some adult-born granule cells develop in ectopic locations, such as the dentate hilus. The generation of hilar ectopic granule cells (HEGCs) is greatly increased in several animal models of epilepsy and has also been demonstrated in surgical specimens from patients with intractable temporal lobe epilepsy (TLE). Herein we review the results of our quantitative neuroanatomic analysis of HEGCs that were filled with Neurobiotin following electrophysiologic characterization in hippocampal slices. The data suggest that two types of HEGCs exist, based on a proximal or distal location of the cell body relative to the granule cell layer, and based on the location of most of the dendrites, in the molecular layer or hilus. Three-dimensional reconstruction revealed that the dendrites of distal HEGCs can extend along the transverse and longitudinal axis of the hippocampus. Analysis of axons demonstrated that HEGCs have projections that contribute to the normal mossy fiber innervation of CA3 as well as the abnormal sprouted fibers in the inner molecular layer of epileptic rodents (mossy fiber sprouting). These data support the idea that HEGCs could function as a “hub” cell in the dentate gyrus and play a critical role in network excitability. PMID:22612815

  14. Effects of spaced learning in the water maze on development of dentate granule cells generated in adult mice.

    PubMed

    Trinchero, Mariela F; Koehl, Muriel; Bechakra, Malik; Delage, Pauline; Charrier, Vanessa; Grosjean, Noelle; Ladeveze, Elodie; Schinder, Alejandro F; Abrous, D Nora

    2015-11-01

    New dentate granule cells (GCs) are generated in the hippocampus throughout life. These adult-born neurons are required for spatial learning in the Morris water maze (MWM). In rats, spatial learning shapes the network by regulating their number and dendritic development. Here, we explored whether such modulatory effects exist in mice. New GCs were tagged using thymidine analogs or a GFP-expressing retrovirus. Animals were exposed to a reference memory protocol for 10-14 days (spaced training) at different times after newborn cells labeling. Cell proliferation, cell survival, cell death, neuronal phenotype, and dendritic and spine development were examined using immunohistochemistry. Surprisingly, spatial learning did not modify any of the parameters under scrutiny including cell number and dendritic morphology. These results suggest that although new GCs are required in mice for spatial learning in the MWM, they are, at least for the developmental intervals analyzed here, refractory to behavioral stimuli generated in the course of learning in the MWM.

  15. Chronic Fluoxetine Induces the Enlargement of Perforant Path-Granule Cell Synapses in the Mouse Dentate Gyrus.

    PubMed

    Kitahara, Yosuke; Ohta, Keisuke; Hasuo, Hiroshi; Shuto, Takahide; Kuroiwa, Mahomi; Sotogaku, Naoki; Togo, Akinobu; Nakamura, Kei-ichiro; Nishi, Akinori

    2016-01-01

    A selective serotonin reuptake inhibitor is the most commonly prescribed antidepressant for the treatment of major depression. However, the mechanisms underlying the actions of selective serotonin reuptake inhibitors are not fully understood. In the dentate gyrus, chronic fluoxetine treatment induces increased excitability of mature granule cells (GCs) as well as neurogenesis. The major input to the dentate gyrus is the perforant path axons (boutons) from the entorhinal cortex (layer II). Through voltage-sensitive dye imaging, we found that the excitatory neurotransmission of the perforant path synapse onto the GCs in the middle molecular layer of the mouse dentate gyrus (perforant path-GC synapse) is enhanced after chronic fluoxetine treatment (15 mg/kg/day, 14 days). Therefore, we further examined whether chronic fluoxetine treatment affects the morphology of the perforant path-GC synapse, using FIB/SEM (focused ion beam/scanning electron microscopy). A three-dimensional reconstruction of dendritic spines revealed the appearance of extremely large-sized spines after chronic fluoxetine treatment. The large-sized spines had a postsynaptic density with a large volume. However, chronic fluoxetine treatment did not affect spine density. The presynaptic boutons that were in contact with the large-sized spines were large in volume, and the volumes of the mitochondria and synaptic vesicles inside the boutons were correlated with the size of the boutons. Thus, the large-sized perforant path-GC synapse induced by chronic fluoxetine treatment contains synaptic components that correlate with the synapse size and that may be involved in enhanced glutamatergic neurotransmission.

  16. Chronic Fluoxetine Induces the Enlargement of Perforant Path-Granule Cell Synapses in the Mouse Dentate Gyrus

    PubMed Central

    Kitahara, Yosuke; Ohta, Keisuke; Hasuo, Hiroshi; Shuto, Takahide; Kuroiwa, Mahomi; Sotogaku, Naoki; Togo, Akinobu; Nakamura, Kei-ichiro; Nishi, Akinori

    2016-01-01

    A selective serotonin reuptake inhibitor is the most commonly prescribed antidepressant for the treatment of major depression. However, the mechanisms underlying the actions of selective serotonin reuptake inhibitors are not fully understood. In the dentate gyrus, chronic fluoxetine treatment induces increased excitability of mature granule cells (GCs) as well as neurogenesis. The major input to the dentate gyrus is the perforant path axons (boutons) from the entorhinal cortex (layer II). Through voltage-sensitive dye imaging, we found that the excitatory neurotransmission of the perforant path synapse onto the GCs in the middle molecular layer of the mouse dentate gyrus (perforant path-GC synapse) is enhanced after chronic fluoxetine treatment (15 mg/kg/day, 14 days). Therefore, we further examined whether chronic fluoxetine treatment affects the morphology of the perforant path-GC synapse, using FIB/SEM (focused ion beam/scanning electron microscopy). A three-dimensional reconstruction of dendritic spines revealed the appearance of extremely large-sized spines after chronic fluoxetine treatment. The large-sized spines had a postsynaptic density with a large volume. However, chronic fluoxetine treatment did not affect spine density. The presynaptic boutons that were in contact with the large-sized spines were large in volume, and the volumes of the mitochondria and synaptic vesicles inside the boutons were correlated with the size of the boutons. Thus, the large-sized perforant path-GC synapse induced by chronic fluoxetine treatment contains synaptic components that correlate with the synapse size and that may be involved in enhanced glutamatergic neurotransmission. PMID:26788851

  17. Long-Term Treatment with Low Doses of Methamphetamine Promotes Neuronal Differentiation and Strengthens Long-Term Potentiation of Glutamatergic Synapses onto Dentate Granule Neurons

    PubMed Central

    Milhazes, Nuno

    2016-01-01

    Abstract Methamphetamine (METH) is a psychostimulant, affecting hippocampal function with disparate cognitive effects, which depends on the dose and time of administration, ranging from improvement to impairment of memory. Importantly, in the United States, METH is approved for the treatment of attention deficit hyperactivity disorder. Modifications of long-term plasticity of synapses originating from the entorhinal cortex onto dentate granule cells (DGCs) have been proposed to underlie cognitive alterations similar to those seen in METH users. However, the effects of METH on synaptic plasticity of the dentate gyrus are unknown. Here, we investigated the impact of long-term administration of METH (2 mg/kg/d) on neurogenesis and synaptic plasticity of immature and mature DGCs of juvenile mice. We used a mouse model of neurogenesis (the G42 line of GAD67-GFP), in which GFP is expressed by differentiating young DGCs. METH treatment enhanced the differentiation of GFP+ cells, as it increased the fraction of GFP+ cells expressing the neuronal marker NeuN, and decreased the amount of immature DGCs coexpressing doublecortin. Interestingly, METH did not change the magnitude of long-term potentiation (LTP) in more immature neurons, but facilitated LTP induction in more differentiated GFP+ and strengthened plasticity in mature GFP− DGCs. The METH-induced facilitation of LTP in GFP+ neurons was accompanied with spine enlargement. Our results reveal a specific action of long-term use of METH in the long-term plasticity of excitatory synapses onto differentiating DGCs and might have important implications toward the understanding of the synaptic basis of METH-induced cognitive alterations. PMID:27419216

  18. Noradrenaline blocks potassium conductance in rat dentate granule cells in vitro.

    PubMed

    Haas, H L; Rose, G M

    1987-07-22

    The actions of noradrenaline and the beta-adrenergic agonist, isoproterenol, were studied on the dentate gyrus in hippocampal slices from rats using extra- and intracellular recording. These agents facilitated field EPSPs (excitatory postsynaptic potentials) and population spikes evoked by perforant path stimulation. Intracellular recording revealed an attenuation of the long lasting afterhyperpolarization (AHP) and the accommodation of cell discharge in response to depolarizing current injection. It is suggested that beta-receptor activation blocks a calcium-dependent potassium current.

  19. Prox1 postmitotically defines dentate gyrus cells by specifying granule cell identity over CA3 pyramidal cell fate in the hippocampus.

    PubMed

    Iwano, Tomohiko; Masuda, Aki; Kiyonari, Hiroshi; Enomoto, Hideki; Matsuzaki, Fumio

    2012-08-01

    The brain is composed of diverse types of neurons that fulfill distinct roles in neuronal circuits, as manifested by the hippocampus, where pyramidal neurons and granule cells constitute functionally distinct domains: cornu ammonis (CA) and dentate gyrus (DG), respectively. Little is known about how these two types of neuron differentiate during hippocampal development, although a set of transcription factors that is expressed in progenitor cells is known to be required for the survival of granule cells. Here, we demonstrate in mice that Prox1, a transcription factor constitutively expressed in the granule cell lineage, postmitotically functions to specify DG granule cell identity. Postmitotic elimination of Prox1 caused immature DG neurons to lose the granule cell identity and in turn terminally differentiate into the pyramidal cell type manifesting CA3 neuronal identity. By contrast, Prox1 overexpression caused opposing effects on presumptive hippocampal pyramidal cells. These results indicate that the immature DG cell has the potential to become a granule cell or a pyramidal cell, and Prox1 defines the granule cell identity. This bi-potency is lost in mature DG cells, although Prox1 is still required for correct gene expression in DG granule cells. Thus, our data indicate that Prox1 acts as a postmitotic cell fate determinant for DG granule cells over the CA3 pyramidal cell fate and is crucial for maintenance of the granule cell identity throughout the life.

  20. Chronic corticosterone administration reduces dendritic complexity in mature, but not young granule cells in the rat dentate gyrus

    PubMed Central

    Yau, Suk-Yu; Li, Ang; Tong, Jian-Bin; Bostrom, Crystal; Christie, Brian R.; Lee, Tatia M.C.; So, Kwok-Fai

    2016-01-01

    Background: Our previous work has shown that exposure to the stress hormone corticosterone (40 mg/kg CORT) for two weeks induces dendritic atrophy of pyramidal neurons in the hippocampal CA3 region and behavioral deficits. However, it is unclear whether this treatment also affects the dentate gyrus (DG), a subregion of the hippocampus comprising a heterogeneous population of young and mature neurons. Objective: We examined the effect of CORT treatment on the dendritic complexity of mature and young granule cells in the DG. Methods: We utilized a Golgi staining method to investigate the dendritic morphology and spine density of young neurons in the inner granular cell layer (GCL) and mature neurons in the outer GCL in response to CORT application. The expressions of glucocorticoid receptors during neuronal maturation were examined using Western blot analysis in a primary hippocampal neuronal culture. Results: Sholl analysis revealed that CORT treatment decreased the number of intersections and shortened the dendritic length in mature, but not young, granule cells. However, the spine density of mature and young neurons was not affected. Western blot analysis showed a progressive increase in the protein levels of glucocorticoid receptors (GRs) in the cultured primary hippocampal neurons during neuronal maturation. Conclusion: These data suggest that mature neurons are likely more vulnerable to chronic exposure to CORT; this may be due to their higher expression of GRs when compared to younger DG neurons. PMID:27567758

  1. Neural injury alters proliferation and integration of adult-generated neurons in the dentate gyrus

    PubMed Central

    Perederiy, Julia V.; Luikart, Bryan W.; Washburn, Eric K.; Schnell, Eric; Westbrook, Gary L.

    2013-01-01

    Neural plasticity following brain injury illustrates the potential for regeneration in the central nervous system. Lesioning of the perforant path, which innervates the outer 2/3rds of the molecular layer of the dentate gyrus, was one of the first models to demonstrate structural plasticity of mature granule cells (Parnavelas, 1974; Caceres and Steward, 1983; Diekmann et al., 1996). The dentate gyrus also harbors a continuously proliferating population of neuronal precursors that can integrate into functional circuits and show enhanced short-term plasticity (Schmidt-Hieber et al., 2004; Abrous et al., 2005). To examine the response of adult-generated granule cells to unilateral complete transection of the perforant path in vivo, we tracked these cells using transgenic POMC-EGFP mice or by retroviral expression of GFP. Lesioning triggered a marked proliferation of newborn neurons. Subsequently, the dendrites of newborn neurons showed reduced complexity within the denervated zone, but dendritic spines still formed in the absence of glutamatergic nerve terminals. Electron micrographs confirmed the lack of intact presynaptic terminals apposing spines on mature cells and on newborn neurons. Newborn neurons, but not mature granule cells, had a higher density of dendritic spines in the inner molecular layer post-lesion, accompanied by an increase in miniature EPSC amplitudes and rise times. Our results indicate that injury causes an increase in newborn neurons and lamina-specific synaptic reorganization, indicative of enhanced plasticity. The presence of de novo dendritic spines in the denervated zone suggests that the post-lesion environment provides the necessary signals for spine formation. PMID:23486947

  2. Beneficial effect of Boswellia serrata gum resin on spatial learning and the dendritic tree of dentate gyrus granule cells in aged rats

    PubMed Central

    Hosseini-Sharifabad, Mohammad; Kamali-Ardakani, Razieh; Hosseini-Sharifabad, Ali

    2016-01-01

    Objective: The hippocampal formation, particularly the dentate gyrus (DG), shows age-related morphological changes that could cause memory decline. It is indicated that Boswellia resins attenuates memory deficits and the major component of Boswellia serrata (Bs) gum resin, beta boswellic acid increased neurite outgrowth and branching in hippocampal neurons. This study was designed to investigate the effect of Boswellia treatment on spatial learning performance and the morphology of dentate granule cells in aged rats. Materials and Methods: Sixteen male Wistar rats (24 months old) were divided into experimental and control groups. Experimental group was intragastrically administered with the aqueous extract of Bs (100 mg/kg/d for 8 weeks) and control group received a similar volume of water. Spatial learning performance of rats was tested using Morris water maze task. At the end of experiment, the brain was removed and the right hippocampus was serially sectioned for morphometric analysis. The Cavalieri principle was employed to estimate the volume of the DG. A quantitative Golgi study was used to analyze the dendritic trees of dentate granule cells. Results: Chronic treatment with Bs improved spatial learning capability during the three acquisition days. Comparisons also revealed that Bs-treated aged rat had greater DG with increased dendritic complexity in the dentate granule cells than control rats. Hippocampal granule cells of Bs-treated aged rats had more dendritic segments, larger arbors, more numerical branching density and more dendritic spines in comparison to control animals. Conclusion: This study provided a neuro-anatomical basis for memory improvement due to chronic treatment with Bs. PMID:27222832

  3. Potential implications of a monosynaptic pathway from mossy cells to adult-born granule cells of the dentate gyrus

    PubMed Central

    Scharfman, Helen E.; Bernstein, Hannah L.

    2015-01-01

    The dentate gyrus (DG) is important to many aspects of hippocampal function, but there are many aspects of the DG that are incompletely understood. One example is the role of mossy cells (MCs), a major DG cell type that is glutamatergic and innervates the primary output cells of the DG, the granule cells (GCs). MCs innervate the GCs as well as local circuit neurons that make GABAergic synapses on GCs, so the net effect of MCs on GCs – and therefore the output of the DG – is unclear. Here we first review fundamental information about MCs and the current hypotheses for their role in the normal DG and in diseases that involve the DG. Then we review previously published data which suggest that MCs are a source of input to a subset of GCs that are born in adulthood (adult-born GCs). In addition, we discuss the evidence that adult-born GCs may support the normal inhibitory ‘gate’ functions of the DG, where the GCs are a filter or gate for information from the entorhinal cortical input to area CA3. The implications are then discussed in the context of seizures and temporal lobe epilepsy (TLE). In TLE, it has been suggested that the DG inhibitory gate is weak or broken and MC loss leads to insufficient activation of inhibitory neurons, causing hyperexcitability. That idea was called the “dormant basket cell hypothesis.” Recent data suggest that loss of normal adult-born GCs may also cause disinhibition, and seizure susceptibility. Therefore, we propose a reconsideration of the dormant basket cell hypothesis with an intervening adult-born GC between the MC and basket cell and call this hypothesis the “dormant immature granule cell hypothesis.” PMID:26347618

  4. Intrinsic neurophysiological properties of hilar ectopic and normotopic dentate granule cells in human temporal lobe epilepsy and a rat model

    PubMed Central

    Althaus, A. L.; Sagher, O.; Parent, J. M.

    2014-01-01

    Hilar ectopic dentate granule cells (DGCs) are a salient feature of aberrant plasticity in human temporal lobe epilepsy (TLE) and most rodent models of the disease. Recent evidence from rodent TLE models suggests that hilar ectopic DGCs contribute to hyperexcitability within the epileptic hippocampal network. Here we investigate the intrinsic excitability of DGCs from humans with TLE and the rat pilocarpine TLE model with the objective of comparing the neurophysiology of hilar ectopic DGCs to their normotopic counterparts in the granule cell layer (GCL). We recorded from 36 GCL and 7 hilar DGCs from human TLE tissue. Compared with GCL DGCs, hilar DGCs in patient tissue exhibited lower action potential (AP) firing rates, more depolarized AP threshold, and differed in single AP waveform, consistent with an overall decrease in excitability. To evaluate the intrinsic neurophysiology of hilar ectopic DGCs, we made recordings from retrovirus-birthdated, adult-born DGCs 2–4 mo after pilocarpine-induced status epilepticus or sham treatment in rats. Hilar DGCs from epileptic rats exhibited higher AP firing rates than normotopic DGCs from epileptic or control animals. They also displayed more depolarized resting membrane potential and wider AP waveforms, indicating an overall increase in excitability. The contrasting findings between disease and disease model may reflect differences between the late-stage disease tissue available from human surgical specimens and the earlier disease stage examined in the rat TLE model. These data represent the first neurophysiological characterization of ectopic DGCs from human hippocampus and prospectively birthdated ectopic DGCs in a rodent TLE model. PMID:25429123

  5. Fluorescent Labeling of Newborn Dentate Granule Cells in GAD67-GFP Transgenic Mice: A Genetic Tool for the Study of Adult Neurogenesis

    PubMed Central

    Zhao, Shengli; Zhou, Yang; Gross, Jimmy; Miao, Pei; Qiu, Li; Wang, Dongqing; Chen, Qian; Feng, Guoping

    2010-01-01

    Neurogenesis in the adult hippocampus is an important form of structural plasticity in the brain. Here we report a line of BAC transgenic mice (GAD67-GFP mice) that selectively and transitorily express GFP in newborn dentate granule cells of the adult hippocampus. These GFP+ cells show a high degree of colocalization with BrdU-labeled nuclei one week after BrdU injection and express the newborn neuron marker doublecortin and PSA-NCAM. Compared to mature dentate granule cells, these newborn neurons show immature morphological features: dendritic beading, fewer dendritic branches and spines. These GFP+ newborn neurons also show immature electrophysiological properties: higher input resistance, more depolarized resting membrane potentials, small and non-typical action potentials. The bright labeling of newborn neurons with GFP makes it possible to visualize the details of dendrites, which reach the outer edge of the molecular layer, and their axon (mossy fiber) terminals, which project to the CA3 region where they form synaptic boutons. GFP expression covers the whole developmental stage of newborn neurons, beginning within the first week of cell division and disappearing as newborn neurons mature, about 4 weeks postmitotic. Thus, the GAD67-GFP transgenic mice provide a useful genetic tool for studying the development and regulation of newborn dentate granule cells. PMID:20824075

  6. Causal Evidence for the Role of Specific GABAergic Interneuron Types in Entorhinal Recruitment of Dentate Granule Cells

    PubMed Central

    Lee, Cheng-Ta; Kao, Min-Hua; Hou, Wen-Hsien; Wei, Yu-Ting; Chen, Chin-Lin; Lien, Cheng-Chang

    2016-01-01

    The dentate gyrus (DG) is the primary gate of the hippocampus and controls information flow from the cortex to the hippocampus proper. To maintain normal function, granule cells (GCs), the principal neurons in the DG, receive fine-tuned inhibition from local-circuit GABAergic inhibitory interneurons (INs). Abnormalities of GABAergic circuits in the DG are associated with several brain disorders, including epilepsy, autism, schizophrenia, and Alzheimer disease. Therefore, understanding the network mechanisms of inhibitory control of GCs is of functional and pathophysiological importance. GABAergic inhibitory INs are heterogeneous, but it is unclear how individual subtypes contribute to GC activity. Using cell-type-specific optogenetic perturbation, we investigated whether and how two major IN populations defined by parvalbumin (PV) and somatostatin (SST) expression, regulate GC input transformations. We showed that PV-expressing (PV+) INs, and not SST-expressing (SST+) INs, primarily suppress GC responses to single cortical stimulation. In addition, these two IN classes differentially regulate GC responses to θ and γ frequency inputs from the cortex. Notably, PV+ INs specifically control the onset of the spike series, whereas SST+ INs preferentially regulate the later spikes in the series. Together, PV+ and SST+ GABAergic INs engage differentially in GC input-output transformations in response to various activity patterns. PMID:27830729

  7. Endogenous intracellular calcium buffering and the activation/inactivation of HVA calcium currents in rat dentate gyrus granule cells

    PubMed Central

    1991-01-01

    Granule cells acutely dissociated from the dentate gyrus of adult rat brains displayed a single class of high-threshold, voltage-activated (HVA) Ca2+ channels. The kinetics of whole-cell Ca2+ currents recorded with pipette solutions containing an intracellular ATP regenerating system but devoid of exogenous Ca2+ buffers, were fit best by Hodgkin- Huxley kinetics (m2h), and were indistinguishable from those recorded with the nystatin perforated patch method. In the absence of exogenous Ca2+ buffers, inactivation of HVA Ca2+ channels was a predominantly Ca(2+)-dependent process. The contribution of endogenous Ca2+ buffers to the kinetics of inactivation was investigated by comparing currents recorded from control cells to currents recorded from neurons that have lost a specific Ca(2+)-binding protein, Calbindin-D28K (CaBP), after kindling-induced epilepsy. Kindled neurons devoid of CaBP showed faster rates of both activation and inactivation. Adding an exogenous Ca2+ chelator, 1,2-bis-(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA), to the intracellular solution largely eliminated inactivation in both control and kindled neurons. The results are consistent with the hypothesis that endogenous intraneuronal CaBP contributes significantly to submembrane Ca2+ sequestration at a concentration range and time domain that regulate Ca2+ channel inactivation. PMID:1662686

  8. Modulation by the BK accessory β4 subunit of phosphorylation-dependent changes in excitability of dentate gyrus granule neurons

    PubMed Central

    Petrik, David; Wang, Bin; Brenner, Robert

    2011-01-01

    BK channels are large conductance calcium- and voltage-activated potassium channels critical for neuronal excitability. Some neurons express so called fast-gated, type I BK channels. Other neurons express BK channels assembled with the accessory β4 subunit conferring slow-gating of type II BK channels. However, it is not clear how protein phosphorylation modulates these two distinct BK channel types. Using β4 knockout mice, we compared fast- or slow-gated BK channels in response to changes in phosphorylation status of hippocampus dentate gyrus granule neurons. We utilized the selective PP2A/PP4 phosphatase inhibitor, Fostriecin, to study changes in action potential shape and firing properties of the neurons. In β4 knockout neurons, Fostriecin increases BK current, speeds BK channel activation, and reduces action potential amplitudes. Fostriecin increases spiking during early components of an action potential train. In contrast, inhibition of BK channels through β4 in wild type neurons or by BK channel inhibitor Paxilline opposes Fostriecin effects. Voltage clamp recordings of neurons reveal that Fostriecin increases both calcium and BK currents. However, Fostriecin does not activate BK α alone channels in transfected HEK293 cells lacking calcium channels. In summary, these results suggest that the fast-gating, type I BK channels lacking β4 can increase neuronal excitability in response to reduced phosphatase activity and activation of calcium channels. By opposing BK channel activation; the β4 subunit plays an important role in moderating firing frequency regardless of changes in phosphorylation status. PMID:21848922

  9. Tumor necrosis factor (TNF)-receptor 1 and 2 mediate homeostatic synaptic plasticity of denervated mouse dentate granule cells

    PubMed Central

    Becker, Denise; Deller, Thomas; Vlachos, Andreas

    2015-01-01

    Neurological diseases are often accompanied by neuronal cell death and subsequent deafferentation of connected brain regions. To study functional changes after denervation we generated entorhino-hippocampal slice cultures, transected the entorhinal pathway, and denervated dentate granule cells in vitro. Our previous work revealed that partially denervated neurons respond to the loss of input with a compensatory, i.e., homeostatic, increase in their excitatory synaptic strength. TNFα maintains this denervation-induced homeostatic strengthening of excitatory synapses. Here, we used pharmacological approaches and mouse genetics to assess the role of TNF-receptor 1 and 2 in lesion-induced excitatory synaptic strengthening. Our experiments disclose that both TNF-receptors are involved in the regulation of denervation-induced synaptic plasticity. In line with this result TNF-receptor 1 and 2 mRNA-levels were upregulated after deafferentation in vitro. These findings implicate TNF-receptor signaling cascades in the regulation of homeostatic plasticity of denervated networks and suggest an important role for TNFα-signaling in the course of neurological diseases accompanied by deafferentation. PMID:26246237

  10. Bidirectional modulation of GABAergic transmission by cholecystokinin in hippocampal dentate gyrus granule cells of juvenile rats

    PubMed Central

    Deng, Pan-Yue; Lei, Saobo

    2006-01-01

    Cholecystokinin (CCK) interacts with two types of G protein-coupled receptors in the brain: CCK-A and CCK-B receptors. Both CCK and CCK-B receptors are widely distributed in the hippocampal formation, but the functions of CCK there have been poorly understood. In the present study, we initially examined the effects of CCK on GABAA receptor-mediated synaptic transmission in the hippocampal formation and then explored the underlying cellular mechanisms by focusing on the dentate gyrus region, where the highest levels of CCK-binding sites have been detected. Our results indicate that activation of CCK-B receptors initially and transiently increased spontaneous IPSC (sIPSC) frequency, followed by a persistent reduction. The effects of CCK were more evident in juvenile rats, suggesting that they are developmentally regulated. Cholecystokinin failed to modulate the miniature IPSCs recorded in the presence of TTX and the amplitude of the evoked IPSCs, but produced a transient increase followed by a reduction in action potential firing frequency recorded from GABAergic interneurons, suggesting that CCK acts by modulating the excitability of the interneurons to regulate GABA release. Cholecystokinin reduced the amplitude of the after-hyperpolarization of the action potentials, and application of paxilline or charybdotoxin considerably reduced CCK-mediated modulation of sIPSC frequency, suggesting that the effects of CCK are related to the inhibition of Ca2+-activated K+ currents (IK(Ca)). The effects of CCK were independent of the functions of phospholipase C, intracellular Ca2+ release, protein kinase C or phospholipase A2, suggesting a direct coupling between the G proteins of CCK-B receptors and IK(Ca). Our results provide a novel mechanism underlying CCK-mediated modulation of GABA release. PMID:16455686

  11. Loss of protohaem IX farnesyltransferase in mature dentate granule cells impairs short‐term facilitation at mossy fibre to CA3 pyramidal cell synapses

    PubMed Central

    Booker, Sam A.; Campbell, Graham R.; Mysiak, Karolina S.; Brophy, Peter J.; Kind, Peter C.

    2017-01-01

    Key points Neurodegenerative disorders can exhibit dysfunctional mitochondrial respiratory chain complex IV activity.Conditional deletion of cytochrome c oxidase, the terminal enzyme in the respiratory electron transport chain of mitochondria, from hippocampal dentate granule cells in mice does not affect low‐frequency dentate to CA3 glutamatergic synaptic transmission.High‐frequency dentate to CA3 glutamatergic synaptic transmission and feedforward inhibition are significantly attenuated in cytochrome c oxidase‐deficient mice.Intact presynaptic mitochondrial function is critical for the short‐term dynamics of mossy fibre to CA3 synaptic function. Abstract Neurodegenerative disorders are characterized by peripheral and central symptoms including cognitive impairments which have been associated with reduced mitochondrial function, in particular mitochondrial respiratory chain complex IV or cytochrome c oxidase activity. In the present study we conditionally removed a key component of complex IV, protohaem IX farnesyltransferase encoded by the COX10 gene, in granule cells of the adult dentate gyrus. Utilizing whole‐cell patch‐clamp recordings from morphologically identified CA3 pyramidal cells from control and complex IV‐deficient mice, we found that reduced mitochondrial function did not result in overt deficits in basal glutamatergic synaptic transmission at the mossy‐fibre synapse because the amplitude, input–output relationship and 50 ms paired‐pulse facilitation were unchanged following COX10 removal from dentate granule cells. However, trains of stimuli given at high frequency (> 20 Hz) resulted in dramatic reductions in short‐term facilitation and, at the highest frequencies (> 50 Hz), also reduced paired‐pulse facilitation, suggesting a requirement for adequate mitochondrial function to maintain glutamate release during physiologically relevant activity patterns. Interestingly, local inhibition was reduced, suggesting the effect

  12. Naringenin ameliorates kainic acid-induced morphological alterations in the dentate gyrus in a mouse model of temporal lobe epilepsy.

    PubMed

    Park, Jungha; Jeong, Kyoung Hoon; Shin, Won-Ho; Bae, Young-Seuk; Jung, Un Ju; Kim, Sang Ryong

    2016-10-19

    Granule cell dispersion (GCD) in the dentate gyrus (DG) of the hippocampus is a morphological alteration characteristic of temporal lobe epilepsy. Recently, we reported that treatment with naringin, a flavonoid found in grapefruit and citrus fruits, reduced spontaneous recurrent seizures by inhibiting kainic acid (KA)-induced GCD and neuronal cell death in mouse hippocampus, suggesting that naringin might have beneficial effects for preventing epileptic events in the adult brain. However, it is still unclear whether the beneficial effects of naringin treatment are mediated by the metabolism of naringin into naringenin in the KA-treated hippocampus. To investigate this possibility, we evaluated whether intraperitoneal injections of naringenin could mimic naringin-induced effects against GCD caused by intrahippocampal KA injections in mice. Our results showed that treatment with naringenin delayed the onset of KA-induced seizures and attenuated KA-induced GCD by inhibiting activation of the mammalian target of rapamycin complex 1 in both neurons and reactive astrocytes in the DG. In addition, its administration attenuated the production of proinflammatory cytokines such as tumor necrosis tumor necrosis factor-α (TNFα) and interleukin-1β (IL-1β) from microglial activation in the DG following KA treatment. These results suggest that naringenin may be an active metabolite of naringin and help prevent the progression of epileptic insults in the hippocampus in vivo; therefore, naringenin may be a beneficial metabolite of naringin for the treatment of epilepsy.

  13. Interactions between Inhibitory Interneurons and Excitatory Associational Circuitry in Determining Spatio-Temporal Dynamics of Hippocampal Dentate Granule Cells: A Large-Scale Computational Study

    PubMed Central

    Hendrickson, Phillip J.; Yu, Gene J.; Song, Dong; Berger, Theodore W.

    2015-01-01

    This paper reports on findings from a million-cell granule cell model of the rat dentate gyrus that was used to explore the contributions of local interneuronal and associational circuits to network-level activity. The model contains experimentally derived morphological parameters for granule cells, which each contain approximately 200 compartments, and biophysical parameters for granule cells, basket cells, and mossy cells that were based both on electrophysiological data and previously published models. Synaptic input to cells in the model consisted of glutamatergic AMPA-like EPSPs and GABAergic-like IPSPs from excitatory and inhibitory neurons, respectively. The main source of input to the model was from layer II entorhinal cortical neurons. Network connectivity was constrained by the topography of the system, and was derived from axonal transport studies, which provided details about the spatial spread of axonal terminal fields, as well as how subregions of the medial and lateral entorhinal cortices project to subregions of the dentate gyrus. Results of this study show that strong feedback inhibition from the basket cell population can cause high-frequency rhythmicity in granule cells, while the strength of feedforward inhibition serves to scale the total amount of granule cell activity. Results furthermore show that the topography of local interneuronal circuits can have just as strong an impact on the development of spatio-temporal clusters in the granule cell population as the perforant path topography does, both sharpening existing clusters and introducing new ones with a greater spatial extent. Finally, results show that the interactions between the inhibitory and associational loops can cause high frequency oscillations that are modulated by a low-frequency oscillatory signal. These results serve to further illustrate the importance of topographical constraints on a global signal processing feature of a neural network, while also illustrating how rich

  14. Phasic boosting of medial perforant path-evoked granule cell output time-locked to spontaneous dentate EEG spikes in awake rats.

    PubMed

    Bramham, C R

    1998-06-01

    Dentate spikes (DSs) are positive-going field potential transients that occur intermittently in the hilar region of the dentate gyrus during alert wakefulness and slow-wave sleep. The function of dentate spikes is unknown; they have been suggested to be triggered by perforant path input and are associated with firing of hilar interneurons and inhibition of CA3 pyramidal cells. Here we investigated the effect of DSs on medial perforant path (MPP)-granule cell-evoked transmission in freely moving rats. The MPP was stimulated selectively in the angular bundle while evoked field potentials and the EEG were recorded with a vertical multielectrode array in the dentate gyrus. DSs were identified readily on the basis of their characteristic voltage-versus-depth profile, amplitude, duration, and state dependency. Using on-line detection of the DS peak, the timing of MPP stimulation relative to single DSs was controlled. DS-triggered evoked responses were compared with conventional, manually evoked responses in still-alert wakefulness (awake immobility) and, in some cases, slow-wave sleep. Input-output curves were obtained with stimulation on the positive DS peak (0 delay) and at delays of 50, 100, and 500 ms. Stimulation on the peak DS was associated with a significant increase in the population spike amplitude, a reduction in population spike latency, and a decrease in the field excitatory postsynaptic potential (fEPSP) slope, relative to manual stimulation. Granule cell excitability was enhanced markedly during DSs, as indicated by a mean 93% increase in the population spike amplitude and a leftward shift in the fEPSP-spike relation. Maximum effects occurred at the DS peak, and lasted between 50 and 100 ms. Paired-pulse inhibition of the population spike was unaffected, indicating intact recurrent inhibition during DSs. The results demonstrate enhancement of perforant path-evoked granule cell output time-locked to DSs. DSs therefore may function to intermittently boost

  15. The Influence of Ectopic Migration of Granule Cells into the Hilus on Dentate Gyrus-CA3 Function

    PubMed Central

    Myers, Catherine E.; Bermudez-Hernandez, Keria; Scharfman, Helen E.

    2013-01-01

    Postnatal neurogenesis of granule cells (GCs) in the dentate gyrus (DG) produces GCs that normally migrate from the subgranular zone to the GC layer. However, GCs can mismigrate into the hilus, the opposite direction. Previous descriptions of these hilar ectopic GCs (hEGCs) suggest that they are rare unless there are severe seizures. However, it is not clear if severe seizures are required, and it also is unclear if severe seizures are responsible for the abnormalities of hEGCs, which include atypical dendrites and electrophysiological properties. Here we show that large numbers of hEGCs develop in a transgenic mouse without severe seizures. The mice have a deletion of BAX, which normally regulates apoptosis. Surprisingly, we show that hEGCs in the BAX-/- mouse have similar abnormalities as hEGCs that arise after severe seizures. We next asked if there are selective effects of hEGCs, i.e., whether a robust population of hEGCs would have any effect on the DG if they were induced without severe seizures. Indeed, this appears to be true, because it has been reported that BAX-/- mice have defects in a behavior that tests pattern separation, which depends on the DG. However, inferring functional effects of hEGCs is difficult in mice with a constitutive BAX deletion because there is decreased apoptosis in and outside the DG. Therefore, a computational model of the normal DG and hippocampal subfield CA3 was used. Adding a small population of hEGCs (5% of all GCs), with characteristics defined empirically, was sufficient to disrupt a simulation of pattern separation and completion. Modeling results also showed that effects of hEGCs were due primarily to “backprojections” of CA3 pyramidal cell axons to the hilus. The results suggest that hEGCs can develop for diverse reasons, do not depend on severe seizures, and a small population of hEGCs may impair DG-dependent function. PMID:23840835

  16. Redistribution of K+ channels into dendrites is unlikely to account for developmental down regulation of A-currents in rat dentate gyrus granule cells.

    PubMed

    Strecker, T; Heinemann, U

    1993-12-24

    The electrical reactions of many central neurons depend on two voltage-activated K+ currents: the fast transient A-current IA and the delayed rectifier current IK. In rat dentate gyrus granule cells, the A-current density decreases during ontogenesis, possibly due to a redistribution of K+ channels from somata into dendrites. We tested this possibility in mechanically isolated granule cells with preserved dendrites of different length. Potassium currents were recorded with the whole-cell patch-clamp technique using prepulse protocols with and without a delay interval to isolate IA. A correlation between the length of the dendrites and the amount of A-current expressed in a given cell could not be demonstrated. Our findings therefore confirm an ontogenetic down regulation of A-currents.

  17. Time-lapse imaging reveals highly dynamic structural maturation of postnatally born dentate granule cells in organotypic entorhino-hippocampal slice cultures

    PubMed Central

    Radic, Tijana; Jungenitz, Tassilo; Singer, Mathias; Beining, Marcel; Cuntz, Hermann; Vlachos, Andreas; Deller, Thomas; Schwarzacher, Stephan W.

    2017-01-01

    Neurogenesis of hippocampal granule cells (GCs) persists throughout mammalian life and is important for learning and memory. How newborn GCs differentiate and mature into an existing circuit during this time period is not yet fully understood. We established a method to visualize postnatally generated GCs in organotypic entorhino-hippocampal slice cultures (OTCs) using retroviral (RV) GFP-labeling and performed time-lapse imaging to study their morphological development in vitro. Using anterograde tracing we could, furthermore, demonstrate that the postnatally generated GCs in OTCs, similar to adult born GCs, grow into an existing entorhino-dentate circuitry. RV-labeled GCs were identified and individual cells were followed for up to four weeks post injection. Postnatally born GCs exhibited highly dynamic structural changes, including dendritic growth spurts but also retraction of dendrites and phases of dendritic stabilization. In contrast, older, presumably prenatally born GCs labeled with an adeno-associated virus (AAV), were far less dynamic. We propose that the high degree of structural flexibility seen in our preparations is necessary for the integration of newborn granule cells into an already existing neuronal circuit of the dentate gyrus in which they have to compete for entorhinal input with cells generated and integrated earlier. PMID:28256620

  18. L-type Ca2+ currents at CA1 synapses, but not CA3 or dentate granule neuron synapses, are increased in 3xTgAD mice in an age-dependent manner

    PubMed Central

    Wang, Yue; Mattson, Mark P.

    2013-01-01

    Abnormal neuronal excitability and impaired synaptic plasticity might occur before the degeneration and death of neurons in Alzheimer’s disease (AD). To elucidate potential biophysical alterations underlying aberrant neuronal network activity in AD, we performed whole-cell patch clamp analyses of L-type (nifedipine-sensitive) Ca2+ currents (L-VGCC), 4–aminopyridine-sensitive K+ currents, and AMPA (2-amino-3-(3-hydroxy-5-methyl-isoxazol-4-yl)propanoic acid) and NMDA (N-methyl-D-aspartate) currents in CA1, CA3, and dentate granule neurons in hippocampal slices from young, middle-age, and old 3xTgAD mice and age-matched wild type mice. 3xTgAD mice develop progressive widespread accumulation of amyloid b-peptide, and selective hyperphosphorylated tau pathology in hippocampal CA1 neurons, which are associated with cognitive deficits, but independent of overt neuronal degeneration. An age-related elevation of L-type Ca2+ channel current density occurred in CA1 neurons in 3xTgAD mice, but not in wild type mice, with the magnitude being significantly greater in older 3xTgAD mice. The NMDA current was also significantly elevated in CA1 neurons of old 3xTgAD mice compared with in old wild type mice. There were no differences in the amplitude of K+ or AMPA currents in CA1 neurons of 3xTgAD mice compared with wild type mice at any age. There were no significant differences in Ca2+, K+, AMPA, or NMDA currents in CA3 and dentate neurons from 3xTgAD mice compared with wild type mice at any age. Our results reveal an age-related increase of L-VGCC density in CA1 neurons, but not in CA3 or dentate granule neurons, of 3xTgAD mice. These findings suggest a potential contribution of altered L-VGCC to the selective vulnerability of CA1 neurons to tau pathology in the 3xTgAD mice and to their degeneration in AD patients. PMID:23932880

  19. Properties of two voltage-activated potassium currents in acutely isolated juvenile rat dentate gyrus granule cells.

    PubMed

    Beck, H; Ficker, E; Heinemann, U

    1992-12-01

    1. The properties of outward currents were investigated in acutely isolated dentate gyrus granule cells at postnatal ages of day 5-7, 10-14, 18-24 (P5-7, P10-14, P18-24) and at adulthood (2-3 mo), with the use of the whole-cell patch-clamp technique. 2. Kinetic analysis and pharmacological properties showed that an A-type K+ current (IA) and a delayed rectifier current (IK) were present in these cells. 3. IA in P10-14 cells activated and inactivated rapidly with a decay time constant of 7.5 +/- 2.1 (SD) ms with command pulses to +30 mV. The removal of inactivation was monoexponential with a time constant of 23.1 ms (holding potential, -50 mV; conditioning voltage steps of varying duration to -110 mV). V 1/2 of the Boltzmann function describing steady-state inactivation was -65.1 +/- 1.8 mV with a slope factor of -6.0. IA was sensitive to 5 mM 4-aminopyridine (4-AP) but not to 10 mM tetraethylammonium (TEA). 4. IK in P10-14 cells displayed a voltage-dependent activation time constant (4.3 +/- 0.8 ms for command pulses to +30 mV and 16.2 +/- 2.4 for command pulses to -10 mV) and a double-exponential decay (time constants 194 +/- 21 and 1,625 +/- 254 ms). The rate constant of removal of inactivation was 332.1 ms. IK showed a reduction by 61.4 +/- 5.3% with 10 mM TEA and was partially blocked by 5 mM 4-AP in a subpopulation of cells. 5. Whereas IA remained stable over time, IK showed a substantial reduction of current amplitude by 67% after 30 min of cell perfusion through the patch pipette. The time course of this reduction was monoexponential with a time constant of 6.9 min and was partly due to a shift in V1/2 of the steady-state inactivation from -79.2 to -99.6 mV. 6. IA and IK remained stable with respect to kinetic properties during ontogenesis. However, the relative contribution and pharmacological properties of the investigated K+ currents varied with age. Although IA dominated in P5-7 cells, IK was prominent in most older cells. Five millimolars 4-AP reduced

  20. GABAergic hyperinnervation of dentate granule cells in the Ts65Dn mouse model of down syndrome: Exploring the role of App.

    PubMed

    Mojabi, Fatemeh S; Fahimi, Atoossa; Moghadam, Shahrzad; Moghadam, Sarah; Windy McNerneny, M; Ponnusamy, Ravikumar; Kleschevnikov, Alexander; Mobley, William C; Salehi, Ahmad

    2016-12-01

    It has been suggested that increased GABAergic innervation in the hippocampus plays a significant role in cognitive dysfunction in Down syndrome (DS). Bolstering this notion, are studies linking hyper-innervation of the dentate gyrus (DG) by GABAergic terminals to failure in LTP induction in the Ts65Dn mouse model of DS. Here, we used extensive morphometrical methods to assess the status of GABAergic interneurons in the DG of young and old Ts65Dn mice and their 2N controls. We detected an age-dependent increase in GABAergic innervation of dentate granule cells (DGCs) in Ts65Dn mice. The primary source of GABAergic terminals to DGCs somata is basket cells (BCs). For this reason, we assessed the status of these cells and found a significant increase in the number of BCs in Ts65Dn mice compared with controls. Then we aimed to identify the gene/s whose overexpression could be linked to increased number of BCs in Ts65Dn and found that deleting the third copy of App gene in Ts65Dn mice led to normalization of the number of BCs in these mice. Our data suggest that App overexpression plays a major role in the pathophysiology of GABAergic hyperinnervation of the DG in Ts65Dn mice. © 2016 Wiley Periodicals, Inc.

  1. Complementary functions of SK and Kv7/M potassium channels in excitability control and synaptic integration in rat hippocampal dentate granule cells

    PubMed Central

    Mateos-Aparicio, Pedro; Murphy, Ricardo; Storm, Johan F

    2014-01-01

    The dentate granule cells (DGCs) form the most numerous neuron population of the hippocampal memory system, and its gateway for cortical input. Yet, we have only limited knowledge of the intrinsic membrane properties that shape their responses. Since SK and Kv7/M potassium channels are key mechanisms of neuronal spiking and excitability control, afterhyperpolarizations (AHPs) and synaptic integration, we studied their functions in DGCs. The specific SK channel blockers apamin or scyllatoxin increased spike frequency (excitability), reduced early spike frequency adaptation, fully blocked the medium-duration AHP (mAHP) after a single spike or spike train, and increased postsynaptic EPSP summation after spiking, but had no effect on input resistance (Rinput) or spike threshold. In contrast, blockade of Kv7/M channels by XE991 increased Rinput, lowered the spike threshold, and increased excitability, postsynaptic EPSP summation, and EPSP–spike coupling, but only slightly reduced mAHP after spike trains (and not after single spikes). The SK and Kv7/M channel openers 1-EBIO and retigabine, respectively, had effects opposite to the blockers. Computational modelling reproduced many of these effects. We conclude that SK and Kv7/M channels have complementary roles in DGCs. These mechanisms may be important for the dentate network function, as CA3 neurons can be activated or inhibition recruited depending on DGC firing rate. PMID:24366266

  2. Dopamine D1 and D5 Receptors Modulate Spike Timing-Dependent Plasticity at Medial Perforant Path to Dentate Granule Cell Synapses

    PubMed Central

    Yang, Kechun

    2014-01-01

    Although evidence suggests that DA modulates hippocampal function, the mechanisms underlying that dopaminergic modulation are largely unknown. Using perforated-patch electrophysiological techniques to maintain the intracellular milieu, we investigated how the activation of D1-type DA receptors regulates spike timing-dependent plasticity (STDP) of the medial perforant path (mPP) synapse onto dentate granule cells. When D1-type receptors were inhibited, a relatively mild STDP protocol induced LTP only within a very narrow timing window between presynaptic stimulation and postsynaptic response. The stimulus protocol produced timing-dependent LTP (tLTP) only when the presynaptic stimulation was followed 30 ms later by depolarization-induced postsynaptic action potentials. That is, the time between presynaptic stimulation and postsynaptic response was 30 ms (Δt = +30 ms). When D1-type receptors were activated, however, the same mild STDP protocol induced tLTP over a much broader timing window: tLTP was induced when −30 ms ≤ Δt ≤ +30 ms. The result indicated that D1-type receptor activation enabled synaptic potentiation even when postsynaptic activity preceded presynaptic stimulation within this Δt range. Results with null mice lacking the Kv4.2 potassium channel and with the potassium channel inhibitor, 4-aminopyridine, suggested that D1-type receptors enhanced tLTP induction by suppressing the transient IA-type K+ current. Results obtained with antagonists and DA receptor knock-out mice indicated that endogenous activity of both D1 and D5 receptors modulated plasticity in the mPP. The DA D5 receptors appeared particularly important in regulating plasticity of the mPP onto the dentate granule cells. PMID:25429131

  3. Development of barley (Hordeum vulgare L.) lines with altered starch granule size distribution.

    PubMed

    Jaiswal, Sarita; Båga, Monica; Ahuja, Geetika; Rossnagel, Brian G; Chibbar, Ravindra N

    2014-03-12

    Microscope analysis of starches prepared from 139 barley genotypes identified a Japanese genotype, Kinai Kyoshinkai-2 (KK-2), with altered starch granule size distribution. Compared to normal barley starch, KK-2 produced consistently higher volumes of starch granules with 5-15 μm diameter and reduced volumes of starch granules with >15 μm diameter when grown in different environments. A cross between KK-2 and normal starch cultivar CDC Kendall was made and led to the production of 154 F5 lines with alterations to the normal 7:3:1 distribution for A-:B-:C-type starch granule volumes. Three F5 lines showed unimodal starch granule size distribution due to apparent lack of very small (<5.0 μm diameter) C-type starch granules, but the phenotype was accompanied by reduced grain weight and total starch concentration. Five F5 lines produced a significantly larger population of large (>15 μm diameter) A-type starch granules as compared to normal starch and showed on average a 10:4:1 distribution for A-:B-:C-type starch granule volumes. The unusual starch phenotypes displayed by the F5 lines confirm starch granule size distribution in barley can be genetically altered.

  4. Exposure to forced swim stress alters local circuit activity and plasticity in the dentate gyrus of the hippocampus.

    PubMed

    Yarom, Orli; Maroun, Mouna; Richter-Levin, Gal

    2008-01-01

    Studies have shown that, depending on its severity and context, stress can affect neural plasticity. Most related studies focused on synaptic plasticity and long-term potentiation (LTP) of principle cells. However, evidence suggests that following high-frequency stimulation, which induces LTP in principal cells, modifications also take place at the level of complex interactions with interneurons within the dentate gyrus, that is, at the local circuit level. So far, the possible effects of stress on local circuit activity and plasticity were not studied. Therefore, we set out to examine the possible alterations in local circuit activity and plasticity following exposure to stress. Local circuit activity and plasticity were measured by using frequency dependant inhibition (FDI) and commissural modulation protocols following exposure to a 15 minute-forced swim trial. Exposure to stress did not alter FDI. The application of theta-burst stimulation (TBS) reduced FDI in both control and stressed rats, but this type of plasticity was greater in stressed rats. Commissural-induced inhibition was significantly higher in stressed rats both before and after applying theta-burst stimulation. These findings indicate that the exposure to acute stress affects aspects of local circuit activity and plasticity in the dentate gyrus. It is possible that these alterations underlie some of the behavioral consequences of the stress experience.

  5. Nonrandom connectivity of the epileptic dentate gyrus predicts a major role for neuronal hubs in seizures

    PubMed Central

    Morgan, Robert J.; Soltesz, Ivan

    2008-01-01

    Many complex neuronal circuits have been shown to display nonrandom features in their connectivity. However, the functional impact of nonrandom network topologies in neurological diseases is not well understood. The dentate gyrus is an excellent circuit in which to study such functional implications because proepileptic insults cause its structure to undergo a number of specific changes in both humans and animals, including the formation of previously nonexistent granule cell-to-granule cell recurrent excitatory connections. Here, we use a large-scale, biophysically realistic model of the epileptic rat dentate gyrus to reconnect the aberrant recurrent granule cell network in four biologically plausible ways to determine how nonrandom connectivity promotes hyperexcitability after injury. We find that network activity of the dentate gyrus is quite robust in the face of many major alterations in granule cell-to-granule cell connectivity. However, the incorporation of a small number of highly interconnected granule cell hubs greatly increases network activity, resulting in a hyperexcitable, potentially seizure-prone circuit. Our findings demonstrate the functional relevance of nonrandom microcircuits in epileptic brain networks, and they provide a mechanism that could explain the role of granule cells with hilar basal dendrites in contributing to hyperexcitability in the pathological dentate gyrus. PMID:18375756

  6. Environmental Pb2+ exposure during early life alters granule cell neurogenesis and morphology in the hippocampus of young adult rats

    PubMed Central

    Verina, Tatyana; Rohde, Charles A.; Guilarte, Tomás R.

    2007-01-01

    Exposure to environmentally relevant levels of lead (Pb2+) during early life produces deficits in hippocampal synaptic plasticity in the form of long-term potentiation (LTP) and spatial learning in young adult rats (Nihei et al., 2000; Guilarte et al., 2003). Other evidence suggests that the performance of rats in the Morris water maze spatial learning tasks is associated with the level of granule cell neurogenesis in the dentate gyrus (DG) (Drapeau et al., 2003). In this study, we examined whether continuous exposure to environmentally relevant levels of Pb2+ during early life altered granule cell neurogenesis and morphology in the rat hippocampus. Control and Pb2+-exposed rats received BrdU injections (100 mg/kg; i.p.) for five consecutive days starting at postnatal day 45 and were sacrificed either one day or four weeks after the last injection. The total number of newborn cells in the DG of Pb2+-exposed rats was significantly decreased (13%; p<0.001) one day after BrdU injections relative to controls. Further, the survival of newborn cells in Pb2+-exposed rats was significantly decreased by 22.7% (p<0.001) relative to control animals. Co-localization of BrdU with neuronal or astrocytic markers did not reveal a significant effect of Pb2+ exposure on cellular fate. In Pb2+-exposed rats, immature granule cells immunolabeled with doublecortin (DCX) displayed aberrant dendritic morphology. That is, the overall length-density of the DCX-positive apical dendrites in the outer portion of the DG molecular layer was significantly reduced up to 36% in the suprapyramidal blade only. We also found that the area of Timm’s-positive staining representative of the mossy fibers terminal fields in the CA3 stratum oriens (SO) was reduced by 26% in Pb2+-exposed rats. These findings demonstrate that exposure to environmentally relevant levels of Pb2+ during early life alter granule cell neurogenesis and morphology in the rat hippocampus. They provide a cellular and morphological

  7. Effects of prenatal stress and exercise on dentate granule cells maturation and spatial memory in adolescent mice.

    PubMed

    Bustamante, Carlos; Bilbao, Pamela; Contreras, William; Martínez, Mauricio; Mendoza, Antonio; Reyes, Alvaro; Pascual, Rodrigo

    2010-11-01

    Exposure to prenatal stress (PS) increases the risk of developing neurobehavioral disturbances later in life. Previous work has shown that exercise can exert beneficial effects on brain damage; however, it is unknown whether voluntary wheel running (VWR) can ameliorate the neurobehavioral impairments induced by PS in adolescent offspring. Pregnant CF-1 mice were randomly assigned to control (n=5) or stressed (n=5) groups. Pregnant dams were subjected to restraint stress between gestational days 14 and 21 (G14-21), whereas controls remained undisturbed in their home cages. On postnatal day 21 (P21), male pups were randomly assigned to the following experimental groups: control (n=5), stressed (n=5), and stressed mice+daily submitted to VWR (n=4). At P52, all groups were behaviorally evaluated in the Morris water maze. Animals were then sacrificed, and Golgi-impregnated granule cells were morphometrically analyzed. The results indicate that PS produced significant behavioral and neuronal impairments in adolescent offspring and that VWR significantly offset these deleterious effects.

  8. Physical Exercise Prevents Stress-Induced Activation of Granule Neurons and Enhances Local Inhibitory Mechanisms in the Dentate Gyrus

    PubMed Central

    Schoenfeld, Timothy J.; Rada, Pedro; Pieruzzini, Pedro R.; Hsueh, Brian

    2013-01-01

    Physical exercise is known to reduce anxiety. The ventral hippocampus has been linked to anxiety regulation but the effects of running on this subregion of the hippocampus have been incompletely explored. Here, we investigated the effects of cold water stress on the hippocampus of sedentary and runner mice and found that while stress increases expression of the protein products of the immediate early genes c-fos and arc in new and mature granule neurons in sedentary mice, it has no such effect in runners. We further showed that running enhances local inhibitory mechanisms in the hippocampus, including increases in stress-induced activation of hippocampal interneurons, expression of vesicular GABA transporter (vGAT), and extracellular GABA release during cold water swim stress. Finally, blocking GABAA receptors in the ventral hippocampus, but not the dorsal hippocampus, with the antagonist bicuculline, reverses the anxiolytic effect of running. Together, these results suggest that running improves anxiety regulation by engaging local inhibitory mechanisms in the ventral hippocampus. PMID:23637169

  9. Growth hormone and melatonin prevent age-related alteration in apoptosis processes in the dentate gyrus of male rats.

    PubMed

    Kireev, R A; Vara, E; Tresguerres, J A F

    2013-08-01

    It has been suggested that the age-related decrease in the number of neurons in the hippocampus that leads to alterations in brain function, may be associated with an increase in apoptosis due to the reduced secretion of growth hormone (GH) and/or melatonin in old animals. In order to investigate this possibility, male Wistar rats of 22 months of age were divided into three groups. One group remained untreated and acted as the control group. The second was treated with growth hormone (hGH) for 10 weeks (2 mg/kg/d sc) and the third was subjected to melatonin treatment (1 mg/kg/d) in the drinking water for the same time. A group of 2-months-old male rats was used as young controls. All rats were killed by decapitation at more than 24 month of age and dentate gyri of the hippocampi were collected. Aging in the dentate gyrus was associated with an increase in apoptosis promoting markers (Bax, Bad and AIF) and with the reduction of some anti-apoptotic ones (XIAP, NIAP, Mcl-1). Expressions of sirtuin 1 and 2 (SIRT1 and 2) as well as levels of HSP 70 were decreased in the dentate gyrus of old rats. GH treatment was able to reduce the pro/anti-apoptotic ratio to levels observed in young animals and also to increase SIRT2. Melatonin reduced also expression of pro-apoptotic genes and proteins (Bax, Bad and AIF), and increased levels of myeloid cell leukemia-1 proteins and SIRT1. Both treatments were able to reduce apoptosis and to enhance survival markers in this part of the hippocampus.

  10. Housing Complexity Alters GFAP-Immunoreactive Astrocyte Morphology in the Rat Dentate Gyrus

    PubMed Central

    Salois, Garrick; Smith, Jeffrey S.

    2016-01-01

    Rats used in research are typically housed singly in cages with limited sensory stimulation. There is substantial evidence that housing rats in these conditions lead to numerous neuroanatomical and behavioral abnormalities. Alternatively, rats can be housed in an enriched environment in which rats are housed in groups and given room for exercise and exploration. Enriched environments result in considerable neuroplasticity in the rodent brain. In the dentate gyrus of the hippocampus, enriched environments evoke especially profound neural changes, including increases in the number of neurons and the number of dendritic spines. However, whether changes in astrocytes, a type of glia increasingly implicated in mediating neuroplasticity, are concurrent with these neural changes remains to be investigated. In order to assess morphological changes among astrocytes of the rat dentate gyrus, piSeeDB was used to optically clear 250 μm sections of tissue labeled using GFAP immunohistochemistry. Confocal imaging and image analysis were then used to measure astrocyte morphology. Astrocytes from animals housed in EE demonstrated a reduced distance between filament branch points. Furthermore, the most complex astrocytes were significantly more complex among animals housed in EE compared to standard environments. PMID:26989515

  11. Calcium permeable AMPA receptor-dependent long lasting plasticity of intrinsic excitability in fast spiking interneurons of the dentate gyrus decreases inhibition in the granule cell layer.

    PubMed

    Dasgupta, Debanjan; Sikdar, Sujit Kumar

    2015-03-01

    The local fast-spiking interneurons (FSINs) are considered to be crucial for the generation, maintenance, and modulation of neuronal network oscillations especially in the gamma frequency band. Gamma frequency oscillations have been associated with different aspects of behavior. But the prolonged effects of gamma frequency synaptic activity on the FSINs remain elusive. Using whole cell current clamp patch recordings, we observed a sustained decrease of intrinsic excitability in the FSINs of the dentate gyrus (DG) following repetitive stimulations of the mossy fibers at 30 Hz (gamma bursts). Surprisingly, the granule cells (GCs) did not express intrinsic plastic changes upon similar synaptic excitation of their apical dendritic inputs. Interestingly, pairing the gamma bursts with membrane hyperpolarization accentuated the plasticity in FSINs following the induction protocol, while the plasticity attenuated following gamma bursts paired with membrane depolarization. Paired pulse ratio measurement of the synaptic responses did not show significant changes during the experiments. However, the induction protocols were accompanied with postsynaptic calcium rise in FSINs. Interestingly, the maximum and the minimum increase occurred during gamma bursts with membrane hyperpolarization and depolarization respectively. Including a selective blocker of calcium-permeable AMPA receptors (CP-AMPARs) in the bath; significantly attenuated the calcium rise and blocked the membrane potential dependence of the calcium rise in the FSINs, suggesting their involvement in the observed phenomenon. Chelation of intracellular calcium, blocking HCN channel conductance or blocking CP-AMPARs during the experiment forbade the long lasting expression of the plasticity. Simultaneous dual patch recordings from FSINs and synaptically connected putative GCs confirmed the decreased inhibition in the GCs accompanying the decreased intrinsic excitability in the FSINs. Experimentally constrained network

  12. Increased Excitatory Synaptic Transmission of Dentate Granule Neurons in Mice Lacking PSD-95-Interacting Adhesion Molecule Neph2/Kirrel3 during the Early Postnatal Period

    PubMed Central

    Roh, Junyeop D.; Choi, Su-Yeon; Cho, Yi Sul; Choi, Tae-Yong; Park, Jong-Sil; Cutforth, Tyler; Chung, Woosuk; Park, Hanwool; Lee, Dongsoo; Kim, Myeong-Heui; Lee, Yeunkum; Mo, Seojung; Rhee, Jeong-Seop; Kim, Hyun; Ko, Jaewon; Choi, Se-Young; Bae, Yong Chul; Shen, Kang; Kim, Eunjoon; Han, Kihoon

    2017-01-01

    Copy number variants and point mutations of NEPH2 (also called KIRREL3) gene encoding an immunoglobulin (Ig) superfamily adhesion molecule have been linked to autism spectrum disorders, intellectual disability and neurocognitive delay associated with Jacobsen syndrome, but the physiological roles of Neph2 in the mammalian brain remain largely unknown. Neph2 is highly expressed in the dentate granule (DG) neurons of the hippocampus and is localized in both dendrites and axons. It was recently shown that Neph2 is required for the formation of mossy fiber filopodia, the axon terminal structure of DG neurons forming synapses with GABAergic neurons of CA3. In contrast, however, it is unknown whether Neph2 also has any roles in the postsynaptic compartments of DG neurons. We here report that, through its C-terminal PDZ domain-binding motif, Neph2 directly interacts with postsynaptic density (PSD)-95, an abundant excitatory postsynaptic scaffolding protein. Moreover, Neph2 protein is detected in the brain PSD fraction and interacts with PSD-95 in synaptosomal lysates. Functionally, loss of Neph2 in mice leads to age-specific defects in the synaptic connectivity of DG neurons. Specifically, Neph2−/− mice show significantly increased spontaneous excitatory synaptic events in DG neurons at postnatal week 2 when the endogenous Neph2 protein expression peaks, but show normal excitatory synaptic transmission at postnatal week 3. The evoked excitatory synaptic transmission and synaptic plasticity of medial perforant pathway (MPP)-DG synapses are also normal in Neph2−/− mice at postnatal week 3, further confirming the age-specific synaptic defects. Together, our results provide some evidence for the postsynaptic function of Neph2 in DG neurons during the early postnatal period, which might be implicated in neurodevelopmental and cognitive disorders caused by NEPH2 mutations. PMID:28381988

  13. Reduction of the immunostainable length of the hippocampal dentate granule cells' primary cilia in 3xAD-transgenic mice producing human A{beta}{sub 1-42} and tau

    SciTech Connect

    Chakravarthy, Balu; Gaudet, Chantal; Menard, Michel; Brown, Leslie; Atkinson, Trevor; LaFerla, Frank M.; Ito, Shingo; Armato, Ubaldo; Dal Pra, Ilaria; Whitfield, James

    2012-10-12

    Highlights: Black-Right-Pointing-Pointer A{beta} and tau-induced neurofibrillary tangles play a key role in Alzheimer's disease. Black-Right-Pointing-Pointer A{beta}{sub 1-42} and mutant tau protein together reduce the primary cilium length. Black-Right-Pointing-Pointer This shortening likely reduces cilium-dependent neurogenesis and memory function. Black-Right-Pointing-Pointer This provides a model of an A{beta}/tau targeting of a neuronal signaling organelle. -- Abstract: The hippocampal dentate gyrus is one of the two sites of continuous neurogenesis in adult rodents and humans. Virtually all dentate granule cells have a single immobile cilium with a microtubule spine or axoneme covered with a specialized cell membrane loaded with receptors such as the somatostatin receptor 3 (SSTR3), and the p75 neurotrophin receptor (p75{sup NTR}). The signals from these receptors have been reported to stimulate neuroprogenitor proliferation and the post-mitotic maturation of newborn granule cells into functioning granule cells. We have found that in 6-24-months-old triple transgenic Alzheimer's disease model mice (3xTg-AD) producing both A{beta}{sub 1-42} and the mutant human tau protein tau{sub P301L,} the dentate granule cells still had immunostainable SSTR3- and p75{sup NTR}-bearing cilia but they were only half the length of the immunostained cilia in the corresponding wild-type mice. However, the immunostainable length of the granule cell cilia was not reduced either in 2xTg-AD mice accumulating large amounts of A{beta}{sub 1-42} or in mice accumulating only a mutant human tau protein. Thus it appears that a combination of A{beta}{sub 1-42} and tau protein accumulation affects the levels of functionally important receptors in 3xTg-AD mice. These observations raise the important possibility that structural and functional changes in granule cell cilia might have a role in AD.

  14. Proteomic profiling of the epileptic dentate gyrus

    PubMed Central

    Li, Aiqing; Choi, Yun-Sik; Dziema, Heather; Cao, Ruifeng; Cho, Hee-Yeon; Jung, Yeon Joo; Obrietan, Karl

    2010-01-01

    The development of epilepsy is often associated with marked changes in central nervous system cell structure and function. Along these lines, reactive gliosis and granule cell axonal sprouting within the dentate gyrus of the hippocampus are commonly observed in individuals with temporal lobe epilepsy. Here we used the pilocarpine model of temporal lobe epilepsy in mice to screen the proteome and phosphoproteome of the dentate gyrus to identify molecular events that are altered as part of the pathogenic process. Using a two-dimensional gel electrophoresis-based approach, followed by liquid chromatography-tandem mass spectrometry, 24 differentially expressed proteins, including 9 phosphoproteins, were identified. Functionally, these proteins were organized into several classes, including synaptic physiology, cell structure, cell stress, metabolism and energetics. The altered expression of three proteins involved in synaptic physiology, actin, profilin 1 and α-synuclein, was validated by secondary methods. Interestingly, marked changes in protein expression were detected in the supragranular cell region, an area where robust mossy fibers sprouting occurs. Together, these data provide new molecular insights into the altered protein profile of the epileptogenic dentate gyrus and point to potential pathophysiologic mechanisms underlying epileptogenesis. PMID:20608933

  15. beta-Estradiol induces synaptogenesis in the hippocampus by enhancing brain-derived neurotrophic factor release from dentate gyrus granule cells.

    PubMed

    Sato, Kaoru; Akaishi, Tatsuhiro; Matsuki, Norio; Ohno, Yasuo; Nakazawa, Ken

    2007-05-30

    We investigated the effect of beta-estradiol (E2) on synaptogenesis in the hippocampus using organotypic hippocampal slice cultures and subregional hippocampal neuron cultures. E2 increased the expression of PSD95, a postsynaptic marker, specifically in stratum lucidum of Cornu Ammonis 3 (CA3SL) in cultured hippocampal slices. E2 also increased the spine density at the proximal site of CA3 apical dendrites in CA3SL and PSD95 was clustered on these spine heads. The effects of E2 on the expression of PSD95 and the spine density disappeared when the dentate gyrus (DG) had been excised at 1 day in vitro (DIV). FM1-43 analysis of subregional hippocampal neuron cultures which were comprised of Ammon's horn neurons, DG neurons, or a mixture of these neurons, revealed that E2 increased the number of presynaptic sites in the cultures that contained DG neurons. K252a, a potent inhibitor of the high affinity receptor of brain-derived neurotrophic factor (BDNF), and function-blocking antibody to BDNF (BDNFAB) completely inhibited the effects of E2 in hippocampal slice cultures and subregional neuron cultures, whereas ICI182,780 (ICI), a strong antagonist of nuclear estrogen receptors (nERs), did not. Expression of BDNF in DG neurons was markedly higher than that in Ammon's horn neurons and E2 did not affect these expression levels. E2 significantly increased the BDNF release from DG neurons. KT5720, a specific inhibitor of 3'-5'-cyclic adenosine monophosphate (cAMP)-dependent protein kinase A (PKA), and Rp-adenosine 3', 5'-cyclic monophosphorothioate triethylammonium salt (Rp-cAMP), a non-hydrolyzable diastereoisomer and a potent inhibitor of PKA, completely suppressed the E2-induced increase in BDNF release, whereas ICI and U0126, a potent inhibitor of MAP kinase kinase (MEK), did not. These results suggest that E2 induces synaptogenesis between mossy fibers and CA3 neurons by enhancing BDNF release from DG granule cells in a nER-independent and PKA-dependent manner.

  16. DEVELOPMENTAL HYPOTHYROIDISM ALTERS SYNAPTIC TRANSMISSION IN DENTATE GYRUS AND AREA CA1 OF HIPPOCAMPUS.

    EPA Science Inventory

    Hypothyroidism during critical periods of brain developmental leads to learning deficits and alterations in hippocampal structure. Neurophysiological properties of the hippocampus, however, have not been well characterized. The present study examined field potentials evoked in...

  17. Environmental lead exposure during early life alters granule cell neurogenesis and morphology in the hippocampus of young adult rats.

    PubMed

    Verina, T; Rohde, C A; Guilarte, T R

    2007-03-30

    Exposure to environmentally relevant levels of lead (Pb(2+)) during early life produces deficits in hippocampal synaptic plasticity in the form of long-term potentiation (LTP) and spatial learning in young adult rats [Nihei MK, Desmond NL, McGlothan JL, Kuhlmann AC, Guilarte TR (2000) N-methyl-D-aspartate receptor subunit changes are associated with lead-induced deficits of long-term potentiation and spatial learning. Neuroscience 99:233-242; Guilarte TR, Toscano CD, McGlothan JL, Weaver SA (2003) Environmental enrichment reverses cognitive and molecular deficits induced by developmental lead exposure. Ann Neurol 53:50-56]. Other evidence suggests that the performance of rats in the Morris water maze spatial learning tasks is associated with the level of granule cell neurogenesis in the dentate gyrus (DG) [Drapeau E, Mayo W, Aurousseau C, Le Moal M, Piazza P-V, Abrous DN (2003) Spatial memory performance of aged rats in the water maze predicts level of hippocampal neurogenesis. Proc Natl Acad Sci U S A 100:14385-14390]. In this study, we examined whether continuous exposure to environmentally relevant levels of Pb(2+) during early life altered granule cell neurogenesis and morphology in the rat hippocampus. Control and Pb(2+)-exposed rats received bromodeoxyuridine (BrdU) injections (100 mg/kg; i.p.) for five consecutive days starting at postnatal day 45 and were killed either 1 day or 4 weeks after the last injection. The total number of newborn cells in the DG of Pb(2+)-exposed rats was significantly decreased (13%; P<0.001) 1 day after BrdU injections relative to controls. Further, the survival of newborn cells in Pb(2+)-exposed rats was significantly decreased by 22.7% (P<0.001) relative to control animals. Co-localization of BrdU with neuronal or astrocytic markers did not reveal a significant effect of Pb(2+) exposure on cellular fate. In Pb(2+)-exposed rats, immature granule cells immunolabeled with doublecortin (DCX) displayed aberrant dendritic morphology

  18. Normal and epilepsy-associated pathologic function of the dentate gyrus

    PubMed Central

    Dengler, C.G.; Coulter, D.A.

    2016-01-01

    The dentate gyrus plays critical roles both in cognitive processing, and in regulation of the induction and propagation of pathological activity. The cellular and circuit mechanisms underlying these diverse functions overlap extensively. At the cellular level, the intrinsic properties of dentate granule cells combine to endow these neurons with a fundamental reluctance to activate, one of their hallmark traits. At the circuit level, the dentate gyrus constitutes one of the more heavily inhibited regions of the brain, with strong, fast feedforward and feedback GABAergic inhibition dominating responses to afferent activation. In pathologic states such as epilepsy, a number of alterations within the dentate gyrus combine to compromise the regulatory properties of this circuit, culminating in a collapse of its normal function. This epilepsy-associated transformation in the fundamental properties of this critical regulatory hippocampal circuit may contribute both to seizure propensity, and cognitive and emotional comorbidities characteristic of this disease state. PMID:27323942

  19. Status Epilepticus Induced Spontaneous Dentate Gyrus Spikes: In Vivo Current Source Density Analysis

    PubMed Central

    Flynn, Sean P.; Barrier, Sylvain; Scott, Rod C.; Lenck- Santini, Pierre-Pascal; Holmes, Gregory L.

    2015-01-01

    The dentate gyrus is considered to function as an inhibitory gate limiting excitatory input to the hippocampus. Following status epilepticus (SE), this gating function is reduced and granule cells become hyper-excitable. Dentate spikes (DS) are large amplitude potentials observed in the dentate gyrus (DG) of normal animals. DS are associated with membrane depolarization of granule cells, increased activity of hilar interneurons and suppression of CA3 and CA1 pyramidal cell firing. Therefore, DS could act as an anti-excitatory mechanism. Because of the altered gating function of the dentate gyrus following SE, we sought to investigate how DS are affected following pilocarpine-induced SE. Two weeks following lithium-pilocarpine SE induction, hippocampal EEG was recorded in male Sprague-Dawley rats with 16-channel silicon probes under urethane anesthesia. Probes were placed dorso-ventrally to encompass either CA1-CA3 or CA1-DG layers. Large amplitude spikes were detected from EEG recordings and subject to current source density analysis. Probe placement was verified histologically to evaluate the anatomical localization of current sinks and the origin of DS. In 9 of 11 pilocarpine-treated animals and two controls, DS were confirmed with large current sinks in the molecular layer of the dentate gyrus. DS frequency was significantly increased in pilocarpine-treated animals compared to controls. Additionally, in pilocarpine-treated animals, DS displayed current sinks in the outer, middle and/or inner molecular layers. However, there was no difference in the frequency of events when comparing between layers. This suggests that following SE, DS can be generated by input from medial and lateral entorhinal cortex, or within the dentate gyrus. DS were associated with an increase in multiunit activity in the granule cell layer, but no change in CA1. These results suggest that following SE there is an increase in DS activity, potentially arising from hyperexcitability along the

  20. Cysteamine depletes prolactin (PRL) but does not alter the structure of PRL-containing granules in the anterior pituitary

    SciTech Connect

    Weinstein, L.A.; Landis, D.M.; Sagar, S.M.; Millard, W.J.; Martin, J.B.

    1984-10-01

    Cysteamine causes a profound depletion of PRL in the anterior pituitary and in the systemic circulation, as measured by RIA and bioassay. However, electron microscopic study of PRL-containing cells in rat anterior pituitary does not reveal changes in secretory granule or cytoplasmic structure during the interval of depressed PRL content and of subsequent recovery to normal levels. In contrast to the results obtained by RIA, PRL-like immunoreactivity as detected by immunocyto-chemistry is present and similar to that of control preparations after cysteamine administration. We suggest that cysteamine alters PRL structure in secretory granules, probably by interacting with the disulfide bonds of PRL, thereby altering bioactivity and immunoreactivity. The presence of cysteamine-altered PRL in secretory granules does not seem to trigger degradation of granules by the lysosomal system.

  1. Adult-onset deficiency in growth hormone and insulin-like growth factor-I decreases survival of dentate granule neurons: insights into the regulation of adult hippocampal neurogenesis.

    PubMed

    Lichtenwalner, Robin J; Forbes, M Elizabeth; Sonntag, William E; Riddle, David R

    2006-02-01

    Insulin-like growth factor-I (IGF-I), long thought to provide critical trophic support during development, also has emerged as a candidate for regulating ongoing neuronal production in adulthood. Whether and how IGF-I influences each phase of neurogenesis, however, remains unclear. In the current study, we used a selective model of growth hormone (GH) and plasma IGF-I deficiency to evaluate the role of GH and IGF-I in regulating cell proliferation, survival, and neuronal differentiation in the adult dentate gyrus. GH/IGF-I-deficient dwarf rats of the Lewis strain were made GH/IGF-I replete throughout development via twice daily injections of GH, and then GH/IGF-I deficiency was initiated in adulthood by removing animals from GH treatment. Bromodeoxyuridine (BrdU) labeling revealed no effect of GH/IGF-I deficiency on cell proliferation, but adult-onset depletion of GH and plasma IGF-I significantly reduced the survival of newly generated cells in the dentate gyrus. Colabeling for BrdU and markers of immature and mature neurons revealed a selective effect of GH/IGF-I deficiency on the survival of more mature new neurons. The number of BrdU-labeled cells expressing the immature neuronal marker TUC-4 did not differ between GH/IGF-I-deficient and -replete animals, but the number expressing only the marker of maturity NeuN was lower in depleted animals. Taken together, results from the present study suggest that, under conditions of short-term GH/IGF-I deficiency during adulthood, dentate granule cells continue to be produced, to commit to a neuronal fate, and to begin the process of neuronal maturation, whereas survival of the new neurons is impaired.

  2. beta-adrenergic receptors primarily are located on the dendrites of granule cells and interneurons but also are found on astrocytes and a few presynaptic profiles in the rat dentate gyrus.

    PubMed

    Milner, T A; Shah, P; Pierce, J P

    2000-06-01

    In the rat dentate gyrus, beta-adrenergic receptor (beta-AR) activation is thought to be important in mediating the effects of norepinephrine (NE). beta-AR-immunoreactivity (beta-AR-I) was localized in this study by light and electron microscopy in the rat dentate gyrus by using two previously characterized antibodies to the beta-AR. By light microscopy, dense beta-AR-I was observed in the somata of granule cells and a few hilar interneurons. Diffuse and slightly granular beta-AR-I was found in all laminae, although it was most noticeable in the molecular layer. Ultrastructurally, the cytoplasm of granule cell and interneuronal perikarya (some of which contained parvalbumin immunoreactivity) contained beta-AR-I. beta-AR-I was associated primarily with the endoplasmic reticula; however, a few patches were observed near the plasmalemma. Quantitative analysis revealed that the greatest proportion of beta-AR-labeled profiles was found in the molecular layer. The majority of beta-AR-labeled profiles were either dendritic or astrocytic. In dendritic profiles, beta-AR-I was prominent near postsynaptic densities in large dendrites, many of which originated from granule cell somata. Moreover, some beta-AR-I was found in dendritic spines, sometimes affiliated with the spine apparati. Astrocytic profiles with beta-AR-I were commonly found next to unlabeled terminals which formed asymmetric (excitatory-type) synapses with dendritic spines. Additionally, beta-AR-I was observed in a few unmyelinated axons and axon terminals, many of which formed synapses with dendritic spines. Dual-labeling studies revealed that axons and axon terminals containing tyrosine hydroxylase (TH), the catecholamine synthesizing enzyme, often were near both neuronal and glial profiles containing beta-AR-I. These studies demonstrate that hippocampal beta-AR-I is localized: 1) principally in postsynaptic sites on granule cells and a few interneurons (some of which were basket cells); and 2) in glial

  3. Blockade of excitatory synaptogenesis with proximal dendrites of dentate granule cells following rapamycin treatment in a mouse model of temporal lobe epilepsy

    PubMed Central

    Yamawaki, Ruth; Thind, Khushdev; Buckmaster, Paul S.

    2014-01-01

    Inhibiting the mTOR signaling pathway with rapamycin blocks granule cell axon (mossy fiber) sprouting after epileptogenic injuries, including pilocarpine-induced status epilepticus. However, it remains unclear whether axons from other types of neurons sprout into the inner molecular layer and synapse with granule cell dendrites despite rapamycin treatment. If so, other aberrant positive-feedback networks might develop. To test this possibility stereological electron microscopy was used to estimate numbers of excitatory synapses in the inner molecular layer per hippocampus in pilocarpine-treated control mice, in mice 5 d after pilocarpine-induced status epilepticus, and after status epilepticus and daily treatment beginning 24 h later with rapamycin or vehicle for 2 months. The optical fractionator method was used to estimate numbers of granule cells in Nissl-stained sections so that numbers of excitatory synapses in the inner molecular layer per granule cell could be calculated. Control mice had an average of 2280 asymmetric synapses in the inner molecular layer per granule cell, which was reduced to 63% of controls 5 d after status epilepticus, recovered to 93% of controls in vehicle-treated mice 2 months after status epilepticus, but remained at only 63% of controls in rapamycin-treated mice. These findings reveal that rapamycin prevented excitatory axons from synapsing with proximal dendrites of granule cells and raise questions about the recurrent excitation hypothesis of temporal lobe epilepsy. PMID:25234294

  4. Transcriptional Profiling of Newly Generated Dentate Granule Cells Using TU Tagging Reveals Pattern Shifts in Gene Expression during Circuit Integration1,2

    PubMed Central

    Chatzi, Christina; Shen, Rongkun; Goodman, Richard H.

    2016-01-01

    Abstract Despite representing only a small fraction of hippocampal granule cells, adult-generated newborn granule cells have been implicated in learning and memory (Aimone et al., 2011). Newborn granule cells undergo functional maturation and circuit integration over a period of weeks. However, it is difficult to assess the accompanying gene expression profiles in vivo with high spatial and temporal resolution using traditional methods. Here we used a novel method [“thiouracil (TU) tagging”] to map the profiles of nascent mRNAs in mouse immature newborn granule cells compared with mature granule cells. We targeted a nonmammalian uracil salvage enzyme, uracil phosphoribosyltransferase, to newborn neurons and mature granule cells using retroviral and lentiviral constructs, respectively. Subsequent injection of 4-TU tagged nascent RNAs for analysis by RNA sequencing. Several hundred genes were significantly enhanced in the retroviral dataset compared with the lentiviral dataset. We compared a selection of the enriched genes with steady-state levels of mRNAs using quantitative PCR. Ontology analysis revealed distinct patterns of nascent mRNA expression, with newly generated immature neurons showing enhanced expression for genes involved in synaptic function, and neural differentiation and development, as well as genes not previously associated with granule cell maturation. Surprisingly, the nascent mRNAs enriched in mature cells were related to energy homeostasis and metabolism, presumably indicative of the increased energy demands of synaptic transmission and their complex dendritic architecture. The high spatial and temporal resolution of our modified TU-tagging method provides a foundation for comparison with steady-state RNA analyses by traditional transcriptomic approaches in defining the functional roles of newborn neurons. PMID:27011954

  5. The forced swimming-induced behavioural immobility response involves histone H3 phospho-acetylation and c-Fos induction in dentate gyrus granule neurons via activation of the N-methyl-D-aspartate/extracellular signal-regulated kinase/mitogen- and stress-activated kinase signalling pathway.

    PubMed

    Chandramohan, Yalini; Droste, Susanne K; Arthur, J Simon C; Reul, Johannes M H M

    2008-05-01

    The hippocampus is involved in learning and memory. Previously, we have shown that the acquisition of the behavioural immobility response after a forced swim experience is associated with chromatin modifications and transcriptional induction in dentate gyrus granule neurons. Given that both N-methyl-D-aspartate (NMDA) receptors and the extracellular signal-regulated kinases (ERK) 1/2 signalling pathway are involved in neuroplasticity processes underlying learning and memory, we investigated in rats and mice whether these signalling pathways regulate chromatin modifications and transcriptional events participating in the acquisition of the immobility response. We found that: (i) forced swimming evoked a transient increase in the number of phospho-acetylated histone H3-positive [P(Ser10)-Ac(Lys14)-H3(+)] neurons specifically in the middle and superficial aspects of the dentate gyrus granule cell layer; (ii) antagonism of NMDA receptors and inhibition of ERK1/2 signalling blocked forced swimming-induced histone H3 phospho-acetylation and the acquisition of the behavioural immobility response; (iii) double knockout (DKO) of the histone H3 kinase mitogen- and stress-activated kinases (MSK) 1/2 in mice completely abolished the forced swimming-induced increases in histone H3 phospho-acetylation and c-Fos induction in dentate granule neurons and the behavioural immobility response; (iv) blocking mineralocorticoid receptors, known not to be involved in behavioural immobility in the forced swim test, did not affect forced swimming-evoked histone H3 phospho-acetylation in dentate neurons; and (v) the pharmacological manipulations and gene deletions did not affect behaviour in the initial forced swim test. We conclude that the forced swimming-induced behavioural immobility response requires histone H3 phospho-acetylation and c-Fos induction in distinct dentate granule neurons through recruitment of the NMDA/ERK/MSK 1/2 pathway.

  6. Reduced tonic inhibition in the dentate gyrus contributes to chronic stress-induced impairments in learning and memory.

    PubMed

    Lee, Vallent; MacKenzie, Georgina; Hooper, Andrew; Maguire, Jamie

    2016-10-01

    It is well established that stress impacts the underlying processes of learning and memory. The effects of stress on memory are thought to involve, at least in part, effects on the hippocampus, which is particularly vulnerable to stress. Chronic stress induces hippocampal alterations, including but not limited to dendritic atrophy and decreased neurogenesis, which are thought to contribute to chronic stress-induced hippocampal dysfunction and deficits in learning and memory. Changes in synaptic transmission, including changes in GABAergic inhibition, have been documented following chronic stress. Recently, our laboratory demonstrated shifts in EGABA in CA1 pyramidal neurons following chronic stress, compromising GABAergic transmission and increasing excitability of these neurons. Interestingly, here we demonstrate that these alterations are unique to CA1 pyramidal neurons, since we do not observe shifts in EGABA following chronic stress in dentate gyrus granule cells. Following chronic stress, there is a decrease in the expression of the GABAA receptor (GABAA R) δ subunit and tonic GABAergic inhibition in dentate gyrus granule cells, whereas there is an increase in the phasic component of GABAergic inhibition, evident by an increase in the peak amplitude of spontaneous inhibitory postsynaptic currents (sIPSCs). Given the numerous changes observed in the hippocampus following stress, it is difficult to pinpoint the pertinent contributing pathophysiological factors. Here we directly assess the impact of a reduction in tonic GABAergic inhibition of dentate gyrus granule cells on learning and memory using a mouse model with a decrease in GABAA R δ subunit expression specifically in dentate gyrus granule cells (Gabrd/Pomc mice). Reduced GABAA R δ subunit expression and function in dentate gyrus granule cells is sufficient to induce deficits in learning and memory. Collectively, these findings suggest that the reduction in GABAA R δ subunit-mediated tonic inhibition

  7. The cannabinoid WIN 55,212-2-mediated protection of dentate gyrus granule cells is driven by CB1 receptors and modulated by TRPA1 and Cav 2.2 channels.

    PubMed

    Koch, Marco; Kreutz, Susanne; Böttger, Charlotte; Grabiec, Urszula; Ghadban, Chalid; Korf, Horst-Werner; Dehghani, Faramarz

    2011-05-01

    Cannabinoids regulate numerous physiological and pathological events like inflammation or neurodegeneration via CB(1) and CB(2) receptors. The mechanisms behind cannabinoid effects show a high variability and may also involve transient receptor potential channels (TRP) and N-type voltage-gated Ca(2+) channels (Ca(v) 2.2). In the present study we investigated the neuroprotective effects of the synthetic cannabinoid WIN 55,212-2 (WIN) on dentate gyrus (DG) granule cells and elucidated the involvement of TRP and Ca(v) 2.2 that are shown to participate in inflammatory processes. Organotypic hippocampal slice cultures were excitotoxically lesioned using NMDA and subsequently incubated with different WIN concentrations (0.001-10 μM). WIN showed neuroprotective properties in an inverse concentration-dependent manner, most effectively at 0.01 μM. The CB(1) receptor antagonist AM251 blocked neuroprotection mediated by WIN whereas the CB(2) receptor antagonist AM630 showed no effects. Application of the TRPA1 blocker HC-030031 enhanced the neuroprotective efficacy of high (10 μM) WIN concentrations and the number of degenerating neurons became equal to that seen after application of the most effective WIN dose (0.01 μM). In contrast, the application of TRPA1 agonist icilin or allyl isothiocyanate (AITC) led to a stronger neurodegeneration. The use of TRPV1 blocker 6-iodo-nordihydrocapsaicin did not affect WIN-mediated neuroprotection. The selective Ca(v) 2.2 blocker ω-conotoxin (GVIA) completely blocked neuroprotection shown by 10 μM WIN. GVIA and HC-030031 exerted no effects at WIN concentrations lower than 10 μM. Our data show that WIN protects dentate gyrus granule cells in a concentration dependent manner by acting upon CB(1) receptors. At high (10 μM) concentrations WIN additionally activates TRPA1 and Ca(v) 2.2 within the hippocampal formation that both interfere with CB(1) receptor-mediated neuroprotection. This leads to the conclusion that physiological and

  8. Differential effects of the histamine H3 receptor agonist methimepip on dentate granule cell excitability, paired-pulse plasticity and long-term potentiation in prenatal alcohol-exposed rats

    PubMed Central

    Varaschin, Rafael K.; Rosenberg, Martina J.; Hamilton, Derek A.; Savage, Daniel D.

    2016-01-01

    We previously reported that prenatal alcohol-induced deficits in dentate gyrus (DG) long-term potentiation (LTP) are ameliorated by the histamine H3 receptor inverse agonist ABT-239. ABT-239 did not enhance LTP in control rats, suggesting a heightened H3 receptor-mediated inhibition of glutamate release in prenatal alcohol-exposed (PAE) offspring. As the modulation of glutamate release is one important facet of LTP, we examined the effect of methimepip, a histamine H3 receptor agonist, on DG granule cell excitability, glutamate release and LTP in control and PAE rats. Long-Evans rat dams voluntarily consumed either a 0% or 5% ethanol solution four hours daily throughout gestation. Male adult offspring were anesthetized with urethane and electrodes implanted into the entorhinal cortex and DG. PAE reduced coupling of excitatory post-synaptic field potentials to population spikes, an effect mimicked in control rats treated with 1 mg/kg methimepip. Methimepip decreased release probability in controls but not in PAE offspring. GABAergic feedback inhibition of granule cell responsiveness was not affected by either PAE or methimepip. PAE reduced LTP in the DG, another effect mimicked in methimepip-treated control rats. Again, methimepip did not exacerbate the PAE-induced LTP deficit. Thus, while methimepip treatment of control rats mimicked some baseline and activity-dependent deficits observed in saline-treated PAE offspring, methimepip treatment of PAE rats did not exacerbate these deficits. Whether the absence of an added methimepip effect in PAE offspring is a consequence of a “floor effect” for the responses measured or is due to differential drug dose responsiveness will require further investigation. Further, more detailed studies of H3 receptor-mediated responses in vitro may provide clearer insights into the role of the H3 receptor regulation of excitatory transmission at the perforant path - DG synapse in PAE rats. PMID:24818819

  9. Sex steroids and the dentate gyrus.

    PubMed

    Hajszan, Tibor; Milner, Teresa A; Leranth, Csaba

    2007-01-01

    In the late 1980s, the finding that the dentate gyrus contains more granule cells in the male than in the female of certain mouse strains provided the first indication that the dentate gyrus is a significant target for the effects of sex steroids during development. Gonadal hormones also play a crucial role in shaping the function and morphology of the adult brain. Besides reproduction-related processes, sex steroids participate in higher brain operations such as cognition and mood, in which the hippocampus is a critical mediator. Being part of the hippocampal formation, the dentate gyrus is naturally involved in these mechanisms and as such, this structure is also a critical target for the activational effects of sex steroids. These activational effects are the results of three major types of steroid-mediated actions. Sex steroids modulate the function of dentate neurons under normal conditions. In addition, recent research suggests that hormone-induced cellular plasticity may play a larger role than previously thought, particularly in the dentate gyrus. Specifically, the regulation of dentate gyrus neurogenesis and synaptic remodeling by sex steroids received increasing attention lately. Finally, the dentate gyrus is influenced by gonadal hormones in the context of cellular injury, and the work in this area demonstrates that gonadal hormones have neuroprotective potential. The expression of estrogen, progestin, and androgen receptors in the dentate gyrus suggests that sex steroids, which could be of gonadal origin and/or synthesized locally in the dentate gyrus, may act directly on dentate cells. In addition, gonadal hormones could also influence the dentate gyrus indirectly, by subcortical hormone-sensitive structures such as the cholinergic septohippocampal system. Importantly, these three sex steroid-related themes, functional effects in the normal dentate gyrus, mechanisms involving neurogenesis and synaptic remodeling, as well as neuroprotection, have

  10. Running per se stimulates the dendritic arbor of newborn dentate granule cells in mouse hippocampus in a duration-dependent manner.

    PubMed

    Dostes, Sandrine; Dubreucq, Sarah; Ladevèze, Elodie; Marsicano, Giovanni; Abrous, Djoher N; Chaouloff, Francis; Koehl, Muriel

    2016-03-01

    Laboratory rodents provided chronic unlimited access to running wheels display increased neurogenesis in the hippocampal dentate gyrus. In addition, recent studies indicate that such an access to wheels stimulates dendritic arborization in newly formed neurons. However, (i) the presence of the running wheel in the housing environment might also bear intrinsic influences on the number and shape of new neurons and (ii) the dendritic arborization of new neurons might be insensitive to moderate daily running activity (i.e., several hours). In keeping with these uncertainties, we have examined neurogenesis and dendritic arborization in newly formed granular cells in adult C57Bl/6N male mice housed for 3 weeks under standard conditions, with a locked wheel, with a running wheel set free 3 h/day, or with a running wheel set permanently free. The results indicate that the presence of a blocked wheel in the home cage increased cell proliferation, but not the number of new neurons while running increased in a duration-dependent manner the number of newborn neurons, as assessed by DCX labeling. Morphological analyses of the dendritic tree of newborn neurons, as identified by BrdU-DCX co-staining, revealed that although the presence of the wheel stimulated their dendritic architecture, the amplitude of this effect was lower than that elicited by running activity, and was found to be running duration-dependent.

  11. Impaired long-term potentiation induction in dentate gyrus of calretinin-deficient mice

    PubMed Central

    Schurmans, Stéphane; Schiffmann, Serge N.; Gurden, Hirac; Lemaire, Martine; Lipp, Hans-Peter; Schwam, Valérie; Pochet, Roland; Imperato, Assunta; Böhme, Georg Andrees; Parmentier, Marc

    1997-01-01

    Calretinin (Cr) is a Ca2+ binding protein present in various populations of neurons distributed in the central and peripheral nervous systems. We have generated Cr-deficient (Cr−/−) mice by gene targeting and have investigated the associated phenotype. Cr−/− mice were viable, and a large number of morphological, biochemical, and behavioral parameters were found unaffected. In the normal mouse hippocampus, Cr is expressed in a widely distributed subset of GABAergic interneurons and in hilar mossy cells of the dentate gyrus. Because both types of cells are part of local pathways innervating dentate granule cells and/or pyramidal neurons, we have explored in Cr−/− mice the synaptic transmission between the perforant pathway and granule cells and at the Schaffer commissural input to CA1 pyramidal neurons. Cr−/− mice showed no alteration in basal synaptic transmission, but long-term potentiation (LTP) was impaired in the dentate gyrus. Normal LTP could be restored in the presence of the GABAA receptor antagonist bicuculline, suggesting that in Cr−/− dentate gyrus an excess of γ-aminobutyric acid (GABA) release interferes with LTP induction. Synaptic transmission and LTP were normal in CA1 area, which contains only few Cr-positive GABAergic interneurons. Cr−/− mice performed normally in spatial memory task. These results suggest that expression of Cr contributes to the control of synaptic plasticity in mouse dentate gyrus by indirectly regulating the activity of GABAergic interneurons, and that Cr−/− mice represent a useful tool to understand the role of dentate LTP in learning and memory. PMID:9294225

  12. Polymeric tannins significantly alter properties and in vitro digestibility of partially gelatinized intact starch granule.

    PubMed

    Amoako, Derrick B; Awika, Joseph M

    2016-10-01

    Excess calorie intake is a growing global problem. This study investigated effect of complexing partially gelatinized starch with condensed tannins on in vitro starch digestibility. Extracts from tannin and non-tannin sorghum, and cellulose control, were reacted with normal and waxy maize starch in 30% (30E) and 50% ethanol (50E) solutions at 70°C/20min. More tannins complexed with the 30E than 50E starches (mean 6.2 vs 3.5mg/g, respectively). In the 30E treatments, tannins significantly increased crystallinity, pasting temperature, peak viscosity, and slow digesting starch (from 100 to 274mg/g) in normal, but not waxy starch, suggesting intragranular cross-linking with amylose. Tannins doubled resistant starch (RS) to approx. 300mg/g in both starches. In 50E treatments, tannins made both maize starches behave like raw potato starch (>90% RS), suggesting granule surface interactions dominated. Non-tannin treatments generally behaved similar to cellulose. Condensed tannins could be used to favorably alter starch digestion profile.

  13. Disambiguating the similar: the dentate gyrus and pattern separation.

    PubMed

    Schmidt, Brandy; Marrone, Diano F; Markus, Etan J

    2012-01-01

    The human hippocampus supports the formation of episodic memory without confusing new memories with old ones. To accomplish this, the brain must disambiguate memories (i.e., accentuate the differences between experiences). There is convergent evidence linking pattern separation to the dentate gyrus. Damage to the dentate gyrus reduces an organism's ability to differentiate between similar objects. The dentate gyrus has tenfold more principle cells than its cortical input, allowing for a divergence in information flow. Dentate gyrus granule neurons also show a very different pattern of representing the environment than "classic" place cells in CA1 and CA3, or grid cells in the entorhinal cortex. More recently immediate early genes have been used to "timestamp" activity of individual cells throughout the dentate gyrus. These data indicate that the dentate gyrus robustly differentiates similar situations. The degree of differentiation is non-linear, with even small changes in input inducing a near maximal response in the dentate. Furthermore this differentiation occurs throughout the dentate gyrus longitudinal (dorsal-ventral) axis. Conversely, the data point to a divergence in information processing between the dentate gyrus suprapyramidal and infrapyramidal blades possibly related to differences in organization within these regions. The accumulated evidence from different approaches converges to support a role for the dentate gyrus in pattern separation. There are however inconsistencies that may require incorporation of neurogenesis and hippocampal microcircuits into the currents models. They also suggest different roles for the dentate gyrus suprapyramidal and infrapyramidal blades, and the responsiveness of CA3 to dentate input.

  14. a-Band Oscillations in Intracellular Membrane Potentials of Dentate Gyrus Neurons in Awake Rodents

    ERIC Educational Resources Information Center

    Anderson, Ross W.; Strowbridge, Ben W.

    2014-01-01

    The hippocampus and dentate gyrus play critical roles in processing declarative memories and spatial information. Dentate granule cells, the first relay in the trisynaptic circuit through the hippocampus, exhibit low spontaneous firing rates even during locomotion. Using intracellular recordings from dentate neurons in awake mice operating a…

  15. Intracellular Zn(2+) signaling in the dentate gyrus is required for object recognition memory.

    PubMed

    Takeda, Atsushi; Tamano, Haruna; Ogawa, Taisuke; Takada, Shunsuke; Nakamura, Masatoshi; Fujii, Hiroaki; Ando, Masaki

    2014-11-01

    The role of perforant pathway-dentate granule cell synapses in cognitive behavior was examined focusing on synaptic Zn(2+) signaling in the dentate gyrus. Object recognition memory was transiently impaired when extracellular Zn(2+) levels were decreased by injection of clioquinol and N,N,N',N'-tetrakis-(2-pyridylmethyl) ethylendediamine. To pursue the effect of the loss and/or blockade of Zn(2+) signaling in dentate granule cells, ZnAF-2DA (100 pmol, 0.1 mM/1 µl), an intracellular Zn(2+) chelator, was locally injected into the dentate molecular layer of rats. ZnAF-2DA injection, which was estimated to chelate intracellular Zn(2+) signaling only in the dentate gyrus, affected object recognition memory 1 h after training without affecting intracellular Ca(2+) signaling in the dentate molecular layer. In vivo dentate gyrus long-term potentiation (LTP) was affected under the local perfusion of the recording region (the dentate granule cell layer) with 0.1 mM ZnAF-2DA, but not with 1-10 mM CaEDTA, an extracellular Zn(2+) chelator, suggesting that the blockade of intracellular Zn(2+) signaling in dentate granule cells affects dentate gyrus LTP. The present study demonstrates that intracellular Zn(2+) signaling in the dentate gyrus is required for object recognition memory, probably via dentate gyrus LTP expression.

  16. Enhanced corticosteroid signaling alters synaptic plasticity in the dentate gyrus in mice lacking the fragile X mental retardation protein.

    PubMed

    Ghilan, M; Hryciw, B N; Brocardo, P S; Bostrom, C A; Gil-Mohapel, J; Christie, B R

    2015-05-01

    The fragile X mental retardation protein (FMRP) is an important regulator of protein translation, and a lack of FMRP expression leads to a cognitive disorder known as fragile X syndrome (FXS). Clinical symptoms characterizing FXS include learning impairments and heightened anxiety in response to stressful situations. Here, we report that, in response to acute stress, mice lacking FMRP show a faster elevation of corticosterone and a more immediate impairment in N-methyl-d-aspartate receptor (NMDAR) dependent long-term potentiation (LTP) in the dentate gyrus (DG). These stress-induced LTP impairments were rescued by administering the glucocorticoid receptor (GR) antagonist RU38486. Administration of RU38486 also enhanced LTP in Fmr1(-/y) mice in the absence of acute stress to wild-type levels, and this enhancement was blocked by application of the NMDAR antagonist 2-amino-5-phosphonopentanoic acid. These results suggest that a loss of FMPR results in enhanced GR signaling that may adversely affect NMDAR dependent synaptic plasticity in the DG.

  17. Increased long-term potentiation at medial-perforant path-dentate granule cell synapses induced by selective inhibition of histone deacetylase 3 requires Fragile X mental retardation protein.

    PubMed

    Franklin, Aimee V; Rusche, James R; McMahon, Lori L

    2014-10-01

    Non-selective inhibition of histone deacetylases (HDACs), enzymes that remove acetyl groups from histone core proteins, enhances cognition and NMDAR-dependent long-term potentiation at hippocampal CA3-CA1 synapses. It is not known whether this is a general mechanism by which HDACs modulate plasticity at other hippocampal synapses. Furthermore, it has yet to be tested whether HDAC inhibition can reverse deficits in synaptic plasticity in disease models. Here, we investigated whether inhibition of HDACs, and specifically HDAC3, a class I HDAC isoform known to negatively regulate hippocampus-dependent learning and memory, enhances LTP at medial perforant path-dentate granule cell (MPP-DGC) synapses in wild-type and Fragile X (Fmr1-/y) mice, a model with known LTP deficits at this synapse. The non-selective HDAC inhibitor trichostatin A (TSA) significantly increased the magnitude of LTP at MPP-DGC synapses in wild-type mice, similar to reports at CA3-CA1 synapses. The enhancement of LTP was mimicked by selective HDAC3 inhibition, implicating a role for this isoform in the negative regulation of synaptic plasticity. However, HDAC3 inhibition was completely ineffective in reversing the deficit in LTP at MPP-DGC synapses in slices from Fmr1-/y mice, and in fact, HDAC3 inhibition was unable to induce any improvement whatsoever. These findings indicate that the enhancing effect of HDAC3 inhibition on LTP in wild-type mice requires FMRP, revealing a novel role for FMRP in hippocampal plasticity.

  18. Genetic regulation of dentate gyrus morphogenesis.

    PubMed

    Li, Guangnan; Pleasure, Samuel J

    2007-01-01

    The dentate gyrus is one of the small number of forebrain areas that have continued adult neurogenesis. During development the dentate gyrus acquires the capacity for neurogenesis by generating a new neurogenic stem cell niche at the border between the hilus and dentate granule cell layer. This is in distinction to the other prominent zone of continued neurogenesis in the subventricular zone where neurons are born in a structure directly descended from the mid-gestation subventricular zone. The ability to generate this newly formed dentate neurogenic niche is controlled by the action of a number of genes during prenatal and early postnatal development that regulate the fate, survival, migration, expansion, and differentiation of the cellular components of the dentate neurogenic niche. In this review, we provide an updated framework discussing the molecular steps and genes involved in these early stages of dentate gyrus formation. We previously described a molecular framework for dentate gyrus morphogenesis that can be associated with specific gene defects (Li, G., Pleasure, S.J. (2005). Dev. Neurosci., 27, 93-99), and here we add additional recently described molecular players and discuss this framework.

  19. Differential regulation of synaptic inputs to dentate hilar border interneurons by metabotropic glutamate receptors.

    PubMed

    Doherty, J; Dingledine, R

    1998-06-01

    Regulation of synaptic transmission by metabotropic glutamate receptors (mGluRs) was examined at two excitatory inputs to interneurons with cell bodies at the granule cell-hilus border in hippocampal slices taken from neonatal rats. Subgroup-selective mGluR agonists altered the reliability, or probability of transmitter release, of evoked minimal excitatory synaptic inputs and decreased the amplitudes of excitatory postsynaptic currents (EPSCs) evoked with conventional stimulation. The group II-selective agonist, (2S,1R',2R',3R')-2-(2, 3-dicarboxylcyclopropyl) glycine (DCG-IV; 1 microM), reversibly depressed the reliability of EPSCs evoked by stimulation of the dentate granule cell layer. However, DCG-IV had no significant effect on EPSCs evoked by CA3 stimulation in the majority (82%) of hilar border interneurons. Both the group III-selective agonist, -(+)-2-amino-4-phosphonobutyric acid (-AP4; 3 microM), and the group I-selective agonist, (RS)-3,5-dihydroxyphenylglycine (DHPG; 20 microM) reversibly depressed synaptic input to interneurons from both CA3 and the granule cell layer. We conclude that multiple pharmacologically distinct mGluRs presynaptically regulate synaptic transmission at two excitatory inputs to hilar border interneurons. Further, the degree of mGluR-meditated depression of excitatory drive is greater at synapses from dentate granule cells onto interneurons than at synapses from CA3 pyramidal cells.

  20. Neurons containing Alz-50-immunoreactive granules around the cerebral infarction: evidence for the lysosomal degradation of altered tau in human brain?

    PubMed

    Ikeda, K; Akiyama, H; Arai, T; Kondo, H; Haga, C; Tsuchiya, K; Yamada, S; Murayama, S; Hori, A

    2000-04-28

    Little is known about the metabolic process of tau and tau-derived substances. Alz-50- and tau 2-immunoreactivities in intracellular granules of neurons were observed in regions surrounding infarcted foci in the human cerebral cortex. Ultrastructurally, these granules in the fresh infarcted region exhibited primary lysosome-like structures, while those in old infarctions were lipofuscin. These findings indicate that tau is metabolized within lysosomes in neurons damaged by ischemic injury in human cortical penumbra. Alz-50-positive granules were more prominent in fresh infarction than in old infarction. After undergoing degradation and modification, altered tau might remain, at least partially, in secondary lysosomes.

  1. Reversibility of D-penicillamine induced collagen alterations in rat skin and granulation tissue.

    PubMed

    Junker, P; Lorenzen, I

    1983-06-01

    Granulation tissue was produced in rats by subcutaneous implantation of Visella sponges. D-penicillamine (D-pen) 100 or 500 mg/kg was administered daily for 42 days by gastric tubing. Pairfed, placebo treated animals were included as controls. Half of the groups were kept for additionally 28 days without medication. The inhibitory effect of D-pen on cross-link formation in newly synthesized collagen was readily reversible. By contrast, cross-link deficiency lasting beyond the observation period was observed in the higher polymeric collagen variants released by dilute acid, heat exposure or limited pepsin proteolysis as estimated by solubility, alpha/beta chain ratio and/or aldehyde content. By SDS-polyacrylamide gel electrophoresis on gels containing 3.6 M urea it was shown that purified dermal acid soluble collagen from treated animals consisted of a mixture of type I and III collagen, whereas only type I collagen was detected in controls. The band pattern was identical in reduced and unreduced collagen samples. Four weeks after D-pen discontinuance type III collagen had disappeared from the acid extract. Moreover, the ratio of type III to type I collagen in the pepsin digest from both granulation tissue and skin showed a persistent rise with D-pen. These observations indicate that D-pen destabilized type III collagen in particular by interference with its disulfide linkages. The amount of granulation tissue remained unaffected throughout the experiment, whereas the skin collagen content decreased at the higher dose level. The regeneration was not completed by the end of the observation period. Modulation of the molecular stability of granuloma collagens may be of relevance for the antirheumatoid effect of D-pen, but the sustained effect on normal tissues may imply a long standing impairment of their supportive capacity.

  2. Adult onset-hypothyroidism: alterations in hippocampal field potentials in the dentate gyrus are largely associated with anaesthesia-induced hypothermia.

    PubMed

    Sánchez-Huerta, K; Pacheco-Rosado, J; Gilbert, M E

    2015-01-01

    Thyroid hormone (TH) is essential for a number of physiological processes and is particularly critical during nervous system development. The hippocampus is strongly implicated in cognition and is sensitive to developmental hypothyroidism. The impact of TH insufficiency in the foetus and neonate on hippocampal synaptic function has been fairly well characterised. Although adult onset hypothyroidism has also been associated with impairments in cognitive function, studies of hippocampal synaptic function with late onset hypothyroidism have yielded inconsistent results. In the present study, we report hypothyroidism induced by the synthesis inhibitor propylthiouracil (10 p.p.m., 0.001%, minimum of 4 weeks), resulted in marginal alterations in excitatory postsynaptic potential (EPSP) and population spike (PS) amplitude in the dentate gyrus measured in vivo. No effects were seen in tests of short-term plasticity, and a minor enhancement of long-term potentiation of the EPSP slope was observed. The most robust synaptic alteration evident in hypothyroid animals was an increase in synaptic response latency, which was paralleled by a failure to maintain normal body temperature under anaesthesia, despite warming on a heating pad. Latency shifts could be reversed in hypothyroid animals by increasing the external heat source and, conversely, synaptic delays could be induced in control animals by removing the heat source, with a consequent drop in body and brain temperature. Thermoregulation is TH- dependent, and anaesthesia necessary for surgical procedures posed a thermoregulatory challenge that was differentially met in control and hypothyroid animals. Minor increases in field potential EPSP slope, decreases in PS amplitudes and increased latencies are consistent with previous reports of hypothermia in naive control rats. We conclude that failures in thyroid-dependent temperature regulation rather than direct action of TH in synaptic physiology are responsible for the

  3. Regulation of excitatory input to inhibitory interneurons of the dentate gyrus during hypoxia.

    PubMed

    Doherty, J; Dingledine, R

    1997-01-01

    The role of metabotropic glutamate receptors (mGluRs) and adenosine receptors in hypoxia-induced suppression of excitatory synaptic input to interneurons residing at the granule cell-hilus border in the dentate gyrus was investigated with the use of whole cell electrophysiological recording techniques in thin (250 microns) slices of immature rat hippocampus. Minimal stimulation evoked glutamatergic excitatory postsynaptic currents (EPSCs) in dentate interneurons in 68 +/- 4% (mean +/- SE) of trials during stimulation in the dentate granule cell layer (GCL) and 48 +/- 3% of trials during stimulation in CA3. Hypoxic episodes, produced by switching the perfusing solution from 95% O2-5% CO2 to a solution containing 95% N2-5% CO2 for 3-5 min, rapidly and reversibly decreased the synaptic reliability, or probability of evoking an EPSC, from either input without reducing EPSC amplitude, consistent with a presynaptic suppression of transmitter release. The mGluR antagonist (+)-alpha-methyl-4-carboxyphenylglycine [(+) MCPG; 500 microM] did not alter synaptic reliability or mean EPSC amplitude in either pathway. However, (+) MCPG significantly attenuated hypoxic suppression of input from both pathways, suggesting that mGluRs activated by release of glutamate partially mediate hypoxic suppression of EPSCs to dentate interneurons. The mGluR agonist (1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid (ACPD; 100 microM) rapidly decreased the reliability of excitatory transmission from both the GCL (19 +/- 5% of control) and CA3 (39 +/- 15% of control). ACPD also increased the frequency of spontaneous EPSCs and evoked a slow inward current in dentate interneurons. Exogenous adenosine (10-300 microM) decreased synaptic reliability for both pathways and reduced the frequency of spontaneous EPSCs, but did not cause a decrease in the mean amplitude of evoked EPSCs, consistent with a presynaptic suppression of excitatory input to dentate interneurons. Conversely, the selective adenosine

  4. Deficiency of Starch Synthase IIIa and IVb Alters Starch Granule Morphology from Polyhedral to Spherical in Rice Endosperm1

    PubMed Central

    Toyosawa, Yoshiko; Kawagoe, Yasushi; Matsushima, Ryo; Ogawa, Masahiro; Fukuda, Masako; Kumamaru, Toshihiro; Okazaki, Yozo; Kusano, Miyako; Saito, Kazuki; Toyooka, Kiminori; Sato, Mayuko; Ai, Yongfeng; Fujita, Naoko

    2016-01-01

    Starch granule morphology differs markedly among plant species. However, the mechanisms controlling starch granule morphology have not been elucidated. Rice (Oryza sativa) endosperm produces characteristic compound-type granules containing dozens of polyhedral starch granules within an amyloplast. Some other cereal species produce simple-type granules, in which only one starch granule is present per amyloplast. A double mutant rice deficient in the starch synthase (SS) genes SSIIIa and SSIVb (ss3a ss4b) produced spherical starch granules, whereas the parental single mutants produced polyhedral starch granules similar to the wild type. The ss3a ss4b amyloplasts contained compound-type starch granules during early developmental stages, and spherical granules were separated from each other during subsequent amyloplast development and seed dehydration. Analysis of glucan chain length distribution identified overlapping roles for SSIIIa and SSIVb in amylopectin chain synthesis, with a degree of polymerization of 42 or greater. Confocal fluorescence microscopy and immunoelectron microscopy of wild-type developing rice seeds revealed that the majority of SSIVb was localized between starch granules. Therefore, we propose that SSIIIa and SSIVb have crucial roles in determining starch granule morphology and in maintaining the amyloplast envelope structure. We present a model of spherical starch granule production. PMID:26747287

  5. HIV-1 Gag Blocks Selenite-Induced Stress Granule Assembly by Altering the mRNA Cap-Binding Complex

    PubMed Central

    Cinti, Alessandro; Le Sage, Valerie; Ghanem, Marwan

    2016-01-01

    ABSTRACT Stress granules (SGs) are dynamic accumulations of stalled preinitiation complexes and translational machinery that assemble under stressful conditions. Sodium selenite (Se) induces the assembly of noncanonical type II SGs that differ in morphology, composition, and mechanism of assembly from canonical SGs. Se inhibits translation initiation by altering the cap-binding activity of eukaryotic translation initiation factor 4E (eIF4E)-binding protein 1 (4EBP1). In this work, we show that human immunodeficiency virus type 1 (HIV-1) Gag is able to block the assembly of type II noncanonical SGs to facilitate continued Gag protein synthesis. We demonstrate that expression of Gag reduces the amount of hypophosphorylated 4EBP1 associated with the 5′ cap potentially through an interaction with its target, eIF4E. These results suggest that the assembly of SGs is an important host antiviral defense that HIV-1 has evolved for inhibition through several distinct mechanisms. PMID:27025252

  6. The CA3 “Backprojection” to the Dentate Gyrus

    PubMed Central

    Scharfman, Helen E.

    2007-01-01

    The hippocampus is typically described in the context of the trisynaptic circuit, a pathway that relays information from the perforant path to the dentate gyrus, dentate to area CA3, and CA3 to area CA1. Associated with this concept is the assumption that most hippocampal information processing occurs along the trisynaptic circuit. However, the entorhinal cortex may not be the only major extrinsic input to consider, and the trisynaptic circuit may not be the only way information is processed in hippocampus. Area CA3 receives input from a variety of sources, and may be as much of an “entry point” to hippocampus as the dentate gyrus. The axon of CA3 pyramidal cells targets diverse cell types, and has commissural projections, which together make it able to send information to much more of the hippocampus than granule cells. Therefore, CA3 pyramidal cells seem better designed to spread information through hippocampus than the granule cells. From this perspective, CA3 may be a point of entry that receives information which needs to be “broadcasted,” whereas the dentate gyrus may be a point of entry that receives information with more selective needs for hippocampal processing. One aspect of the argument that CA3 pyramidal cells have a widespread projection is based on a part of its axonal arbor that has received relatively little attention, the collaterals that project in the opposite direction to the trisynaptic circuit, “back” to the dentate gyrus. The evidence for this “backprojection” to the dentate gyrus is strong, particularly in area CA3c, the region closest to the dentate gyrus, and in temporal hippocampus. The influence on granule cells is indirect, through hilar mossy cells and GABAergic neurons of the dentate gyrus, and appears to include direct projections in the case of CA3c pyramidal cells of ventral hippocampus. Physiological studies suggest that normally area CA3 does not have a robust excitatory influence on granule cells, but serves

  7. The CA3 "backprojection" to the dentate gyrus.

    PubMed

    Scharfman, Helen E

    2007-01-01

    The hippocampus is typically described in the context of the trisynaptic circuit, a pathway that relays information from the perforant path to the dentate gyrus, dentate to area CA3, and CA3 to area CA1. Associated with this concept is the assumption that most hippocampal information processing occurs along the trisynaptic circuit. However, the entorhinal cortex may not be the only major extrinsic input to consider, and the trisynaptic circuit may not be the only way information is processed in hippocampus. Area CA3 receives input from a variety of sources, and may be as much of an "entry point" to hippocampus as the dentate gyrus. The axon of CA3 pyramidal cells targets diverse cell types, and has commissural projections, which together make it able to send information to much more of the hippocampus than granule cells. Therefore, CA3 pyramidal cells seem better designed to spread information through hippocampus than the granule cells. From this perspective, CA3 may be a point of entry that receives information which needs to be "broadcasted," whereas the dentate gyrus may be a point of entry that receives information with more selective needs for hippocampal processing. One aspect of the argument that CA3 pyramidal cells have a widespread projection is based on a part of its axonal arbor that has received relatively little attention, the collaterals that project in the opposite direction to the trisynaptic circuit, "back" to the dentate gyrus. The evidence for this "backprojection" to the dentate gyrus is strong, particularly in area CA3c, the region closest to the dentate gyrus, and in temporal hippocampus. The influence on granule cells is indirect, through hilar mossy cells and GABAergic neurons of the dentate gyrus, and appears to include direct projections in the case of CA3c pyramidal cells of ventral hippocampus. Physiological studies suggest that normally area CA3 does not have a robust excitatory influence on granule cells, but serves instead to inhibit

  8. Monosynaptic inputs to new neurons in the dentate gyrus.

    PubMed

    Vivar, Carmen; Potter, Michelle C; Choi, Jiwon; Lee, Ji-Young; Stringer, Thomas P; Callaway, Edward M; Gage, Fred H; Suh, Hoonkyo; van Praag, Henriette

    2012-01-01

    Adult hippocampal neurogenesis is considered important for cognition. The integration of newborn dentate gyrus granule cells into the existing network is regulated by afferent neuronal activity of unspecified origin. Here we combine rabies virus-mediated retrograde tracing with retroviral labelling of new granule cells (21, 30, 60, 90 days after injection) to selectively identify and quantify their monosynaptic inputs in vivo. Our results show that newborn granule cells receive afferents from intra-hippocampal cells (interneurons, mossy cells, area CA3 and transiently, mature granule cells) and septal cholinergic cells. Input from distal cortex (perirhinal (PRH) and lateral entorhinal cortex (LEC)) is sparse 21 days after injection and increases over time. Patch-clamp recordings support innervation by the LEC rather than from the medial entorhinal cortex. Mice with excitotoxic PRH/LEC lesions exhibit deficits in pattern separation but not in water maze learning. Thus, PRH/LEC input is an important functional component of new dentate gyrus neuron circuitry.

  9. Actin disruption alters the localization of tau in the growth cones of cerebellar granule neurons.

    PubMed

    Zmuda, J F; Rivas, R J

    2000-08-01

    Cultured cerebellar granule neurons initially extend a single axon, followed by the extension of a second axon to attain a bipolar morphology. Differentiation culminates with the extension of several short dendrites from the cell body. In the present study, we determined the location of the dephosphorylated form of the microtubule-associated protein tau (dtau) within the growth cones of newly forming axons and examined whether this localization was influenced by the actin cytoskeleton. Following elongation of the initial axon at 2-3 days in vitro, dtau immunoreactivity was present along the entire length of the axon, becoming most intense just proximal to the growth cone. Dtau labeling dropped off dramatically along the microtubules of the growth cone and was undetectable along the most distal tips of these microtubules. As the initial axon continued to elongate at 3-4 days in vitro, the actin-rich growth cone peripheral domain characteristically underwent a dramatic reduction in size. Dtau immunoreactivity extended all the way to the most distal tips of the microtubules in the growth cones of these cells. Cytochalasin D and latrunculin A mimicked the effects of this characteristic reduction in growth cone size with regard to dtau localization in the growth cone. Depolymerization of filamentous actin caused the collapse of the peripheral domain and allowed dtau to bind all the way to the most distal tips of microtubules in the axon. Upon removal of the drugs, the peripheral domain of the growth cone rapidly re-formed and dtau was once again excluded from the most distal regions of growth cone microtubules. These findings suggest a novel role for actin in determining the localization of the microtubule-associated protein &tgr; within the growth cones of neurons.

  10. Adult neurogenesis in the mammalian hippocampus: Why the dentate gyrus?

    PubMed Central

    Drew, Liam J.; Fusi, Stefano; Hen, René

    2013-01-01

    In the adult mammalian brain, newly generated neurons are continuously incorporated into two networks: interneurons born in the subventricular zone migrate to the olfactory bulb, whereas the dentate gyrus (DG) of the hippocampus integrates locally born principal neurons. That the rest of the mammalian brain loses significant neurogenic capacity after the perinatal period suggests that unique aspects of the structure and function of DG and olfactory bulb circuits allow them to benefit from the adult generation of neurons. In this review, we consider the distinctive features of the DG that may account for it being able to profit from this singular form of neural plasticity. Approaches to the problem of neurogenesis are grouped as “bottom-up,” where the phenotype of adult-born granule cells is contrasted to that of mature developmentally born granule cells, and “top-down,” where the impact of altering the amount of neurogenesis on behavior is examined. We end by considering the primary implications of these two approaches and future directions. PMID:24255101

  11. Differential Alterations in Excitatory and Inhibitory Networks Involving Dentate Granule Cells Following Chronic Treatment with Distinct Classes of NMDAR Antagonists in Hippocampal Slice Cultures

    DTIC Science & Technology

    2010-03-08

    to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data ...encouragement when things got tough. I would like to acknowledge Dr. Yu Dong and Dr. Xiao-Min Wang for providing seizure data and Dr. Wang Yu for providing...immunohistochemistry data . I would like to thank my former colleagues, Dr. Yu Dong, Dr. Yelena Petrova, Dr. Yingbing Liu, Dr. Yu Wang, Ms

  12. The dentate gyrus: fundamental neuroanatomical organization (dentate gyrus for dummies).

    PubMed

    Amaral, David G; Scharfman, Helen E; Lavenex, Pierre

    2007-01-01

    The dentate gyrus is a simple cortical region that is an integral portion of the larger functional brain system called the hippocampal formation. In this review, the fundamental neuroanatomical organization of the dentate gyrus is described, including principal cell types and their connectivity, and a summary of the major extrinsic inputs of the dentate gyrus is provided. Together, this information provides essential information that can serve as an introduction to the dentate gyrus--a "dentate gyrus for dummies."

  13. Host cell subversion by Toxoplasma GRA16, an exported dense granule protein that targets the host cell nucleus and alters gene expression.

    PubMed

    Bougdour, Alexandre; Durandau, Eric; Brenier-Pinchart, Marie-Pierre; Ortet, Philippe; Barakat, Mohamed; Kieffer, Sylvie; Curt-Varesano, Aurélie; Curt-Bertini, Rose-Laurence; Bastien, Olivier; Coute, Yohann; Pelloux, Hervé; Hakimi, Mohamed-Ali

    2013-04-17

    After invading host cells, Toxoplasma gondii multiplies within a parasitophorous vacuole (PV) that is maintained by parasite proteins secreted from organelles called dense granules. Most dense granule proteins remain within the PV, and few are known to access the host cell cytosol. We identify GRA16 as a dense granule protein that is exported through the PV membrane and reaches the host cell nucleus, where it positively modulates genes involved in cell-cycle progression and the p53 tumor suppressor pathway. GRA16 binds two host enzymes, the deubiquitinase HAUSP and PP2A phosphatase, which exert several functions, including regulation of p53 and the cell cycle. GRA16 alters p53 levels in a HAUSP-dependent manner and induces nuclear translocation of the PP2A holoenzyme. Additionally, certain GRA16-deficient strains exhibit attenuated virulence, indicating the importance of these host alterations in pathogenesis. Therefore, GRA16 represents a potentially emerging subfamily of exported dense granule proteins that modulate host function.

  14. Modulation of paired-pulse responses in the dentate gyrus: effects of prenatal protein malnutrition.

    PubMed

    Bronzino, J D; Blaise, J H; Mokler, D J; Galler, J R; Morgane, P J

    1999-12-04

    Since our major hypothesis is that prenatal protein malnutrition significantly affects hippocampal neuroplasticity, this study examined the effects of prenatal protein malnutrition on the modulation of dentate granule cell excitability in freely moving rats at 15, 30 and 90 days of age across the vigilance states of quiet waking (QW), slow-wave sleep (SWS) and rapid eye movement (REM) sleep. Using paired-pulse stimulation, the paired-pulse index (PPI), a measure of the type and degree of modulation of dentate granule cell excitability elicited by stimulation of the medial perforant path, was obtained for each vigilance state at each stage of development. Four specific measures of granule cell excitability were computed, namely, PPI using both population spike amplitude (PSA) and EPSP slope measures, absolute values of PSA(1) and EPSP(1) slope. PPI values obtained at 15, 30 and 90 days of age, however, were altered during normal ontogenetic development, but not by vigilance state. At 15 days of age, the malnourished group exhibits greater early inhibition of the PPI using the PSA measure at IPIs between 20 and 30 ms regardless of vigilance state, while at 30 days of age, the malnourished group exhibits greater facilitation at IPIs between 50 and 70 ms during QW and SWS, but not during REM sleep. In the control adult (PND90) and juvenile (PND30) animal, PSA(1) values are significantly higher during SWS than in QW or REM sleep. However, for the younger malnourished animals (PND15 and PND30), PSA(1) values were found to be significantly greater during REM sleep rather than SWS. Therefore, as the animal matures, there appears to be a shift in vigilance state dependent synaptic transmission through the hippocampal trisynaptic circuit from REM sleep to SWS in both control and malnourished animals, with the change occurring later in malnourished animals when compared to control ones. Furthermore, our findings suggests that prenatal protein malnutrition significantly alters

  15. Distribution of the receptor-anchoring protein gephyrin in the rat dentate gyrus and changes following entorhinal cortex lesion.

    PubMed

    Simbürger, E; Plaschke, M; Kirsch, J; Nitsch, R

    2000-04-01

    We analyzed the distribution of the receptor-anchoring protein gephyrin in the normal and deafferented rat dentate gyrus to investigate whether the expression of this postsynaptic protein is altered in response to the formation of new synaptic contacts. Confocal microscopy and digital image analysis revealed that in normal dentate gyrus immunolabeling was most prominent in the outer molecular layer and decreased successively in the direction of the granule cell layer. Simultaneous immunolabeling for gephyrin and cell-specific markers showed that granule cells and parvalbumin-positive interneurons express gephyrin. Large, intensely stained, gephyrin-positive clusters were distributed along distinct dendrites, and most of them were positive for parvalbumin. Calbindin-immunostained dendrites were associated with smaller, gephyrin-positive clusters. Lesion of the medial entorhinal cortex leads to deafferentiation of the middle molecular layer which resulted in an increased gephyrin immunoreactivity. These changes were due to a significantly increased concentration of the very small gephyrin-positive clusters. Parvalbumin-positive dendrites did not display any increase in co-localizing gephyrin-positive structures. The altered immunolabeling pattern persisted until 12 weeks after lesion, a time when the process of synaptic reorganization is complete. Our findings suggest that synaptogenesis following deafferentiation results in a cell-specific redistribution of gephyrin immunoreactivity at specific inhibitory synapses.

  16. Differential properties of dentate gyrus and CA1 neural precursors.

    PubMed

    Becq, H; Jorquera, I; Ben-Ari, Y; Weiss, S; Represa, A

    2005-02-05

    In the present article we investigated the properties of CA1 and dentate gyrus cell precursors in adult rodents both in vivo and in vitro. Cell proliferation in situ was investigated by rating the number of cells incorporating BrdU after kainate-induced seizures. CA1 precursors displayed a greater proliferation capacity than dentate gyrus precursors. The majority of BrdU-labeled cells in CA1 expressed Nestin and Mash-1, two markers of neural precursors. BrdU-positive cells in the dentate gyrus expressed Nestin, but only a few expressed Mash-1. In animals pretreated with the antimitotic azacytidine, the capacity of kainate to enhance the proliferation was higher in CA1 than in the dentate gyrus. Differences in intrinsic progenitor cell activity could underlie these different expansion capacities. Thus, we compared the renewal- expansion and multipotency of dentate gyrus and CA1 precursors isolated in vitro. We found that the dissected CA1 region, including the periventricular zone, is enriched in neurosphere-forming cells (presumed stem cells), which respond to either EGF or FGF-2. Dentate gyrus contains fewer neurosphere-forming cells and none that respond to FGF-2 alone. Neurospheres generated from CA1 were multipotent and produced neurons, astrocytes, and oligodendrocytes, while dentate gyrus neurospheres mostly produced glial cells. The analysis of the effects of EGF on organotypic cultures of hippocampal slices depicted similar features: BrdU and Nestin immunoreactivities increased after EGF treatment in CA1 but not in the dentate gyrus. These results suggest that CA1 precursors are more stem-cell-like than granule cell precursors, which may represent a more restricted precursor cell.

  17. Effects of lead exposure on dendrite and spine development in hippocampal dentate gyrus areas of rats.

    PubMed

    Hu, Fan; Ge, Meng-Meng; Chen, Wei-Heng

    2016-03-01

    Lead exposure has been implicated in the impairment of synaptic plasticity in the hippocampal dentate gyrus (DG) areas of rats. However, whether the degradation of physiological properties is based on the morphological alteration of granule neurons in DG areas remains elusive. Here, we examined the dendritic branch extension and spine formation of granule neurons after lead exposure during development in rats. Dendritic morphology was studied using Golgi-Cox stain method, which was followed by Sholl analysis at postnatal days 14 and 21. Our results indicated that, for both ages, lead exposure significantly decreased the total dendritic length and spine density of granule neurons in the DG of the rat hippocampus. Further branch order analysis revealed that the decrease of dendritic length was observed only at the second branch order. Moreover, there were obvious deficits in the proportion and size of mushroom-type spines. These deficits in spine formation and maturity were accompanied by a decrease in Arc/Arg3.1 expression. Our present findings are the first to show that developmental lead exposure disturbs branch and spine formation in hippocampal DG areas. Arc/Arg3.1 may have a critical role in the disruption of neuronal morphology and synaptic plasticity in lead-exposed rats.

  18. Expansion of the dentate mossy fiber-CA3 projection in the BDNF-enriched mouse hippocampus

    PubMed Central

    Isgor, Ceylan; Pare, Christopher; McDole, Brittnee; Coombs, Paulette; Guthrie, Kathleen

    2015-01-01

    Structural changes that alter hippocampal functional circuitry are implicated in learning impairments, mood disorders and epilepsy. Reorganization of mossy fiber (MF) axons from dentate granule cells is one such form of plasticity. Increased neurotrophin signaling is proposed to underlie MF plasticity, and there is evidence to support a mechanistic role for brain-derived neurotrophic factor (BDNF) in this process. Transgenic mice overexpressing BDNF in forebrain under the α-calcium/calmodulin-dependent protein kinase II promoter (TgBDNF mice) exhibit spatial learning deficits at 2–3 months of age, followed by the emergence of spontaneous seizures at ~6 months. These behavioral changes suggest that chronic increases in BDNF progressively disrupt hippocampal functional organization. To determine if the dentate MF pathway is structurally altered in this strain, the present study employed Timm staining and design-based stereology to compare MF distribution and projection volumes in transgenic and wild-type mice at 2–3 months, and at 6–7 months. Mice in the latter age group were assessed for seizure vulnerability with a low dose of pilocarpine given 2 hrs before euthanasia. At 2–3 months, TgBDNF mice showed moderate expansion of CA3-projecting MFs (~20%), with increased volumes measured in the suprapyramidal (SP-MF) and intra/infrapyramidal (IIP-MF) compartments. At 6–7 months, a subset of transgenic mice exhibited increased seizure susceptibility, along with an increase in IIP-MF volume (~30%). No evidence of MF sprouting was seen in the inner molecular layer. Additional stereological analyses demonstrated significant increases in molecular layer (ML) volume in TgBDNF mice at both ages, as well as an increase in granule cell number by 8 months of age. Collectively, these results indicate that sustained increases in endogenous BDNF modify dentate structural organization over time, and may thereby contribute to the development of pro-epileptic circuitry. PMID

  19. Bone morphogenic protein signaling is a major determinant of dentate development.

    PubMed

    Choe, Youngshik; Kozlova, Anastasiia; Graf, Daniel; Pleasure, Samuel J

    2013-04-17

    To understand life-long neurogenesis in the dentate gyrus (DG), characterizing dentate neural stem cells and the signals controlling their development are crucial. In the present study, we show that bone morphogenic protein (Bmp) signaling is a critical regulator of embryonic dentate development, required for initiating neurogenesis in embryonic DG progenitors and required for the establishment of dentate neural stem cells postnatally. We tested the hypothesis that Bmp signaling regulates dentate development in part by controlling the expression of Lef1, a Wnt responsive transcription factor expressed in dentate stem cells and absolutely required for dentate granule cell production. Bmp activation through the Acvr1 receptor induced Lef1 expression and neurogenesis in the embryonic DG. Ectopic expression of Bmp7 in the embryonic midline increased DG neurogenesis and inhibition of local Bmp signaling decreased embryonic DG neurogenesis. Mice with selective loss of Bmp expression due to defective meningeal development or with selective conditional deletion of meningeal Bmp7 also have dentate developmental defects. Conditional deletion of Activin receptor type I (Acvr1) or Smad4 (a downstream target nuclear effector of Bmp signaling) in DG neural stem cells resulted in defects in the postnatal subgranular zone and reduced neurogenesis. These results suggest that Acvr1-mediated meningeal Bmp signaling regulates Lef1 expression in the dentate, regulating embryonic DG neurogenesis, DG neural stem cell niche formation, and maintenance.

  20. Dentate Gyrus-Specific Knockdown of Adult Neurogenesis Impairs Spatial and Object Recognition Memory in Adult Rats

    ERIC Educational Resources Information Center

    Jessberger, Sebastian; Clark, Robert E.; Broadbent, Nicola J.; Clemenson, Gregory D., Jr.; Consiglio, Antonella; Lie, D. Chichung; Squire, Larry R.; Gage, Fred H.

    2009-01-01

    New granule cells are born throughout life in the dentate gyrus of the hippocampal formation. Given the fundamental role of the hippocampus in processes underlying certain forms of learning and memory, it has been speculated that newborn granule cells contribute to cognition. However, previous strategies aiming to causally link newborn neurons…

  1. Gene Expression Alterations in the Cerebellum and Granule Neurons of Cstb−/− Mouse Are Associated with Early Synaptic Changes and Inflammation

    PubMed Central

    Reinmaa, Eva; Segerstråle, Mikael; Hakala, Paula; Pehkonen, Heidi; Korpi, Esa R.; Tyynelä, Jaana; Taira, Tomi; Hovatta, Iiris; Kopra, Outi; Lehesjoki, Anna-Elina

    2014-01-01

    Progressive myoclonus epilepsy of Unverricht-Lundborg type (EPM1) is an autosomal recessively inherited neurodegenerative disease, manifesting with myoclonus, seizures and ataxia, caused by mutations in the cystatin B (CSTB) gene. With the aim of understanding the molecular basis of pathogenetic events in EPM1 we characterized gene expression changes in the cerebella of pre-symptomatic postnatal day 7 (P7) and symptomatic P30 cystatin B -deficient (Cstb−/−) mice, a model for the disease, and in cultured Cstb−/− cerebellar granule cells using a pathway-based approach. Differentially expressed genes in P7 cerebella were connected to synaptic function and plasticity, and in cultured cerebellar granule cells, to cell cycle, cytoskeleton, and intracellular transport. In particular, the gene expression data pinpointed alterations in GABAergic pathway. Electrophysiological recordings from Cstb−/− cerebellar Purkinje cells revealed a shift of the balance towards decreased inhibition, yet the amount of inhibitory interneurons was not declined in young animals. Instead, we found diminished number of GABAergic terminals and reduced ligand binding to GABAA receptors in Cstb−/− cerebellum. These results suggest that alterations in GABAergic signaling could result in reduced inhibition in Cstb−/− cerebellum leading to the hyperexcitable phenotype of Cstb−/− mice. At P30, the microarray data revealed a marked upregulation of immune and defense response genes, compatible with the previously reported early glial activation that precedes neuronal degeneration. This further implies the role of early-onset neuroinflammation in the pathogenesis of EPM1. PMID:24586687

  2. Localization of two major GABA(A) receptor subunits in the dentate gyrus of the rat and cell type-specific up-regulation following entorhinal cortex lesion.

    PubMed

    Simbürger, E; Plaschke, M; Fritschy, J M; Nitsch, R

    2001-01-01

    GABA(A) receptor subunits show a specific regional distribution in the CNS during development and in the adult animal. In the hippocampal formation, individual subsets of GABAergic interneurons are highly immunoreactive for the alpha1-subunit, whereas granule and pyramidal cells show a strong expression of the alpha2-subunit. Using confocal microscopy and digital image analysis, we demonstrate that in the dentate gyrus the alpha1-subunit immunolabeling appears in differently sized clusters. The large clusters, which are confined to dendrites of interneurons, show no alpha2 labeling, whereas the smaller ones coincide with alpha2-subunit-positive clusters. In the molecular layer, the clusters of both alpha-subunits co-localize with the anchoring protein gephyrin. In the granule cell layer and hilus, we found alpha1- and alpha2-subunit-positive clusters which were devoid of gephyrin labeling. Lesions of the medial entorhinal cortex led to the deafferentation of dendrites in the middle molecular layer of the dentate gyrus. This resulted in a significantly increased concentration of alpha2-subunit-positive clusters. We also observed an increase of alpha1-subunit immunolabeling in the deafferented area. We found no change in the co-localization between alpha1 and alpha2, and no significant change in the number of large alpha1-positive clusters along individual dendritic segments of interneurons. In a previous study, we demonstrated that calbindin-immunoreactive dendrites of granule cells revealed a significant increase in gephyrin immunoreactivity following lesion, whereas parvalbumin-positive dendrites showed no such alterations. The predominant localization of small gephyrin clusters in dendrites of granule cells, which was also described in this study, leads to the conclusion that the increase of the alpha2-subunit-positive clusters, demonstrated in the present study, indicates that, following entorhinal cortex lesion, new GABAergic synapses may be formed and that

  3. Breaches of the pial basement membrane are associated with defective dentate gyrus development in mouse models of congenital muscular dystrophies.

    PubMed

    Li, Jing; Yu, Miao; Feng, Gang; Hu, Huaiyu; Li, Xiaofeng

    2011-11-07

    A subset of congenital muscular dystrophies (CMDs) has central nervous system manifestations. There are good mouse models for these CMDs that include POMGnT1 knockout, POMT2 knockout and Large(myd) mice with all exhibiting defects in dentate gyrus. It is not known how the abnormal dentate gyrus is formed during the development. In this study, we conducted a detailed morphological examination of the dentate gyrus in adult and newborn POMGnT1 knockout, POMT2 knockout, and Large(myd) mice by immunofluorescence staining and electron microscopic analyses. We observed that the pial basement membrane overlying the dentate gyrus was disrupted and there was ectopia of granule cell precursors through the breached pial basement membrane. Besides these, the knockout dentate gyrus exhibited reactive gliosis in these mouse models. Thus, breaches in the pial basement membrane are associated with defective dentate gyrus development in mouse models of congenital muscular dystrophies.

  4. Granulator Selection

    SciTech Connect

    Gould, T H; Armantrout, G

    1999-08-02

    Following our detailed review of the granulation reports and additional conversations with process and development personnel, we have reached a consensus position regarding granulator selection. At this time, we recommend going forward with implementation of the tumbling granulator approach (GEMCO) based on our assessment of the tested granulation techniques using the established criteria. The basis for this selection is summarized in the following sections, followed by our recommendations for proceeding with implementation of the tumbling granulation approach. All five granulation technologies produced granulated products that can be made into acceptable sintered pucks. A possible exception is the product from the fluidized bed granulator. This material has been more difficult to press into uniform pucks without subsequent cracking of the puck during the sintering cycle for the pucks in this series of tests. This problem may be an artifact of the conditions of the particular granulation demonstration run involved, but earlier results have also been mixed. All granulators made acceptable granulated feed from the standpoint of transfer and press feeding, though the roller compactor and fluidized bed products were dustier than the rest. There was also differentiation among the granulators in the operational areas of (1) potential for process upset, (2) plant implementation and operational complexity, and (3) maintenance concerns. These considerations will be discussed further in the next section. Note that concerns also exist regarding the extension of the granulation processes to powders containing actinides. Only the method that involves tumbling and moisture addition has been tested with uranium, and in that instance, significant differences were found in the granulation behavior of the powders.

  5. Loss of BETA2/NeuroD leads to malformation of the dentate gyrus and epilepsy

    PubMed Central

    Liu, Min; Pleasure, Samuel J.; Collins, Abigail E.; Noebels, Jeffrey L.; Naya, Francesco J.; Tsai, Ming-Jer; Lowenstein, Daniel H.

    2000-01-01

    BETA2/NeuroD is a homologue of the Drosophila atonal gene that is widely expressed during development in the mammalian brain and pancreas. Although studies in Xenopus suggest that BETA2/NeuroD is involved in cellular differentiation, its function in the mammalian nervous system is unclear. Here we show that mutant mice homozygous for a deletion at the BETA2/NeuroD locus fail to develop a granule cell layer within the dentate gyrus, one of the principal structures of the hippocampal formation. To understand the basis of this abnormality, we analyzed dentate gyrus development by using immunocytochemical markers in BETA2/NeuroD-deficient mice. The early cell populations in the dentate gyrus, including Cajal–Retzius cells and radial glia, are present and appear normally organized. The migration of dentate precursor cells and newly born granule cells from the neuroepithelium to the dentate gyrus remains intact. However, there is a dramatic defect in the proliferation of precursor cells once they reach the dentate and a significant delay in the differentiation of granule cells. This leads to malformation of the dentate granule cell layer and excess cell death. BETA2/NeuroD null mice also exhibit spontaneous limbic seizures associated with electrophysiological evidence of seizure activity in the hippocampus and cortex. These findings thus establish a critical role of BETA2/NeuroD in the development of a specific class of neurons. Furthermore, failure to express BETA2/NeuroD leads to a stereotyped pattern of pathological excitability of the adult central nervous system. PMID:10639171

  6. Inactivation of the mTORC1-Eukaryotic Translation Initiation Factor 4E Pathway Alters Stress Granule Formation

    PubMed Central

    Fournier, Marie-Josée; Coudert, Laetitia; Mellaoui, Samia; Adjibade, Pauline; Gareau, Cristina; Côté, Marie-France; Sonenberg, Nahum; Gaudreault, René C.

    2013-01-01

    Stress granules (SG) are cytoplasmic multimeric RNA bodies that form under stress conditions known to inhibit cap-dependent translation. SG contain translation initiation factors, RNA binding proteins, and signaling molecules. SG are known to inhibit apoptotic pathways, thus contributing to chemo- and radioresistance in tumor cells. However, whether stress granule formation involves oncogenic signaling pathways is currently unknown. Here, we report a novel role of the mTORC1-eukaryotic translation initiation factor 4E (eIF4E) pathway, a key regulator of cap-dependent translation initiation of oncogenic factors, in SG formation. mTORC1 specifically drives the eIF4E-mediated formation of SG through the phosphorylation of 4E-BP1, a key factor known to inhibit formation of the mTORC1-dependent eIF4E-eIF4GI interactions. Disrupting formation of SG by inactivation of mTOR with its specific inhibitor pp242 or by depletion of eIF4E or eIF4GI blocks the SG-associated antiapoptotic p21 pathway. Finally, pp242 sensitizes cancer cells to death in vitro and inhibits the growth of chemoresistant tumors in vivo. This work therefore highlights a novel role of the oncogenic mTORC1-eIF4E pathway, namely, the promotion of formation of antiapoptotic SG. PMID:23547259

  7. Dentate Gyrus Development Requires ERK Activity to Maintain Progenitor Population and MAPK Pathway Feedback Regulation

    PubMed Central

    Vithayathil, Joseph; Pucilowska, Joanna; Goodnough, L. Henry; Atit, Radhika P.

    2015-01-01

    The ERK/MAPK pathway is an important developmental signaling pathway. Mutations in upstream elements of this pathway result in neuro-cardio-facial cutaneous (NCFC) syndromes, which are typified by impaired neurocognitive abilities that are reliant upon hippocampal function. The role of ERK signaling during hippocampal development has not been examined and may provide critical insight into the cause of hippocampal dysfunction in NCFC syndromes. In this study, we have generated ERK1 and conditional ERK2 compound knock-out mice to determine the role of ERK signaling during development of the hippocampal dentate gyrus. We found that loss of both ERK1 and ERK2 resulted in 60% fewer granule cells and near complete absence of neural progenitor pools in the postnatal dentate gyrus. Loss of ERK1/2 impaired maintenance of neural progenitors as they migrate from the dentate ventricular zone to the dentate gyrus proper, resulting in premature depletion of neural progenitor cells beginning at E16.5, which prevented generation of granule cells later in development. Finally, loss of ERK2 alone does not impair development of the dentate gyrus as animals expressing only ERK1 developed a normal hippocampus. These findings establish that ERK signaling regulates maintenance of progenitor cells required for development of the dentate gyrus. PMID:25926459

  8. Reelin and Notch1 cooperate in the development of the dentate gyrus.

    PubMed

    Sibbe, Mirjam; Förster, Eckart; Basak, Onur; Taylor, Verdon; Frotscher, Michael

    2009-07-01

    The development of the hippocampal dentate gyrus is a complex process in which several signaling pathways are involved and likely interact with each other. The extracellular matrix molecule Reelin is necessary both for normal development of the dentate gyrus radial glia and neuronal migration. In Reelin-deficient Reeler mice, the hippocampal radial glial scaffold fails to form, and granule cells are dispersed throughout the dentate gyrus. Here, we show that both formation of the radial glia scaffold and lamination of the dentate gyrus depend on intact Notch signaling. Inhibition of Notch signaling in organotypic hippocampal slice cultures induced a phenotype reminiscent of the Reelin-deficient hippocampus, i.e., a reduced density of radial glia fibers and granule cell dispersion. Moreover, a Reelin-dependent rescue of the Reeler phenotype was blocked by inhibition of Notch activation. In the Reeler dentate gyrus, we found reduced Notch1 signaling; the activated Notch intracellular domain as well as the transcriptional targets, brain lipid-binding protein, and Hes5 are decreased. Disabled1, a component of the Reelin-signaling pathway colocalizes with Notch1, thus indicating a direct interaction between the Reelin- and Notch1-signaling pathways. These results suggest that Reelin enhances Notch1 signaling, thereby contributing to the formation of the radial glial scaffold and the normal development of the dentate gyrus.

  9. "Dormant basket cell" hypothesis revisited: relative vulnerabilities of dentate gyrus mossy cells and inhibitory interneurons after hippocampal status epilepticus in the rat.

    PubMed

    Sloviter, Robert S; Zappone, Colin A; Harvey, Brian D; Bumanglag, Argyle V; Bender, Roland A; Frotscher, Michael

    2003-04-21

    The "dormant basket cell" hypothesis suggests that postinjury hippocampal network hyperexcitability results from the loss of vulnerable neurons that normally excite insult-resistant inhibitory basket cells. We have reexamined the experimental basis of this hypothesis in light of reports that excitatory hilar mossy cells are not consistently vulnerable and inhibitory basket cells are not consistently seizure resistant. Prolonged afferent stimulation that reliably evoked granule cell discharges always produced extensive hilar neuron degeneration and immediate granule cell disinhibition. Conversely, kainic acid-induced status epilepticus in chronically implanted animals produced similarly extensive hilar cell loss and immediate granule cell disinhibition, but only when granule cells discharged continuously during status epilepticus. In both preparations, electron microscopy revealed degeneration of presynaptic terminals forming asymmetrical synapses in the mossy cell target zone, including some terminating on gamma-aminobutyric acid-immunoreactive elements, but no evidence of axosomatic or axoaxonic degeneration in the adjacent granule cell layer. Although parvalbumin immunocytochemistry and in situ hybridization revealed decreased staining, this apparently was due to altered parvalbumin expression rather than basket cell death, because substance P receptor-positive interneurons, some of which contained residual parvalbumin immunoreactivity, survived. These results confirm the inherent vulnerability of dendritically projecting hilar mossy cells and interneurons and the relative resistance of dentate inhibitory basket and chandelier cells that target granule cell somata. The variability of hippocampal cell loss after status epilepticus suggests that altered hippocampal structure and function cannot be assumed to cause the spontaneous seizures that develop in these animals and highlights the importance of confirming hippocampal pathology and pathophysiology in vivo in

  10. Expansion of the dentate mossy fiber-CA3 projection in the brain-derived neurotrophic factor-enriched mouse hippocampus.

    PubMed

    Isgor, C; Pare, C; McDole, B; Coombs, P; Guthrie, K

    2015-03-12

    Structural changes that alter hippocampal functional circuitry are implicated in learning impairments, mood disorders and epilepsy. Reorganization of mossy fiber (MF) axons from dentate granule cells is one such form of plasticity. Increased neurotrophin signaling is proposed to underlie MF plasticity, and there is evidence to support a mechanistic role for brain-derived neurotrophic factor (BDNF) in this process. Transgenic mice overexpressing BDNF in the forebrain under the α-calcium/calmodulin-dependent protein kinase II promoter (TgBDNF mice) exhibit spatial learning deficits at 2-3months of age, followed by the emergence of spontaneous seizures at ∼6months. These behavioral changes suggest that chronic increases in BDNF progressively disrupt hippocampal functional organization. To determine if the dentate MF pathway is structurally altered in this strain, the present study employed Timm staining and design-based stereology to compare MF distribution and projection volumes in transgenic and wild-type mice at 2-3months, and at 6-7months. Mice in the latter age group were assessed for seizure vulnerability with a low dose of pilocarpine given 2h before euthanasia. At 2-3months, TgBDNF mice showed moderate expansion of CA3-projecting MFs (∼20%), with increased volumes measured in the suprapyramidal (SP-MF) and intra/infrapyramidal (IIP-MF) compartments. At 6-7months, a subset of transgenic mice exhibited increased seizure susceptibility, along with an increase in IIP-MF volume (∼30%). No evidence of MF sprouting was seen in the inner molecular layer. Additional stereological analyses demonstrated significant increases in molecular layer (ML) volume in TgBDNF mice at both ages, as well as an increase in granule cell number by 8months of age. Collectively, these results indicate that sustained increases in endogenous BDNF modify dentate structural organization over time, and may thereby contribute to the development of pro-epileptic circuitry.

  11. Inhibition and interneuron distribution in the dentate gyrus of p35 knockout mice.

    PubMed

    Knight, Leena S; Wenzel, H Jürgen; Schwartzkroin, Philip A

    2012-06-01

    The p35 knockout (p35-/-) mouse is an animal model of temporal lobe epilepsy that recapitulates key neuroanatomic abnormalities-granule cell dispersion and mossy fiber sprouting-observed in the hippocampal formation of humans, as well as spontaneous seizure activity. It is a useful model in which to study the relationship between the abnormal neuronal structure and seizure activity to further our understanding of cortical dysplasia in epileptogenesis. Our previous work using this mouse model characterized the anatomic features of the dentate granule cells and the functional implications of these abnormalities on increased recurrent excitation. These data also suggested that there might be compromised inhibition in this animal model. We pursued this possibility, focusing our investigation on inhibitory circuitry. In preliminary investigations using neuroanatomic tools (immunocytochemistry, camera lucida reconstructions of individually labeled interneurons, and electron microscopy) combined with intracellular electrophysiology, we observed no significant reduction in the number of symmetric versus asymmetric synaptic contacts on dentate granule cell somata, and no statistically significant changes in evoked early or late inhibition. Although there were some abnormalities in the morphology/distribution of inhibitory interneurons (as well as a larger population of dentate granule cells) of the dentate gyrus, overall inhibition in the p35 knockout mouse appeared to be largely intact.

  12. Structure of the granular layer of the rat dentate gyrus. A light microscopic and Golgi study.

    PubMed Central

    Seress, L; Pokorny, J

    1981-01-01

    The rat dentate gyrus was examined with the Golgi method. Cell counts were performed in Nissl-stained serial sections. The number of granule cells was 635,000 +/- 33,000. The number of basket cells in the granular layer was 3600 +/- 570. In whole dentate gyrus, the average ratio between granule and basket cells was 160-220:1. The ratio was higher in the caudal part of the dorsal and ventral blades and significantly less basket cells were found in the ventral than in the dorsal blade of dentate gyrus. 60% of all the basket cells were found at the margin between the granular layer and hilus, 35% were found in the lower half of molecular layer and 5% within the granular layer. Five types of basket cells were differentiated in Golgi sections on the basis of their location and cell morphology. The granule cells in their early development stages sent dendrites in every direction even in the hilus, but the developed granule cells never had basal dendrites. Spines were seen on the 5 days old granule cell dendrites, but the spine density was found to grow until adulthood. As a rule several axon collaterals could be seen on the granule cell axons. The whole length of granule cell dendrites totaled 2400 micron +/- 331, those of the basket cell dendrites totaled 1100 micron +/- 144. The possible role of basket cells in the regulation of the dentate gyrus granular layer was considered. Images Fig. 1 Fig. 2 Fig. 3 Fig. 5 Fig. 6 Fig. 11 Fig. 12 PMID:7333948

  13. Developmental cuprizone exposure impairs oligodendrocyte lineages differentially in cortical and white matter tissues and suppresses glutamatergic neurogenesis signals and synaptic plasticity in the hippocampal dentate gyrus of rats.

    PubMed

    Abe, Hajime; Saito, Fumiyo; Tanaka, Takeshi; Mizukami, Sayaka; Hasegawa-Baba, Yasuko; Imatanaka, Nobuya; Akahori, Yumi; Yoshida, Toshinori; Shibutani, Makoto

    2016-01-01

    Developmental cuprizone (CPZ) exposure impairs rat hippocampal neurogenesis. Here, we captured the developmental neurotoxicity profile of CPZ using a region-specific expression microarray analysis in the hippocampal dentate gyrus, corpus callosum, cerebral cortex and cerebellar vermis of rat offspring exposed to 0, 0.1, or 0.4% CPZ in the maternal diet from gestation day 6 to postnatal day (PND) 21. Transcripts of those genes identified as altered were subjected to immunohistochemical analysis on PNDs 21 and 77. Our results showed that transcripts for myelinogenesis-related genes, including Cnp, were selectively downregulated in the cerebral cortex by CPZ at ≥0.1% or 0.4% on PND 21. CPZ at 0.4% decreased immunostaining intensity for 2',3'-cyclic-nucleotide 3'-phosphodiesterase (CNPase) and CNPase(+) and OLIG2(+) oligodendrocyte densities in the cerebral cortex, whereas CNPase immunostaining intensity alone was decreased in the corpus callosum. By contrast, a striking transcript upregulation for Klotho gene and an increased density of Klotho(+) oligodendrocytes were detected in the corpus callosum at ≥0.1%. In the dentate gyrus, CPZ at ≥0.1% or 0.4% decreased the transcript levels for Gria1, Grin2a and Ptgs2, genes related to the synapse and synaptic transmission, and the number of GRIA1(+) and GRIN2A(+) hilar γ-aminobutyric acid (GABA)-ergic interneurons and cyclooxygenase-2(+) granule cells. All changes were reversed at PND 77. Thus, developmental CPZ exposure reversibly decreased mature oligodendrocytes in both cortical and white matter tissues, and Klotho protected white matter oligodendrocyte growth. CPZ also reversibly targeted glutamatergic signals of GABAergic interneuron to affect dentate gyrus neurogenesis and synaptic plasticity in granule cells.

  14. Benzodiazepines And The Potential Trophic Effect Of Antidepressants On Dentate Gyrus Cells In Mood Disorders

    PubMed Central

    Boldrini, Maura; Butt, Tanya H.; Santiago, Adrienne N.; Tamir, Hadassah; Dwork, Andrew J.; Rosoklija, Gorazd B.; Arango, Victoria; Hen, René; Mann, J. John

    2015-01-01

    Modest antidepressant response rates of mood disorders (MD) encourage benzodiazepine (BZD) co-medication with debatable benefit. Adult hippocampal neurogenesis may underlie antidepressant responses, but diazepam co-administration impairs murine neuron maturation and survival in response to fluoxetine. We counted neural progenitor cells (NPCs), mitotic cells, and mature granule neurons postmortem in dentate gyrus (DG) from subjects with: untreated DSM-IV MD (n=17); antidepressant-treated MD (MD*ADT, n=10); benzodiazepine-antidepressant-treated MD (MD*ADT*BZD, n=7); no psychopathology or treatment (controls, n=18). MD*ADT*BZD had fewer granule neurons vs. MD*ADT in anterior DG and vs. controls in mid DG, and did not differ from untreated-MD in any DG subregion. MD*ADT had more granule neurons than untreated-MD in anterior and mid DG and comparable granule neuron number to controls in all dentate subregions. Untreated-MD had fewer granule neurons than controls in anterior and mid DG, and did not differ from any other group in posterior DG. MD*ADT*BZD had fewer NPCs vs. MD*ADT in mid DG. MD*ADT had more NPCs vs. untreated-MD and controls in anterior and mid DG. MD*ADT*BZD and MD*ADT had more mitotic cells in anterior DG vs. controls and untreated-MD. There were no between-group differences in mid DG in mitotic cells or in posterior DG for any cell type. Our results in mid-dentate, and to some degree anterior dentate, gyrus are consistent with murine findings that benzodiazepines counteract antidepressant-induced increases in neurogenesis by interfering with progenitor proliferation. We also confirmed, in this expanded sample, our previous finding of granule neuron deficit in untreated MD. PMID:24969726

  15. Evolution of the mammalian dentate gyrus.

    PubMed

    Hevner, Robert F

    2016-02-15

    The dentate gyrus (DG), a part of the hippocampal formation, has important functions in learning, memory, and adult neurogenesis. Compared with homologous areas in sauropsids (birds and reptiles), the mammalian DG is larger and exhibits qualitatively different phenotypes: 1) folded (C- or V-shaped) granule neuron layer, concave toward the hilus and delimited by a hippocampal fissure; 2) nonperiventricular adult neurogenesis; and 3) prolonged ontogeny, involving extensive abventricular (basal) migration and proliferation of neural stem and progenitor cells (NSPCs). Although gaps remain, available data indicate that these DG traits are present in all orders of mammals, including monotremes and marsupials. The exception is Cetacea (whales, dolphins, and porpoises), in which DG size, convolution, and adult neurogenesis have undergone evolutionary regression. Parsimony suggests that increased growth and convolution of the DG arose in stem mammals concurrently with nonperiventricular adult hippocampal neurogenesis and basal migration of NSPCs during development. These traits could all result from an evolutionary change that enhanced radial migration of NSPCs out of the periventricular zones, possibly by epithelial-mesenchymal transition, to colonize and maintain nonperiventricular proliferative niches. In turn, increased NSPC migration and clonal expansion might be a consequence of growth in the cortical hem (medial patterning center), which produces morphogens such as Wnt3a, generates Cajal-Retzius neurons, and is regulated by Lhx2. Finally, correlations between DG convolution and neocortical gyrification (or capacity for gyrification) suggest that enhanced abventricular migration and proliferation of NSPCs played a transformative role in growth and folding of neocortex as well as archicortex.

  16. Indomethacin ameliorates trimethyltin-induced neuronal damage in vivo by attenuating oxidative stress in the dentate gyrus of mice.

    PubMed

    Huong, Nguyen Quynh; Nakamura, Yukary; Kuramoto, Nobuyuki; Yoneyama, Masanori; Nagashima, Reiko; Shiba, Tatsuo; Yamaguchi, Taro; Hasebe, Shigeru; Ogita, Kiyokazu

    2011-01-01

    The organotin trimethyltin (TMT) is well known to cause neuronal degeneration in the hippocampal dentate gyrus of mice. The first purpose of the present study was to examine whether the cyclooxygenase (COX) inhibitor indomethacin could ameliorate neuronal degeneration in the dentate gyrus of mice following TMT treatment in vivo. The systemic injection into mice of TMT at 2.8 mg/kg produced activation of endogenous caspase-3 and calpain, enhanced the gene expression of COX-1 and COX-2, activated microglial cells, and caused the formation of the lipid peroxidation product 4-hydroxynonenal in the hippocampus. Given at 12-h post-TMT treatment, the systemic injection of indomethacin (5 or 10 mg/kg, subcutaneously) significantly decreased the TMT-induced damage to neurons having active caspase-3 and single-stranded DNA in the dentate granule cell layer of the hippocampus. The results of the α-Fodrin degradation test revealed that the post-treatment with indomethacin was effective in attenuating TMT-induced activation of endogenous caspases and calpain in the hippocampus. In TMT-treated animals, interestingly, the post-treatment with indomethacin produced not only activation of microglial cells in the dentate gyrus but also the formation of 4-hydroxynonenal in the dentate granule cell layer. Taken together, our data suggest that COX inhibition by indomethacin ameliorated TMT-induced neuronal degeneration in the dentate gyrus by attenuating intensive oxidative stress.

  17. The ventral hippocampus is the embryonic origin for adult neural stem cells in the dentate gyrus.

    PubMed

    Li, Guangnan; Fang, Li; Fernández, Gloria; Pleasure, Samuel J

    2013-05-22

    Adult neurogenesis represents a unique form of plasticity in the dentate gyrus requiring the presence of long-lived neural stem cells (LL-NSCs). However, the embryonic origin of these LL-NSCs remains unclear. The prevailing model assumes that the dentate neuroepithelium throughout the longitudinal axis of the hippocampus generates both the LL-NSCs and embryonically produced granule neurons. Here we show that the NSCs initially originate from the ventral hippocampus during late gestation and then relocate into the dorsal hippocampus. The descendants of these cells are the source for the LL-NSCs in the subgranular zone (SGZ). Furthermore, we show that the origin of these cells and their maintenance in the dentate are controlled by distinct sources of Sonic Hedgehog (Shh). The revelation of the complexity of both the embryonic origin of hippocampal LL-NSCs and the sources of Shh has important implications for the functions of LL-NSCs in the adult hippocampus.

  18. VTA Projection Neurons Releasing GABA and Glutamate in the Dentate Gyrus

    PubMed Central

    2016-01-01

    Abstract Both dopamine and nondopamine neurons from the ventral tegmental area (VTA) project to a variety of brain regions. Here we examine nondopaminergic neurons in the mouse VTA that send long-range projections to the hippocampus. Using a combination of retrograde tracers, optogenetic tools, and electrophysiological recordings, we show that VTA GABAergic axons make synaptic contacts in the granule cell layer of the dentate gyrus, where we can elicit small postsynaptic currents. Surprisingly, the currents displayed a partial sensitivity to both bicuculline and NBQX, suggesting that these mesohippocampal neurons corelease both GABA and glutamate. Finally, we show that this projection is functional in vivo and its stimulation reduces granule cell-firing rates under anesthesia. Altogether, the present results describe a novel connection between GABA and glutamate coreleasing of cells of the VTA and the dentate gyrus. This connection could be relevant for a variety of functions, including reward-related memory and neurogenesis. PMID:27648470

  19. Innervation from the entorhinal cortex to the dentate gyrus and the vulnerability to Zn(2).

    PubMed

    Takeda, Atsushi; Tamano, Hanuna

    2016-12-01

    Hippocampal Zn(2+) homeostasis is critical for cognitive activity and hippocampus-dependent memory. Extracellular Zn(2+) signaling is linked to extracellular glutamate signaling and leads to intracellular Zn(2+) signaling, which is involved in cognitive activity. On the other hand, excess intracellular Zn(2+) signaling that is induced by excess glutamate signaling is involved in cognitive decline. In the hippocampal formation, the dentate gyrus is the most vulnerable to aging and is thought to contribute to age-related cognitive decline. The layer II of the entorhinal cortex is the most vulnerable to neuronal death in Alzheimer's disease. The perforant pathway provides input from the layer II to the dentate gyrus and is one of the earliest affected pathways in Alzheimer's disease. Medial perforant pathway-dentate granule cell synapses are vulnerable to either excess intracellular Zn(2+) or β-amyloid (Aβ)-bound zinc, which induce transient cognitive decline via attenuation of medial perforant pathway LTP. However, it is unknown whether the vulnerability to excess intracellular Zn(2+) is involved in region-specific vulnerability to aging and Alzheimer's disease. To discover a strategy to prevent short-term cognitive decline in normal aging process and the pre-dementia stage of Alzheimer's disease, the present paper deals with vulnerability of medial perforant pathway-dentate granule cell synapses to intracellular Zn(2+) dyshomeostasis and its possible involvement in differential vulnerability to aging and Alzheimer's disease in the hippocampal formation.

  20. A million-plus neuron model of the hippocampal dentate gyrus: Dependency of spatio-temporal network dynamics on topography.

    PubMed

    Hendrickson, Phillip J; Yu, Gene J; Song, Dong; Berger, Theodore W

    2015-01-01

    This paper describes a million-plus granule cell compartmental model of the rat hippocampal dentate gyrus, including excitatory, perforant path input from the entorhinal cortex, and feedforward and feedback inhibitory input from dentate interneurons. The model includes experimentally determined morphological and biophysical properties of granule cells, together with glutamatergic AMPA-like EPSP and GABAergic GABAA-like IPSP synaptic excitatory and inhibitory inputs, respectively. Each granule cell was composed of approximately 200 compartments having passive and active conductances distributed throughout the somatic and dendritic regions. Modeling excitatory input from the entorhinal cortex was guided by axonal transport studies documenting the topographical organization of projections from subregions of the medial and lateral entorhinal cortex, plus other important details of the distribution of glutamatergic inputs to the dentate gyrus. Results showed that when medial and lateral entorhinal cortical neurons maintained Poisson random firing, dentate granule cells expressed, throughout the million-cell network, a robust, non-random pattern of spiking best described as spatiotemporal "clustering". To identify the network property or properties responsible for generating such firing "clusters", we progressively eliminated from the model key mechanisms such as feedforward and feedback inhibition, intrinsic membrane properties underlying rhythmic burst firing, and/or topographical organization of entorhinal afferents. Findings conclusively identified topographical organization of inputs as the key element responsible for generating a spatio-temporal distribution of clustered firing. These results uncover a functional organization of perforant path afferents to the dentate gyrus not previously recognized: topography-dependent clusters of granule cell activity as "functional units" that organize the processing of entorhinal signals.

  1. Dynorphin up-regulation in the dentate granule cell mossy fiber pathway following chronic inhibition of GluN2B-containing NMDAR is associated with increased CREB (Ser 133) phosphorylation, but is independent of BDNF/TrkB signaling pathways

    PubMed Central

    Rittase, W. Bradley; Dong, Yu; Barksdale, DaRel; Galdzicki, Zygmunt; Bausch, Suzanne B.

    2014-01-01

    Emerging evidence suggests that neuronal responses to N-methyl-d-aspartate (NMDAR) activation/inactivation are influenced by subunit composition. For example, activation of synaptic NMDAR (comprised of GluN2A > GluN2B) phosphorylates cAMP-response-element-binding protein (CREB) at Ser 133, induces BDNF expression and promotes neuronal survival. Activation of extrasynaptic NMDAR (comprised of GluN2B>GluN2), dephosphorylates CREB (Ser 133), reduces BDNF expression and triggers neuronal death. These results led us to hypothesize that chronic inhibition of GluN2B-containing NMDAR would increase CREB (Ser 133) phosphorylation, increase BDNF levels and subsequently alter downstream dynorphin (DYN) and neuropeptide Y (NPY) expression. We focused on DYN and NPY because these neuropeptides can decrease excitatory neurotransmission and seizure occurrence and we reported previously that seizure-like events are reduced following chronic treatment with GluN2B antagonists. Consistent with our hypothesis, chronic treatment (17-21 days) of hippocampal slice cultures with the GluN2B-selective antagonists ifenprodil or Ro25,6981 increased both CREB (Ser 133) phosphorylation and granule cell mossy fiber pathway DYN expression. Similar treatment with the non-subtype-selective NMDAR antagonists D-APV or memantine had no significant effect on either CREB (Ser 133) phosphorylation or DYN expression. In contrast to our hypothesis, BDNF levels were decreased following chronic treatment with Ro25,6981, but not ifenprodil, D-APV or memantine. Blockade of BDNF actions and TrkB activation did not significantly augment hilar DYN expression in vehicle-treated cultures and had no effect in Ro25,6981 treated cultures. These finding suggest that chronic exposure to GluN2B-selective NMDAR antagonists increased DYN expression through a putatively pCREB-dependent, but BDNF/TrkB-independent mechanism. PMID:24769103

  2. Running Induces Widespread Structural Alterations in the Hippocampus and Entorhinal Cortex

    PubMed Central

    Stranahan, Alexis M.; Khalil, David; Gould, Elizabeth

    2010-01-01

    Physical activity enhances hippocampal function but its effects on neuronal structure remain relatively unexplored outside of the dentate gyrus. Using Golgi impregnation and the lipophilic tracer DiI, we show that long-term voluntary running increases the density of dendritic spines in the entorhinal cortex and hippocampus of adult rats. Exercise was associated with increased dendritic spine density not only in granule neurons of the dentate gyrus, but also in CA1 pyramidal neurons, and in layer III pyramidal neurons of the entorhinal cortex. In the CA1 region, changes in dendritic spine density are accompanied by changes in dendritic arborization and alterations in the morphology of individual spines. These findings suggest that physical activity exerts pervasive effects on neuronal morphology in the hippocampus and one of its afferent populations. These structural changes may contribute to running-induced changes in cognitive function. PMID:17636549

  3. Morphological alterations in the hippocampus of the Ts65Dn mouse model for Down Syndrome correlate with structural plasticity markers.

    PubMed

    Villarroya, Olga; Ballestín, Raúl; López-Hidalgo, Rosa; Mulet, Maria; Blasco-Ibáñez, José Miguel; Crespo, Carlos; Nacher, Juan; Gilabert-Juan, Javier; Varea, Emilio

    2017-04-04

    Down syndrome (DS) is the most common chromosomal aneuploidy. Although trisomy on chromosome 21 can display variable phenotypes, there is a common feature among all DS individuals: the presence of intellectual disability. This condition is partially attributed to abnormalities found in the hippocampus of individuals with DS and in the murine model for DS, Ts65Dn. To check if all hippocampal areas were equally affected in 4-5 month adult Ts65Dn mice, we analysed the morphology of dentate gyrus granule cells and cornu ammonis pyramidal neurons using Sholl method on Golgi-Cox impregnated neurons. Structural plasticity has been analysed using immunohistochemistry for plasticity molecules followed by densitometric analysis (Brain Derived Neurotrophic Factor (BDNF), Polysialylated form of the Neural Cell Adhesion Molecule (PSA-NCAM) and the Growth Associated Protein 43 (GAP43)). We observed an impairment in the dendritic arborisation of granule cells, but not in the pyramidal neurons in the Ts65Dn mice. When we analysed the expression of molecules related to structural plasticity in trisomic mouse hippocampus, we observed a reduction in the expression of BDNF and PSA-NCAM, and an increment in the expression of GAP43. These alterations were restricted to the regions related to dentate granule cells suggesting an interrelation. Therefore the impairment in dendritic arborisation and molecular plasticity is not a general feature of all Down Syndrome principal neurons. Pharmacological manipulations of the levels of plasticity molecules could provide a way to restore granule cell morphology and function.

  4. Hippocampal granule cells opt for early retirement.

    PubMed

    Alme, C B; Buzzetti, R A; Marrone, D F; Leutgeb, J K; Chawla, M K; Schaner, M J; Bohanick, J D; Khoboko, T; Leutgeb, S; Moser, E I; Moser, M-B; McNaughton, B L; Barnes, C A

    2010-10-01

    Increased excitability and plasticity of adult-generated hippocampal granule cells during a critical period suggests that they may "orthogonalize" memories according to time. One version of this "temporal tag" hypothesis suggests that young granule cells are particularly responsive during a specific time period after their genesis, allowing them to play a significant role in sculpting CA3 representations, after which they become much less responsive to any input. An alternative possibility is that the granule cells active during their window of increased plasticity, and excitability become selectively tuned to events that occurred during that time and participate in later reinstatement of those experiences, to the exclusion of other cells. To discriminate between these possibilities, rats were exposed to different environments at different times over many weeks, and cell activation was subsequently assessed during a single session in which all environments were revisited. Dispersing the initial experiences in time did not lead to the increase in total recruitment at reinstatement time predicted by the selective tuning hypothesis. The data indicate that, during a given time frame, only a very small number of granule cells participate in many experiences, with most not participating significantly in any. Based on these and previous data, the small excitable population of granule cells probably correspond to the most recently generated cells. It appears that, rather than contributing to the recollection of long past events, most granule cells, possibly 90-95%, are effectively "retired." If granule cells indeed sculpt CA3 representations (which remains to be shown), then a possible consequence of having a new set of granule cells participate when old memories are reinstated is that new representations of these experiences might be generated in CA3. Whatever the case, the present data may be interpreted to undermine the standard "orthogonalizer" theory of the role of

  5. Trim9 Deletion Alters the Morphogenesis of Developing and Adult-Born Hippocampal Neurons and Impairs Spatial Learning and Memory

    PubMed Central

    Winkle, Cortney C.; Olsen, Reid H. J.; Kim, Hyojin; Moy, Sheryl S.

    2016-01-01

    During hippocampal development, newly born neurons migrate to appropriate destinations, extend axons, and ramify dendritic arbors to establish functional circuitry. These developmental stages are recapitulated in the dentate gyrus of the adult hippocampus, where neurons are continuously generated and subsequently incorporate into existing, local circuitry. Here we demonstrate that the E3 ubiquitin ligase TRIM9 regulates these developmental stages in embryonic and adult-born mouse hippocampal neurons in vitro and in vivo. Embryonic hippocampal and adult-born dentate granule neurons lacking Trim9 exhibit several morphological defects, including excessive dendritic arborization. Although gross anatomy of the hippocampus was not detectably altered by Trim9 deletion, a significant number of Trim9−/− adult-born dentate neurons localized inappropriately. These morphological and localization defects of hippocampal neurons in Trim9−/− mice were associated with extreme deficits in spatial learning and memory, suggesting that TRIM9-directed neuronal morphogenesis may be involved in hippocampal-dependent behaviors. SIGNIFICANCE STATEMENT Appropriate generation and incorporation of adult-born neurons in the dentate gyrus are critical for spatial learning and memory and other hippocampal functions. Here we identify the brain-enriched E3 ubiquitin ligase TRIM9 as a novel regulator of embryonic and adult hippocampal neuron shape acquisition and hippocampal-dependent behaviors. Genetic deletion of Trim9 elevated dendritic arborization of hippocampal neurons in vitro and in vivo. Adult-born dentate granule cells lacking Trim9 similarly exhibited excessive dendritic arborization and mislocalization of cell bodies in vivo. These cellular defects were associated with severe deficits in spatial learning and memory. PMID:27147649

  6. Mutation of the maize sbe1a and ae genes alters morphology and physical behavior of wx-type endosperm starch granules.

    PubMed

    Li, Ji-Hong; Guiltinan, Mark J; Thompson, Donald B

    2007-12-10

    In maize, three isoforms of starch-branching enzyme, SBEI, SBEIIa, and SBEIIb, are encoded by the Sbe1a, Sbe2a, and Amylose extender (Ae) genes, respectively. The objective of this research was to explore the effects of null mutations in the Sbe1a and Ae genes alone and in combination in wx background on kernel characteristics and on the morphology and physical behavior of endosperm starch granules. Differences in kernel morphology and weight, starch accumulation, starch granule size and size distribution, starch microstructure, and thermal properties were observed between the ae wx and sbe1a ae wx plants but not between the sbe1a wx mutants when compared to wx. Starch from sbe1a ae wx plants exhibited a larger granule size with a wider gelatinization temperature range and a lower endotherm enthalpy than ae wx. Microscopy shows weaker iodine staining in sbe1a ae wx starch granules. X-ray diffraction revealed A-type crystallinity in wx and sbe1a wx starches and B-type in sbe1a ae wx and ae wx. This study suggests that, while the SBEIIb isoform plays a dominant role in maize endosperm starch synthesis, SBEI also plays a role, which is only observable in the presence of the ae mutation.

  7. Starch granule formation and protein deposition in wheat (Triticum aestivum L.) starchy endosperm cells is altered by high temperature during grain fill

    NASA Astrophysics Data System (ADS)

    Hurkman, William J.; Wood, Delilah F.

    2010-06-01

    High temperatures during wheat grain fill decrease starch and protein levels, adversely affecting wheat yield and flour quality. To determine the effect of high temperature on starchy endosperm cell development, grain (Triticum aestivum L. 'Butte 86') was produced under a 24/17°C or 37/28°C day/night regimen imposed from flowering to maturity and starch and protein deposition examined using scanning electron microscopy. The high temperature regimen shortened the duration of grain fill from 40 to 18 days. Under the 37/28°C regimen, A- and B-type starch granules decreased in size. A-type starch granules also exhibited pitting, suggesting enhanced action of starch degradative enzymes. Under both temperature regimens, protein bodies originated early in development and coalesced during mid to late development to form a continuous protein matrix surrounding the starch granules. Under the 37/28°C regimen, the proportion of protein matrix increased in endosperm cells of mature grain. Taken together, the changes in starch granule number and size and in protein matrix amount provide clues for understanding how high temperature during grain fill can affect end use properties of wheat flour.

  8. Behavior modification after inactivation of cerebellar dentate nuclei.

    PubMed

    Peterson, Todd C; Villatoro, Lee; Arneson, Tom; Ahuja, Brittany; Voss, Stephanie; Swain, Rodney A

    2012-08-01

    Effort-based decision making occurs when subjects are given a choice between a reward available at a high response cost and a reward available at a low response cost and is altered in individuals with disorders such as autism or particular patterns of brain injury. The current study explored the relationship between effort-based decision making and reinforcement characteristics in the T maze. This was done using both normal animals and animals with bilateral inactivation of the cerebellar dentate nuclei. Rats chose between alternatives in which one arm contained high-density reinforcement (HR) and the other arm contained low-density reinforcement (LR). During training, the HR arm was obstructed and the point at which the animal no longer worked for reinforcement (breaking point) was determined. The cerebellar dentate nuclei were then transiently inactivated and once again breaking points were assessed. The results indicated that inactivation of the dentate nucleus disrupted effort-based decision making. Additionally, altering both the palatability and the magnitude of the reinforcement were assessed in an attempt to reestablish the original preinactivation breaking point. It was hypothesized that an increase in the strength or magnitude of the reinforcement would promote an increase in the breaking point of the animal even when the cerebellum was inactivated. The results indicated that with both strategies animals effectively reestablished original breaking points. The results of this study will inform the current literature regarding the modification of behavior after brain injury and further the understanding of the behavioral deficits associated with cerebellar dysfunction.

  9. Twin screw granulation: steps in granule growth.

    PubMed

    Dhenge, Ranjit M; Cartwright, James J; Hounslow, Michael J; Salman, Agba D

    2012-11-15

    The present work focuses on the study of the progression of granules in different compartments along the length of screws in a twin screw granulator (TSG). The effects of varying powder feed rate; liquid to solid ratio and viscosity of granulation liquid on properties of granules was studied. The bigger granules produced at the start of the process were found to change in terms of size, shape and strength along the screw length at all the conditions investigated. The granules became more spherical and their strength increased along the screw length. Tracer granules were also introduced in order to understand the role of kneading and conveying elements in the TSG. The kneading elements promoted consolidation and breakage while the conveying elements led to coalescence, breakage and some consolidation. The results presented here help to provide a qualitative and quantitative understanding of the twin screw granulation process.

  10. Increased synaptic inhibition in dentate gyrus of mice with reduced levels of endogenous brain-derived neurotrophic factor.

    PubMed

    Olofsdotter, K; Lindvall, O; Asztély, F

    2000-01-01

    The aim of this study was to explore the role of endogenous neurotrophins for inhibitory synaptic transmission in the dentate gyrus of adult mice. Heterozygous knockout (+/-) mice or neurotrophin scavenging proteins were used to reduce the levels of endogenous brain-derived neurotrophic factor and neurotrophin-3. Patch-clamp recordings from dentate granule cells in brain slices showed that the frequency, but not the kinetics or amplitude, of miniature inhibitory postsynaptic currents was modulated in brain-derived neurotrophic factor +/- compared to wild-type (+/+) mice. Furthermore, paired-pulse depression of evoked inhibitory synaptic responses was increased in brain-derived neurotrophic factor +/- mice. Similar results were obtained in brain slices from brain-derived neurotrophic factor +/+ mice incubated with tyrosine receptor kinase B-immunoglobulin G, which scavenges endogenous brain-derived neurotrophic factor. The increased inhibitory synaptic activity in brain-derived neurotrophic factor +/- mice was accompanied by decreased excitability of the granule cells. No differences in the frequency, amplitude or kinetics of miniature inhibitory postsynaptic currents were seen between neurotrophin-3 +/- and +/+ mice. From these results we suggest that endogenous brain-derived neurotrophic factor, but not neurotrophin-3, has acute modulatory effects on synaptic inhibition onto dentate granule cells. The site of action seems to be located presynaptically, i.e. brain-derived neurotrophic factor regulates the properties of inhibitory interneurons, leading to increased excitability of dentate granule cells. We propose that through this mechanism, brain-derived neurotrophic factor can change the gating/filtering properties of the dentate gyrus for incoming information from the entorhinal cortex to hippocampus. This will have consequences for the recruitment of hippocampal neural circuitries both under physiological and pathological conditions, such as epileptogenesis.

  11. Shifts in excitatory/inhibitory balance by juvenile stress: A role for neuron-astrocyte interaction in the dentate gyrus.

    PubMed

    Albrecht, Anne; Ivens, Sebastian; Papageorgiou, Ismini E; Çalışkan, Gürsel; Saiepour, Nasrin; Brück, Wolfgang; Richter-Levin, Gal; Heinemann, Uwe; Stork, Oliver

    2016-06-01

    Childhood trauma is a well-described risk factor for the development of stress-related psychopathology such as posttraumatic stress disorder or depression later in life. Childhood adversity can be modeled in rodents by juvenile stress (JS) protocols, resulting in impaired coping with stressful challenges in adulthood. In the current study, we investigated the long-lasting impact of JS on the expression of molecular factors for glutamate and γ-aminobutyric acid (GABA) uptake and turnover in sublayers of the dentate gyrus (DG) using laser microdissection and quantitative real-time polymerase chain reaction. We observed reduced mRNA expression levels after JS for factors mediating astrocytic glutamate and GABA uptake and degradation. These alterations were prominently observed in the dorsal but not ventral DG granule cell layer, indicating a lasting change in astrocytic GABA and glutamate metabolism that may affect dorsal DG network activity. Indeed, we observed increased inhibition and a lack of facilitation in response to paired-pulse stimulation at short interstimulus intervals in the dorsal DG after JS, while no alterations were evident in basal synaptic transmission or forms of long-term plasticity. The shift in paired-pulse response was mimicked by pharmacologically blocking the astrocytic GABA transporter GAT-3 in naïve animals. Accordingly, reduced expression levels of GAT-3 were confirmed at the protein level in the dorsal granule cell layer of rats stressed in juvenility. Together, these data demonstrate a lasting shift in the excitatory/inhibitory balance of dorsal DG network activity by JS that appears to be mediated by decreased GABA uptake into astrocytes.

  12. Commissurally projecting inhibitory interneurons of the rat hippocampal dentate gyrus: a colocalization study of neuronal markers and the retrograde tracer Fluoro-gold.

    PubMed

    Zappone, C A; Sloviter, R S

    2001-12-24

    Improved methods for detecting neuronal markers and the retrograde tracer Fluoro-Gold (FG) were used to identify commissurally projecting neurons of the rat hippocampus. In addition to the dentate hilar mossy cells and CA3 pyramidal cells shown previously to transport retrograde tracers after injection into the dorsal hippocampus, FG-positive interneurons of the dentate granule cell layer and hilus were detected in numbers greater than previously reported. FG labeling of interneurons was variable among animals, but was as high as 96% of hilar somatostatin-positive interneurons, 84% of parvalbumin-positive cells of the granule cell layer and hilus combined, and 33% of hilar calretinin-positive cells. By comparison, interneurons of the dentate molecular layer and all hippocampal subregions were conspicuously FG-negative. Whereas hilar mossy cells and CA3 pyramidal cells were FG-labeled throughout the longitudinal axis, FG-positive interneurons exhibited a relatively homotopic distribution. "Control" injections of FG into the neocortex, septum, and ventral hippocampus demonstrated that the homotopic labeling of dentate interneurons was injection site-specific, and that the CA1-CA3 interneurons unlabeled by contralateral hippocampal FG injection were nonetheless able to transport FG from the septum. These data suggest a hippocampal organizing principle according to which virtually all commissurally projecting hippocampal neurons share the property of being monosynaptic targets of dentate granule cells. Because granule cells innervate their exclusively ipsilateral target cells in a highly lamellar pattern, these results suggest that focal granule cell excitation may result in commissural inhibition of the corresponding "twin" granule cell lamella, thereby lateralizing and amplifying the influence of the initiating discharge.

  13. Selective alterations of neurons and circuits related to early memory loss in Alzheimer's disease.

    PubMed

    Llorens-Martín, Maria; Blazquez-Llorca, Lidia; Benavides-Piccione, Ruth; Rabano, Alberto; Hernandez, Felix; Avila, Jesus; DeFelipe, Javier

    2014-01-01

    A progressive loss of episodic memory is a well-known clinical symptom that characterizes Alzheimer's disease (AD). The beginning of this loss of memory has been associated with the very early, pathological accumulation of tau and neuronal degeneration observed in the entorhinal cortex (EC). Tau-related pathology is thought to then spread progressively to the hippocampal formation and other brain areas as the disease progresses. The major cortical afferent source of the hippocampus and dentate gyrus is the EC through the perforant pathway. At least two main circuits participate in the connection between EC and the hippocampus; one originating in layer II and the other in layer III of the EC giving rise to the classical trisynaptic (ECII → dentate gyrus → CA3 → CA1) and monosynaptic (ECIII → CA1) circuits. Thus, the study of the early pathological changes in these circuits is of great interest. In this review, we will discuss mainly the alterations of the granule cell neurons of the dentate gyrus and the atrophy of CA1 pyramidal neurons that occur in AD in relation to the possible differential alterations of these two main circuits.

  14. Selective alterations of neurons and circuits related to early memory loss in Alzheimer’s disease

    PubMed Central

    Llorens-Martín, Maria; Blazquez-Llorca, Lidia; Benavides-Piccione, Ruth; Rabano, Alberto; Hernandez, Felix; Avila, Jesus; DeFelipe, Javier

    2014-01-01

    A progressive loss of episodic memory is a well-known clinical symptom that characterizes Alzheimer’s disease (AD). The beginning of this loss of memory has been associated with the very early, pathological accumulation of tau and neuronal degeneration observed in the entorhinal cortex (EC). Tau-related pathology is thought to then spread progressively to the hippocampal formation and other brain areas as the disease progresses. The major cortical afferent source of the hippocampus and dentate gyrus is the EC through the perforant pathway. At least two main circuits participate in the connection between EC and the hippocampus; one originating in layer II and the other in layer III of the EC giving rise to the classical trisynaptic (ECII → dentate gyrus → CA3 → CA1) and monosynaptic (ECIII → CA1) circuits. Thus, the study of the early pathological changes in these circuits is of great interest. In this review, we will discuss mainly the alterations of the granule cell neurons of the dentate gyrus and the atrophy of CA1 pyramidal neurons that occur in AD in relation to the possible differential alterations of these two main circuits. PMID:24904307

  15. Hilar mossy cells of the dentate gyrus: a historical perspective

    PubMed Central

    Scharfman, Helen E.; Myers, Catherine E.

    2013-01-01

    The circuitry of the dentate gyrus (DG) of the hippocampus is unique compared to other hippocampal subfields because there are two glutamatergic principal cells instead of one: granule cells, which are the vast majority of the cells in the DG, and the so-called “mossy cells.” The distinctive appearance of mossy cells, the extensive divergence of their axons, and their vulnerability to excitotoxicity relative to granule cells has led to a great deal of interest in mossy cells. Nevertheless, there is no consensus about the normal functions of mossy cells and the implications of their vulnerability. There even seems to be some ambiguity about exactly what mossy cells are. Here we review initial studies of mossy cells, characteristics that define them, and suggest a practical definition to allow investigators to distinguish mossy cells from other hilar neurons even if all morphological and physiological information is unavailable due to technical limitations of their experiments. In addition, hypotheses are discussed about the role of mossy cells in the DG network, reasons for their vulnerability and their implications for disease. PMID:23420672

  16. Dentate Gyrus Local Circuit is Implicated in Learning Under Stress--a Role for Neurofascin.

    PubMed

    Zitman, Femke M P; Lucas, Morgan; Trinks, Sabine; Grosse-Ophoff, Laura; Kriebel, Martin; Volkmer, Hansjürgen; Richter-Levin, Gal

    2016-03-01

    The inhibitory synapses at the axon initial segment (AIS) of dentate gyrus granular cells are almost exclusively innervated by the axo-axonic chandelier interneurons. However, the role of chandelier neurons in local circuitry is poorly understood and controversially discussed. The cell adhesion molecule neurofascin is specifically expressed at the AIS. It is crucially required for the stabilization of axo-axonic synapses. Knockdown of neurofascin is therefore a convenient tool to interfere with chandelier input at the AIS of granular neurons of the dentate gyrus. In the current study, feedback and feedforward inhibition of granule cells was measured in the dentate gyrus after knockdown of neurofascin and concomitant reduction of axo-axonic input. Results show increased feedback inhibition as a result of neurofascin knockdown, while feedforward inhibition remained unaffected. This suggests that chandelier neurons are predominantly involved in feedback inhibition. Neurofascin knockdown rats also exhibited impaired learning under stress in the two-way shuttle avoidance task. Remarkably, this learning impairment was not accompanied by differences in electrophysiological measurements of dentate gyrus LTP. This indicates that the local circuit may be involved in (certain types) of learning.

  17. The similarity of astrocytes number in dentate gyrus and CA3 subfield of rats hippocampus.

    PubMed

    Jahanshahi, Mehrdad; Sadeghi, Y; Hosseini, A; Naghdi, N

    2007-01-01

    The dentate gyrus is a part of hippocampal formation that it contains granule cells, which project to the pyramidal cells and interneurons of the CA3 subfield of the hippocampus. Astrocytes play a more active role in neuronal activity, including regulating ion flux currents, energy production, neurotransmitter release and synaptogenesis. Astrocytes are the only cells in the brain that contain the energy molecule glycogen. The close relationship between dentate gyrus and CA3 area can cause the similarity of the number of astrocytes in these areas. In this study 5 male albino wistar rats were used. Rats were housed in large plastic cage in animal house and were maintained under standard conditions, after histological processing, The 7 microm slides of the brains were stained with PTAH staining for showing the astrocytes. This staining is specialized for astrocytes. We showed that the number of astrocytes in different (ant., mid., post) parts of dentate gyrus and CA3 of hippocampus is the same. For example, the anterior parts of two area have the most number of astrocytes and the middle parts of two area have the least number of astrocytes. We concluded that dentate gyrus and CA3 area of hippocampus have the same group of astrocytes.

  18. Isolation of chromaffin granules.

    PubMed

    Creutz, Carl E

    2010-09-01

    Adrenal medullary chromaffin granules (dense core secretory vesicles) have been a valuable model system for the study of the proteins and membrane components involved in the process of exocytosis. Because of the abundance of chromaffin granules in a readily available tissue source, bovine adrenal medullae, and their unique sedimentation properties, it is possible to obtain large quantities of highly purified granules and granule membranes in a short period of time. Two protocols are presented here for the isolation of chromaffin granules: a basic protocol based on differential centrifugation in an iso-osmotic medium that yields intact chromaffin granules, and an alternate protocol based on sedimentation through a density step gradient that provides a greater yield of more highly purified chromaffin granules. Since in the latter case the granules cannot be returned to a medium of physiological osmolarity without lysis after purification on the step gradient, the alternate protocol is more useful to obtain the granule membranes or contents for further study.

  19. Actions of brain-derived neurotrophic factor in slices from rats with spontaneous seizures and mossy fiber sprouting in the dentate gyrus.

    PubMed

    Scharfman, H E; Goodman, J H; Sollas, A L

    1999-07-01

    This study examined the acute actions of brain-derived neurotrophic factor (BDNF) in the rat dentate gyrus after seizures, because previous studies have shown that BDNF has acute effects on dentate granule cell synaptic transmission, and other studies have demonstrated that BDNF expression increases in granule cells after seizures. Pilocarpine-treated rats were studied because they not only have seizures and increased BDNF expression in granule cells, but they also have reorganization of granule cell "mossy fiber" axons. This reorganization, referred to as "sprouting," involves collaterals that grow into novel areas, i.e., the inner molecular layer, where granule cell and interneuron dendrites are located. Thus, this animal model allowed us to address the effects of BDNF in the dentate gyrus after seizures, as well as the actions of BDNF on mossy fiber transmission after reorganization. In slices with sprouting, BDNF bath application enhanced responses recorded in the inner molecular layer to mossy fiber stimulation. Spontaneous bursts of granule cells occurred, and these were apparently generated at the site of the sprouted axon plexus. These effects were not accompanied by major changes in perforant path-evoked responses or paired-pulse inhibition, occurred only after prolonged (30-60 min) exposure to BDNF, and were blocked by K252a. The results suggest a preferential action of BDNF at mossy fiber synapses, even after substantial changes in the dentate gyrus network. Moreover, the results suggest that activation of trkB receptors could contribute to the hyperexcitability observed in animals with sprouting. Because human granule cells also express increased BDNF mRNA after seizures, and sprouting can occur in temporal lobe epileptics, the results may have implications for understanding temporal lobe epilepsy.

  20. Single granule cells reliably discharge targets in the hippocampal CA3 network in vivo.

    PubMed

    Henze, Darrell A; Wittner, Lucia; Buzsáki, György

    2002-08-01

    Processing of neuronal information depends on interactions between the anatomical connectivity and cellular properties of single cells. We examined how these computational building blocks work together in the intact rat hippocampus. Single spikes in dentate granule cells, controlled intracellularly, generally failed to discharge either interneurons or CA3 pyramidal cells. In contrast, trains of spikes effectively discharged both CA3 cell types. Increasing the discharge rate of the granule cell increased the discharge probability of its target neuron and decreased the delay between the onset of a granule cell train and evoked firing in postsynaptic targets. Thus, we conclude that the granule cell to CA3 synapses are 'conditional detonators,' dependent on granule cell firing pattern. In addition, we suggest that information in single granule cells is converted into a temporal delay code in target CA3 pyramidal cells and interneurons. These data demonstrate how a neural circuit of the CNS may process information.

  1. Roles of afadin in the formation of the cellular architecture of the mouse hippocampus and dentate gyrus.

    PubMed

    Miyata, Muneaki; Maruo, Tomohiko; Kaito, Aika; Wang, Shujie; Yamamoto, Hideaki; Fujiwara, Takeshi; Mizoguchi, Akira; Mandai, Kenji; Takai, Yoshimi

    2017-03-01

    The hippocampal formation with tightly packed neurons, mainly at the dentate gyrus, CA3, CA2, and CA1 regions, constitutes a one-way neural circuit, which is associated with learning and memory. We previously showed that the cell adhesion molecules nectins and its binding protein afadin play roles in the formation of the mossy fiber synapses which are formed between the mossy fibers of the dentate gyrus granule cells and the dendrites of the CA3 pyramidal cells. We showed here that in the afadin-deficient hippocampal formation, the dentate gyrus granules cells and the CA3, CA2, and CA1 pyramidal cells were abnormally located; the mossy fiber trajectory was abnormally elongated; the CA3 pyramidal cells were abnormally differentiated; and the densities of the presynaptic boutons on the mossy fibers and the apical dendrites of the CA3 pyramidal cells were decreased. These results indicate that afadin plays roles not only in the formation of the mossy fiber synapses but also in the formation of the cellular architecture of the hippocampus and the dentate gyrus.

  2. Sensorimotor Intervention Recovers Noradrenaline Content in the Dentate Gyrus of Cortical Injured Rats.

    PubMed

    Ramos-Languren, Laura E; García-Díaz, Gabriela; González-Maciel, Angélica; Rosas-López, Laura E; Bueno-Nava, Antonio; Avila-Luna, Alberto; Ramírez-Anguiano, Hayde; González-Piña, Rigoberto

    2016-12-01

    Nowadays, a consensus has been reached that designates the functional and structural reorganization of synapses as the primary mechanisms underlying the process of recovery from brain injury. We have reported that pontine noradrenaline (NA) is increased in animals after cortical ablation (CA). The aim of the present study was to explore the noradrenergic and morphological response after sensorimotor intervention (SMI) in rats injured in the motor cortex. We used male Wistar adult rats allocated in four conditions: sham-operated, injured by cortical ablation, sham-operated with SMI and injured by cortical ablation with SMI. Motor and somatosensory performance was evaluated prior to and 20 days after surgery. During the intervening period, a 15-session, SMI program was implemented. Subsequently, total NA analysis in the pons and dentate gyrus (DG) was performed. All groups underwent histological analysis. Our results showed that NA content in the DG was reduced in the injured group versus control, and this reduction was reverted in the injured group that underwent SMI. Moreover, injured rats showed reduction in the number of granule cells in the DG and decreased dentate granule cell layer thickness. Notably, after SMI, the loss of granule cells was reverted. Locus coeruleus showed turgid cells in the injured rats. These results suggest that SMI elicits biochemical and structural modifications in the hippocampus that could reorganize the system and lead the recovery process, modulating structural and functional plasticity.

  3. Prox1 is required for granule cell maturation and intermediate progenitor maintenance during brain neurogenesis.

    PubMed

    Lavado, Alfonso; Lagutin, Oleg V; Chow, Lionel M L; Baker, Suzanne J; Oliver, Guillermo

    2010-08-17

    The dentate gyrus has an important role in learning and memory, and adult neurogenesis in the subgranular zone of the dentate gyrus may play a role in the acquisition of new memories. The homeobox gene Prox1 is expressed in the dentate gyrus during embryonic development and adult neurogenesis. Here we show that Prox1 is necessary for the maturation of granule cells in the dentate gyrus during development and for the maintenance of intermediate progenitors during adult neurogenesis. We also demonstrate that Prox1-expressing intermediate progenitors are required for adult neural stem cell self-maintenance in the subgranular zone; thus, we have identified a previously unknown non-cell autonomous regulatory feedback mechanism that controls adult neurogenesis in this region of the mammalian brain. Finally, we show that the ectopic expression of Prox1 induces premature differentiation of neural stem cells.

  4. Pharmacotherapy with Fluoxetine Restores Functional Connectivity from the Dentate Gyrus to Field CA3 in the Ts65Dn Mouse Model of Down Syndrome

    PubMed Central

    Guidi, Sandra; Ciani, Elisabetta; Mangano, Chiara; Calzà, Laura; Bartesaghi, Renata

    2013-01-01

    Down syndrome (DS) is a high-incidence genetic pathology characterized by severe impairment of cognitive functions, including declarative memory. Impairment of hippocampus-dependent long-term memory in DS appears to be related to anatomo-functional alterations of the hippocampal trisynaptic circuit formed by the dentate gyrus (DG) granule cells - CA3 pyramidal neurons - CA1 pyramidal neurons. No therapies exist to improve cognitive disability in individuals with DS. In previous studies we demonstrated that pharmacotherapy with fluoxetine restores neurogenesis, granule cell number and dendritic morphology in the DG of the Ts65Dn mouse model of DS. The goal of the current study was to establish whether treatment rescues the impairment of synaptic connectivity between the DG and CA3 that characterizes the trisomic condition. Euploid and Ts65Dn mice were treated with fluoxetine during the first two postnatal weeks and examined 45–60 days after treatment cessation. Untreated Ts65Dn mice had a hypotrophyc mossy fiber bundle, fewer synaptic contacts, fewer glutamatergic contacts, and fewer dendritic spines in the stratum lucidum of CA3, the terminal field of the granule cell projections. Electrophysiological recordings from CA3 pyramidal neurons showed that in Ts65Dn mice the frequency of both mEPSCs and mIPSCs was reduced, indicating an overall impairment of excitatory and inhibitory inputs to CA3 pyramidal neurons. In treated Ts65Dn mice all these aberrant features were fully normalized, indicating that fluoxetine can rescue functional connectivity between the DG and CA3. The positive effects of fluoxetine on the DG-CA3 system suggest that early treatment with this drug could be a suitable therapy, possibly usable in humans, to restore the physiology of the hippocampal networks and, hence, memory functions. PMID:23620781

  5. Diet-induced alterations in the ontogeny of long-term potentiation.

    PubMed

    Bronzino, J D; Austin La France, R J; Morgane, P J; Galler, J R

    1996-01-01

    malnutrition significantly affects the magnitude of tetanization-induced enhancement of dentate granule cell response in preweanling rats (15-day-old animals) and significantly alters the time-course and magnitude of potentiation in approximately half of prenatally malnourished animals tested at 30 and 90 days of age. Given the primarily postnatal development of the dentate granule cells, these results may reflect malnutrition-induced delays in the neurogenesis and functional development of granule cells previously reported by our group. Most striking is the fact that significant impairments in LTP establishment were obtained from prenatally malnourished animals at 90 days of age, implying that dietary rehabilitation commencing at birth is an intervention strategy incapable of ameliorating the effects of the gestational insult.

  6. Reelin Regulates the Maturation of Dendritic Spines, Synaptogenesis and Glial Ensheathment of Newborn Granule Cells.

    PubMed

    Bosch, Carles; Masachs, Nuria; Exposito-Alonso, David; Martínez, Albert; Teixeira, Cátia M; Fernaud, Isabel; Pujadas, Lluís; Ulloa, Fausto; Comella, Joan X; DeFelipe, Javier; Merchán-Pérez, Angel; Soriano, Eduardo

    2016-09-13

    The Reelin pathway is essential for both neural migration and for the development and maturation of synaptic connections. However, its role in adult synaptic formation and remodeling is still being investigated. Here, we investigated the impact of the Reelin/Dab1 pathway on the synaptogenesis of newborn granule cells (GCs) in the young-adult mouse hippocampus. We show that neither Reelin overexpression nor the inactivation of its intracellular adapter, Dab1, substantially alters dendritic spine numbers in these neurons. In contrast, 3D-electron microscopy (focused ion beam milling/scanning electron microscope) revealed that dysregulation of the Reelin/Dab1 pathway leads to both transient and permanent changes in the types and morphology of dendritic spines, mainly altering mushroom, filopodial, and branched GC spines. We also found that the Reelin/Dab1 pathway controls synaptic configuration of presynaptic boutons in the dentate gyrus, with its dysregulation leading to a substantial decrease in multi-synaptic bouton innervation. Lastly, we show that the Reelin/Dab1 pathway controls astroglial ensheathment of synapses. Thus, the Reelin pathway is a key regulator of adult-generated GC integration, by controlling dendritic spine types and shapes, their synaptic innervation patterns, and glial ensheathment. These findings may help to better understanding of hippocampal circuit alterations in neurological disorders in which the Reelin pathway is implicated.

  7. Neurons of the Dentate Molecular Layer in the Rabbit Hippocampus

    PubMed Central

    Sancho-Bielsa, Francisco J.; Navarro-López, Juan D.; Alonso-Llosa, Gregori; Molowny, Asunción; Ponsoda, Xavier; Yajeya, Javier; López-García, Carlos

    2012-01-01

    The molecular layer of the dentate gyrus appears as the main entrance gate for information into the hippocampus, i.e., where the perforant path axons from the entorhinal cortex synapse onto the spines and dendrites of granule cells. A few dispersed neuronal somata appear intermingled in between and probably control the flow of information in this area. In rabbits, the number of neurons in the molecular layer increases in the first week of postnatal life and then stabilizes to appear permanent and heterogeneous over the individuals’ life span, including old animals. By means of Golgi impregnations, NADPH histochemistry, immunocytochemical stainings and intracellular labelings (lucifer yellow and biocytin injections), eight neuronal morphological types have been detected in the molecular layer of developing adult and old rabbits. Six of them appear as interneurons displaying smooth dendrites and GABA immunoreactivity: those here called as globoid, vertical, small horizontal, large horizontal, inverted pyramidal and polymorphic. Additionally there are two GABA negative types: the sarmentous and ectopic granular neurons. The distribution of the somata and dendritic trees of these neurons shows preferences for a definite sublayer of the molecular layer: small horizontal, sarmentous and inverted pyramidal neurons are preferably found in the outer third of the molecular layer; vertical, globoid and polymorph neurons locate the intermediate third, while large horizontal and ectopic granular neurons occupy the inner third or the juxtagranular molecular layer. Our results reveal substantial differences in the morphology and electrophysiological behaviour between each neuronal archetype in the dentate molecular layer, allowing us to propose a new classification for this neural population. PMID:23144890

  8. Doublecortin-positive newly born granule cells of hippocampus have abnormal apical dendritic morphology in the pilocarpine model of temporal lobe epilepsy.

    PubMed

    Arisi, Gabriel Maisonnave; Garcia-Cairasco, Norberto

    2007-08-24

    Here, we describe dentate gyrus newly born granule cells morphology in rats' temporal lobe epilepsy pilocarpine model. Digital reconstruction of doublecortin-positive neurons revealed that apical dendrites had the same total length and number of nodes in epileptic and control animals. Nonetheless, concentric spheres analyses revealed that apical dendrites spatial distribution was radically altered in epileptic animals. The apical dendrites had more bifurcations inside the granular cell layer and more terminations in the inner molecular layer of epileptic dentate gyrus. Branch order analyses showed that second- and third-order dendrites were shorter in epileptic animals. Apical dendrites were concentrated in regions like the inner molecular layer where granular neuron axons, named mossy fibers, sprout in epileptic animals. The combination of altered dendritic morphology and number enhancement of the new granular neurons suggests a deleterious role of hippocampal neurogenesis in epileptogenesis. Being more numerous and with dendrites concentrated in regions where aberrant axon terminals sprout, the new granular neurons could contribute to the slow epileptogenesis at hippocampal circuits commonly observed in temporal lobe epilepsy.

  9. Inhibition of PI3K-Akt Signaling Blocks Exercise-Mediated Enhancement of Adult Neurogenesis and Synaptic Plasticity in the Dentate Gyrus

    PubMed Central

    Bruel-Jungerman, Elodie; Veyrac, Alexandra; Dufour, Franck; Horwood, Jennifer; Laroche, Serge; Davis, Sabrina

    2009-01-01

    Background Physical exercise has been shown to increase adult neurogenesis in the dentate gyrus and enhances synaptic plasticity. The antiapoptotic kinase, Akt has also been shown to be phosphorylated following voluntary exercise; however, it remains unknown whether the PI3K-Akt signaling pathway is involved in exercise-induced neurogenesis and the associated facilitation of synaptic plasticity in the dentate gyrus. Methodology/Principal Findings To gain insight into the potential role of this signaling pathway in exercise-induced neurogenesis and LTP in the dentate gyrus rats were infused with the PI3K inhibitor, LY294002 or vehicle control solution (icv) via osmotic minipumps and exercised in a running wheel for 10 days. Newborn cells in the dentate gyrus were date-labelled with BrdU on the last 3 days of exercise. Then, they were either returned to the home cage for 2 weeks to assess exercise-induced LTP and neurogenesis in the dentate gyrus, or were killed on the last day of exercise to assess proliferation and activation of the PI3K-Akt cascade using western blotting. Conclusions/Significance Exercise increases cell proliferation and promotes survival of adult-born neurons in the dentate gyrus. Immediately after exercise, we found that Akt and three downstream targets, BAD, GSK3β and FOXO1 were activated. LY294002 blocked exercise-induced phosphorylation of Akt and downstream target proteins. This had no effect on exercise-induced cell proliferation, but it abolished most of the beneficial effect of exercise on the survival of newly generated dentate gyrus neurons and prevented exercise-induced increase in dentate gyrus LTP. These results suggest that activation of the PI3 kinase-Akt signaling pathway plays a significant role via an antiapoptotic function in promoting survival of newly formed granule cells generated during exercise and the associated increase in synaptic plasticity in the dentate gyrus. PMID:19936256

  10. Granulation of fine powder

    DOEpatents

    Chen, Ching-Fong

    2016-08-09

    A mixture of fine powder including thorium oxide was converted to granulated powder by forming a first-green-body and heat treating the first-green-body at a high temperature to strengthen the first-green-body followed by granulation by crushing or milling the heat-treated first-green-body. The granulated powder was achieved by screening through a combination of sieves to achieve the desired granule size distribution. The granulated powder relies on the thermal bonding to maintain its shape and structure. The granulated powder contains no organic binder and can be stored in a radioactive or other extreme environment. The granulated powder was pressed and sintered to form a dense compact with a higher density and more uniform pore size distribution.

  11. Status epilepticus enhances tonic GABA currents and depolarizes GABA reversal potential in dentate fast-spiking basket cells

    PubMed Central

    Yu, Jiandong; Proddutur, Archana; Elgammal, Fatima S.; Ito, Takahiro

    2013-01-01

    Temporal lobe epilepsy is associated with loss of interneurons and inhibitory dysfunction in the dentate gyrus. While status epilepticus (SE) leads to changes in granule cell inhibition, whether dentate basket cells critical for regulating granule cell feedforward and feedback inhibition express tonic GABA currents (IGABA) and undergo changes in inhibition after SE is not known. We find that interneurons immunoreactive for parvalbumin in the hilar-subgranular region express GABAA receptor (GABAAR) δ-subunits, which are known to underlie tonic IGABA. Dentate fast-spiking basket cells (FS-BCs) demonstrate baseline tonic IGABA blocked by GABAAR antagonists. In morphologically and physiologically identified FS-BCs, tonic IGABA is enhanced 1 wk after pilocarpine-induced SE, despite simultaneous reduction in spontaneous inhibitory postsynaptic current (sIPSC) frequency. Amplitude of tonic IGABA in control and post-SE FS-BCs is enhanced by 4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol (THIP), demonstrating the contribution of GABAAR δ-subunits. Whereas FS-BC resting membrane potential is unchanged after SE, perforated-patch recordings from FS-BCs show that the reversal potential for GABA currents (EGABA) is depolarized after SE. In model FS-BCs, increasing tonic GABA conductance decreased excitability when EGABA was shunting and increased excitability when EGABA was depolarizing. Although simulated focal afferent activation evoked seizurelike activity in model dentate networks with FS-BC tonic GABA conductance and shunting EGABA, excitability of identical networks with depolarizing FS-BC EGABA showed lower activity levels. Thus, together, post-SE changes in tonic IGABA and EGABA maintain homeostasis of FS-BC activity and limit increases in dentate excitability. These findings have implications for normal FS-BC function and can inform studies examining comorbidities and therapeutics following SE. PMID:23324316

  12. The Ever-Changing Morphology of Hippocampal Granule Neurons in Physiology and Pathology

    PubMed Central

    Llorens-Martín, María; Rábano, Alberto; Ávila, Jesús

    2016-01-01

    Newborn neurons are continuously added to the hippocampal dentate gyrus throughout adulthood. In this review, we analyze the maturational stages that newborn granule neurons go through, with a focus on their unique morphological features during each stage under both physiological and pathological circumstances. In addition, the influence of deleterious (such as schizophrenia, stress, Alzheimer's disease, seizures, stroke, inflammation, dietary deficiencies, or the consumption of drugs of abuse or toxic substances) and neuroprotective (physical exercise and environmental enrichment) stimuli on the maturation of these cells will be examined. Finally, the regulation of this process by proteins involved in neurodegenerative and neurological disorders such as Glycogen synthase kinase 3β, Disrupted in Schizophrenia 1 (DISC-1), Glucocorticoid receptor, pro-inflammatory mediators, Presenilin-1, Amyloid precursor protein, Cyclin-dependent kinase 5 (CDK5), among others, will be evaluated. Given the recently acquired relevance of the dendritic branch as a functional synaptic unit required for memory storage, a full understanding of the morphological alterations observed in newborn neurons may have important consequences for the prevention and treatment of the cognitive and affective alterations that evolve in conjunction with impaired adult hippocampal neurogenesis. PMID:26834550

  13. Enhanced Synaptic Connectivity in the Dentate Gyrus during Epileptiform Activity: Network Simulation

    PubMed Central

    França, Keite Lira de Almeida; Guimarães de Almeida, Antônio-Carlos; Infantosi, Antonio Fernando Catelli; Duarte, Mario Antônio; da Silveira, Gilcélio Amaral; Scorza, Fulvio Alexandre; Arida, Ricardo Mario; Cavalheiro, Esper Abrão; Rodrigues, Antônio Márcio

    2013-01-01

    Structural rearrangement of the dentate gyrus has been described as the underlying cause of many types of epilepsies, particularly temporal lobe epilepsy. It is said to occur when aberrant connections are established in the damaged hippocampus, as described in human epilepsy and experimental models. Computer modelling of the dentate gyrus circuitry and the corresponding structural changes has been used to understand how abnormal mossy fibre sprouting can subserve seizure generation observed in experimental models when epileptogenesis is induced by status epilepticus. The model follows the McCulloch-Pitts formalism including the representation of the nonsynaptic mechanisms. The neuronal network comprised granule cells, mossy cells, and interneurons. The compensation theory and the Hebbian and anti-Hebbian rules were used to describe the structural rearrangement including the effects of the nonsynaptic mechanisms on the neuronal activity. The simulations were based on neuroanatomic data and on the connectivity pattern between the cells represented. The results suggest that there is a joint action of the compensation theory and Hebbian rules during the inflammatory process that accompanies the status epilepticus. The structural rearrangement simulated for the dentate gyrus circuitry promotes speculation about the formation of the abnormal mossy fiber sprouting and its role in epileptic seizures. PMID:23431287

  14. Sustained transcription of the immediate early gene Arc in the dentate gyrus after spatial exploration.

    PubMed

    Ramirez-Amaya, Victor; Angulo-Perkins, Arafat; Chawla, Monica K; Barnes, Carol A; Rosi, Susanna

    2013-01-23

    After spatial exploration in rats, Arc mRNA is expressed in ∼2% of dentate gyrus (DG) granule cells, and this proportion of Arc-positive neurons remains stable for ∼8 h. This long-term presence of Arc mRNA following behavior is not observed in hippocampal CA1 pyramidal cells. We report here that in rats ∼50% of granule cells with cytoplasmic Arc mRNA, induced some hours previously during exploration, also show Arc expression in the nucleus. This suggests that recent transcription can occur long after the exploration behavior that elicited it. To confirm that the delayed nuclear Arc expression was indeed recent transcription, Actinomycin D was administered immediately after exploration. This treatment resulted in inhibition of recent Arc expression both when evaluated shortly after exploratory behavior as well as after longer time intervals. Together, these data demonstrate a unique kinetic profile for Arc transcription in hippocampal granule neurons following behavior that is not observed in other cell types. Among a number of possibilities, this sustained transcription may provide a mechanism that ensures that the synaptic connection weights in the sparse population of granule cells recruited during a given behavioral event are able to be modified.

  15. Object/Context-Specific Memory Deficits Associated with Loss of Hippocampal Granule Cells after Adrenalectomy in Rats

    ERIC Educational Resources Information Center

    Spanswick, Simon C.; Sutherland, Robert J.

    2010-01-01

    Chronic adrenalectomy (ADX) causes a gradual and selective loss of granule cells in the dentate gyrus (DG) of the rat. Here, we administered replacement corticosterone to rats beginning 10 wk after ADX. We then tested them in three discrimination tasks based on object novelty, location, or object/context association. Only during testing of the…

  16. Neonatal stress alters LTP in freely moving male and female adult rats.

    PubMed

    Kehoe, P; Bronzino, J D

    1999-01-01

    We previously reported that neonatal isolation stress significantly changes measures of hippocampal long-term potentiation (LTP) in male and female juvenile rats, i.e., at 30 days of age. The changes in dentate granule population measures, i.e., excitatory postsynaptic potential (EPSP) and population spike amplitude (PSA), evoked by tetanization of the medial perforant pathway, indicated that juvenile rats exposed to neonatal isolation exhibit different enhancement profiles with respect to both the magnitude and duration of LTP in a sex-specific manner. Isolated males showed a significantly greater enhancement of LTP, while female "isolates" showed significantly longer LTP duration when compared to all other groups. The present study was designed to determine whether the effects of the neonatal isolation stress paradigm endures into adulthood. Rats isolated from their mothers for 1 h per day during postnatal days 2-9 were surgically prepared at 70-90 days of age, with stimulating and recording electrodes placed in the medial perforant pathway and the hippocampal dentate gyrus, respectively. Prior to tetanization, no significant effect of sex or treatment was obtained for baseline measures of EPSP slope or PSA. In order to rule out baseline differences in hippocampal cell excitability in female adult rats, we measured the response of dentate granule cells for one estrus cycle and found no pretetanization enhancement in the evoked response in either controls or previously stressed rats. Following tetanization, there was a significant treatment and sex effect. During the induction of LTP, PSA values were significantly enhanced in both isolated males and females and had significantly longer LTP duration when compared to the unhandled control group. Additionally, we observed that females took longer to reach baseline levels than males. Taken together, these results indicate that repeated infant isolation stress enhances LTP induction and duration in both males and

  17. Modulation of paired-pulse responses in the dentate gyrus: effects of normal maturation and vigilance state.

    PubMed

    Blaise, J H; Bronzino, J D

    2000-01-01

    This study examined the effect of normal development and vigilance state on the modulation of dentate granule cell activity in the freely moving rat at 15, 30, and 90 days of age across three vigilance states: quiet waking, slow-wave sleep, and rapid eye movement sleep. Using paired-pulse stimulation, the paired-pulse index (PPI) was obtained for the dentate evoked field potentials elicited by the stimulation of the medial perforant path. Although significant differences in PPI values were observed during development, no significant vigilance state related changes were obtained. Preweaning infant rats, i.e., 15-day old, exhibited significantly less early (interpulse intervals, IPI= 20-50 ms) and late (IPI = 300-1,000 ms) inhibition, and less facilitation (IPI = 50-150 ms) when compared to the 90-day old adult rats during all three vigilance states. PPI values obtained from the 30-day old group fell intermediate between the 15- and 90-day old animals. These changes in PPI values provide a quantitative measure of changes in the modulation of dentate granule cell excitability during normal maturation. They can now can be used to evaluate the impact of various insults, such as prenatal protein malnutrition or neonatal stress, on hippocampal development.

  18. C9orf72 Hexanucleotide Expansions Are Associated with Altered Endoplasmic Reticulum Calcium Homeostasis and Stress Granule Formation in Induced Pluripotent Stem Cell‐Derived Neurons from Patients with Amyotrophic Lateral Sclerosis and Frontotemporal Dementia

    PubMed Central

    Dafinca, Ruxandra; Scaber, Jakub; Ababneh, Nida'a; Lalic, Tatjana; Weir, Gregory; Christian, Helen; Vowles, Jane; Douglas, Andrew G.L.; Fletcher‐Jones, Alexandra; Browne, Cathy; Nakanishi, Mahito; Turner, Martin R.; Wade‐Martins, Richard

    2016-01-01

    Abstract An expanded hexanucleotide repeat in a noncoding region of the C9orf72 gene is a major cause of amyotrophic lateral sclerosis (ALS), accounting for up to 40% of familial cases and 7% of sporadic ALS in European populations. We have generated induced pluripotent stem cells (iPSCs) from fibroblasts of patients carrying C9orf72 hexanucleotide expansions, differentiated these to functional motor and cortical neurons, and performed an extensive phenotypic characterization. In C9orf72 iPSC‐derived motor neurons, decreased cell survival is correlated with dysfunction in Ca2+ homeostasis, reduced levels of the antiapoptotic protein Bcl‐2, increased endoplasmic reticulum (ER) stress, and reduced mitochondrial membrane potential. Furthermore, C9orf72 motor neurons, and also cortical neurons, show evidence of abnormal protein aggregation and stress granule formation. This study is an extensive characterization of iPSC‐derived motor neurons as cellular models of ALS carrying C9orf72 hexanucleotide repeats, which describes a novel pathogenic link between C9orf72 mutations, dysregulation of calcium signaling, and altered proteostasis and provides a potential pharmacological target for the treatment of ALS and the related neurodegenerative disease frontotemporal dementia. Stem Cells 2016;34:2063–2078 PMID:27097283

  19. Age-dependent kinetics of dentate gyrus neurogenesis in the absence of cyclin D2

    PubMed Central

    2012-01-01

    Background Adult neurogenesis continuously adds new neurons to the dentate gyrus and the olfactory bulb. It involves the proliferation and subsequent differentiation of neuronal progenitors, and is thus closely linked to the cell cycle machinery. Cell cycle progression is governed by the successive expression, activation and degradation of regulatory proteins. Among them, D-type cyclins control the exit from the G1 phase of the cell cycle. Cyclin D2 (cD2) has been shown to be required for the generation of new neurons in the neurogenic niches of the adult brain. It is differentially expressed during hippocampal development, and adult cD2 knock out (cD2KO) mice virtually lack neurogenesis in the dentate gyrus and olfactory bulb. In the present study we examined the dynamics of postnatal and adult neurogenesis in the dentate gyrus (DG) of cD2KO mice. Animals were injected with bromodeoxyuridine at seven time points during the first 10 months of life and brains were immunohistochemically analyzed for their potential to generate new neurons. Results Compared to their WT litters, cD2KO mice had considerably reduced numbers of newly born granule cells during the postnatal period, with neurogenesis becoming virtually absent around postnatal day 28. This was paralleled by a reduction in granule cell numbers, in the volume of the granule cell layer as well as in apoptotic cell death. CD2KO mice did not show any of the age-related changes in neurogenesis and granule cell numbers that were seen in WT litters. Conclusions The present study suggests that hippocampal neurogenesis becomes increasingly dependent on cD2 during early postnatal development. In cD2KO mice, hippocampal neurogenesis ceases at a time point at which the tertiary germinative matrix stops proliferating, indicating that cD2 becomes an essential requirement for ongoing neurogenesis with the transition from developmental to adult neurogenesis. Our data further support the notion that adult neurogenesis

  20. Prolonged protein deprivation differentially affects calretinin- and parvalbumin-containing interneurons in the hippocampal dentate gyrus of adult rats.

    PubMed

    Hipólito-Reis, José; Pereira, Pedro Alberto; Andrade, José Paulo; Cardoso, Armando

    2013-10-25

    Protein deprivation is a detrimental nutritional state that induces several deleterious changes in the rat hippocampal formation. In this study, we compared the effects of protein deprivation in the number of parvalbumin (PV)-immunoreactive and calretinin (CR)-immunoreactive interneurons of the dentate gyrus, which are involved in the control of calcium homeostasis and fine tuning of the hippocampal circuits. Two month-old rats were randomly assigned to control and low-protein diet groups. The rats of the latter group were fed with a low-protein diet (8% casein) for 6 months. All animals were perfused at 8 months of age. The number of neurons expressing CR in the molecular layer and in the hilus of dentate gyrus was reduced in protein-deprived rats. Conversely, protein deprivation increased the number of PV-containing interneurons in the dentate granule cell layer and hilus. These results support the view that protein deprivation may disturb calcium homeostasis, leading to neuronal death including GABAergic interneurons expressing CR. In the other hand, the up-regulation of PV cells may reflect a protective mechanism to counteract the calcium overload and protect the remaining neurons of the dentate gyrus.

  1. Assessment of the Role of MAP Kinase in Mediating Activity-Dependent Transcriptional Activation of the Immediate Early Gene "Arc/Arg3.1" in the Dentate Gyrus in Vivo

    ERIC Educational Resources Information Center

    Chotiner, Jennifer K.; Nielson, Jessica; Farris, Shannon; Lewandowski, Gail; Huang, Fen; Banos, Karla; de Leon, Ray; Steward, Oswald

    2010-01-01

    Different physiological and behavioral events activate transcription of "Arc/Arg3.1" in neurons in vivo, but the signal transduction pathways that mediate induction in particular situations remain to be defined. Here, we explore the relationships between induction of "Arc/Arg3.1" transcription in dentate granule cells in vivo and activation of…

  2. Functional and structural deficits of the dentate gyrus network coincide with emerging spontaneous seizures in an Scn1a mutant Dravet Syndrome model during development.

    PubMed

    Tsai, Ming-Shian; Lee, Meng-Larn; Chang, Chun-Yun; Fan, Hsiang-Hsuan; Yu, I-Shing; Chen, You-Tzung; You, Jhih-Yi; Chen, Chun-Yu; Chang, Fang-Chia; Hsiao, Jane H; Khorkova, Olga; Liou, Horng-Huei; Yanagawa, Yuchio; Lee, Li-Jen; Lin, Shu-Wha

    2015-05-01

    Dravet syndrome (DS) is characterized by severe infant-onset myoclonic epilepsy along with delayed psychomotor development and heightened premature mortality. A primary monogenic cause is mutation of the SCN1A gene, which encodes the voltage-gated sodium channel subunit Nav1.1. The nature and timing of changes caused by SCN1A mutation in the hippocampal dentate gyrus (DG) network, a core area for gating major excitatory input to hippocampus and a classic epileptogenic zone, are not well known. In particularly, it is still not clear whether the developmental deficit of this epileptogenic neural network temporally matches with the progress of seizure development. Here, we investigated the emerging functional and structural deficits of the DG network in a novel mouse model (Scn1a(E1099X/+)) that mimics the genetic deficit of human DS. Scn1a(E1099X/+) (Het) mice, similarly to human DS patients, exhibited early spontaneous seizures and were more susceptible to hyperthermia-induced seizures starting at postnatal week (PW) 3, with seizures peaking at PW4. During the same period, the Het DG exhibited a greater reduction of Nav1.1-expressing GABAergic neurons compared to other hippocampal areas. Het DG GABAergic neurons showed altered action potential kinetics, reduced excitability, and generated fewer spontaneous inhibitory inputs into DG granule cells. The effect of reduced inhibitory input to DG granule cells was exacerbated by heightened spontaneous excitatory transmission and elevated excitatory release probability in these cells. In addition to electrophysiological deficit, we observed emerging morphological abnormalities of DG granule cells. Het granule cells exhibited progressively reduced dendritic arborization and excessive spines, which coincided with imbalanced network activity and the developmental onset of spontaneous seizures. Taken together, our results establish the existence of significant structural and functional developmental deficits of the DG network

  3. Understanding size enlargement and hardening of granules on tabletability of unlubricated granules prepared by dry granulation.

    PubMed

    Patel, Sarsvatkumar; Dahiya, Sandeepkumar; Sun, Changquan Calvin; Bansal, Arvind Kumar

    2011-02-01

    The mechanism of loss of "reworkability" or tabletability of dry granulated microcrystalline cellulose (MCC) was investigated in relation to both granule size enlargement and granule hardness. Slugs of MCC were prepared under three pressures (12.5, 37.5, and 93.8 MPa) and tabletability (tensile strength vs. pressure) of respective granules (three different sizes) was determined. Nominal single granule fracture strength and granule friability were measured. The reduction in tabletability was profound for harder granules, which were obtained from higher slugging pressure. This is consistent with their ability to resist granule fragmentation during tableting. Variation in granule size exhibits negligible effect on tabletability for the lowest slugging pressure and only a small effect for the middle and highest slugging pressure. This observation is again related to different tendency to granule fragmentation during compaction. The results suggest that granule-hardening negatively affects tensile strength more than that of granule size enlargement for MCC.

  4. Determinants of masticatory performance in dentate adults.

    PubMed

    Hatch, J P; Shinkai, R S; Sakai, S; Rugh, J D; Paunovich, E D

    2001-07-01

    Masticatory performance results from a complex interplay of direct and indirect effects, yet most studies employ univariate models. This study tested a multivariate model of masticatory performance for dentate subjects. Explanatory variables included number of functional tooth units, bite force, sex, age, masseter cross-sectional area, presence of temporomandibular disorders, and presence of diabetes mellitus. The population-based sample consisted of 631 dentate subjects aged 37-80 years. Covariance structure analysis showed that 68% of the variability in masticatory performance could be explained by the combined effects of the explanatory variables. Age and sex did not show a strong effect on masticatory performance, either directly or indirectly through masseter cross-sectional area, temporomandibular disorders, and bite force. Number of functional tooth units and bite force were confirmed as the key determinants of masticatory performance, which suggests that their maintenance may be of major importance for promoting healthful functional status.

  5. Increased dentate neurogenesis after grafting of glial restricted progenitors or neural stem cells in the aging hippocampus.

    PubMed

    Hattiangady, Bharathi; Shuai, Bing; Cai, Jingli; Coksaygan, Turhan; Rao, Mahendra S; Shetty, Ashok K

    2007-08-01

    Neurogenesis in the dentate gyrus (DG) declines severely by middle age, potentially because of age-related changes in the DG microenvironment. We hypothesize that providing fresh glial restricted progenitors (GRPs) or neural stem cells (NSCs) to the aging hippocampus via grafting enriches the DG microenvironment and thereby stimulates the production of new granule cells from endogenous NSCs. The GRPs isolated from the spinal cords of embryonic day 13.5 transgenic F344 rats expressing human alkaline phosphatase gene and NSCs isolated from embryonic day 9 caudal neural tubes of Sox-2:EGFP transgenic mice were expanded in vitro and grafted into the hippocampi of middle-aged (12 months old) F344 rats. Both types of grafts survived well, and grafted NSCs in addition migrated to all layers of the hippocampus. Phenotypic characterization revealed that both GRPs and NSCs differentiated predominantly into astrocytes and oligodendrocytic progenitors. Neuronal differentiation of graft-derived cells was mostly absent except in the dentate subgranular zone (SGZ), where some of the migrated NSCs but not GRPs differentiated into neurons. Analyses of the numbers of newly born neurons in the DG using 5'-bromodeoxyuridine and/or doublecortin assays, however, demonstrated considerably increased dentate neurogenesis in animals receiving grafts of GRPs or NSCs in comparison with both naïve controls and animals receiving sham-grafting surgery. Thus, both GRPs and NSCs survive well, differentiate predominantly into glia, and stimulate the endogenous NSCs in the SGZ to produce more new dentate granule cells following grafting into the aging hippocampus. Grafting of GRPs or NSCs therefore provides an attractive approach for improving neurogenesis in the aging hippocampus. Disclosure of potential conflicts of interest is found at the end of this article.

  6. Differentiation of apical and basal dendrites in pyramidal cells and granule cells in dissociated hippocampal cultures.

    PubMed

    Wu, You Kure; Fujishima, Kazuto; Kengaku, Mineko

    2015-01-01

    Hippocampal pyramidal cells and dentate granule cells develop morphologically distinct dendritic arbors, yet also share some common features. Both cell types form a long apical dendrite which extends from the apex of the cell soma, while short basal dendrites are developed only in pyramidal cells. Using quantitative morphometric analyses of mouse hippocampal cultures, we evaluated the differences in dendritic arborization patterns between pyramidal and granule cells. Furthermore, we observed and described the final apical dendrite determination during dendritic polarization by time-lapse imaging. Pyramidal and granule cells in culture exhibited similar dendritic patterns with a single principal dendrite and several minor dendrites so that the cell types were not readily distinguished by appearance. While basal dendrites in granule cells are normally degraded by adulthood in vivo, cultured granule cells retained their minor dendrites. Asymmetric growth of a single principal dendrite harboring the Golgi was observed in both cell types soon after the onset of dendritic growth. Time-lapse imaging revealed that up until the second week in culture, final principal dendrite designation was not stabilized, but was frequently replaced by other minor dendrites. Before dendritic polarity was stabilized, the Golgi moved dynamically within the soma and was repeatedly repositioned at newly emerging principal dendrites. Our results suggest that polarized growth of the apical dendrite is regulated by cell intrinsic programs, while regression of basal dendrites requires cue(s) from the extracellular environment in the dentate gyrus. The apical dendrite designation is determined from among multiple growing dendrites of young developing neurons.

  7. Both increases in immature dentate neuron number and decreases of immobility time in the forced swim test occurred in parallel after environmental enrichment of mice.

    PubMed

    Llorens-Martín, M V; Rueda, N; Martínez-Cué, C; Torres-Alemán, I; Flórez, J; Trejo, J L

    2007-07-13

    A direct relation between the rate of adult hippocampal neurogenesis in mice and the immobility time in a forced swim test after living in an enriched environment has been suggested previously. In the present work, young adult mice living in an enriched environment for 2 months developed considerably more immature differentiating neurons (doublecortin-positive, DCX(+)) than control, non-enriched animals. Furthermore, we found that the more DCX(+) cells they possessed, the lower the immobility time they scored in the forced swim test. This DCX(+) subpopulation is composed of mostly differentiating dentate neurons independently of the birthdates of every individual cell. However, variations found in this subpopulation were not the result of a general effect on the survival of any newborn neuron in the granule cell layer, as 5-bromo-2-deoxyuridine (BrdU)-labeled cells born during a narrow time window included in the longer lifetime period of DCX(+) cells, were not significantly modified after enrichment. In contrast, the survival of the mature population of neurons in the granule cell layer of the dentate gyrus in enriched animals increased, although this did not influence their performance in the Porsolt test, nor did it influence the dentate gyrus volume or granule neuronal nuclei size. These results indicate that the population of immature, differentiating neurons in the adult hippocampus is one factor directly related to the protective effect of an enriched environment against a highly stressful event.

  8. Kindling induces transient fast inhibition in the dentate gyrus--CA3 projection.

    PubMed

    Gutiérrez, R; Heinemann, U

    2001-04-01

    The granule cells of the dentate gyrus (DG) send a strong glutamatergic projection, the mossy fibre tract, toward the hippocampal CA3 field, where it excites pyramidal cells and neighbouring inhibitory interneurons. Despite their excitatory nature, granule cells contain small amounts of GAD (glutamate decarboxylase), the main synthetic enzyme for the inhibitory transmitter GABA. Chronic temporal lobe epilepsy results in transient upregulation of GAD and GABA in granule cells, giving rise to the speculation that following overexcitation, mossy fibres exert an inhibitory effect by release of GABA. We therefore stimulated the DG and recorded synaptic potentials from CA3 pyramidal cells in brain slices from kindled and control rats. In both preparations, DG stimulation caused excitatory postsynaptic potential (EPSP)/inhibitory postsynaptic potential (IPSP) sequences. These potentials could be completely blocked by glutamate receptor antagonists in control rats, while in the kindled rats, a bicuculline-sensitive fast IPSP remained, with an onset latency similar to that of the control EPSP. Interestingly, this IPSP disappeared 1 month after the last seizure. When synaptic responses were evoked by high-frequency stimulation, EPSPs in normal rats readily summate to evoke action potentials. In slices from kindled rats, a summation of IPSPs overrides that of the EPSPs and reduces the probability of evoking action potentials. Our data show for the first time that kindling induces functionally relevant activity-dependent expression of fast inhibition onto pyramidal cells, coming from the DG, that can limit CA3 excitation in a frequency-dependent manner.

  9. Autophagy meets fused in sarcoma-positive stress granules.

    PubMed

    Matus, Soledad; Bosco, Daryl A; Hetz, Claudio

    2014-12-01

    Mutations in fused in sarcoma and/or translocated in liposarcoma (FUS, TLS or FUS) are linked to familial cases of amyotrophic lateral sclerosis (ALS). Mutant FUS selectively accumulates into discrete cytosolic structures known as stress granules under various stress conditions. In addition, mutant FUS expression can alter the dynamics and morphology of stress granules. Although the link between mutant FUS and stress granules is well established, the mechanisms modulating stress granule formation and disassembly in the context of ALS are poorly understood. In this issue of Neurobiology of Aging, Ryu et al. uncover the impact of autophagy on the potential toxicity of mutant FUS-positive stress granules. The authors provide evidence indicating that enhanced autophagy activity reduces the number of stress granules, which in the case of cells containing mutant FUS-positive stress granules, is neuroprotective. Overall, this study identifies an intersection between the proteostasis network and alterations in RNA metabolism in ALS through the dynamic assembly and disassembly of stress granules.

  10. Histamine H3 receptor-mediated inhibition of excitatory synaptic transmission in the rat dentate gyrus in vivo.

    PubMed

    Chang, M; Saito, H; Abe, K

    1998-07-01

    We investigated the effects of histamine H3-receptor ligands on hippocampal synaptic transmission by using anesthetized rats in vivo. The medial perforant path was stimulated, and the population excitatory postsynaptic potential (pEPSP) and population spike were recorded from the granule cell layer of the dentate gyrus. Intracerebroventricular injection of the H3-receptor agonist (R)-alpha-methylhistamine decreased both the pEPSP and population spike, while H3-receptor antagonists, clobenpropit and thioperamide, increased both the pEPSP and population spike. These results suggest that the histaminergic system plays a role in inhibition of hippocampal synaptic excitation via the H3 receptor.

  11. Reelin Regulates the Maturation of Dendritic Spines, Synaptogenesis and Glial Ensheathment of Newborn Granule Cells

    PubMed Central

    Bosch, Carles; Masachs, Nuria; Exposito-Alonso, David; Martínez, Albert; Teixeira, Cátia M.; Fernaud, Isabel; Pujadas, Lluís; Ulloa, Fausto; Comella, Joan X.; DeFelipe, Javier; Merchán-Pérez, Angel; Soriano, Eduardo

    2016-01-01

    The Reelin pathway is essential for both neural migration and for the development and maturation of synaptic connections. However, its role in adult synaptic formation and remodeling is still being investigated. Here, we investigated the impact of the Reelin/Dab1 pathway on the synaptogenesis of newborn granule cells (GCs) in the young-adult mouse hippocampus. We show that neither Reelin overexpression nor the inactivation of its intracellular adapter, Dab1, substantially alters dendritic spine numbers in these neurons. In contrast, 3D-electron microscopy (focused ion beam milling/scanning electron microscope) revealed that dysregulation of the Reelin/Dab1 pathway leads to both transient and permanent changes in the types and morphology of dendritic spines, mainly altering mushroom, filopodial, and branched GC spines. We also found that the Reelin/Dab1 pathway controls synaptic configuration of presynaptic boutons in the dentate gyrus, with its dysregulation leading to a substantial decrease in multi-synaptic bouton innervation. Lastly, we show that the Reelin/Dab1 pathway controls astroglial ensheathment of synapses. Thus, the Reelin pathway is a key regulator of adult-generated GC integration, by controlling dendritic spine types and shapes, their synaptic innervation patterns, and glial ensheathment. These findings may help to better understanding of hippocampal circuit alterations in neurological disorders in which the Reelin pathway is implicated. Significance Statement The extracellular protein Reelin has an important role in neurological diseases, including epilepsy, Alzheimer's disease and psychiatric diseases, targeting hippocampal circuits. Here we address the role of Reelin in the development of synaptic contacts in adult-generated granule cells (GCs), a neuronal population that is crucial for learning and memory and implicated in neurological and psychiatric diseases. We found that the Reelin pathway controls the shapes, sizes, and types of dendritic

  12. Inferred properties of stellar granulation

    SciTech Connect

    Gray, D.F.; Toner, C.G.

    1985-06-01

    Apparent characteristics of stellar granulation in F and G main-sequence stars are inferred directly from observed spectral-line asymmetries and from comparisons of numerical simulations with the observations: (1) the apparent granulation velocity increases with effective temperature, (2) the dispersion of granule velocities about their mean velocity of rise increases with the apparent granulation velocity, (3) the mean velocity of rise of granules must be less than the total line broadening, (4) the apparent velocity difference between granules and dark lanes corresponds to the granulation velocity deduced from stellar line bisectors, (5) the dark lanes show velocities of fall approximately twice as large as the granule rise velocities, (6) the light contributed to the stellar flux by the granules is four to ten times more than the light from the dark lanes. Stellar rotation is predicted to produce distortions in the line bisectors which may give information on the absolute velocity displacements of the line bisectors. 37 references.

  13. Maternal Forced Swimming Reduces Cell Proliferation in the Postnatal Dentate Gyrus of Mouse Offspring

    PubMed Central

    Wasinski, Frederick; Estrela, Gabriel R.; Arakaki, Aline M.; Bader, Michael; Alenina, Natalia; Klempin, Friederike; Araújo, Ronaldo C.

    2016-01-01

    Physical exercise positively affects the metabolism and induces proliferation of precursor cells in the adult brain. Maternal exercise likewise provokes adaptations early in the offspring. Using a high-intensity swimming protocol that comprises forced swim training before and during pregnancy, we determined the effect of maternal swimming on the mouse offspring's neurogenesis. Our data demonstrate decreased proliferation in sublayers of the postnatal dentate gyrus in offspring of swimming mother at postnatal day (P) 8 accompanied with decreased survival of newly generated cells 4 weeks later. The reduction in cell numbers was predominantly seen in the hilus and molecular layer. At P35, the reduced amount of cells was also reflected by a decrease in the population of newly generated immature and mature neurons of the granule cell layer. Our data suggest that forced maternal swimming at high-intensity has a negative effect on the neurogenic niche development in postnatal offspring. PMID:27621701

  14. Experience-dependent remodeling of basket cell networks in the dentate gyrus

    PubMed Central

    Pieraut, Simon; Gounko, Natalia; Sando, Richard; Dang, Westley; Rebboah, Elisabeth; Panda, Satchidananda; Madisen, Linda; Zeng, Hongkui; Maximov, Anton

    2014-01-01

    SUMMARY The structural organization of neural circuits is strongly influenced by experience, but the underlying mechanisms are incompletely understood. We found that, in the developing dentate gyrus (DG), excitatory drive promotes the somatic innervation of principal granule cells (GCs) by parvalbumin (PV)-positive basket cells. By contrast, presynaptic differentiation of GCs and interneuron sub-types that inhibit GC dendrites is largely resistant to loss of glutamatergic neurotransmission. The networks of PV basket cells in the DG are regulated by vesicular release from projection entorhinal cortical neurons and, at least in part, by NMDA receptors in interneurons. Finally, we present evidence that glutamatergic inputs and NMDA receptors regulate these networks through a presynaptic mechanism that appears to control the branching of interneuron axons. Our results provide insights into how cortical activity tunes the inhibition in a subcortical circuit, and reveal new principles of interneuron plasticity. PMID:25277456

  15. Differential control of learning and anxiety along the dorsoventral axis of the dentate gyrus.

    PubMed

    Kheirbek, Mazen A; Drew, Liam J; Burghardt, Nesha S; Costantini, Daniel O; Tannenholz, Lindsay; Ahmari, Susanne E; Zeng, Hongkui; Fenton, André A; Hen, René

    2013-03-06

    The dentate gyrus (DG), in addition to its role in learning and memory, is increasingly implicated in the pathophysiology of anxiety disorders. Here, we show that, dependent on their position along the dorsoventral axis of the hippocampus, DG granule cells (GCs) control specific features of anxiety and contextual learning. Using optogenetic techniques to either elevate or decrease GC activity, we demonstrate that GCs in the dorsal DG control exploratory drive and encoding, not retrieval, of contextual fear memories. In contrast, elevating the activity of GCs in the ventral DG has no effect on contextual learning but powerfully suppresses innate anxiety. These results suggest that strategies aimed at modulating the excitability of the ventral DG may be beneficial for the treatment of anxiety disorders.

  16. Structural and Functional Asymmetry in the Normal and Epileptic Rat Dentate Gyrus

    PubMed Central

    Scharfman, Helen E.; Sollas, Anne L.; Smith, Karen L.; Jackson, Meyer B.; Goodman, Jeffrey H.

    2008-01-01

    The rat dentate gyrus is usually described as relatively homogeneous. Here, we present anatomic and physiological data which demonstrate that there are striking differences between the supra- and infrapyramidal blades after status epilepticus and recurrent seizures. These differences appear to be an accentuation of a subtle asymmetry present in normal rats. In both pilocarpine and kainic acid models, there was greater mossy fiber sprouting in the infrapyramidal blade. This occurred primarily in the middle third of the hippocampus. Asymmetric sprouting was evident both with Timm stain as well as antisera to brain-derived neurotrophic factor (BDNF) or neuropeptide Y (NPY). In addition, surviving NPY-immunoreactive hilar neurons were distributed preferentially in the suprapyramidal region of the hilus. Extracellular recordings from infrapyramidal sites in hippocampal slices of pilocarpine-treated rats showed larger population spikes and weaker paired-pulse inhibition in response to perforant path stimulation relative to suprapyramidal recordings. A single stimulus could evoke burst discharges in infrapyramidal granule cells but not suprapyramidal blade neurons. BDNF exposure led to spontaneous epileptiform discharges that were larger in amplitude and longer lasting in the infrapyramidal blade. Stimulation of the infrapyramidal molecular layer evoked larger responses in area CA3 than suprapyramidal stimulation. In slices from the temporal pole, in which anatomic evidence of asymmetry waned, there was little evidence of physiological asymmetry either. Of interest, some normal rats also showed signs of greater evoked responses in the infrapyramidal blade, and this could be detected with both microelectrode recording and optical imaging techniques. Although there were no signs of hyperexcitability in normal rats, the data suggest that there is some asymmetry in the normal dentate gyrus and this asymmetry is enhanced by seizures. Taken together, the results suggest that

  17. Activation of dentate hilar neurons by stimulation of the fimbria in rat hippocampal slices

    PubMed Central

    Scharfman, Helen E.

    2012-01-01

    It is has been shown that the major afferent input to the dentate gyrus, the perforant path, excites dentate hilar neurons. However, little is known about the other inputs to hilar cells. Therefore, we examined the responses of hilar neurons to stimulation of the fimbria. We positioned our stimulating electrodes so that granule cells were not excited antidromically by fimbria stimulation, although action potentials were easily triggered in area CA3b and CA3c pyramidal cells by such stimulation. In these experiments, fimbria stimulation evoked responses from every hilar cell tested, including examples of both of the major cell types, the spiny hilar ‘mossy’ cells (n=15) and the relatively aspiny. ‘fast-spiking’ cells (putative interneurons, n=5). Hilar cell responses consisted primarily of EPSPs that could trigger action potentials, but small IPSPs were also evoked in some cases, particularly in the fast-spiking cells. Excitation was blocked by an antagonist of the AMPA/kainate receptor subtype of excitatory amino acid receptors, 6-cyano-7-nitroquinoxaline-2,3-dione(CNQX, 5μM, n=5), whereas the cholinergic antagonist atropine (10μM) had no effect (n=4). When sequential intracellular recordings were made from hilar cells and area CA3 pyramidal cells in the same slice, hilar cell EPSPs began after action potentials of CA3b pyramidal cells, and stimulus strengths required to evoke hilar cell EPSPs were above threshold for area CA3b pyramidal cells. Taken together with the evidence that area CA3 pyramidal cells use an excitatory amino acid as a neurotransmitter [7, 21], and the demonstrations of area CA3 axon collaterals in the hilus [11, 16], the results raise the possibility that some area CA3 pyramidal cells excite dentate hilar neurons. PMID:8105429

  18. Structural and functional asymmetry in the normal and epileptic rat dentate gyrus.

    PubMed

    Scharfman, Helen E; Sollas, Anne L; Smith, Karen L; Jackson, Meyer B; Goodman, Jeffrey H

    2002-12-23

    The rat dentate gyrus is usually described as relatively homogeneous. Here, we present anatomic and physiological data which demonstrate that there are striking differences between the supra- and infrapyramidal blades after status epilepticus and recurrent seizures. These differences appear to be an accentuation of a subtle asymmetry present in normal rats. In both pilocarpine and kainic acid models, there was greater mossy fiber sprouting in the infrapyramidal blade. This occurred primarily in the middle third of the hippocampus. Asymmetric sprouting was evident both with Timm stain as well as antisera to brain-derived neurotrophic factor (BDNF) or neuropeptide Y (NPY). In addition, surviving NPY-immunoreactive hilar neurons were distributed preferentially in the suprapyramidal region of the hilus. Extracellular recordings from infrapyramidal sites in hippocampal slices of pilocarpine-treated rats showed larger population spikes and weaker paired-pulse inhibition in response to perforant path stimulation relative to suprapyramidal recordings. A single stimulus could evoke burst discharges in infrapyramidal granule cells but not suprapyramidal blade neurons. BDNF exposure led to spontaneous epileptiform discharges that were larger in amplitude and longer lasting in the infrapyramidal blade. Stimulation of the infrapyramidal molecular layer evoked larger responses in area CA3 than suprapyramidal stimulation. In slices from the temporal pole, in which anatomic evidence of asymmetry waned, there was little evidence of physiological asymmetry either. Of interest, some normal rats also showed signs of greater evoked responses in the infrapyramidal blade, and this could be detected with both microelectrode recording and optical imaging techniques. Although there were no signs of hyperexcitability in normal rats, the data suggest that there is some asymmetry in the normal dentate gyrus and this asymmetry is enhanced by seizures. Taken together, the results suggest that

  19. Development of the human dentate nucleus.

    PubMed

    Mihajlovic, P; Zecevic, N

    1986-01-01

    The developing human dentate nucleus (DN) was studied in a series of specimens of various pre- and postnatal ages ranging from 8 gestational weeks (gw) to 10 years, in Golgi-impregnated and Nissl-stained material. The DN emerges from the cerebellar white matter at around 16 gestational weeks (gw) as a thick band of cells (600-700 micron in width) that gradually attenuates to a final width of 150-250 micron as it undergoes extensive infolding beginning around 24 gw. The highly convoluted configuration of the adult DN is recognizable by 35 gw. Around 16 gw, two basic classes of DN neurons can be identified. Differentiation of these neurons is especially intensive during the mid-gestational period (20-25 gw). At this time the size of cell bodies increases, dendrites branch profusely and acquire spines. A second, slower phase of maturation consisting of addition of secondary and tertiary branches, continues into the postnatal period. At all prenatal ages examined, dentate neurons are morphologically more mature than the Purkinje cells in the overlying cortex. DN neurons of premature infants did not show cytomorphological differences when compared with babies born at term.

  20. CREB Phosphorylation Coincides with Transient Synapse Formation in the Rat Hippocampal Dentate Gyrus Following Avoidance Learning

    PubMed Central

    O'Connell, Cormac; Gallagher, Helen C.; O'Malley, Aoibheinn; Bourke, Mary; Regan, Ciaran M.

    2000-01-01

    Spine density change in the hippocampal dentate gyrus accompanies memory consolidation and coincides with the increased expression of ribosome-rich, hyperchromatic granule cells. Although this suggests increased protein synthesis to be required for synaptic growth in the 5 to 7 h post-training period, little temporal mapping of the associated molecular mechanisms has been done. Here, we demonstrate a similar frequency of hyperchromatic cells in naïve animals and in those sacrificed 6 h post-training, suggesting a transient repression of protein synthesis in the early post-training period. Immunoblot analysis of CREB phosphorylation in the dentate gyrus supported this view, with downregulation from basal levels observed at 2 to 3 h and at 12 h posttraining. Protein synthesis reactivation appears to be specific for de novo spine production as no change in spine frequency accompanies the immediate post-training period of depressed protein synthesis. These findings support the view that CREB-mediated gene transcription is a requirement for long-term memory consolidation and may be directly implicated in the process of synaptic growth. PMID:11486487

  1. Failure of neuronal maturation in Alzheimer disease dentate gyrus.

    PubMed

    Li, Bin; Yamamori, Hidenaga; Tatebayashi, Yoshitaka; Shafit-Zagardo, Bridget; Tanimukai, Hitoshi; Chen, She; Iqbal, Khalid; Grundke-Iqbal, Inge

    2008-01-01

    The dentate gyrus, an important anatomic structure of the hippocampal formation, is one of the major areas in which neurogenesis takes place in the adult mammalian brain. Neurogenesis in the dentate gyrus is thought to play an important role in hippocampus-dependent learning and memory. Neurogenesis has been reported to be increased in the dentate gyrus of patients with Alzheimer disease, but it is not known whether the newly generated neurons differentiate into mature neurons. In this study, the expression of the mature neuronal marker high molecular weight microtubule-associated protein (MAP) isoforms MAP2a and b was found to be dramatically decreased in Alzheimer disease dentate gyrus, as determined by immunohistochemistry and in situ hybridization. The total MAP2, including expression of the immature neuronal marker, the MAP2c isoform, was less affected. These findings suggest that newly generated neurons in Alzheimer disease dentate gyrus do not become mature neurons, although neuroproliferation is increased.

  2. Regulated proteolysis by cortical granule serine protease 1 at fertilization.

    PubMed

    Haley, Sheila A; Wessel, Gary M

    2004-05-01

    Cortical granules are specialized organelles whose contents interact with the extracellular matrix of the fertilized egg to form the block to polyspermy. In sea urchins, the granule contents form a fertilization envelope (FE), and this construction is critically dependent upon protease activity. An autocatalytic serine protease, cortical granule serine protease 1 (CGSP1), has been identified in the cortical granules of Strongylocentrotus purpuratus eggs, and here we examined the regulation of the protease activity and tested potential target substrates of CGSP1. We found that CGSP1 is stored in its full-length, enzymatically quiescent form in the granule, and is inactive at pH 6.5 or below. We determined the pH of the cortical granule by fluorescent indicators and micro-pH probe measurements and found the granules to be pH 5.5, a condition inhibitory to CGSP1 activity. Exposure of the protease to the pH of seawater (pH 8.0) at exocytosis immediately activates the protease. Activation of eggs at pH 6.5 or lower blocks activation of the protease and the resultant FE phenotypes are indistinguishable from a protease-null phenotype. We find that native cortical granule targets of the protease are beta-1,3 glucanase, ovoperoxidase, and the protease itself, but the structural proteins of the granule are not proteolyzed by CGSP1. Whole mount immunolocalization experiments demonstrate that inhibition of CGSP1 activity affects the localization of ovoperoxidase but does not alter targeting of structural proteins to the FE. The mistargeting of ovoperoxidase may lead to spurious peroxidative cross-linking activity and contribute to the lethality observed in protease-null cells. Thus, CGSP1 is proteolytically active only when secreted, due to the low pH of the cortical granules, and it has a small population of targets for cleavage within the cortical granules.

  3. Modeling the Nonlinear Properties of the in vitro Hippocampal Perforant Path-Dentate System Using Multielectrode Array Technology

    PubMed Central

    Courellis, Spiros H.; Gholmieh, Ghassan I.; Marmarelis, Vasilis Z.; Berger, Theodore W.

    2009-01-01

    A modeling approach to characterize the nonlinear dynamic transformations of the dentate gyrus of the hippocampus is presented and experimentally validated. The dentate gyrus is the first region of the hippocampus which receives and integrates sensory information via the perforant path. The perforant path is composed of two distinct pathways: 1) the lateral path and 2) the medial perforant path. The proposed approach examines and captures the short-term dynamic characteristics of these two pathways using a nonparametric, third-order Poisson–Volterra model. The nonlinear characteristics of the two pathways are represented by Poisson–Volterra kernels, which are quantitative descriptors of the nonlinear dynamic transformations. The kernels were computed with experimental data from in vitro hippocampal slices. The electrophysiological activity was measured with custom-made multielectrode arrays, which allowed selective stimulation with random impulse trains and simultaneous recordings of extracellular field potential activity. The results demonstrate that this mathematically rigorous approach is suitable for the multipathway complexity of the hippocampus and yields interpretable models that have excellent predictive capabilities. The resulting models not only accurately predict previously reported electrophysiological descriptors, such as paired pulses, but more important, can be used to predict the electrophysiological activity of dentate granule cells to arbitrary stimulation patterns at the perforant path. PMID:18270006

  4. Stereotactic injection of cerebrospinal fluid from anti-NMDA receptor encephalitis into rat dentate gyrus impairs NMDA receptor function.

    PubMed

    Würdemann, Till; Kersten, Maxi; Tokay, Tursonjan; Guli, Xiati; Kober, Maria; Rohde, Marco; Porath, Katrin; Sellmann, Tina; Bien, Christian G; Köhling, Rüdiger; Kirschstein, Timo

    2016-02-15

    Autoimmune encephalitis is increasingly recognized in patients with otherwise unexplained encephalopathy with epilepsy. Among these, patients with anti-N-methyl D-aspartate receptor (NMDAR) encephalitis present epileptic seizures, memory deficits, and psychiatric symptoms. However, the functional consequences of such autoantibodies are poorly understood. In order to investigate the pathophysiology of this disease, we stereotactically injected either cerebrospinal fluid (CSF) from three anti-NMDAR encephalitis patients or commercially available anti-NMDAR1 into the dentate gyrus of adult female rats. Control animals were injected with either CSF obtained from three epilepsy patients (ganglioglioma, posttraumatic epilepsy, focal cortical dysplasia) lacking anti-NMDAR or saline. Intracellular recordings from dentate gyrus granule cells showed a significant reduction of the NMDAR-evoked excitatory postsynaptic potentials (NMDAR-EPSPs) in animals treated with anti-NMDAR. As a consequence of this, action potential firing in these cells by NMDAR-EPSPs was significantly impaired. Long-term potentiation in the dentate gyrus was also significantly reduced in rats injected with anti-NMDAR as compared to control animals. This was accompanied by a significantly impaired learning performance in the Morris water maze hidden platform task when the animals had been injected with anti-NMDAR antibody-containing CSF. Our findings suggest that anti-NMDAR lead to reduced NMDAR function in vivo which could contribute to the memory impairment found in patients with anti-NMDAR encephalitis.

  5. Apparatus for granulating coal

    SciTech Connect

    Ogino, E.; Harada, K.; Yoshii, N.

    1983-08-30

    A granulating apparatus is disclosed comprising a stirring tank or a duct for containing a slurry particulate to granular coal having a binder incorporated therein, a rotary shaft disposed in the tank or duct and at least one agitating blade made of metal netting and attached to the rotary shaft.

  6. Delayed coupling to feedback inhibition during a critical period for the integration of adult-born granule cells.

    PubMed

    Temprana, Silvio G; Mongiat, Lucas A; Yang, Sung M; Trinchero, Mariela F; Alvarez, Diego D; Kropff, Emilio; Giacomini, Damiana; Beltramone, Natalia; Lanuza, Guillermo M; Schinder, Alejandro F

    2015-01-07

    Developing granule cells (GCs) of the adult dentate gyrus undergo a critical period of enhanced activity and synaptic plasticity before becoming mature. The impact of developing GCs on the activity of preexisting dentate circuits remains unknown. Here we combine optogenetics, acute slice electrophysiology, and in vivo chemogenetics to activate GCs at different stages of maturation to study the recruitment of local target networks. We show that immature (4-week-old) GCs can efficiently drive distal CA3 targets but poorly activate proximal interneurons responsible for feedback inhibition (FBI). As new GCs transition toward maturity, they reliably recruit GABAergic feedback loops that restrict spiking of neighbor GCs, a mechanism that would promote sparse coding. Such inhibitory loop impinges only weakly in new cohorts of young GCs. A computational model reveals that the delayed coupling of new GCs to FBI could be crucial to achieve a fine-grain representation of novel inputs in the dentate gyrus.

  7. Delayed coupling to feedback inhibition during a critical period for the integration of adult-born granule cells

    PubMed Central

    Temprana, Silvio G.; Mongiat, Lucas A.; Yang, Sung M.; Trinchero, Mariela F.; Alvarez, Diego D.; Kropff, Emilio; Giacomini, Damiana; Beltramone, Natalia; Lanuza, Guillermo M.; Schinder, Alejandro F.

    2014-01-01

    SUMMARY Developing granule cells (GCs) of the adult dentate gyrus undergo a critical period of enhanced activity and synaptic plasticity before becoming mature. The impact of developing GCs on the activity of preexisting dentate circuits remains unknown. Here we combine optogenetics, acute slice electrophysiology, and in vivo chemogenetics to activate GCs at different stages of maturation to study the recruitment of local target networks. We show that immature (four-week-old) GCs can efficiently drive distal CA3 targets, but poorly activate proximal interneurons responsible for feedback inhibition (FBI). As new GCs transition towards maturity, they reliably recruit GABAergic feedback loops that restrict spiking of neighbor GCs, a mechanism that would promote sparse coding. Such inhibitory loop impinges only weakly in new cohorts of young GCs. A computational model reveals that the delayed coupling of new GCs to FBI could be crucial to achieve a fine-grain representation of novel inputs in the dentate gyrus. PMID:25533485

  8. Prolonged protein deprivation, but not food restriction, affects parvalbumin-containing interneurons in the dentate gyrus of adult rats.

    PubMed

    Cardoso, Armando; Castro, João Paulo; Pereira, Pedro Alberto; Andrade, José Paulo

    2013-07-19

    Several studies have demonstrated the vulnerability of the hippocampal formation to malnutrition. In this study, we compared the effects of food restriction and protein malnutrition in the total number of neurons of the dentate gyrus and in the number of parvalbumin-immunoreactive (PV-IR) interneurons, which are related to the control of calcium homeostasis and fine tuning of the hippocampal circuits. Two month-old rats were randomly assigned to control, food-restricted and low-protein diet groups. After 6 months, 10 rats from the low-protein diet group were selected at random and fed with a normal protein diet for 2 months. The total number of granule and hilar cells was reduced in protein-deprived rats and the nutritional reestablishment with a normal protein diet did not recover neuron numbers. Protein deprivation increased the number of PV-IR interneurons in the granule cell layer and hilus, but their number returned to values similar to controls after nutritional rehabilitation. Food restriction did not affect the total number of neurons or the density of PV-IR interneurons in the dentate gyrus. These results support the view that protein deprivation may disturb calcium homeostasis, leading to neuronal death. The up-regulation of PV-IR cells may reflect a protective mechanism to counteract the calcium overload and protect the remaining neurons of the dentate gyrus. This imbalance in cell-ratio favoring GABAergic interneurons may justify some learning and memory impairments described in protein-deprived animals. This contrast between the results of food restriction and protein deprivation should be further analyzed in future studies.

  9. Chronically dysregulated NOTCH1 interactome in the dentate gyrus after traumatic brain injury

    PubMed Central

    Puhakka, Noora; Bot, Anna Maria; Vuokila, Niina; Debski, Konrad Jozef; Lukasiuk, Katarzyna; Pitkänen, Asla

    2017-01-01

    Traumatic brain injury (TBI) can result in several dentate gyrus-regulated disabilities. Almost nothing is known about the chronic molecular changes after TBI, and their potential as treatment targets. We hypothesized that chronic transcriptional alterations after TBI are under microRNA (miRNA) control. Expression of miRNAs and their targets in the dentate gyrus was analyzed using microarrays at 3 months after experimental TBI. Of 305 miRNAs present on the miRNA-array, 12 were downregulated (p<0.05). In parallel, 75 of their target genes were upregulated (p<0.05). A bioinformatics analysis of miRNA targets highlighted the dysregulation of the transcription factor NOTCH1 and 39 of its target genes (NOTCH1 interactome). Validation assays confirmed downregulation of miR-139-5p, upregulation of Notch1 and its activated protein, and positive enrichment of NOTCH1 target gene expression. These findings demonstrate that miRNA-based transcriptional regulation can be present at chronic time points after TBI, and highlight the NOTCH1 interactome as one of the mechanisms behind the dentate gyrus pathology-related morbidities. PMID:28273100

  10. Prenatal Alcohol Exposure Affects Progenitor Cell Numbers in Olfactory Bulbs and Dentate Gyrus of Vervet Monkeys

    PubMed Central

    Burke, Mark W.; Inyatkin, Alexey; Ptito, Maurice; Ervin, Frank R.; Palmour, Roberta M.

    2016-01-01

    Fetal alcohol exposure (FAE) alters hippocampal cell numbers in rodents and primates, and this may be due, in part, to a reduction in the number or migration of neuronal progenitor cells. The olfactory bulb exhibits substantial postnatal cellular proliferation and a rapid turnover of newly formed cells in the rostral migratory pathway, while production and migration of postnatal neurons into the dentate gyrus may be more complex. The relatively small size of the olfactory bulb, compared to the hippocampus, potentially makes this structure ideal for a rapid analysis. This study used the St. Kitts vervet monkey (Chlorocebus sabeus) to (1) investigate the normal developmental sequence of post-natal proliferation in the olfactory bulb and dentate gyrus and (2) determine the effects of naturalistic prenatal ethanol exposure on proliferation at three different ages (neonate, five months and two years). Using design-based stereology, we found an age-related decrease of actively proliferating cells in the olfactory bulb and dentate gyrus for both control and FAE groups. Furthermore, at the neonatal time point, the FAE group had fewer actively proliferating cells as compared to the control group. These data are unique with respect to fetal ethanol effects on progenitor proliferation in the primate brain and suggest that the olfactory bulb may be a useful structure for studies of cellular proliferation. PMID:27801790

  11. Chronically dysregulated NOTCH1 interactome in the dentate gyrus after traumatic brain injury.

    PubMed

    Puhakka, Noora; Bot, Anna Maria; Vuokila, Niina; Debski, Konrad Jozef; Lukasiuk, Katarzyna; Pitkänen, Asla

    2017-01-01

    Traumatic brain injury (TBI) can result in several dentate gyrus-regulated disabilities. Almost nothing is known about the chronic molecular changes after TBI, and their potential as treatment targets. We hypothesized that chronic transcriptional alterations after TBI are under microRNA (miRNA) control. Expression of miRNAs and their targets in the dentate gyrus was analyzed using microarrays at 3 months after experimental TBI. Of 305 miRNAs present on the miRNA-array, 12 were downregulated (p<0.05). In parallel, 75 of their target genes were upregulated (p<0.05). A bioinformatics analysis of miRNA targets highlighted the dysregulation of the transcription factor NOTCH1 and 39 of its target genes (NOTCH1 interactome). Validation assays confirmed downregulation of miR-139-5p, upregulation of Notch1 and its activated protein, and positive enrichment of NOTCH1 target gene expression. These findings demonstrate that miRNA-based transcriptional regulation can be present at chronic time points after TBI, and highlight the NOTCH1 interactome as one of the mechanisms behind the dentate gyrus pathology-related morbidities.

  12. Probing platelet factor 4 alpha-granule targeting.

    PubMed

    Briquet-Laugier, V; Lavenu-Bombled, C; Schmitt, A; Leboeuf, M; Uzan, G; Dubart-Kupperschmitt, A; Rosa, J-P

    2004-12-01

    The storage mechanism of endogenous secretory proteins in megakaryocyte alpha-granules is poorly understood. We have elected to study the granule storage of platelet factor 4 (PF4), a well-known platelet alpha-granule protein. The reporter protein green fluorescent protein (GFP), PF4, or PF4 fused to GFP (PF4-GFP), were transfected in the well-characterized mouse pituitary AtT20 cell line, and in the megakaryocytic leukemic DAMI cell line. These proteins were also transduced using a lentiviral vector, in human CD34+ cells differentiated into megakaryocytes in vitro. Intracellular localization of expressed proteins, and colocalization studies were achieved by laser scanning confocal microscopy and immuno-electronmicroscopy. In preliminary experiments, GFP, a non-secretory protein (no signal peptide), localized in the cytoplasm, while PF4-GFP colocalized with adrenocorticotropin hormone (ACTH)-containing granules in AtT20 cells. In the megakaryocytic DAMI cell line and in human megakaryocytes differentiated in vitro, PF4-GFP localized in alpha-granules along with the alpha granular protein von Willebrand factor (VWF). The signal peptide of PF4 was not sufficient to specify alpha-granule storage of PF4, since when PF4 signal peptide was fused to GFP (SP4-GFP), GFP was not stored into granules in spite of its efficient translocation to the ER-Golgi constitutive secretory pathway. We conclude that the PF4 storage pathway in alpha-granules is not a default pathway, but rather a regular granule storage pathway probably requiring specific sorting mechanisms. In addition PF4-GFP appears as an appropriate probe with which to analyze alpha-granule biogenesis and its alterations in the congenital defect gray platelet syndrome.

  13. Neuroligin-1 Overexpression in Newborn Granule Cells In Vivo

    PubMed Central

    Schnell, Eric; Bensen, AeSoon L.; Washburn, Eric K.; Westbrook, Gary L.

    2012-01-01

    Adult-born dentate granule cells integrate into the hippocampal network, extend neurites and form synapses in otherwise mature tissue. Excitatory and inhibitory inputs innervate these new granule cells in a stereotyped, temporally segregated manner, which presents a unique opportunity to study synapse development in the adult brain. To examine the role of neuroligins as synapse-inducing molecules in vivo, we infected dividing neural precursors in adult mice with a retroviral construct that increased neuroligin-1 levels during granule cell differentiation. By 21 days post-mitosis, exogenous neuroligin-1 was expressed at the tips of dendritic spines and increased the number of dendritic spines. Neuroligin-1-overexpressing cells showed a selective increase in functional excitatory synapses and connection multiplicity by single afferent fibers, as well as an increase in the synaptic AMPA/NMDA receptor ratio. In contrast to its synapse-inducing ability in vitro, neuroligin-1 overexpression did not induce precocious synapse formation in adult-born neurons. However, the dendrites of neuroligin-1-overexpressing cells did have more thin protrusions during an early period of dendritic outgrowth, suggesting enhanced filopodium formation or stabilization. Our results indicate that neuroligin-1 expression selectively increases the degree, but not the onset, of excitatory synapse formation in adult-born neurons. PMID:23110172

  14. Characterization of canine neutrophil granules.

    PubMed Central

    O'Donnell, R T; Andersen, B R

    1982-01-01

    The purpose of this study was to isolate distinct populations of canine neutrophil granules and to compare them with neutrophil granules from other species. Size, shape, density, and content of canine neutrophil granules were determined. Neutrophils obtained by Ficoll-Hypaque sedimentation were homogenized, and granule populations were separated by isopycnic centrifugation on a linear sucrose gradient (rho, 1.14 to 1.22 g/ml). The most dense granule population (rho, 1.197 g/ml) contained all of the myeloperoxidase, beta-glucuronidase, and elastase, more than half of the acid beta-glycerophosphatase, and most of the lysozyme. The population with intermediate density (rho, 1.179 g/ml) contained lactoferrin, vitamin B12-binding protein, and the remainder of the acid beta-glycerophosphatase and lysozyme. The least dense granule population did not contain a major peak of any of the enzymes or binding proteins tested but was distinguished by density and morphology. The size and shape of the granules were determined from scanning electron micrographs and assessment of shape was aided by transmission electron micrographs. By these methods three populations of canine neutrophil granules were characterized and named: myeloperoxidase granules, vitamin B12-binding protein granules, and low-density granules. Images PMID:6292095

  15. Dendritic remodeling of hippocampal neurons is associated with altered NMDA receptor expression in alcohol dependent rats

    PubMed Central

    Staples, Miranda C.; Kim, Airee; Mandyam, Chitra D.

    2015-01-01

    Prolonged alcohol exposure has been previously shown to impair the structure and function of the hippocampus, although the underlying structural and biochemical alterations contributing to these deleterious effects are unclear. Also unclear is whether these changes persist into prolonged periods of abstinence. Previous work from our lab utilizing a clinically relevant rodent model of alcohol consumption demonstrated that alcohol dependence (induced by chronic intermittent ethanol vapor exposure or CIE) decreases proliferation and survival of neural stem cells in the hippocampal subgranular zone and hippocampal neurogenesis in the dentate gyrus, implicating this region of the cortex as particularly sensitive to the toxic effects of prolonged ethanol exposure. For this study, we investigated seven weeks of CIE-induced morphological changes (dendritic complexity and dendritic spine density) of dentate gyrus (DG) granule cell neurons, CA3, and CA1 pyramidal neurons and the associated alterations in biochemical markers of synaptic plasticity and toxicity (NMDA receptors and PSD-95) in the hippocampus in ethanol-experienced Wistar rats 3h (CIE) and 21 days (protracted abstinence) after the last ethanol vapor exposure. CIE reduced dendritic arborization of DG neurons and this effect persisted into protracted abstinence. CIE enhanced dendritic arborization of pyramidal neurons and this effect did not persist into protracted abstinence. The architectural changes in dendrites did not correlate with alterations in dendritic spine density, however, they were associated with increases in the expression of pNR2B, total NR2B, and total NR2A immediately following CIE with expression levels returning to control levels in prolonged abstinence. Overall, these data provide the evidence that CIE produces profound changes in hippocampal structural plasticity and in molecular tools that maintain hippocampal structural plasticity, and these alterations may underlie cognitive dysfunction

  16. Properties of doublecortin expressing neurons in the adult mouse dentate gyrus.

    PubMed

    Spampanato, Jay; Sullivan, Robert K; Turpin, Fabrice R; Bartlett, Perry F; Sah, Pankaj

    2012-01-01

    The dentate gyrus is a neurogenic zone where neurons continue to be born throughout life, mature and integrate into the local circuitry. In adults, this generation of new neurons is thought to contribute to learning and memory formation. As newborn neurons mature, they undergo a developmental sequence in which different stages of development are marked by expression of different proteins. Doublecortin (DCX) is an early marker that is expressed in immature granule cells that are beginning migration and dendritic growth but is turned off before neurons reach maturity. In the present study, we use a mouse strain in which enhanced green fluorescent protein (EGFP) is expressed under the control of the DCX promoter. We show that these neurons have high input resistances and some cells can discharge trains of action potentials. In mature granule cells, action potentials are followed by a slow afterhyperpolarization that is absent in EGFP-positive neurons. EGFP-positive neurons had a lower spine density than mature neurons and stimulation of either the medial or lateral perforant pathway activated dual component glutamatergic synapses that had both AMPA and NMDA receptors. NMDA receptors present at these synapses had slow kinetics and were blocked by ifenprodil, indicative of high GluN2B subunit content. These results show that EGFP-positive neurons in the DCX-EGFP mice are functionally immature both in their firing properties and excitatory synapses.

  17. Reduced excitatory drive onto interneurons in the dentate gyrus after status epilepticus.

    PubMed

    Doherty, J; Dingledine, R

    2001-03-15

    Impaired GABAergic inhibition may contribute to the development of hyperexcitability in epilepsy. We used the pilocarpine model of epilepsy to demonstrate that regulation of excitatory synaptic drive onto GABAergic interneurons is impaired during epileptogenesis. Synaptic input from granule cells (GCs), perforant path, and CA3 inputs onto hilar border interneurons of the dentate gyrus were examined in rat hippocampal slices during the latent period (1-8 d) after induction of status epilepticus (SE). Short-term depression (STD) of GC inputs to interneurons induced by brief (500-800 msec), repetitive (5-20 Hz) stimulation, as well as paired-pulse depression at both GC and CA3 inputs to interneurons, were significantly (p < 0.05) enhanced in SE-experienced rats. In contrast, we found no significant differences between SE-experienced and age-matched control rats in the properties of minimal EPSCs evoked at low frequency (0.3 Hz). Consistent with reduced GABAergic inhibition onto granule cells, paired-pulse depression of perforant path-evoked granule cell population spikes was lost in SE-experienced rats. Enhanced STD was partially mediated by group II metabotropic glutamate receptors, because the selective antagonist, 2S-2-amino-2-(1S,2S-2-carboxycyclopropyl-1-yl)-3-(xanth-9-yl)propanoic acid, attenuated STD in SE-experienced rats but had no effect on STD of GC inputs in the normal adult rat. The group II mGluR agonist, (2S',1R',2R',3R')-2-(2,3-dicarboxylcyclopropyl) glycine (1 micrometer), produced a greater depression of GC input to hilar border interneurons in SE-experienced rats than in controls. These results indicate that, in the SE-experienced rat, excitatory drive to hilar border inhibitory interneurons is weakened through a use-dependent mechanism involving group II metabotropic glutamate receptors.

  18. Cell types, lineage, and architecture of the germinal zone in the adult dentate gyrus.

    PubMed

    Seri, Bettina; García-Verdugo, José Manuel; Collado-Morente, Lucia; McEwen, Bruce S; Alvarez-Buylla, Arturo

    2004-10-25

    New neurons continue to be born in the subgranular zone (SGZ) of the dentate gyrus in the hippocampus of adult mammals, including humans. Previous work has shown that astrocytes function as the progenitors of these new neurons through immature intermediate D cells. In the first part of the present study, we determined the structure of each of these progenitors and how they are organized in three dimensions. Serial-section reconstructions of the SGZ, using confocal and electron microscopy demonstrate that SGZ astrocytes form baskets that hold clusters of D cells, largely insulating them from the hilus. Two types of glial fibrillary acidic protein-expressing astrocytes (radial and horizontal) and three classes of doublecortin and PSA-NCAM-positive D cells (D1, D2, D3) were observed. Radial astrocytes appear to interact closely with clusters of D cells forming radial proliferative units. In the second part of this study, we show that retrovirally labeled radial astrocytes give rise to granule neurons. We also used bromodeoxyuridine and [3H]thymidine labeling to study the sequence of appearance of the different D cells after a 7-day treatment with anti-mitotics. This analysis, together with retroviral labeling data, suggest that radial astrocytes divide to generate D1 cells, which in turn divide once to form postmitotic D2 cells. D2 cells mature through a D3 stage to form new granule neurons. These observations provide a model of how the germinal zone of the adult hippocampus is organized and suggest a sequence of cellular stages in the generation of new granule neurons.

  19. Quantitative analysis of long-term potentiation in the hippocampal dentate gyrus of the freely-moving 15-day-old rat.

    PubMed

    Bronzino, J D; Abu-Hasaballah, K; Austin-LaFrance, R J; Morgane, P J

    1995-01-01

    The magnitude and duration of long-term potentiation (LTP) of perforant path/dentate granule cell synapses was examined in freely moving rats beginning at 15 days of age. Measures of dentate granule cell population EPSP slope and population spike amplitude (PSA) obtained before and after tetanization were used to evaluate the level of LTP. Tetanization resulted in significant enhancement of both the population EPSP slope (approximately +75%) and PSA (approximately +40%) measures. This enhancement was maintained without significant change for 18 h, after which both measures began a steady and continuous rise. Daily input/output response measures from age-matched nontetanized animals were used to factor out enhancement related to normal development. Under this schema, tetanization-induced enhancement of both EPSP slope and PSA measures decayed slowly, beginning 18-24 h after tetanization, returning to baseline 5 days after tetanization. Enhancement obtained from 90-day-old animals decayed to baseline 24 h after tetanization. The longer duration of LTP obtained from preweanlings is discussed with regard to the development of inhibitory systems modulating granule cell excitability.

  20. Granulation of increasingly hydrophobic formulations using a twin screw granulator.

    PubMed

    Yu, Shen; Reynolds, Gavin K; Huang, Zhenyu; de Matas, Marcel; Salman, Agba D

    2014-11-20

    The application of twin screw granulation in the pharmaceutical industry has generated increasing interest due to its suitability for continuous processing. However, an understanding of the impact of formulation properties such as hydrophobicity on intermediate and finished product quality has not yet been established. Hence, the current work investigated the granulation behaviour of three formulations containing increasing amounts of hydrophobic components using a Consigma™-1 twin screw granulator. Process conditions including powder feed rate, liquid to solid ratio, granulation liquid composition and screw configuration were also evaluated. The size of the wet granules was measured in order to enable exploration of granulation behaviour in isolation without confounding effects from downstream processes such as drying. The experimental observations indicated that the granulation process was not sensitive to the powder feed rate. The hydrophobicity led to heterogeneous liquid distribution and hence a relatively large proportion of un-wetted particles. Increasing numbers of kneading elements led to high shear and prolonged residence time, which acted to enhance the distribution of liquid and feeding materials. The bimodal size distributions considered to be characteristic of twin screw granulation were primarily ascribed to the breakage of relatively large granules by the kneading elements.

  1. High Pressure and [Ca2+] Produce an Inverse Modulation of Synaptic Input Strength and Network Excitability in the Rat Dentate Gyrus

    PubMed Central

    Talpalar, Thomas I.; Talpalar, Adolfo E.

    2016-01-01

    Hyperbaric environments induce the high pressure neurological syndrome (HPNS) characterized by hyperexcitability of the central nervous system (CNS) and memory impairment. Human divers and other animals experience the HPNS at pressures beyond 1.1 MPa. High pressure depresses synaptic transmission and alters its dynamics in various animal models. Medial perforant path (MPP) synapses connecting the medial entorhinal cortex with the hippocampal formation are suppressed by 50% at 10.1MPa. Reduction of synaptic inputs is paradoxically associated with enhanced ability of dentate gyrus (DG)’ granule cells (GCs) to generate spikes at high pressure. This mechanism allows MPP inputs to elicit standard GC outputs at 0.1–25 Hz frequencies under hyperbaric conditions. An increased postsynaptic gain of MPP inputs probably allows diving animals to perform in hyperbaric environments, but makes them vulnerable to high intensity/frequency stimuli producing hyperexcitability. Increasing extracellular Ca2+ ([Ca2+]o) partially reverted pressure-mediated depression of MPP inputs and increased MPP’s low-pass filter properties. We postulated that raising [Ca2+]o in addition to increase synaptic inputs may reduce network excitability in the DG potentially improving its function and reducing sensitivity to high intensity and pathologic stimuli. For this matter, we activated the MPP with single and 50 Hz frequency stimuli that simulated physiologic and deleterious conditions, while assessing the GC’s output under various conditions of pressure and [Ca2+]o. Our results reveal that the pressure and [Ca2+]o produce an inverse modulation on synaptic input strength and network excitability. These coincident phenomena suggest a potential general mechanism of networks that adjusts gain as an inverse function of synaptic inputs’ strength. Such mechanism may serve for adaptation to variable pressure and other physiological and pathological conditions and may explain the increased

  2. Chromaffin granules in the rat adrenal medulla release their secretory content in a particulate fashion.

    PubMed

    Crivellato, Enrico; Belloni, Anna; Nico, Beatrice; Nussdorfer, Gastone G; Ribatti, Domenico

    2004-03-01

    Exocytosis is considered the main route of granule discharge in chromaffin cells. We recently provided ultrastructural evidence suggesting that piecemeal degranulation (PMD) occurs in mouse adrenal chromaffin cells. In the present study, we processed rat adrenal glands for transmission electron microscopy (TEM), and examined chromaffin cells for changes characteristic of PMD. Both adrenaline (A)- and noradrenaline (NA)-storing cells express ultrastructural features suggestive of a slow and particulate mode of granule discharge. In adrenaline-containing cells, some granules present enlarged dimensions accompanied by eroded or dissolved matrices. Likewise, a number of granules in NA-releasing cells show content reduction with variably expanded granule chambers. Dilated, empty granule containers are recognizable in the cytoplasm of both cell types. Characteristically, altered granules and empty containers are seen intermingled with normal, resting granules. In addition, chromaffin granules often show irregular profiles, with budding or tail-like projections of their limiting membranes. Thirty 150-nm-diameter membrane-bound vesicles with a moderately electron-dense or -lucent internal structure are observable in the cytoplasm of both cell types. These vesicles are seen among the granules and some of them are fused with the perigranule membranes in the process of attachment to or budding from the granules. These data add further support to the concept that PMD may be an alternative secretory pathway in adrenal chromaffin cells.

  3. Altered regulation of brain-derived neurotrophic factor protein in hippocampus following slice preparation.

    PubMed

    Danzer, S C; Pan, E; Nef, S; Parada, L F; McNamara, J O

    2004-01-01

    Brain-derived neurotrophic factor (BDNF) and its cognate receptor tyrosine kinase B (TrkB) play important roles in regulating survival, structure, and function of CNS neurons. One method of studying the functions of these molecules has utilized in vitro hippocampal slice preparations. An important caveat to using slices, however, is that slice preparation itself might alter the expression of BDNF, thereby confounding experimental results. To address this concern, BDNF immunoreactivity was examined in rodent slices using two different methods of slice preparation. Rapid and anatomically selective regulation of BDNF content followed slice preparation using both methodologies; however, different patterns of altered BDNF immunoreactivity were observed. First, in cultured slices, BDNF content decreased in the dentate molecular layer and increased in the CA3 pyramidal cell layer and the mossy fiber pathway of the hippocampus after 30 min. Furthermore, an initially "punctate" pattern of BDNF labeling observed in the mossy fiber pathway of control sections changed to homogenous labeling of the pathway in vitro. In contrast to these findings, slices prepared as for acute slice physiology exhibited no change in BDNF content in the molecular layer and mossy fiber pathway 30 min after slicing, but exhibited significant increases in the dentate granule and CA3 pyramidal cell layers. These findings demonstrate that BDNF protein content is altered following slice preparation, that different methods of slice preparation produce different patterns of BDNF regulation, and raise the possibility that BDNF release and TrkB activation may also be regulated. These consequences of hippocampal slice preparation may confound analyses of exogenous or endogenous BDNF on hippocampal neuronal structure or function.

  4. Brain-derived neurotrophic factor, phosphorylated cyclic AMP response element binding protein and neuropeptide Y decline as early as middle age in the dentate gyrus and CA1 and CA3 subfields of the hippocampus.

    PubMed

    Hattiangady, Bharathi; Rao, Muddanna S; Shetty, Geetha A; Shetty, Ashok K

    2005-10-01

    The hippocampus is very susceptible to aging. Severely diminished dentate neurogenesis at middle age is one of the most conspicuous early changes in the aging hippocampus, which is likely linked to an early decline in the concentration of neurotrophic factors and signaling proteins that influence neurogenesis. We analyzed three proteins that are well-known to promote dentate neurogenesis and learning and memory function in the dentate gyrus and the hippocampal CA1 and CA3 subfields of young, middle-aged and aged F344 rats. These include the brain-derived neurotrophic factor (BDNF), the transcription factor phosphorylated cyclic AMP response element binding protein (p-CREB) and the neuropeptide neuropeptide Y (NPY). The BDNF was analyzed via ELISA and BDNF immunohistochemistry, the p-CREB through densitometric analysis of p-CREB immunopositive cells, and the NPY via stereological counting of NPY-immunopositive interneurons. We provide new evidence that the BDNF concentration, the p-CREB immunoreactivity and the number of NPY immunopositive interneurons decline considerably by middle age in both dentate gyrus and CA1 and CA3 subfields of the hippocampus. However, both BDNF concentration and NPY immunopositive interneuron numbers exhibit no significant decrease between middle age and old age. In contrast, the p-CREB immunoreactivity diminishes further during this period, which is also associated with reduced BDNF immunoreaction within the soma of dentate granule cells and hippocampal pyramidal neurons. Collectively, these results suggest that severely dampened dentate neurogenesis observed at middle age is linked at least partially to reduced concentrations of BDNF, p-CREB and NPY, as each of these proteins is a positive regulator of dentate neurogenesis. Dramatically diminished CREB phosphorylation (and persistently reduced levels of BDNF and NPY) at old age may underlie the learning and memory impairments observed during senescence.

  5. Gene expression profiling of the hippocampal dentate gyrus in an adult toxicity study captures a variety of neurodevelopmental dysfunctions in rat models of hypothyroidism.

    PubMed

    Shiraki, Ayako; Saito, Fumiyo; Akane, Hirotoshi; Akahori, Yumi; Imatanaka, Nobuya; Itahashi, Megu; Yoshida, Toshinori; Shibutani, Makoto

    2016-01-01

    We previously found that developmental hypothyroidism changed the expression of genes in the rat hippocampal dentate gyrus, a brain region where adult neurogenesis is known to occur. In the present study, we performed brain region-specific global gene expression profiling in an adult rat hypothyroidism model to see if it reflected the developmental neurotoxicity we saw in the developmental hypothyroidism model. Starting when male rats were 5 weeks old, we administered 6-propyl-2-thiouracil at a doses of 0, 0.1 and 10 mg kg(-1) body weight by gavage for 28 days. We selected four brain regions to represent both cerebral and cerebellar tissues: hippocampal dentate gyrus, cerebral cortex, corpus callosum and cerebellar vermis. We observed significant alterations in the expression of genes related to neural development (Eph family genes and Robo3) in the cerebral cortex and hippocampal dentate gyrus and in the expression of genes related to myelination (Plp1 and Mbp) in the hippocampal dentate gyrus. We observed only minor changes in the expression of these genes in the corpus callosum and cerebellar vermis. We used real-time reverse-transcription polymerase chain reaction to confirm Chrdl1, Hes5, Mbp, Plp1, Slit1, Robo3 and the Eph family transcript expression changes. The most significant changes in gene expression were found in the dentate gyrus. Considering that the gene expression profile of the adult dentate gyrus closely related to neurogenesis, 28-day toxicity studies looking at gene expression changes in adult hippocampal dentate gyrus may also detect possible developmental neurotoxic effects.

  6. Sex-related long-term behavioral and hippocampal cellular alterations after nociceptive stimulation throughout postnatal development in rats.

    PubMed

    Lima, Márcia; Malheiros, Jackeline; Negrigo, Aline; Tescarollo, Fabio; Medeiros, Magda; Suchecki, Deborah; Tannús, Alberto; Guinsburg, Ruth; Covolan, Luciene

    2014-02-01

    Early noxious stimuli may alter the neurogenesis rate in the dentate gyrus and the behavioral repertoire of adult rats. This study evaluated the long-term effects of noxious stimulation, imposed in different phases of development, on nociceptive and anxiety-like behaviors, hippocampal activation, cell proliferation, hippocampal BDNF and plasma corticosterone levels in 40 day-old male and female adolescents. Noxious stimulation was induced by intra-plantar injection of Complete Freund's adjuvant (CFA), on postnatal days (P) 1 (group P1), 8 (P8) or 21 (P21). Control animals were not stimulated in any way. On P21 a subset of animals from each group received BrdU and was perfused on P40 for identification of proliferating cells in the granule cell layer of the dentate gyrus. Another subset of rats was subjected to behavioral testing on P40 and one week later, to magnetic resonance imaging (MRI) acquisition. Noxious stimulation evoked hypoalgesia in adolescents, mainly in females (P < 0.02), reflected by greater latency to withdraw the paw and less paw lickings in the hot plate test than controls (P < 0.001). It also resulted in more time spent in the open arms, e.g., less anxiety-like behavior than controls (P < 0.01), especially in females (P < 0.01, compared with males). Proliferative cell rate in the dentate gyrus was the highest in P8 males and females (P < 0.001), with males exhibiting more proliferation than females on P1 and P8, which was directly related to the hippocampal levels of BDNF and inversely related to plasma corticosterone. Sex differences were also detected in manganese-enhanced MRI signal, which was more prominent in P1 females than males (P < 0.01). This study represents the first step of investigation on the cellular basis of the sex-dependent long-term consequences of nociceptive stimuli in newborns.

  7. Granulation techniques and technologies: recent progresses

    PubMed Central

    Shanmugam, Srinivasan

    2015-01-01

    Granulation, the process of particle enlargement by agglomeration technique, is one of the most significant unit operations in the production of pharmaceutical dosage forms, mostly tablets and capsules. Granulation process transforms fine powders into free-flowing, dust-free granules that are easy to compress. Nevertheless, granulation poses numerous challenges due to high quality requirement of the formed granules in terms of content uniformity and physicochemical properties such as granule size, bulk density, porosity, hardness, moisture, compressibility, etc. together with physical and chemical stability of the drug. Granulation process can be divided into two types: wet granulation that utilize a liquid in the process and dry granulation that requires no liquid. The type of process selection requires thorough knowledge of physicochemical properties of the drug, excipients, required flow and release properties, to name a few. Among currently available technologies, spray drying, roller compaction, high shear mixing, and fluid bed granulation are worth of note. Like any other scientific field, pharmaceutical granulation technology also continues to change, and arrival of novel and innovative technologies are inevitable. This review focuses on the recent progress in the granulation techniques and technologies such as pneumatic dry granulation, reverse wet granulation, steam granulation, moisture-activated dry granulation, thermal adhesion granulation, freeze granulation, and foamed binder or foam granulation. This review gives an overview of these with a short description about each development along with its significance and limitations. PMID:25901297

  8. Dentate total molecular layer interneurons mediate cannabinoid-sensitive inhibition.

    PubMed

    Yu, Jiandong; Swietek, Bogumila; Proddutur, Archana; Santhakumar, Vijayalakshmi

    2015-08-01

    Activity of the dentate gyrus, which gates information flow to the hippocampus, is under tight inhibitory regulation by interneurons with distinctive axonal projections, intrinsic and synaptic characteristics and neurochemical identities. Total molecular layer cells (TML-Cs), a class of morphologically distinct GABAergic neurons with axonal projections across the molecular layer, are among the most frequent interneuronal type in the dentate subgranular region. However, little is known about their synaptic and neurochemical properties. We demonstrate that synapses from morphologically identified TML-Cs to dentate interneurons are characterized by low release probability, facilitating short-term dynamics and asynchronous release. TML-Cs consistently show somatic and axonal labeling for the cannabinoid receptor type 1 (CB1 R) yet fail to express cholecystokinin (CCK) indicating their distinctive neurochemical identity. In paired recordings, the release probability at synapses between TML-Cs was increased by the CB1 R antagonist AM251, demonstrating baseline endocannabinoid regulation of TML-C synapses. Apart from defining the synaptic and neurochemical features of TML-Cs, our findings reveal the morphological identity of a class of dentate CB1 R-positive neurons that do not express CCK. Our findings indicate that TML-Cs can mediate cannabinoid sensitive feed-forward and feedback inhibition of dentate perforant path inputs.

  9. Distinct stages in stress granule assembly and disassembly

    PubMed Central

    Wheeler, Joshua R; Matheny, Tyler; Jain, Saumya; Abrisch, Robert; Parker, Roy

    2016-01-01

    Stress granules are non-membrane bound RNA-protein (RNP) assemblies that form when translation initiation is limited and contain a biphasic structure with stable core structures surrounded by a less concentrated shell. The order of assembly and disassembly of these two structures remains unknown. Time course analysis of granule assembly suggests that core formation is an early event in granule assembly. Stress granule disassembly is also a stepwise process with shell dissipation followed by core clearance. Perturbations that alter liquid-liquid phase separations (LLPS) driven by intrinsically disordered protein regions (IDR) of RNA binding proteins in vitro have the opposite effect on stress granule assembly in vivo. Taken together, these observations argue that stress granules assemble through a multistep process initiated by stable assembly of untranslated mRNPs into core structures, which could provide sufficient high local concentrations to allow for a localized LLPS driven by IDRs on RNA binding proteins. DOI: http://dx.doi.org/10.7554/eLife.18413.001 PMID:27602576

  10. Enhanced acoustic startle responding in rats with radiation-induced hippocampal granule cell hypoplasia

    SciTech Connect

    Mickley, G.A.; Ferguson, J.L.

    1989-01-01

    Irradiation of the neonatal rat hippocampus reduces the proliferation of granule cells in the dentate gyrus and results in locomotor hyperactivity, behavioral preservation, and deficits on some learned tasks. In order to address the role of changes in stimulus salience and behavioral inhibition in animals with this type of brain damage, irradiated and normal rats were compared in their startle reactions to an acoustic stimulus. Irradiated rats startled with a consistently higher amplitude than control and were more likely to exhibit startle responses. These animals with hippocampal damage also failed to habituate to the startle stimulus and, under certain circumstances, showed potentiated startle responses after many tone presentations.

  11. A comparison of granules produced by high-shear and fluidized-bed granulation methods.

    PubMed

    Morin, Garett; Briens, Lauren

    2014-08-01

    Placebo granules were manufactured by both wet high-shear and fluidized-bed techniques. The granules were compared based on size, shape, surface morphology, and a variety of different flowability measurements. This comparison showed that granule formation and growth were different, with induction growth for high-shear granulation and steady growth for fluidized-bed granulation. Final granules from high-shear granulation were more spherical and dense compared with the irregular granules from fluidized-bed granulation. The high-shear granules demonstrated better overall flow properties.

  12. NMDA-dependent mechanisms only affect the BOLD response in the rat dentate gyrus by modifying local signal processing

    PubMed Central

    Tiede, Regina; Krautwald, Karla; Fincke, Anja; Angenstein, Frank

    2012-01-01

    The role of N-methyl--aspartate (NMDA) receptor-mediated mechanisms in the formation of a blood oxygen level-dependent (BOLD) response was studied using electrical stimulation of the right perforant pathway. Stimulation of this fiber bundle triggered BOLD responses in the right hippocampal formation and in the left entorhinal cortex. The perforant pathway projects to and activates the dentate gyrus monosynaptically, activation in the contralateral entorhinal cortex is multisynaptic and requires forwarding and processing of signals. Application of the NMDA receptor antagonist MK801 during stimulation had no effect on BOLD responses in the right dentate gyrus, but reduced the BOLD responses in the left entorhinal cortex. In contrast, application of MK801 before the first stimulation train reduced the BOLD response in both regions. Electrophysiological recordings revealed that the initial stimulation trains changed the local processing of the incoming signals in the dentate gyrus. This altered electrophysiological response was not further changed by a subsequent application of MK801, which is in agreement with an unchanged BOLD response. When MK801 was present during the first stimulation train, a dissimilar electrophysiological response pattern was observed and corresponds to an altered BOLD response, indicating that NMDA-dependent mechanisms indirectly affect the BOLD response, mainly via modifying local signal processing and subsequent propagation. PMID:22167232

  13. The enigmatic mossy cell of the dentate gyrus

    PubMed Central

    Scharfman, Helen E.

    2017-01-01

    Mossy cells comprise a large fraction of the cells in the hippocampal dentate gyrus, suggesting that their function in this region is important. They are vulnerable to ischaemia, traumatic brain injury and seizures, and their loss could contribute to dentate gyrus dysfunction in such conditions. Mossy cell function has been unclear because these cells innervate both glutamatergic and GABAergic neurons within the dentate gyrus, contributing to a complex circuitry. It has also been difficult to directly and selectively manipulate mossy cells to study their function. In light of the new data generated using methods to preferentially eliminate or activate mossy cells in mice, it is timely to ask whether mossy cells have become any less enigmatic than they were in the past. PMID:27466143

  14. Doublecortin (DCX) is not Essential for Survival and Differentiation of Newborn Neurons in the Adult Mouse Dentate Gyrus

    PubMed Central

    Dhaliwal, Jagroop; Xi, Yanwei; Bruel-Jungerman, Elodie; Germain, Johanne; Francis, Fiona; Lagace, Diane C.

    2016-01-01

    In the adult brain, expression of the microtubule-associated protein Doublecortin (DCX) is associated with neural progenitor cells (NPCs) that give rise to new neurons in the dentate gyrus. Many studies quantify the number of DCX-expressing cells as a proxy for the level of adult neurogenesis, yet no study has determined the effect of removing DCX from adult hippocampal NPCs. Here, we use a retroviral and inducible mouse transgenic approach to either knockdown or knockout DCX from adult NPCs in the dentate gyrus and examine how this affects cell survival and neuronal maturation. Our results demonstrate that shRNA-mediated knockdown of DCX or Cre-mediated recombination in floxed DCX mice does not alter hippocampal neurogenesis and does not change the neuronal fate of the NPCs. Together these findings show that the survival and maturation of adult-generated hippocampal neurons does not require DCX. PMID:26793044

  15. Age-related changes in dentate gyrus cell numbers, neurogenesis, and associations with cognitive impairments in the rhesus monkey

    PubMed Central

    Ngwenya, Laura B.; Heyworth, Nadine C.; Shwe, Yamin; Moore, Tara L.; Rosene, Douglas L.

    2015-01-01

    The generation of new neurons in the adult mammalian brain is well-established for the hippocampal dentate gyrus (DG). However, the role of neurogenesis in hippocampal function and cognition, how it changes in aging, and the mechanisms underlying this are yet to be elucidated in the monkey brain. To address this, we investigated adult neurogenesis in the DG of 42 rhesus monkeys (39 cognitively tested) ranging in age from young adult to the elderly. We report here that there is an age-related decline in proliferation and a delayed development of adult neuronal phenotype. Additionally, we show that many of the new neurons survive throughout the lifetime of the animal and may contribute to a modest increase in total neuron number in the granule cell layer of the DG over the adult life span. Lastly, we find that measures of decreased adult neurogenesis are only modestly predictive of age-related cognitive impairment. PMID:26236203

  16. A hypothesis for temporal coding of young and mature granule cells

    PubMed Central

    Rangel, Lara M.; Quinn, Laleh K.; Chiba, Andrea A.; Gage, Fred H.; Aimone, James B.

    2013-01-01

    While it has been hypothesized that adult neurogenesis (NG) plays a role in the encoding of temporal information at long time-scales, the temporal relationship of immature cells to the highly rhythmic network activity of the hippocampus has been largely unexplored. Here, we present a theory for how the activity of immature adult-born granule cells relates to hippocampal oscillations. Our hypothesis is that theta rhythmic (5–10 Hz) excitatory and inhibitory inputs into the hippocampus could differentially affect young and mature granule cells due to differences in intrinsic physiology and synaptic inhibition between the two cell populations. Consequently, immature cell activity may occur at broader ranges of theta phase than the activity of their mature counterparts. We describe how this differential influence on young and mature granule cells could separate the activity of differently aged neurons in a temporal coding regime. Notably, this process could have considerable implications on how the downstream CA3 region interprets the information conveyed by young and mature granule cells. To begin to investigate the phasic behavior of granule cells, we analyzed in vivo recordings of the rat dentate gyrus (DG), observing that the temporal behavior of granule cells with respect to the theta rhythm is different between rats with normal and impaired levels of NG. Specifically, in control animals, granule cells exhibit both strong and weak coupling to the phase of the theta rhythm. In contrast, the distribution of phase relationships in NG-impaired rats is shifted such that they are significantly stronger. These preliminary data support our hypothesis that immature neurons could distinctly affect the temporal dynamics of hippocampal encoding. PMID:23717259

  17. Properties of doublecortin-(DCX)-expressing cells in the piriform cortex compared to the neurogenic dentate gyrus of adult mice.

    PubMed

    Klempin, Friederike; Kronenberg, Golo; Cheung, Giselle; Kettenmann, Helmut; Kempermann, Gerd

    2011-01-01

    The piriform cortex receives input from the olfactory bulb and (via the entorhinal cortex) sends efferents to the hippocampus, thereby connecting the two canonical neurogenic regions of the adult rodent brain. Doublecortin (DCX) is a cytoskeleton-associated protein that is expressed transiently in the course of adult neurogenesis. Interestingly, the adult piriform cortex, which is usually considered non-neurogenic (even though some reports exist that state otherwise), also contains an abundant population of DCX-positive cells. We asked how similar these cells would be to DCX-positive cells in the course of adult hippocampal neurogenesis. Using BAC-generated transgenic mice that express GFP under the DCX promoter, we studied DCX-expression and electrophysiological properties of DCX-positive cells in the mouse piriform cortex in comparison with the dentate gyrus. While one class of cells in the piriform cortex indeed showed features similar to newly generated immature granule neurons, the majority of DCX cells in the piriform cortex was mature and revealed large Na+ currents and multiple action potentials. Furthermore, when proliferative activity was assessed, we found that all DCX-expressing cells in the piriform cortex were strictly postmitotic, suggesting that no DCX-positive "neuroblasts" exist here as they do in the dentate gyrus. We conclude that DCX in the piriform cortex marks a unique population of postmitotic neurons with a subpopulation that retains immature characteristics associated with synaptic plasticity. DCX is thus, per se, no marker of neurogenesis but might be associated more broadly with plasticity.

  18. RB regulates the production and the survival of newborn neurons in the embryonic and adult dentate gyrus.

    PubMed

    Vandenbosch, Renaud; Clark, Alysen; Fong, Bensun C; Omais, Saad; Jaafar, Carine; Dugal-Tessier, Delphie; Dhaliwal, Jagroop; Lagace, Diane C; Park, David S; Ghanem, Noël; Slack, Ruth S

    2016-11-01

    In mammals, hippocampal dentate gyrus granule cells (DGCs) constitute a particular neuronal population produced both during embryogenesis and adult life, and play key roles in neural plasticity and memory. However, the molecular mechanisms regulating neurogenesis in the dentate lineage throughout development and adulthood are still not well understood. The Retinoblastoma protein (RB), a transcriptional repressor primarily involved in cell cycle control and cell death, plays crucial roles during cortical development but its function in the formation and maintenance of DGCs remains unknown. Here, we show that loss of RB during embryogenesis induces massive ectopic proliferation and delayed cell cycle exit of young DGCs specifically at late developmental stages but without affecting stem cells. This phenotype was partially counterbalanced by increased cell death. Similarly, during adulthood, loss of RB causes ectopic proliferation of newborn DGCs and dramatically impairs their survival. These results demonstrate a crucial role for RB in the generation and the survival of DGCs in the embryonic and the adult brain. © 2016 Wiley Periodicals, Inc.

  19. Mesostructure of the Solar Granulation

    NASA Astrophysics Data System (ADS)

    Abdussamatov, H. I.

    2000-03-01

    Quasi-periodic variations in the thermodynamic and hydrodynamic fine-structure properties of the granulation field along the photospheric surface are estimated quantitatively. The darkest vast intergranular lanes, called the intergranular knots, are the most important indicator of their physical properties. The formulated new definitions of "granule" and "intergranular lane" require a revision of the previous results. The definition of mesogranulation is given, and the method of its detection in the granulation field is described. The following important quantitative results, which established the extent and nature of the physical relationship between the granulation and mesogranulation fields, have been obtained for the first time: (1) the intensity amplitude of granules in mesogranules (Delta I(gr)/I_0)_msgr = +10.3% is a factor of 1.4 larger than that of granules in intermesogranular regions [(Delta I(gr)/I_0)_imsgr = +7.3%], whereas the intensity amplitude of intergranular lanes in mesogranules [(Delta I(igr)/I_0)_msgr = -6.0%] is a factor of 1.4 smaller than that of intergranular lanes in intermesogranular regions [(Delta I(igr)/I_0)_imsgr = -8.4%]; (2) the mean intensities of photospheric granules and intergranular lanes are (Delta I(gr)/I_0)_phot = +9.2% and (Delta I(igr)/I_0)_phot = -7.5%, respectively; (3) granules cover 59% of the area of mesogranules, 45% of the area of the photosphere, and 31% of the area of intermesogranular regions, while intergranular lanes cover 41, 55, and 69% of these areas, respectively; (4) intergranular knots and bright granules virtually never formed and do not exist in mesogranules and intermesogranular regions, respectively; (5) the amplitudes of intensity fluctuations in mesogranules and intermesogranular regions, as well as the areas occupied by them (49.4 and 50.6%, respectively), essentially level off, Delta I(msgr)/I_0 = +3.6% and Delta I(imsgr)/I_0 = -3.5%, respectively.

  20. Increased excitatory synaptic input to granule cells from hilar and CA3 regions in a rat model of temporal lobe epilepsy

    PubMed Central

    Zhang, Wei; Huguenard, John R.; Buckmaster, Paul S.

    2012-01-01

    One potential mechanism of temporal lobe epilepsy is recurrent excitation of dentate granule cells through aberrant sprouting of their axons (mossy fibers), which is found in many patients and animal models. However, correlations between the extent of mossy fiber sprouting and seizure frequency are weak. Additional potential sources of granule cell recurrent excitation that would not have been detected by markers of mossy fiber sprouting in previous studies include surviving mossy cells and proximal CA3 pyramidal cells. To test those possibilities in hippocampal slices from epileptic pilocarpine-treated rats, laser scanning glutamate uncaging was used to randomly and focally activate neurons in the granule cell layer, hilus, and proximal CA3 pyramidal cell layer while measuring evoked excitatory postsynaptic currents (EPSCs) in normotopic granule cells. Consistent with mossy fiber sprouting, a higher proportion of glutamate-uncaging spots in the granule cell layer evoked EPSCs in epileptic rats compared to controls. In addition, stimulation spots in the hilus and proximal CA3 pyramidal cell layer were more likely to evoke EPSCs in epileptic rats, despite significant neuron loss in those regions. Furthermore, synaptic strength of recurrent excitatory inputs to granule cells from CA3 pyramidal cells and other granule cells was increased in epileptic rats. These findings reveal substantial levels of excessive, recurrent, excitatory synaptic input to granule cells from neurons in the hilus and proximal CA3 field. The aberrant development of these additional positive-feedback circuits might contribute to epileptogenesis in temporal lobe epilepsy. PMID:22279204

  1. Calcium precipitate induced aerobic granulation.

    PubMed

    Wan, Chunli; Lee, Duu-Jong; Yang, Xue; Wang, Yayi; Wang, Xingzu; Liu, Xiang

    2015-01-01

    Aerobic granulation is a novel biotechnology for wastewater treatment. This study refined existing aerobic granulation mechanisms as a sequencing process including formation of calcium precipitate under alkaline pH to form inorganic cores, followed by bacterial attachment and growth on these cores to form the exopolysaccharide matrix. Mature granules comprised an inner core and a matrix layer and a rim layer with enriched microbial strains. The inorganic core was a mix of different crystals of calcium and phosphates. Functional strains including Sphingomonas sp., Paracoccus sp. Sinorhizobium americanum strain and Flavobacterium sp. attached onto the cores. These functional strains promote c-di-GMP production and the expression by Psl and Alg genes for exopolysaccharide production to enhance formation of mature granules.

  2. Process optimization for continuous extrusion wet granulation.

    PubMed

    Tan, Li; Carella, Anthony J; Ren, Yukun; Lo, Julian B

    2011-08-01

    Three granulating binders in high drug-load acetaminophen blends were evaluated using high shear granulation and extrusion granulation. A polymethacrylate binder enhanced tablet tensile strength with rapid disintegration in simulated gastric fluid, whereas polyvinylpyrrolidone and hydroxypropyl cellulose binders produced less desirable tablets. Using the polymethacrylate binder, the extrusion granulation process was studied regarding the effects of granulating liquid, injection rate and screw speed on granule properties. A full factorial experimental design was conducted to allow the statistical analysis of interactions between extrusion process parameters. Response variables considered in the study included extruder power consumption (screw loading), granule bulk/tapped density, particle size distribution, tablet hardness, friability, disintegration time and dissolution.

  3. Adult Neurogenesis in the Mammalian Hippocampus: Why the Dentate Gyrus?

    ERIC Educational Resources Information Center

    Drew, Liam J.; Fusi, Stefano; Hen, René

    2013-01-01

    In the adult mammalian brain, newly generated neurons are continuously incorporated into two networks: interneurons born in the subventricular zone migrate to the olfactory bulb, whereas the dentate gyrus (DG) of the hippocampus integrates locally born principal neurons. That the rest of the mammalian brain loses significant neurogenic capacity…

  4. Differential Recruitment of Dentate Gyrus Interneuron Types by Commissural Versus Perforant Pathways.

    PubMed

    Hsu, Tsan-Ting; Lee, Cheng-Ta; Tai, Ming-Hong; Lien, Cheng-Chang

    2016-06-01

    Gamma-aminobutyric acidergic (GABAergic) interneurons (INs) in the dentate gyrus (DG) provide inhibitory control to granule cell (GC) activity and thus gate incoming signals to the hippocampus. However, how various IN subtypes inhibit GCs in response to different excitatory input pathways remains mostly unknown. By using electrophysiology and optogenetics, we investigated neurotransmission of the hilar commissural pathway (COM) and the medial perforant path (MPP) to the DG in acutely prepared mouse slices. We found that the short-term dynamics of excitatory COM-GC and MPP-GC synapses was similar, but that the dynamics of COM- and MPP-mediated inhibition measured in GCs was remarkably different, during theta-frequency stimulation. This resulted in the increased inhibition-excitation (I/E) ratios in single GCs for COM stimulation, but decreased I/E ratios for MPP stimulation. Further analysis of pathway-specific responses in identified INs revealed that basket cell-like INs, total molecular layer- and molecular layer-like cells, received greater excitation and were more reliably recruited by the COM than by the MPP inputs. In contrast, hilar perforant path-associated and hilar commissural-associational pathway-related-like cells were minimally activated by both inputs. These results demonstrate that distinct IN subtypes are preferentially recruited by different inputs to the DG, and reveal their relative contributions in COM-mediated feedforward inhibition.

  5. Neonatal isolation enhances hippocampal dentate response to tetanization in freely moving juvenile male rats.

    PubMed

    Kehoe, P; Hoffman, J H; Austin-LaFrance, R J; Bronzino, J D

    1995-12-01

    The impact of early neonatal isolation on measures of hippocampal neuronal plasticity was examined in freely moving male rats at 30 days of age. Beginning on Postnatal (PN) Day 2, one-half of pups from each experimental litter were individually isolated from the nest, dam, and siblings for a period of 1 h per day over PN Days 2-9, while their siblings remained in the nest. In addition, randomly selected litters served as unhandled controls. On PN Day 26 all pups were weaned and chronically implanted for recording of evoked field potentials and induction of hippocampal longterm potentiation. At 30 days of age, pups from the three treatment groups (isolated, nonisolated siblings, and unhandled controls) were tested for their ability to establish and maintain long-term potentiation across the perforant path/hippocampal dentate granule cell synapse. Changes in population EPSP slope and population spike amplitude (PSA) recorded following tetanization were used to assess the effects of neonatal isolation of hippocampal response measures. No significant between-group differences were obtained for input/output response curves constructed prior to tetanization. All three groups showed immediate and significant enhancement of the PSA measure at 15 min posttetanization. The level of PSA enhancement obtained from previously isolated pups was significantly greater than that obtained from both the nonisolated sibling and unhandled control groups.(ABSTRACT TRUNCATED AT 250 WORDS)

  6. Retrieval of morphine-associated context induces cFos in dentate gyrus neurons.

    PubMed

    Rivera, Phillip D; Raghavan, Ramya K; Yun, Sanghee; Latchney, Sarah E; McGovern, Mary-Katherin; García, Emily F; Birnbaum, Shari G; Eisch, Amelia J

    2015-04-01

    Addiction has been proposed to emerge from associations between the drug and the reward-associated contexts. This associative learning has a cellular correlate, as there are more cFos+ neurons in the hippocampal dentate gyrus (DG) after psychostimulant conditioned place preference (CPP) versus saline controls. However, it is unknown whether morphine CPP leads to a similar DG activation, or whether DG activation is due to locomotion, handling, pharmacological effects, or-as data from contextual fear learning suggests-exposure to the drug-associated context. To explore this, we employed an unbiased, counterbalanced, and shortened CPP design that led to place preference and more DG cFos+ cells. Next, mice underwent morphine CPP but were then sequestered into the morphine-paired (conditioned stimulus+ [CS+]) or saline-paired (CS-) context on test day. Morphine-paired mice sequestered to CS+ had ∼30% more DG cFos+ cells than saline-paired mice. Furthermore, Bregma analysis revealed morphine-paired mice had more cFos+ cells in CS+ compared to CS- controls. Notably, there was no significant difference in DG cFos+ cell number after handling alone or after receiving morphine in home cage. Thus, retrieval of morphine-associated context is accompanied by activation of hippocampal DG granule cell neurons.

  7. Mossy fiber synaptic transmission: communication from the dentate gyrus to area CA3.

    PubMed

    Jaffe, David B; Gutiérrez, Rafael

    2007-01-01

    Communication between the dentate gyrus (DG) and area CA3 of the hippocampus proper is transmitted via axons of granule cells--the mossy fiber (MF) pathway. In this review we discuss and compare the properties of transmitter release from the MFs onto pyramidal neurons and interneurons. An examination of the anatomical connectivity from DG to CA3 reveals a surprising interplay between excitation and inhibition for this circuit. In this respect it is particularly relevant that the major targets of the MFs are interneurons and that the consequence of MF input into CA3 may be inhibitory or excitatory, conditionally dependent on the frequency of input and modulatory regulation. This is further complicated by the properties of transmitter release from the MFs where a large number of co-localized transmitters, including GABAergic inhibitory transmitter release, and the effects of presynaptic modulation finely tune transmitter release. A picture emerges that extends beyond the hypothesis that the MFs are simply "detonators" of CA3 pyramidal neurons; the properties of synaptic information flow from the DG have more subtle and complex influences on the CA3 network.

  8. Formation of secretory granules by chromogranins.

    PubMed

    Inomoto, Chie; Osamura, Robert Yoshiyuki

    2009-12-01

    This review article covers the molecular mechanisms of secretory granule formation by chromogranin transfection. Recently, a few investigators have reported that the transfection of chromogranin A and B produces the structures of secretory granules. We used the GFP-chromogranin A transfection method to nonendocrine cells, COS-7 cells, which are not equipped with secretory granules. Despite the absence of endogenous secretory granules in nontransfected COS-7 cells, COS-7 cells transfected with chromogranin A contained granule-like structures in electron micrographs. The granules were composed of an outer limiting membrane with core structures that were interpreted as secretory granules. Human chromogranin A (CgA) labeled with 5-nm gold particles was present in several dense-core granules in our previous electron microscopy study. This review depicts the role of chromogranin A in the formation of secretory granules. It emphasizes the application of recently developed new technologies and the genesis of secretory granules.

  9. Fine processes of Nestin-GFP–positive radial glia-like stem cells in the adult dentate gyrus ensheathe local synapses and vasculature

    PubMed Central

    Moss, Jonathan; Gebara, Elias; Sánchez-Pascual, Irene; O’Laoi, Ruadhan; El M’Ghari, Imane; Kocher-Braissant, Jacqueline; Ellisman, Mark H.; Toni, Nicolas

    2016-01-01

    Adult hippocampal neurogenesis relies on the activation of neural stem cells in the dentate gyrus, their division, and differentiation of their progeny into mature granule neurons. The complex morphology of radial glia-like (RGL) stem cells suggests that these cells establish numerous contacts with the cellular components of the neurogenic niche that may play a crucial role in the regulation of RGL stem cell activity. However, the morphology of RGL stem cells remains poorly described. Here, we used light microscopy and electron microscopy to examine Nestin-GFP transgenic mice and provide a detailed ultrastructural reconstruction analysis of Nestin-GFP–positive RGL cells of the dentate gyrus. We show that their primary processes follow a tortuous path from the subgranular zone through the granule cell layer and ensheathe local synapses and vasculature in the inner molecular layer. They share the ensheathing of synapses and vasculature with astrocytic processes and adhere to the adjacent processes of astrocytes. This extensive interaction of processes with their local environment could allow them to be uniquely receptive to signals from local neurons, glia, and vasculature, which may regulate their fate. PMID:27091993

  10. Linking granulation performance with residence time and granulation liquid distributions in twin-screw granulation: An experimental investigation.

    PubMed

    Kumar, Ashish; Alakarjula, Maija; Vanhoorne, Valérie; Toiviainen, Maunu; De Leersnyder, Fien; Vercruysse, Jurgen; Juuti, Mikko; Ketolainen, Jarkko; Vervaet, Chris; Remon, Jean Paul; Gernaey, Krist V; De Beer, Thomas; Nopens, Ingmar

    2016-07-30

    Twin-screw granulation is a promising wet granulation technique for the continuous manufacturing of pharmaceutical solid dosage forms. A twin screw granulator displays a short residence time. Thus, the solid-liquid mixing must be achieved quickly by appropriate arrangement of transport and kneading elements in the granulator screw allowing the production of granules with a size distribution appropriate for tableting. The distribution of residence time and granulation liquid is governed by the field conditions (such as location and length of mixing zones) in the twin-screw granulator, thus contain interesting information on granulation time, mixing and resulting sub-processes such as wetting, aggregation and breakage. In this study, the impact of process (feed rate, screw speed and liquid-to-solid ratio) and equipment parameters (number of kneading discs and stagger angle) on the residence time (distribution), the granulation liquid-powder mixing and the resulting granule size distributions during twin-screw granulation were investigated. Residence time and axial mixing data was extracted from tracer maps and the solid-liquid mixing was quantified from moisture maps, obtained by monitoring the granules at the granulator outlet using near infra-red chemical imaging (NIR-CI). The granule size distribution was measured using the sieving method. An increasing screw speed dominantly reduced the mean residence time. Interaction of material throughput with the screw speed and with the number of kneading discs led to most variation in the studied responses including residence time and mixing capacity. At a high screw speed, granulation yield improved due to high axial mixing. However, increasing material throughput quickly lowers the yield due to insufficient mixing of liquid and powder. Moreover, increasing liquid-to-solid ratio resulted in more oversized granules, and the fraction of oversized granules further increased at higher throughput. Although an increasing number

  11. Microtubule-dependent association of AKAP350A and CCAR1 with RNA stress granules

    PubMed Central

    Kolobova, Elena; Efimov, Andrey; Kaverina, Irina; Rishi, Arun K.; Schrader, John W.; Ham, Amy-Joan; Larocca, M. Cecilia; Goldenring, James R.

    2009-01-01

    Recent investigations have highlighted the importance of subcellular localization of mRNAs to cell function. While AKAP350A, a multifunctional scaffolding protein, localizes to the Golgi apparatus and centrosomes, we have now identified a cytosolic pool of AKAP350A. Analysis of AKAP350A scaffolded complexes revealed two novel interacting proteins, CCAR1 and caprin-1. CCAR1, caprin-1 and AKAP350A along with G3BP, a stress granule marker, relocate to RNA stress granules after arsenite treatment. Stress also caused loss of AKAP350 from the Golgi and fragmentation of the Golgi apparatus. Disruption of microtubules with nocodazole altered stress granule formation and changed their morphology by preventing fusion of stress granules. In the presence of nocodazole, arsenite induced smaller granules with the vast majority of AKAP350A and CCAR1 separated from G3BP-containing granules. Similar to nocodazole treatment, reduction of AKAP350A or CCAR1 expression also altered the size and number of G3BP-containing stress granules induced by arsenite treatment. A limited set of 69 mRNA transcripts was immunisolated with AKAP350A even in the absence of stress, suggesting the association of AKAP350A with mRNA transcripts. These results provide the first evidence for the microtubule dependent association of AKAP350A and CCAR1 with RNA stress granules. PMID:19073175

  12. Expression of an engineered granule-bound Escherichia coli glycogen branching enzyme in potato results in severe morphological changes in starch granules.

    PubMed

    Huang, Xing-Feng; Nazarian-Firouzabadi, Farhad; Vincken, Jean-Paul; Ji, Qin; Suurs, Luc C J M; Visser, Richard G F; Trindade, Luisa M

    2013-05-01

    The Escherichia coli glycogen branching enzyme (GLGB) was fused to either the C- or N-terminus of a starch-binding domain (SBD) and expressed in two potato genetic backgrounds: the amylose-free mutant (amf) and an amylose-containing line (Kardal). Regardless of background or construct used, a large amount of GLGB/SBD fusion protein was accumulated inside the starch granules, however, without an increase in branching. The presence of GLGB/SBD fusion proteins resulted in altered morphology of the starch granules in both genetic backgrounds. In the amf genetic background, the starch granules showed both amalgamated granules and porous starch granules, whereas in Kardal background, the starch granules showed an irregular rough surface. The altered starch granules in both amf and Kardal backgrounds were visible from the initial stage of potato tuber development. High-throughput transcriptomic analysis showed that expression of GLGB/SBD fusion protein in potato tubers did not affect the expression level of most genes directly involved in the starch biosynthesis except for the up-regulation of a beta-amylase gene in Kardal background. The beta-amylase protein could be responsible for the degradation of the extra branches potentially introduced by GLGB.

  13. Identification of miRNAs differentially expressed in human epilepsy with or without granule cell pathology.

    PubMed

    Zucchini, Silvia; Marucci, Gianluca; Paradiso, Beatrice; Lanza, Giovanni; Roncon, Paolo; Cifelli, Pierangelo; Ferracin, Manuela; Giulioni, Marco; Michelucci, Roberto; Rubboli, Guido; Simonato, Michele

    2014-01-01

    The microRNAs (miRNAs) are small size non-coding RNAs that regulate expression of target mRNAs at post-transcriptional level. miRNAs differentially expressed under pathological conditions may help identifying mechanisms underlying the disease and may represent biomarkers with prognostic value. However, this kind of studies are difficult in the brain because of the cellular heterogeneity of the tissue and of the limited access to fresh tissue. Here, we focused on a pathology affecting specific cells in a subpopulation of epileptic brains (hippocampal granule cells), an approach that bypasses the above problems. All patients underwent surgery for intractable temporal lobe epilepsy and had hippocampal sclerosis associated with no granule cell pathology in half of the cases and with type-2 granule cell pathology (granule cell layer dispersion or bilamination) in the other half. The expression of more than 1000 miRNAs was examined in the laser-microdissected dentate granule cell layer. Twelve miRNAs were differentially expressed in the two groups. One of these, miR487a, was confirmed to be expressed at highly differential levels in an extended cohort of patients, using RT-qPCR. Bioinformatics searches and RT-qPCR verification identified ANTXR1 as a possible target of miR487a. ANTXR1 may be directly implicated in granule cell dispersion because it is an adhesion molecule that favors cell spreading. Thus, miR487a could be the first identified element of a miRNA signature that may be useful for prognostic evaluation of post-surgical epilepsy and may drive mechanistic studies leading to the identification of therapeutic targets.

  14. Dentate gyrus–CA3 glutamate release/NMDA transmission mediates behavioral despair and antidepressant-like responses to leptin

    PubMed Central

    Wang, Xuezhen; Zhang, Di; Lu, Xin-Yun

    2014-01-01

    Compelling evidence supports the important role of the glutamatergic system in the pathophysiology of major depression and also as a target for rapid-acting antidepressants. However, the functional role of glutamate release/transmission in behavioral processes related to depression and antidepressant efficacy remains to be elucidated. In this study, glutamate release and behavioral responses to tail suspension, a procedure commonly used for inducing behavioral despair, were simultaneously monitored in real time. The onset of tail suspension stress evoked a rapid increase in glutamate release in hippocampal field CA3, which declined gradually after its offset. Blockade of NMDA receptors by intra-CA3 infusion of MK-801, a non-competitive NMDA receptor antagonist, reversed behavioral despair. The CA3 was innervated by granule neurons expressing the leptin receptor (LepRb) in the dentate gyrus (DG), representing a subpopulation of granule neurons that were devoid of stress-induced activation. Leptin treatment dampened tail suspension-evoked glutamate release in CA3. On the other hand, intra-CA3 infusion of NMDA blocked the antidepressant-like effect of leptin in reversing behavioral despair in both the tail suspension and forced swim tests, which involved activation of Akt signaling in DG. Together, these results suggest that the DG-CA3 glutamatergic pathway is critical for mediating behavioral despair and antidepressant-like responses to leptin. PMID:25092243

  15. Riluzole enhances expression of brain-derived neurotrophic factor with consequent proliferation of granule precursor cells in the rat hippocampus.

    PubMed

    Katoh-Semba, Ritsuko; Asano, Tomiko; Ueda, Hiroshi; Morishita, Rika; Takeuchi, Ikuo K; Inaguma, Yutaka; Kato, Kanefusa

    2002-08-01

    The dentate gyrus of the hippocampus, generating new cells throughout life, is essential for normal recognition memory performance. Reduction of brain-derived neurotrophic factor (BDNF) in this structure impairs its functions. To elucidate the association between BDNF levels and hippocampal neurogenesis, we first conducted a search for compounds that stimulate endogenous BDNF production in hippocampal granule neurons. Among ion channel modulators tested, riluzole, a neuroprotective agent with anticonvulsant properties that is approved for treatment of amyotrophic lateral sclerosis, was highly effective as a single dose by an intraperitoneal injection, causing a rise in BDNF localized in dentate granule neurons, the hilus, and the stratum radiatum of the CA3 region. Repeated, but not single, injections resulted in prolonged elevation of hippocampal BDNF and were associated with increased numbers of newly generated cells in the granule cell layer. This appeared due to promoted proliferation rather than survival of precursor cells, many of which differentiated into neurons. Intraventricular administration of BDNF-specific antibodies blocked such riluzole effects, suggesting that BDNF increase is necessary for the promotion of precursor proliferation. Our results suggest the basis for a new strategy for treatment of memory dysfunction.

  16. Control of bisphosphonate release using hydroxyapatite granules.

    PubMed

    Seshima, Hisashi; Yoshinari, Masao; Takemoto, Shinji; Hattori, Masayuki; Kawada, Eiji; Inoue, Takashi; Oda, Yutaka

    2006-08-01

    The efficacy of hydroxyapatite (HAp) as a carrier was investigated to establish a method of local administration of bisphosphonates (Bps), which has currently been administered systemically. HAp granules (300-500 microm in size) with different physicochemical features were prepared by altering the sintering temperature. To ascertain the physicochemical properties of the HAp granules, their crystallinity was assessed using X-ray diffraction, the surface morphology was examined under scanning electron microscopy, and the specific surface area and calcium dissolution were evaluated. Different Bps-HAp composites were subsequently prepared and the concentration of Bps released from these composites was measured. The influence of Bps-HAp composites on the rate of osteoclast survival was also evaluated. The results revealed that (1) HAp solubility depends on the sintering temperature; (2) The concentration of released Bps could be controlled by regulating the sintering temperature of HAp as a carrier; and (3) Bps released from Bps-HAp composites reduced the number of osteoclasts. These findings indicated that Bps-HAp composites could be locally administered as a drug delivery system to areas with bone resorption.

  17. Ovarian steroids alter mu opioid receptor trafficking in hippocampal parvalbumin GABAergic interneurons.

    PubMed

    Torres-Reveron, Annelyn; Williams, Tanya J; Chapleau, Jeanette D; Waters, Elizabeth M; McEwen, Bruce S; Drake, Carrie T; Milner, Teresa A

    2009-09-01

    The endogenous hippocampal opioid systems are implicated in learning associated with drug use. Recently, we showed that ovarian hormones regulate enkephalin levels in the mossy fiber pathway. This pathway overlaps with parvalbumin (PARV)-basket interneurons that contain the enkephalin-activated mu opioid receptors (MORs) and are important for controlling the "temporal timing" of granule cells. Here, we evaluated the influence of ovarian steroids on the trafficking of MORs in PARV interneurons. Two groups of female rats were analyzed: cycling rats in proestrus (relatively high estrogens) or diestrus; and ovariectomized rats euthanized 6, 24 or 72 h after estradiol benzoate (10 microg, s.c.) administration. Dorsal hippocampal sections were dually immunolabeled for MOR and PARV and examined by light and electron microscopy. As in males, in females MOR-immunoreactivity (-ir) was in numerous PARV-labeled perikarya, dendrites and terminals in the dentate hilar region. Variation in ovarian steroid levels altered the subcellular distribution of MORs in PARV-labeled dendrites but not terminals. In normal cycling rats, MOR-gold particles on the plasma membrane of small PARV-labeled dendrites (area <1 microm2) had higher density in proestrus rats than in diestrus rats. Likewise, in ovariectomized rats MORs showed higher density on the plasma membrane of small PARV-labeled dendrites 72 h after estradiol exposure. The number of PARV-labeled cells was not affected by estrous cycle phase or estrogen levels. These results demonstrate that estrogen levels positively regulate the availability of MORs on GABAergic interneurons in the dentate gyrus, suggesting cooperative interaction between opioids and estrogens in modulating principal cell excitability.

  18. Conditional Disabled-1 Deletion in Mice Alters Hippocampal Neurogenesis and Reduces Seizure Threshold

    PubMed Central

    Korn, Matthew J.; Mandle, Quinton J.; Parent, Jack M.

    2016-01-01

    Many animal models of temporal lobe epilepsy (TLE) exhibit altered neurogenesis arising from progenitors within the dentate gyrus subgranular zone (SGZ). Aberrant integration of new neurons into the existing circuit is thought to contribute to epileptogenesis. In particular, adult-born neurons that exhibit ectopic migration and hilar basal dendrites (HBDs) are suggested to be pro-epileptogenic. Loss of reelin signaling may contribute to these morphological changes in patients with epilepsy. We previously demonstrated that conditional deletion of the reelin adaptor protein, disabled-1 (Dab1), from postnatal mouse SGZ progenitors generated dentate granule cells (DGCs) with abnormal dendritic development and ectopic placement. To determine whether the early postnatal loss of reelin signaling is epileptogenic, we conditionally deleted Dab1 in neural progenitors and their progeny on postnatal days 7–8 and performed chronic video-EEG recordings 8–10 weeks later. Dab1-deficient mice did not have spontaneous seizures but exhibited interictal epileptiform abnormalities and a significantly reduced latency to pilocarpine-induced status epilepticus. After chemoconvulsant treatment, over 90% of mice deficient for Dab1 developed generalized motor convulsions with tonic-clonic movements, rearing, and falling compared to <20% of wild-type mice. Recombination efficiency, measured by Cre reporter expression, inversely correlated with time to the first sustained seizure. These pro-epileptogenic changes were associated with decreased neurogenesis and increased numbers of hilar ectopic DGCs. Interestingly, neurons co-expressing the Cre reporter comprised a fraction of these hilar ectopic DGCs cells, suggesting a non-cell autonomous effect for the loss of reelin signaling. We also noted a dispersion of the CA1 pyramidal layer, likely due to hypomorphic effects of the conditional Dab1 allele, but this abnormality did not correlate with seizure susceptibility. These findings suggest

  19. Extrusion granulation and high shear granulation of different grades of lactose and highly dosed drugs: a comparative study.

    PubMed

    Keleb, E I; Vermeire, A; Vervaet, C; Remon, Jean Paul

    2004-07-01

    Formulations containing different lactose grades, paracetamol, and cimetidine were granulated by extrusion granulation and high shear granulation. Granules were evaluated for yield, friability, and compressibility. Tablets were prepared from those granules and evaluated for tensile strength, friability, disintegration time, and dissolution. The different lactose grades had an important effect on the extrusion granulation process. Particle size and morphology affected powder feeding and power consumption, but had only a minor influence on the granule and tablet properties obtained by extrusion granulation. In contrast, the lactose grades had a major influence on the granule properties obtained by high shear granulation. Addition of polyvinylpyrrolidone (PVP) was required to process pure paracetamol and cimetidine by high shear granulation, whereas it was feasible to granulate these drugs without PVP by extrusion granulation. Granules prepared by extrusion granulation exhibited a higher yield and a lower friability than those produced by high shear granulation. Paracetamol and cimetidine tablets compressed from granules prepared by extrusion granulation showed a higher tensile strength, lower friability, and lower disintegration time than those prepared from granules produced by high shear granulation. Paracetamol tablets obtained via extrusion granulation exhibited faster dissolution than those obtained via high shear granulation. For all lactose grades studied, extrusion granulation resulted in superior granule and tablet properties in comparison with those obtained by high shear granulation. These results indicate that extrusion granulation is more efficient than high shear granulation.

  20. The biosynthesis of starch granules.

    PubMed

    Smith, A M

    2001-01-01

    Although composed simply of glucose polymers, the starch granule is a complex, semicrystalline structure. Much of this complexity arises from the fact that the two primary enzymes of synthesis-starch synthase and starch-branching enzyme-exist as multiple isoforms. Each form has distinct properties and plays a unique role in the synthesis of the two starch polymers, amylose and amylopectin. The debranching enzyme isoamylase also has a profound influence on the synthesis of amylopectin. Despite much speculation, no acceptable model to explain the interactions of all of these enzymes to produce amylose and amylopectin has thus far emerged. The organization of newly synthesized amylopectin to form the semicrystalline matrix of the granule appears to be a physical process, implying the existence of complex interactions between biological and physical processes at the surface of the growing granule. The synthesis of the amylose component occurs within the amylopectin matrix.

  1. Neuromodulation of the Feedforward Dentate Gyrus-CA3 Microcircuit.

    PubMed

    Prince, Luke Y; Bacon, Travis J; Tigaret, Cezar M; Mellor, Jack R

    2016-01-01

    The feedforward dentate gyrus-CA3 microcircuit in the hippocampus is thought to activate ensembles of CA3 pyramidal cells and interneurons to encode and retrieve episodic memories. The creation of these CA3 ensembles depends on neuromodulatory input and synaptic plasticity within this microcircuit. Here we review the mechanisms by which the neuromodulators aceylcholine, noradrenaline, dopamine, and serotonin reconfigure this microcircuit and thereby infer the net effect of these modulators on the processes of episodic memory encoding and retrieval.

  2. Neuromodulation of the Feedforward Dentate Gyrus-CA3 Microcircuit

    PubMed Central

    Prince, Luke Y.; Bacon, Travis J.; Tigaret, Cezar M.; Mellor, Jack R.

    2016-01-01

    The feedforward dentate gyrus-CA3 microcircuit in the hippocampus is thought to activate ensembles of CA3 pyramidal cells and interneurons to encode and retrieve episodic memories. The creation of these CA3 ensembles depends on neuromodulatory input and synaptic plasticity within this microcircuit. Here we review the mechanisms by which the neuromodulators aceylcholine, noradrenaline, dopamine, and serotonin reconfigure this microcircuit and thereby infer the net effect of these modulators on the processes of episodic memory encoding and retrieval. PMID:27799909

  3. BDNF over-expression increases olfactory bulb granule cell dendritic spine density in vivo

    PubMed Central

    McDole, Brittnee; Isgor, Ceylan; Pare, Christopher; Guthrie, Kathleen

    2015-01-01

    Olfactory bulb granule cells are axon-less, inhibitory interneurons that regulate the activity of the excitatory output neurons, the mitral and tufted cells, through reciprocal dendrodendritic synapses located on granule cell spines. These contacts are established in the distal apical dendritic compartment, while granule cell basal dendrites and more proximal apical segments bear spines that receive glutamatergic inputs from the olfactory cortices. This synaptic connectivity is vital to olfactory circuit function and is remodeled during development, and in response to changes in sensory activity and lifelong granule cell neurogenesis. Manipulations that alter levels of the neurotrophin brain-derived neurotrophic factor (BDNF) in vivo have significant effects on dendritic spine morphology, maintenance and activity-dependent plasticity for a variety of CNS neurons, yet little is known regarding BDNF effects on bulb granule cell spine maturation or maintenance. Here we show that, in vivo, sustained bulbar over-expression of BDNF produces a marked increase in granule cell spine density that includes an increase in mature spines on their apical dendrites. Morphometric analysis demonstrated that changes in spine density were most notable in the distal and proximal apical domains, indicating that multiple excitatory inputs are potentially modified by BDNF. Our results indicate that increased levels of endogenous BDNF can promote the maturation and/or maintenance of dendritic spines on granule cells, suggesting a role for this factor in modulating granule cell functional connectivity within adult olfactory circuitry. PMID:26211445

  4. Statistical analysis and comparison of a continuous high shear granulator with a twin screw granulator: Effect of process parameters on critical granule attributes and granulation mechanisms.

    PubMed

    Meng, Wei; Kotamarthy, Lalith; Panikar, Savitha; Sen, Maitraye; Pradhan, Shankali; Marc, Michaelis; Litster, James D; Muzzio, Fernando J; Ramachandran, Rohit

    2016-11-20

    This study is concerned with identifying the design space of two different continuous granulators and their respective granulation mechanisms. Performance of a continuous high shear granulator and a twin screw granulator with paracetamol formulations were examined by face-centered cubic design, which focused on investigating key performance metrics, namely, granule size, porosity, flowability and particle morphology of granules as a function of essential input process parameters (liquid content, throughput and rotation speed). Liquid and residence time distribution tests were also performed to gain insights into the liquid-powder mixing and flow behavior. The results indicated that continuous high shear granulation was more sensitive to process variation and produced spherical granules with monomodal size distribution and distinct internal structure and strength variation. Twin screw granulation with such a particular screw configuration showed narrower design space and granules were featured with multimodal size distribution, irregular shape, less detectible porosity difference and tighter range of strength. Granulation mechanisms explored on the basis of nucleation and growth regime maps revealed that for most cases liquid binder was uniformly distributed with fast droplet penetration into the powder bed and that granule consolidation and coalescence mainly took place in the nucleation, steady growth and rapid growth regimes.

  5. Epithelial cells supply Sonic Hedgehog to the perinatal dentate gyrus via transport by platelets.

    PubMed

    Choe, Youngshik; Huynh, Trung; Pleasure, Samuel J

    2015-10-12

    Dentate neural stem cells produce neurons throughout life in mammals. Sonic hedgehog (Shh) is critical for maintenance of these cells; however, the perinatal source of Shh is enigmatic. In the present study, we examined the role of Shh expressed by hair follicles (HFs) that expand perinatally in temporal concordance with the proliferation of Shh-responding dentate stem cells. Specific inhibition of Shh from HFs or from epithelial sources in general hindered development of Shh-responding dentate stem cells. We also found that the blood-brain barrier (BBB) of the perinatal dentate gyrus (DG) is leaky with stem cells in the dentate exposed to blood-born factors. In attempting to identify how Shh might be transported in blood, we found that platelets contain epithelial Shh, provide Shh to the perinatal DG and that inhibition of platelet generation reduced hedgehog-responsive dentate stem cells.

  6. Maturation of long-term potentiation in the hippocampal dentate gyrus of the freely moving rat.

    PubMed

    Bronzino, J D; Abu-Hasaballah, K; Austin-LaFrance, R J; Morgane, P J

    1994-08-01

    The ability of the perforant path/dentate granule cell synapse of the hippocampal formation to establish and maintain enhanced levels of synaptic transmission in response to tetanization (long-term potentiation, LTP) was investigated in freely moving rats at 15, 30, and 90 days of age. Measures of 1) the slope of the population excitatory postsynaptic potential (EPSP), and 2) the population spike amplitude (PSA) obtained before, and at several times following tetanization, were used to evaluate the magnitude and duration of LTP as a function of age. Significant enhancement of both EPSP slope and PSA measures was obtained from animals of all three ages in response to perforant path tetanization. The initial degree of enhancement was essentially the same across the age groups, ranging from +27% to +38% of pretetanization levels for EPSP slope measures and +60% to +75% of pretetanization levels for PSA measures, obtained 15 min after tetanization. The duration of this enhancement obtained from animals of the preweaning group was significantly longer than that obtained from either 30- or 90-day-old animals. Enhanced measures of both EPSP slope and PSA decayed to baseline levels in these older animals 18 to 24 h after tetanization, while animals tetanized at 15 days of age maintained potentiated levels of both measures for a period of 5 days following tetanization. Tetanization of 15-day-old animals resulted in a significant reduction in the latency to EPSP onset without affecting the time-based relationships among the other measured parameters, which included latency of the population spike onset, population spike minimum, and population spike offset.(ABSTRACT TRUNCATED AT 250 WORDS)

  7. Ketamine Affects the Neurogenesis of the Hippocampal Dentate Gyrus in 7-Day-Old Rats.

    PubMed

    Huang, He; Liu, Cun-Ming; Sun, Jie; Hao, Ting; Xu, Chun-Mei; Wang, Dan; Wu, Yu-Qing

    2016-08-01

    Ketamine has been reported to cause neonatal neurotoxicity via a neuronal apoptosis mechanism; however, no in vivo research has reported whether ketamine could affect postnatal neurogenesis in the hippocampal dentate gyrus (DG). A growing number of experiments suggest that postnatal hippocampal neurogenesis is the foundation of maintaining normal hippocampus function into adulthood. Therefore, this study investigated the effect of ketamine on hippocampal neurogenesis. Male Sprague-Dawley rats were divided into two groups: the control group (equal volume of normal saline), and the ketamine-anesthesia group (40 mg/kg ketamine in four injections at 1 h intervals). The S-phase marker 5-bromodeoxyuridine (BrdU) was administered after ketamine exposure to postnatal day 7 (PND-7) rats, and the neurogenesis in the hippocampal DG was assessed using single- or double-immunofluorescence staining. The expression of GFAP in the hippocampal DG was measured by western blot analysis. Spatial reference memory was tested by Morris water maze at 2 months after PND-7 rats exposed to ketamine treatment. The present results showed that neonatal ketamine exposure significantly inhibited neural stem cell (NSC) proliferation, decreased astrocytic differentiation, and markedly enhanced neuronal differentiation. The disruptive effect of ketamine on the proliferation and differentiation of NSCs lasted at least 1 week and disappeared by 2 weeks after ketamine exposure. Moreover, the migration of newborn neurons in the granule cell layer and the growth of astrocytes in the hippocampal DG were inhibited by ketamine on PND-37 and PND-44. Finally, ketamine caused a deficit in hippocampal-dependent spatial reference memory tasks at 2 months old. Our results suggested that ketamine may interfere with hippocampal neurogenesis and long-term neurocognitive function in PND-7 rats. These findings may provide a new perspective to explain the adult neurocognitive dysfunction induced by neonatal

  8. Dentate gyrus network dysfunctions precede the symptomatic phase in a genetic mouse model of seizures

    PubMed Central

    Toader, Oana; Forte, Nicola; Orlando, Marta; Ferrea, Enrico; Raimondi, Andrea; Baldelli, Pietro; Benfenati, Fabio; Medrihan, Lucian

    2013-01-01

    Neuronal circuit disturbances that lead to hyperexcitability in the cortico-hippocampal network are one of the landmarks of temporal lobe epilepsy. The dentate gyrus (DG) network plays an important role in regulating the excitability of the entire hippocampus by filtering and integrating information received via the perforant path. Here, we investigated possible epileptogenic abnormalities in the function of the DG neuronal network in the Synapsin II (Syn II) knockout mouse (Syn II−/−), a genetic mouse model of epilepsy. Syn II is a presynaptic protein whose deletion in mice reproducibly leads to generalized seizures starting at the age of 2 months. We made use of a high-resolution microelectrode array (4096 electrodes) and patch-clamp recordings, and found that in acute hippocampal slices of young pre-symptomatic (3–6 week-old) Syn II−/− mice excitatory synaptic output of the mossy fibers is reduced. Moreover, we showed that the main excitatory neurons present in the polymorphic layer of the DG, hilar mossy cells, display a reduced excitability. We also provide evidence of a predominantly inhibitory regulatory output from mossy cells to granule cells, through feed-forward inhibition, and show that the excitatory-inhibitory ratio is increased in both pre-symptomatic and symptomatic Syn II−/− mice. These results support the key role of the hilar mossy neurons in maintaining the normal excitability of the hippocampal network and show that the late epileptic phenotype of the Syn II−/− mice is preceded by neuronal circuitry dysfunctions. Our data provide new insights into the mechanisms of epileptogenesis in the Syn II−/− mice and open the possibility for early diagnosis and therapeutic interventions. PMID:24009558

  9. Cytoplasmic RNA Granules and Viral Infection

    PubMed Central

    Tsai, Wei-Chih; Lloyd, Richard E.

    2016-01-01

    RNA granules are dynamic cellular structures essential for proper gene expression and homeostasis. The two principle types of cytoplasmic RNA granules are stress granules (SGs), which contain stalled translation initiation complexes, and processing bodies (P-bodies, PBs), which concentrate factors involved in mRNA degradation. RNA granules are associated with gene silencing of transcripts, thus, viruses repress RNA granule functions to favor replication. This review discusses the breadth of viral interactions with cytoplasmic RNA granules, focusing on mechanisms that modulate the functions of RNA granules and that typically promote viral replication. Currently mechanisms for virus manipulation of RNA granules can be loosely grouped into three non-exclusive categories; i) cleavage of key RNA granule factors, ii) regulation of PKR activation and iii) co-opting RNA granule factors for new roles in viral replication. Viral repression of RNA granules supports productive infection by inhibiting their gene silencing functions and counteracting their role in linking stress sensing with innate immune activation. PMID:26958719

  10. Selective sorting of alpha-granule proteins.

    PubMed

    Italiano, J E; Battinelli, E M

    2009-07-01

    One of the main functions of blood platelets is to secrete a variety of substances that can modify a developing thrombus, regulate the growth of the vasculature, promote wound repair, and contribute to cell-adhesive events. A majority of this vast array of secreted proteins are stored in alpha-granules. Until recently, it was assumed that platelets contained one homogeneous population of alpha-granules that undergo complete de-granulation during platelet activation. This review focuses on the mechanisms of alpha-granule biogenesis and secretion, with a particular emphasis on recent findings that clearly demonstrate that platelets contain distinct subpopulations of alpha-granules that undergo differential release during activation. We consider the implications of this new paradigm of platelet secretion, discuss mechanisms of alpha-granule biogenesis, and review the molecular basis of transport and delivery of alpha-granules to assembling platelets.

  11. Principles and Properties of Stress Granules.

    PubMed

    Protter, David S W; Parker, Roy

    2016-09-01

    Stress granules are assemblies of untranslating messenger ribonucleoproteins (mRNPs) that form from mRNAs stalled in translation initiation. Stress granules form through interactions between mRNA-binding proteins that link together populations of mRNPs. Interactions promoting stress granule formation include conventional protein-protein interactions as well as interactions involving intrinsically disordered regions (IDRs) of proteins. Assembly and disassembly of stress granules are modulated by various post-translational modifications as well as numerous ATP-dependent RNP or protein remodeling complexes, illustrating that stress granules represent an active liquid wherein energy input maintains their dynamic state. Stress granule formation modulates the stress response, viral infection, and signaling pathways. Persistent or aberrant stress granule formation contributes to neurodegenerative disease and some cancers.

  12. Persistent Hyperactivity of Hippocampal Dentate Interneurons After a Silent Period in the Rat Pilocarpine Model of Epilepsy

    PubMed Central

    Wang, Xiaochen; Song, Xinyu; Wu, Lin; Nadler, J. Victor; Zhan, Ren-Zhi

    2016-01-01

    Profile of GABAergic interneuron activity after pilocarpine-induced status epilepticus (SE) was examined in the rat hippocampal dentate gyrus by analyzing immediate early gene expression and recording spontaneous firing at near resting membrane potential (REM). SE for exact 2 h or more than 2 h was induced in the male Sprague-Dawley rats by an intraperitoneal injection of pilocarpine. Expression of immediate early genes (IEGs) was examined at 1 h, 1 week, 2 weeks or more than 10 weeks after SE. For animals to be examined at 1 h after SE, SE lasted for exact 2 h was terminated by an intraperitoneal injection of diazepam. Spontaneous firing at near the REM was recorded in interneurons located along the border between the granule cell layer and the hilus more than 10 weeks after SE. Results showed that both c-fos and activity-regulated cytoskeleton associated protein (Arc) in hilar GABAergic interneurons were up-regulated after SE in a biphasic manner; they were increased at 1 h and more than 2 weeks, but not at 1 week after SE. Ten weeks after SE, nearly 60% of hilar GABAergic cells expressed c-fos. With the exception of calretinin (CR)-positive cells, percentages of hilar neuronal nitric oxide synthase (nNOS)-, neuropeptide Y (NPY)-, parvalbumin (PV)-, and somatostatin (SOM)-positive cells with c-fos expression are significantly higher than those of controls more than 10 weeks after SE. Without the REM to be more depolarizing and changed threshold potential level in SE-induced rats, cell-attached recording revealed that nearly 90% of hilar interneurons fired spontaneously at near the REM while only 22% of the same cell population did so in the controls. In conclusion, pilocarpine-induced SE eventually leads to a state in which surviving dentate GABAergic interneurons become hyperactive with a subtype-dependent manner; this implies that a fragile balance between excitation and inhibition exists in the dentate gyrus and in addition, the activity-dependent up

  13. Functional analysis of neurovascular adaptations to exercise in the dentate gyrus of young adult mice associated with cognitive gain.

    PubMed

    Clark, Peter J; Brzezinska, Weronika J; Puchalski, Emily K; Krone, David A; Rhodes, Justin S

    2009-10-01

    The discovery that aerobic exercise increases adult hippocampal neurogenesis and can enhance cognitive performance holds promise as a model for regenerative medicine. This study adds two new pieces of information to the rapidly growing field. First, we tested whether exercise increases vascular density in the granular layer of the dentate gyrus, whole hippocampus, and striatum in C57BL/6J mice known to display procognitive effects of exercise. Second, we determined the extent to which new neurons from exercise participate in the acute neuronal response to high levels of running in B6D2F1/J (F1 hybrid of C57BL/6J female by DBA/2J male). Mice were housed with or without a running wheel for 50 days (runner vs. sedentary). The first 10 days, they received daily injections of BrdU to label dividing cells. The last 10 days, mice were tested for performance on the Morris water maze and rotarod and then euthanized to measure neurogenesis, c-Fos induction from running and vascular density. In C57BL/6J, exercise increased neurogenesis, density of blood vessels in the dentate gyrus and striatum (but not whole hippocampus), and enhanced performance on the water maze and rotarod. In B6D2F1/J, exercise also increased hippocampal neurogenesis but not vascular density in the granular layer. Improvement on the water maze from exercise was marginal, and no gain was seen for rotarod, possibly because of a ceiling effect. Running increased the number of c-Fos positive neurons in the granular layer by fivefold, and level of running was strongly correlated with c-Fos within 90 min before euthanasia. In runners, approximately 3.3% (+/-0.008 S.E.) of BrdU-positive neurons in the middle of the granule layer displayed c-Fos when compared with 0.8% (+/-0.001) of BrdU-negative neurons. Results suggest that procognitive effects of exercise are associated with increased vascular density in the dentate gyrus and striatum in C57BL/6J mice, and that new neurons from exercise preferentially

  14. Functional Analysis of Neurovascular Adaptations to Exercise in the Dentate Gyrus of Young Adult Mice Associated With Cognitive Gain

    PubMed Central

    Clark, Peter J.; Brzezinska, Weronika J.; Puchalski, Emily K.; Krone, David A.; Rhodes, Justin S.

    2009-01-01

    The discovery that aerobic exercise increases adult hippocampal neurogenesis and can enhance cognitive performance holds promise as a model for regenerative medicine. This study adds two new pieces of information to the rapidly growing field. First, we tested whether exercise increases vascular density in the granular layer of the dentate gyrus, whole hippocampus, and striatum in C57BL/6J mice known to display procognitive effects of exercise. Second, we determined the extent to which new neurons from exercise participate in the acute neuronal response to high levels of running in B6D2F1/J (F1 hybrid of C57BL/6J female by DBA/2J male). Mice were housed with or without a running wheel for 50 days (runner vs. sedentary). The first 10 days, they received daily injections of BrdU to label dividing cells. The last 10 days, mice were tested for performance on the Morris water maze and rotarod and then euthanized to measure neurogenesis, c-Fos induction from running and vascular density. In C57BL/6J, exercise increased neurogenesis, density of blood vessels in the dentate gyrus and striatum (but not whole hippocampus), and enhanced performance on the water maze and rotarod. In B6D2F1/J, exercise also increased hippocampal neurogenesis but not vascular density in the granular layer. Improvement on the water maze from exercise was marginal, and no gain was seen for rotarod, possibly because of a ceiling effect. Running increased the number of c-Fos positive neurons in the granular layer by fivefold, and level of running was strongly correlated with c-Fos within 90 min before euthanasia. In runners, ~3.3% (±0.008 S.E.) of BrdU-positive neurons in the middle of the granule layer displayed c-Fos when compared with 0.8% (±0.001) of BrdU-negative neurons. Results suggest that procognitive effects of exercise are associated with increased vascular density in the dentate gyrus and striatum in C57BL/6J mice, and that new neurons from exercise preferentially function in the

  15. Stress-induced gene expression and behavior are controlled by DNA methylation and methyl donor availability in the dentate gyrus

    PubMed Central

    Saunderson, Emily A.; Spiers, Helen; Gutierrez-Mecinas, Maria; Trollope, Alexandra F.; Shaikh, Abeera; Mill, Jonathan; Reul, Johannes M. H. M.

    2016-01-01

    Stressful events evoke long-term changes in behavioral responses; however, the underlying mechanisms in the brain are not well understood. Previous work has shown that epigenetic changes and immediate-early gene (IEG) induction in stress-activated dentate gyrus (DG) granule neurons play a crucial role in these behavioral responses. Here, we show that an acute stressful challenge [i.e., forced swimming (FS)] results in DNA demethylation at specific CpG (5′-cytosine–phosphate–guanine-3′) sites close to the c-Fos (FBJ murine osteosarcoma viral oncogene homolog) transcriptional start site and within the gene promoter region of Egr-1 (early growth response protein 1) specifically in the DG. Administration of the (endogenous) methyl donor S-adenosyl methionine (SAM) did not affect CpG methylation and IEG gene expression at baseline. However, administration of SAM before the FS challenge resulted in an enhanced CpG methylation at the IEG loci and suppression of IEG induction specifically in the DG and an impaired behavioral immobility response 24 h later. The stressor also specifically increased the expression of the de novo DNA methyltransferase Dnmt3a [DNA (cytosine-5-)-methyltransferase 3 alpha] in this hippocampus region. Moreover, stress resulted in an increased association of Dnmt3a enzyme with the affected CpG loci within the IEG genes. No effects of SAM were observed on stress-evoked histone modifications, including H3S10p-K14ac (histone H3, phosphorylated serine 10 and acetylated lysine-14), H3K4me3 (histone H3, trimethylated lysine-4), H3K9me3 (histone H3, trimethylated lysine-9), and H3K27me3 (histone H3, trimethylated lysine-27). We conclude that the DNA methylation status of IEGs plays a crucial role in FS-induced IEG induction in DG granule neurons and associated behavioral responses. In addition, the concentration of available methyl donor, possibly in conjunction with Dnmt3a, is critical for the responsiveness of dentate neurons to environmental

  16. Alterations of hippocampal GAbaergic system contribute to development of spontaneous recurrent seizures in the rat lithium-pilocarpine model of temporal lobe epilepsy.

    PubMed

    André, V; Marescaux, C; Nehlig, A; Fritschy, J M

    2001-01-01

    Reorganization of excitatory and inhibitory circuits in the hippocampal formation following seizure-induced neuronal loss has been proposed to underlie the development of chronic seizures in temporal lobe epilepsy (TLE). Here, we investigated whether specific morphological alterations of the GABAergic system can be related to the onset of spontaneous recurrent seizures (SRS) in the rat lithium-pilocarpine model of TLE. Immunohistochemical staining for markers of interneurons and their projections, including parvalbumin (PV), calretinin (CR), calbindin (CB), glutamic acid decarboxylase (GAD), and type 1 GABA transporter (GAT1), was performed in brain sections of rats treated with lithium-pilocarpine and sacrificed after 24 h, during the silent phase (6 and 12 days), or after the onset of SRS (10-18 days after treatment). Semiquantitative analysis revealed a selective loss of interneurons in the stratum oriens of CA1, associated with a reduction of GAT1 staining in the stratum radiatum and stratum oriens. In contrast, interneurons in CA3 were largely preserved, although GAT1 staining was also reduced. These changes occurred within 6 days after treatment and were therefore insufficient to cause SRS. In the dentate gyrus, extensive cell loss occurred in the hilus. The pericellular innervation of granule cells by PV-positive axons was markedly reduced, although the loss of PV-interneurons was only partial. Most strikingly, the density of GABAergic axons, positive for both GAD and GAT1, was dramatically increased in the inner molecular layer. This change emerged during the silent period, but was most marked in animals with SRS. Finally, supernumerary CB-positive neurons were detected in the hilus, selectively in rats with SRS. These findings suggest that alterations of GABAergic circuits occur early after lithium-pilocarpine-induced status epilepticus and contribute to epileptogenesis. In particular, the reorganization of GABAergic axons in the dentate gyrus might

  17. Neonatal isolation alters LTP in freely moving juvenile rats: sex differences.

    PubMed

    Bronzino, J D; Kehoe, P; Austin-LaFrance, R J; Rushmore, R J; Kurdian, J

    1996-01-01

    We have previously reported that neonatal isolation significantly enhanced the magnitude of hippocampal long-term potentiation (LTP) recorded from freely moving male rats tested at 30 days of age. The present study extends this work to examine the effects of neonatal isolation on hippocampal LTP in male and female juvenile rats. Changes in dentate granule cell population measures, i.e., EPSP slope and population spike amplitude (PSA), evoked by tetanization of the medial perforant pathway were used to assess the effects of neonatal isolation on LTP over a period of 96 hrs. Prior to tetanization, significant sex differences were obtained for input/output (I/O) response measures of EPSP slope and PSA, with males showing consistently higher values than females. No significant effect of treatment was obtained within either sex for baseline measures. Following tetanization significant sex differences were also obtained for both measures, with males showing significantly greater enhancement than females. Comparisons made at 1 hr post-tetanization (establishment of LTP) indicated that isolated males showed significantly greater enhancement than any other group. On the other hand, treatment differences were not obtained from females. At 96 hrs (maintenance of LTP), however, both neonatally isolated males and females showed significantly greater enhancement than either non-isolated siblings or unhandled controls. These results indicate that males and females exhibit different enhancement profiles with respect to both the magnitude and duration of LTP, and that neonatal isolation alters these profiles in a sex-specific manner.

  18. Internalized Tau sensitizes cells to stress by promoting formation and stability of stress granules

    PubMed Central

    Brunello, Cecilia A.; Yan, Xu; Huttunen, Henri J.

    2016-01-01

    Stress granules are membrane-less RNA- and RNA-binding protein-containing complexes that are transiently assembled in stressful conditions to promote cell survival. Several stress granule-associated RNA-binding proteins have been associated with neurodegenerative diseases. In addition, a close link was recently identified between the stress granule core-nucleating protein TIA-1 and Tau. Tau is a central pathological protein in Alzheimer’s disease and other tauopathies, and misfolded, aggregated Tau is capable of propagating pathology via cell-to-cell transmission. Here we show that following internalization hyperphosphorylated extracellular Tau associates with stress granules in a TIA-1 dependent manner. Cytosolic Tau normally only weakly interacts with TIA-1 but mutations mimicking abnormal phosphorylation promote this interaction. We show that internalized Tau significantly delays normal clearance of stress granules in the recipient cells sensitizing them to secondary stress. These results suggest that secreted Tau species may have properties, likely related to its hyperphosphorylation and oligomerization, which promote pathological association of internalized Tau with stress granules altering their dynamics and reducing cell viability. We suggest that stress granules and TIA-1 play a central role in the cell-to-cell transmission of Tau pathology. PMID:27460788

  19. 5-Fluorouracil affects assembly of stress granules based on RNA incorporation.

    PubMed

    Kaehler, Christian; Isensee, Jörg; Hucho, Tim; Lehrach, Hans; Krobitsch, Sylvia

    2014-06-01

    The antimetabolite 5-fluorouracil is a widely used chemotherapeutic for the treatment of several solid cancers. However, resistance to 5-fluorouracil remains a major drawback in its clinical use. In this study we report that treatment of HeLa cells with 5-fluorouracil resulted in de novo assembly of stress granules. Moreover, we revealed that stress granule assembly under stress conditions as well as disassembly is altered in cells treated with 5-fluorouracil. Notably, we discovered that RACK1, a protein mediating cell survival and apoptosis, is a component of 5-fluorouracil-induced stress granules. To explore the mode of action of 5-fluorouracil accountable for de novo stress granule assembly, we analyzed 5-fluorouracil metabolites and noticed that stress granule assembly is caused by RNA, not DNA incorporating 5-fluorouracil metabolites. Interestingly, we observed that other RNA incorporating drugs also cause assembly of stress granules. Thus, our results suggest that incorporation of chemotherapeutics into RNA may result in stress granule assembly with potential significance in chemoresistance.

  20. In vivo evidence of hippocampal dentate gyrus expansion in multiple sclerosis.

    PubMed

    Rocca, Maria A; Longoni, Giulia; Pagani, Elisabetta; Boffa, Giacomo; Colombo, Bruno; Rodegher, Mariaemma; Martino, Gianvito; Falini, Andrea; Comi, Giancarlo; Filippi, Massimo

    2015-11-01

    Using MR-based radial mapping, we assessed morphological alterations of the hippocampal dentate gyrus (DG) in patients with relapse-onset multiple sclerosis (MS). We analyzed different stages of the disease and the association of DG alterations with hippocampal-related cognitive functions. Using high-resolution morphological imaging, hippocampal radial mapping analysis was performed in 28 relapsing-remitting (RR), 34 secondary progressive, and 26 benign MS patients and 28 healthy controls (HC). Between-groups differences of DG radial distance (from surface points to the central core of the hippocampus) and correlations with clinical, neuropsychological, and radiological measures were evaluated using surface-based mesh modeling. Compared with HC, all MS clinical phenotypes revealed a larger radial distance of the DG, which was more marked on the left side. Radial distance enlargement was more pronounced in RRMS patients compared with the other disease clinical phenotypes and was inversely correlated to disease duration. Radial distance enlargement was correlated with higher T2 lesion volume and a better cognitive performance in RRMS and with a poor cognitive performance in secondary progressive and benign MS patients. Surface expansion of the DG might represent an inflammation-induced neurogenic (reactive) process of the subgranular zone of the hippocampus primarily aimed at rescuing the functional competence of hippocampal circuitry.

  1. Multi-omics profile of the mouse dentate gyrus after kainic acid-induced status epilepticus

    PubMed Central

    Schouten, Marijn; Bielefeld, Pascal; Fratantoni, Silvina A.; Hubens, Chantal J.; Piersma, Sander R.; Pham, Thang V.; Voskuyl, Rob A.; Lucassen, Paul J.; Jimenez, Connie R.; Fitzsimons, Carlos P.

    2016-01-01

    Temporal lobe epilepsy (TLE) can develop from alterations in hippocampal structure and circuit characteristics, and can be modeled in mice by administration of kainic acid (KA). Adult neurogenesis in the dentate gyrus (DG) contributes to hippocampal functions and has been reported to contribute to the development of TLE. Some of the phenotypical changes include neural stem and precursor cells (NPSC) apoptosis, shortly after their birth, before they produce hippocampal neurons. Here we explored these early phenotypical changes in the DG 3 days after a systemic injection of KA inducing status epilepticus (KA-SE), in mice. We performed a multi-omics experimental setup and analyzed DG tissue samples using proteomics, transcriptomics and microRNA profiling techniques, detecting the expression of 2327 proteins, 13401 mRNAs and 311 microRNAs. We here present a description of how these data were obtained and make them available for further analysis and validation. Our data may help to further identify and characterize molecular mechanisms involved in the alterations induced shortly after KA-SE in the mouse DG. PMID:27529540

  2. Immature Dentate Gyrus: An Endophenotype of Neuropsychiatric Disorders

    PubMed Central

    Walton, Noah M.; Matsumoto, Mitsuyuki; Miyakawa, Tsuyoshi

    2013-01-01

    Adequate maturation of neurons and their integration into the hippocampal circuit is crucial for normal cognitive function and emotional behavior, and disruption of this process could cause disturbances in mental health. Previous reports have shown that mice heterozygous for a null mutation in α-CaMKII, which encodes a key synaptic plasticity molecule, display abnormal behaviors related to schizophrenia and other psychiatric disorders. In these mutants, almost all neurons in the dentate gyrus are arrested at a pseudoimmature state at the molecular and electrophysiological levels, a phenomenon defined as “immature dentate gyrus (iDG).” To date, the iDG phenotype and shared behavioral abnormalities (including working memory deficit and hyperlocomotor activity) have been discovered in Schnurri-2 knockout, mutant SNAP-25 knock-in, and forebrain-specific calcineurin knockout mice. In addition, both chronic fluoxetine treatment and pilocarpine-induced seizures reverse the neuronal maturation, resulting in the iDG phenotype in wild-type mice. Importantly, an iDG-like phenomenon was observed in post-mortem analysis of brains from patients with schizophrenia/bipolar disorder. Based on these observations, we proposed that the iDG is a potential endophenotype shared by certain types of neuropsychiatric disorders. This review summarizes recent data describing this phenotype and discusses the data's potential implication in elucidating the pathophysiology of neuropsychiatric disorders. PMID:23840971

  3. Morpho-physiological criteria divide dentate gyrus interneurons into classes.

    PubMed

    Hosp, Jonas A; Strüber, Michael; Yanagawa, Yuchio; Obata, Kunihiko; Vida, Imre; Jonas, Peter; Bartos, Marlene

    2014-02-01

    GABAergic inhibitory interneurons control fundamental aspects of neuronal network function. Their functional roles are assumed to be defined by the identity of their input synapses, the architecture of their dendritic tree, the passive and active membrane properties and finally the nature of their postsynaptic targets. Indeed, interneurons display a high degree of morphological and physiological heterogeneity. However, whether their morphological and physiological characteristics are correlated and whether interneuron diversity can be described by a continuum of GABAergic cell types or by distinct classes has remained unclear. Here we perform a detailed morphological and physiological characterization of GABAergic cells in the dentate gyrus, the input region of the hippocampus. To achieve an unbiased and efficient sampling and classification we used knock-in mice expressing the enhanced green fluorescent protein (eGFP) in glutamate decarboxylase 67 (GAD67)-positive neurons and performed cluster analysis. We identified five interneuron classes, each of them characterized by a distinct set of anatomical and physiological parameters. Cross-correlation analysis further revealed a direct relation between morphological and physiological properties indicating that dentate gyrus interneurons fall into functionally distinct classes which may differentially control neuronal network activity.

  4. Chronic Porphyromonas gingivalis infection accelerates the occurrence of age-related granules in ApoE– / – mice brains

    PubMed Central

    Singhrao, Sim K.; Chukkapalli, Sasanka; Poole, Sophie; Velsko, Irina; Crean, St John; Kesavalu, Lakshmyya

    2017-01-01

    ABSTRACT This study explored the origin of age-related granules in the apolipoprotein E gene knockout (ApoE−/−) B6 background mice brains following chronic gingival infection with Porphyromonas gingivalis for 24 weeks. Intracerebral localization of P. gingivalis was detected by fluorescence in situ hybridization (FISH) and its protease by immunohistochemistry. The age-related granules were observed by periodic acid–Schiff (PAS), silver impregnation, and immunostaining. FISH showed intracerebral dissemination of P. gingivalis cells (p = 0.001). PAS and silver impregnation demonstrated the presence of larger inclusions restricted to the CA1, CA2, and dentate gyrus sectors of the hippocampus. A specific monoclonal antibody to bacterial peptidoglycan detected clusters of granules with variable sizes in mice brains infected with P. gingivalis (p = 0.004), and also highlighted areas of diffuse punctate staining equating to physical tissue damage. Mouse immunoglobulin G was observed in the capillaries of the cerebral parenchyma of all P. gingivalis–infected brains (p = 0.001), and on pyramidal neurons in some severely affected mice, compared with the sham-infected mice. Gingipains was also observed in microvessels of the hippocampus in the infected mice. This study supports the possibility of early appearance of age-related granules in ApoE−/− mice following inflammation-mediated tissue injury, accompanied by loss of cerebral blood-brain barrier integrity. PMID:28326151

  5. Neurogliaform Cells in the Molecular Layer of the Dentate Gyrus as Feed-Forward γ-Aminobutyric Acidergic Modulators of Entorhinal–Hippocampal Interplay

    PubMed Central

    Armstrong, Caren; Szabadics, János; Tamás, Gábor; Soltesz, Ivan

    2014-01-01

    Feed-forward inhibition from molecular layer interneurons onto granule cells (GCs) in the dentate gyrus is thought to have major effects regulating entorhinal–hippocampal interactions, but the precise identity, properties, and functional connectivity of the GABAergic cells in the molecular layer are not well understood. We used single and paired intracellular patch clamp recordings from post-hoc-identified cells in acute rat hippocampal slices and identified a subpopulation of molecular layer interneurons that expressed immunocytochemical markers present in members of the neurogliaform cell (NGFC) class. Single NGFCs displayed small dendritic trees, and their characteristically dense axonal arborizations covered significant portions of the outer and middle one-thirds of the molecular layer, with frequent axonal projections across the fissure into the CA1 and subicular regions. Typical NGFCs exhibited a late firing pattern with a ramp in membrane potential prior to firing action potentials, and single spikes in NGFCs evoked biphasic, prolonged GABAA and GABAB postsynaptic responses in GCs. In addition to providing dendritic GABAergic inputs to GCs, NGFCs also formed chemical synapses and gap junctions with various molecular layer interneurons, including other NGFCs. NGFCs received low-frequency spontaneous synaptic events, and stimulation of perforant path fibers revealed direct, facilitating synaptic inputs from the entorhinal cortex. Taken together, these results indicate that NGFCs form an integral part of the local molecular layer microcircuitry generating feed-forward inhibition and provide a direct GABAergic pathway linking the dentate gyrus to the CA1 and subicular regions through the hippocampal fissure PMID:21452204

  6. Progressive behavioral changes during the maturation of rats with early radiation-induced hypoplasia of fascia dentata granule cells

    SciTech Connect

    Mickley, G.A.; Ferguson, J.L.; Mulvihill, M.A.; Nemeth, T.J.

    1989-01-01

    Localized exposure of the neonatal rat brain to x rays produces neuronal hypoplasia specific to the granule cell layer of the hippocampal dentate gyrus. This brain damage causes locomotor hyperactivity, slowed acquisition of passive avoidance tasks and long bouts of spontaneous turning (without reversals) in a bowl apparatus. The authors report here how these behavioral deficits change as a function of subject aging and behavioral test replications. Portions of the neonatal rat cerebral hemispheres were X-irradiated in order to selectively damage the granule cells of the dentate gyrus. Rats between the ages of 71-462 days were tested 3 separate times on each of the following 3 behavioral tests: (1) spontaneous locomotion, (2) passive avoidance acquisition, and (3) spontaneous circling in a large plastic hemisphere. Rats with radiation-induced damage to the fascia dentata exhibited long bouts of slow turns without reversals. Once they began, irradiated subjects perseverated in turning to an extent significantly greater than sham-irradiated control subjects. The hyperactivity of the irradiated animals decreased significantly as they matured. These data suggest that radiation-induced damage to the fascia dentata produces task-dependent behavioral deficits that change as a function of subject age and/or behavioral testing.

  7. Neuroligin-1 regulates excitatory synaptic transmission, LTP and EPSP-spike coupling in the dentate gyrus in vivo.

    PubMed

    Jedlicka, Peter; Vnencak, Matej; Krueger, Dilja D; Jungenitz, Tassilo; Brose, Nils; Schwarzacher, Stephan W

    2015-01-01

    Neuroligins are transmembrane cell adhesion proteins with a key role in the regulation of excitatory and inhibitory synapses. Based on previous in vitro and ex vivo studies, neuroligin-1 (NL1) has been suggested to play a selective role in the function of glutamatergic synapses. However, the role of NL1 has not yet been investigated in the brain of live animals. We studied the effects of NL1-deficiency on synaptic transmission in the hippocampal dentate gyrus using field potential recordings evoked by perforant path stimulation in urethane-anesthetized NL1 knockout (KO) mice. We report that in NL1 KOs the activation of glutamatergic perforant path granule cell inputs resulted in reduced synaptic responses. In addition, NL1 KOs displayed impairment in long-term potentiation. Furthermore, field EPSP-population spike (E-S) coupling was greater in NL1 KO than WT mice and paired-pulse inhibition was reduced, indicating a compensatory rise of excitability in NL1 KO granule cells. Consistent with changes in excitatory transmission, NL1 KOs showed a significant reduction in hippocampal synaptosomal expression levels of the AMPA receptor subunit GluA2 and NMDA receptor subunits GluN1, GluN2A and GluN2B. Taken together, we provide first evidence that NL1 is essential for normal excitatory transmission and long-term synaptic plasticity in the hippocampus of intact animals. Our data provide insights into synaptic and circuit mechanisms of neuropsychiatric abnormalities such as learning deficits and autism.

  8. BMP signaling in the developing telencephalon controls formation of the hippocampal dentate gyrus and modifies fear-related behavior

    PubMed Central

    Caronia, Giuliana; Wilcoxon, Jennifer; Feldman, Polina; Grove, Elizabeth A.

    2010-01-01

    The cortical hem is an embryonic signaling center that generates bone morphogenetic (BMP) proteins and acts as an organizer for the hippocampus. The role of BMP signaling in hippocampal neurogenesis, however, has not been established. We therefore generated mice that were deficient in Bmpr1b constitutively, and deficient in Bmpr1a conditionally in the dorsal telencephalon. In double mutant male and female mice, the dentate gyrus (DG) was dramatically smaller than in control mice, reflecting decreased generation of granule neurons at the peak period of DG neurogenesis. Additionally, the pool of cells that generates new DG neurons throughout life was reduced, commensurate with the smaller size of the DG. Effects of diminished BMP signaling on the cortical hem were at least partly responsible for these defects in DG development. Reduction of the DG and its major extrinsic output to CA3 raised the possibility that the DG was functionally compromised. We therefore looked for behavioral deficits in double mutants, and found that the mice were less responsive to fear or anxiety-provoking stimuli, whether the association of the stimulus with fear or anxiety was learned or innate. Given that no anatomical defects appeared in the double mutant telencephalon outside the DG, our observations support a growing literature that implicates the hippocampus in circuitry mediating fear and anxiety. Our results additionally indicate a requirement for BMP signaling in generating the dorsalmost neuronal lineage of the telencephalon, DG granule neurons, and in the development of the stem cell niche that generates neurons in the adult hippocampus. PMID:20445055

  9. Twin screw granulation - review of current progress.

    PubMed

    Thompson, M R

    2015-01-01

    Twin screw granulation (TSG) is a new process of interest to the pharmaceutical community that can continuously wet granulate powders, doing so at lower liquid concentrations and with better product consistency than found by a high shear batch mixer. A considerable body of research has evolved over the short time since this process was introduced but generally with little comparison of results. A certain degree of confidence has been developed through these studies related to how process variables and many attributes of machinery configuration will affect granulation but some major challenges still lay ahead related to scalability, variations in the processing regimes related to degree of channel fill and the impact of wetting and granulation of complex powder formulations. This review examines the current literature for wet granulation processes studied in twin screw extrusion machinery, summarizing the influences of operational and system parameters affecting granule properties as well as strives to provide some practical observations to newly interested users of the technique.

  10. Numerical Experiments with Flows of Elongated Granules

    DTIC Science & Technology

    1992-01-01

    NASA AVSCOM Technical Memorandum 105567 Technical Report 91- C- 006 𔃼e- 0ok, Numerical Experiments With Flows of Elongated Granules AD-A251 853 DTIC...EXPERIMENTS WITH FLOWS OF ELONGATED GRANULES H.G. Elrod 14 Cromwell Court Old Saybrook, Connecticut 06475 and D.E. Brewe Propulsion Directorate U.S. Army...granular flows (1) between two infinite, counter-moving, parallel, roughened walls, and (2) for an infinitely-wide slider. Each granule is simulated by a

  11. Granulation In and Out of Magnetic Region

    DTIC Science & Technology

    1988-06-25

    Italy. 21-25 June 1988 / edited by Robert J. Rutten and Giuseppe Severino . p. cm. -- (NATO ASI series. Series C, Mathemati-cal and physical sciences...granulation--Congresses. 2. Stellar granulation- -Congresses. I. Rutten. Robert J. II. Severino . Giuseppe. III. North Atlantic Treaty Organization. IV. North...the seeing effects) to correctly 253 R. J. Rutten and G. Severino (eds.), Solar and Stellar Granulation, 253-271.1989 by Klawer Academic Publishers

  12. Balloon-borne imagery of the solar granulation. II - The lifetime of solar granulation

    NASA Technical Reports Server (NTRS)

    Mehltretter, J. P.

    1978-01-01

    Phenomenological aspects of the temporal evolution of photospheric granulation are reported as derived from time series of granulation photographs obtained during a flight of a balloon-borne telescope. The distribution of granule lifetime probabilities is determined, and it is found that the data can be represented by an exponential decrease with a 'decay constant' of 5.9 min. The general properties of granular evolution are described along with the way individual granules evolve with time. The most common type of granule is shown to be a medium-sized or small fragment, and it is suggested that all granules are produced by fragmentation of preexisting granules. The relative frequencies of granule destruction by fragmentation, fading, and merging are determined to be 51%, 21%, and 28%, respectively. An average radial velocity of 0.8 km/s is computed for conglomerates with an average diameter of 2.25 arcsec.

  13. Recruitment of an inhibitory hippocampal network after bursting in a single granule cell.

    PubMed

    Mori, Masahiro; Gähwiler, Beat H; Gerber, Urs

    2007-05-01

    The hippocampal CA3 area, an associational network implicated in memory function, receives monosynaptic excitatory as well as disynaptic inhibitory input through the mossy-fiber axons of the dentate granule cells. Synapses made by mossy fibers exhibit low release probability, resulting in high failure rates at resting discharge frequencies of 0.1 Hz. In recordings from functionally connected pairs of neurons, burst firing of a granule cell increased the probability of glutamate release onto both CA3 pyramidal cells and inhibitory interneurons, such that subsequent low-frequency stimulation evoked biphasic excitatory/inhibitory responses in a CA3 pyramidal cell, an effect lasting for minutes. Analysis of the unitary connections in the circuit revealed that granule cell bursting caused powerful activation of an inhibitory network, thereby transiently suppressing excitatory input to CA3 pyramidal cells. This phenomenon reflects the high incidence of spike-to-spike transmission at granule cell to interneuron synapses, the numerically much greater targeting by mossy fibers of inhibitory interneurons versus principal cells, and the extensively divergent output of interneurons targeting CA3 pyramidal cells. Thus, mossy-fiber input to CA3 pyramidal cells appears to function in three distinct modes: a resting mode, in which synaptic transmission is ineffectual because of high failure rates; a bursting mode, in which excitation predominates; and a postbursting mode, in which inhibitory input to the CA3 pyramidal cells is greatly enhanced. A mechanism allowing the transient recruitment of inhibitory input may be important for controlling network activity in the highly interconnected CA3 pyramidal cell region.

  14. Resting-State Functional Connectivity Changes Between Dentate Nucleus and Cortical Social Brain Regions in Autism Spectrum Disorders.

    PubMed

    Olivito, Giusy; Clausi, Silvia; Laghi, Fiorenzo; Tedesco, Anna Maria; Baiocco, Roberto; Mastropasqua, Chiara; Molinari, Marco; Cercignani, Mara; Bozzali, Marco; Leggio, Maria

    2017-04-01

    Autism spectrum disorders (ASDs) are known to be characterized by restricted and repetitive behaviors and interests and by impairments in social communication and interactions mainly including "theory of mind" (ToM) processes. The cerebellum has emerged as one of the brain regions affected by ASDs. As the cerebellum is known to influence cerebral cortex activity via cerebello-thalamo-cortical (CTC) circuits, it has been proposed that cerebello-cortical "disconnection" could in part underlie autistic symptoms. We used resting-state (RS) functional magnetic resonance imaging (fMRI) to investigate the potential RS connectivity changes between the cerebellar dentate nucleus (DN) and the CTC circuit targets, that may contribute to ASD pathophysiology. When comparing ASD patients to controls, we found decreased connectivity between the left DN and cerebral regions known to be components of the ToM network and the default mode network, implicated in specific aspects of mentalizing, social cognition processing, and higher order emotional processes. Further, a pattern of overconnectivity was also detected between the left DN and the supramodal cerebellar lobules associated with the default mode network. The presented RS-fMRI data provide evidence that functional connectivity (FC) between the dentate nucleus and the cerebral cortex is altered in ASD patients. This suggests that the dysfunction reported within the cerebral cortical network, typically related to social features of ASDs, may be at least partially related to an impaired interaction between cerebellum and key cortical social brain regions.

  15. Mature BDNF, but not proBDNF, reduces excitability of fast-spiking interneurons in mouse dentate gyrus.

    PubMed

    Holm, Mai Marie; Nieto-Gonzalez, Jose Luis; Vardya, Irina; Vaegter, Christian Bjerggaard; Nykjaer, Anders; Jensen, Kimmo

    2009-10-07

    Mature BDNF and its precursor proBDNF may both be secreted to exert opposite effects on synaptic plasticity in the hippocampus. However, it is unknown how proBDNF and mature BDNF affect the excitability of GABAergic interneurons and thereby regulate GABAergic inhibition. We made recordings of GABAergic spontaneous IPSCs (sIPSCs) in mouse dentate gyrus granule cells and found that chronic or acute BDNF reductions led to large increases in the sIPSC frequencies, which were TTX (tetrodotoxin) sensitive and therefore action-potential driven. Conversely, addition of mature BDNF, but not proBDNF, within minutes led to a decrease in the sIPSC frequency to 44%. Direct recordings from fast-spiking GABAergic interneurons revealed that mature BDNF reduced their excitability and depressed their action potential firing, whereas proBDNF had no effect. Using the TrkB inhibitor K-252a, or mice deficient for the common neurotrophin receptor p75(NTR), the regulation of GABAergic activity was shown specifically to be mediated by BDNF binding to the neurotrophin receptor TrkB. In agreement, immunohistochemistry demonstrated that TrkB, but not p75(NTR), was expressed in parvalbumin-positive interneurons. Our results suggest that mature BDNF decreases the excitability of GABAergic interneurons via activation of TrkB, while proBDNF does not impact on GABAergic activity. Thus, by affecting the firing of GABAergic interneurons, mature BDNF may play an important role in regulating network oscillations in the hippocampus.

  16. The regulation of platelet-dense granules by Rab27a in the ashen mouse, a model of Hermansky-Pudlak and Griscelli syndromes, is granule-specific and dependent on genetic background.

    PubMed

    Novak, Edward K; Gautam, Rashi; Reddington, Madonna; Collinson, Lucy M; Copeland, Neal G; Jenkins, Nancy A; McGarry, Michael P; Swank, Richard T

    2002-07-01

    The ashen (ash) mouse, a model for Hermansky-Pudlak syndrome (HPS) and for a subset of patients with Griscelli syndrome, presents with hypopigmentation, prolonged bleeding times, and platelet storage pool deficiency due to a mutation which abrogates expression of the Rab27a protein. Platelets of mice with the ashen mutation on the C3H/HeSnJ inbred strain background have greatly reduced amounts of dense granule components such as serotonin and adenine nucleotides though near-normal numbers of dense granules as enumerated by the dense granule-specific fluorescent dye mepacrine. Thus, essentially normal numbers of platelet dense granules are produced but the granule interiors are abnormal. Collagen-mediated aggregation of mutant platelets is significantly depressed. No abnormalities in the concentrations or secretory rates of 2 other major platelet granules, lysosomes and alpha granules, were apparent. Similarly, no platelet ultrastructural alterations other than those involving dense granules were detected. Therefore, Rab27a regulates the synthesis and secretion of only one major platelet organelle, the dense granule. There were likewise no mutant effects on levels or secretion of lysosomal enzymes of several other tissues. Together with other recent analyses of the ashen mouse, these results suggest a close relationship between platelet dense granules, melanosomes of melanocytes and secretory lysosomes of cytotoxic T lymphocytes, all mediated by Rab27a. Surprisingly, the effects of the ashen mutation on platelet-dense granule components, platelet aggregation, and bleeding times were highly dependent on genetic background. This suggests that bleeding tendencies may likewise vary among patients with Griscelli syndrome and HPS with Rab27a mutations.

  17. [Properties of anaerobic granules developed by bioflocculant].

    PubMed

    Wang, Jing-Song

    2009-11-01

    Three identical UASB reactors (labeled R1, R2, R3) were applied to treat synthetic wastewater of COD concentration 5 500-6 500 mg x L(-1). Under the same process conditions, R1 was operated with addition of 7.5 g CaCl2 and 400 mL bioflocculant MBF21 weekly, R2 was operated with addition of 140 mg cationic PAM weekly, R3 was operated without any addition of flocculants served as control. The objectives of this study were to investigate the effect of bioflocculant MBF21 on development of anaerobic granules and compare it to cationic PAM. The results showed that after 67 days of operation, anaerobic granules developed in these three UASB reactors. The average diameters of granules in R1, R2 and R3 were 1.18, 1.21 and 0.76 mm, respectively, the granulation rates in R1, R2, R3 were 15.37, 15.82 and 9.10 microm x d(-1), respectively, the values of SMA (COD-CH4/VSS x t) of granules were 0.740, 0.657 and 0.558 g x (g x d)(-1), respectively, the VSS/SS of granules were 0.667, 0.629 and 0.607, respectively, the SVI of granules were 14.7, 13.1 and 20.4 mL x g(-1), respectively, the densities of granules were 1.061, 1.064 and 1.054 g x cm(-3), respectively, the integrity coefficients of granules were 92.1, 93.5 and 84.7, respectively. From the photos of SEM, granules developed in R1 and R2 were tighter than those in R3. In the formation of mature granules, all the three reactors showed similar laws, i.e. filamentous microorganisms were predominant on the surface of the seed sludge while bacillus and cocci bacteria were predominant on the surface of the mature granules. This study demonstrated that in the development of anaerobic granules, the effect of bioflocculant MBF21 on enhancement the physical properties of granules was similar to cationic PAM, but the effect of bioflocculant MBF21 on improvement of biochemical and physiological properties of granules was better than cationic PAM.

  18. Physicochemical properties of starches and proteins in alkali-treated mungbean and cassava starch granules.

    PubMed

    Israkarn, Kamolwan; Na Nakornpanom, Nantarat; Hongsprabhas, Parichat

    2014-05-25

    This study explored the influences of envelope integrity of cooked starch granules on physicochemical and thermophysical properties of mungbean and cassava starches. Alkali treatment was used to selectively leach amylose from the amorphous region of both starches and partially fragmented starch molecules into lower-molecular-weight polymers. It was found that despite the loss of 40% of the original content of amylose, both mungbean and cassava starches retained similar crystallinities, gelatinization temperature ranges, and pasting profiles compared to the native starches. However, the loss of granule-bound starch synthases during alkali treatment and subsequent alkali cooking in excess water played significant roles in determining granular disintegration. The alterations in envelope integrity due to the negative charge repulsion among polymers within the envelope of swollen granules, and the fragmentation of starch molecules, were responsible for the alterations in thermophysical properties of mungbean and cassava starches cooked under alkaline conditions.

  19. Evidence for a motor somatotopy in the cerebellar dentate nucleus--an FMRI study in humans.

    PubMed

    Küper, Michael; Thürling, Markus; Stefanescu, Roxana; Maderwald, Stefan; Roths, Johannes; Elles, Hans G; Ladd, Mark E; Diedrichsen, Jörn; Timmann, Dagmar

    2012-11-01

    Previous anatomical studies in monkeys have shown that forelimb motor representation is located caudal to hindlimb representation within the dorso-rostral dentate nucleus. Here we investigate human dentate nucleus motor somatotopy by means of ultra-highfield (7 T) functional magnetic brain imaging (fMRI). Twenty five young healthy males participated in the study. Simple finger and foot movement tasks were performed to identify dentate nucleus motor areas. Recently developed normalization procedures for group analyses were used for the cerebellar cortex and the cerebellar dentate nucleus. Cortical activations were in good accordance with the known somatotopy of the human cerebellar cortex. Dentate nucleus activations following motor tasks were found in particular in the ipsilateral dorso-rostral nucleus. Activations were also present in other parts of the nucleus including the contralateral side, and there was some overlap between the body part representations. Within the ipsilateral dorso-rostral dentate, finger activations were located caudally compared to foot movement-related activations in fMRI group analysis. Likewise, the centre of gravity (COG) for the finger activation was more caudal than the COG of the foot activation across participants. A multivariate analysis of variance (MANOVA) on the x, y, and z coordinates of the COG indicated that this difference was significant (P = 0.043). These results indicate that in humans, the lower and upper limbs are arranged rostro-caudally in the dorsal aspect of the dentate nucleus, which is consistent with studies in non-human primates.

  20. Curtain-granulation process. Circular Z-129

    SciTech Connect

    Not Available

    1982-01-01

    A curtain granulation process is described for production of urea fertilizer pellets from a melt by spray coating onto seed granules. The process provides a product that is smooth, hard, and almost dust-free. A picture of the pilot plant and a flow sheet of the process are given.

  1. Twin screw wet granulation: Binder delivery.

    PubMed

    Saleh, Mohammed F; Dhenge, Ranjit M; Cartwright, James J; Hounslow, Michael J; Salman, Agba D

    2015-06-20

    The effects of three ways of binder delivery into the twin screw granulator (TSG) on the residence time, torque, properties of granules (size, shape, strength) and binder distribution were studied. The binder distribution was visualised through the transparent barrel using high speed imaging as well as quantified using offline technique. Furthermore, the effect of binder delivery and the change of screw configuration (conveying elements only and conveying elements with kneading elements) on the surface velocity of granules across the screw channel were investigated using particle image velocimetry (PIV). The binder was delivered in three ways; all solid binder incorporated with powder mixture, 50% of solid binder mixed with powder mixture and 50% mixed with water, all the solid binder dissolved in water. Incorporation of all solid binder with powder mixture resulted in the relatively longer residence time and higher torque, narrower granule size distribution, more spherical granules, weaker big-sized granules, stronger small-sized granules and better binder distribution compared to that in other two ways. The surface velocity of granules showed variation from one screw to another as a result of uneven liquid distribution as well as shown a reduction while introducing the kneading elements into the screw configuration.

  2. Methamphetamine decreases dentate gyrus stem cell self-renewal and shifts the differentiation towards neuronal fate.

    PubMed

    Baptista, Sofia; Lasgi, Charlène; Benstaali, Caroline; Milhazes, Nuno; Borges, Fernanda; Fontes-Ribeiro, Carlos; Agasse, Fabienne; Silva, Ana Paula

    2014-09-01

    Methamphetamine (METH) is a highly addictive psychostimulant drug of abuse that negatively interferes with neurogenesis. In fact, we have previously shown that METH triggers stem/progenitor cell death and decreases neuronal differentiation in the dentate gyrus (DG). Still, little is known regarding its effect on DG stem cell properties. Herein, we investigate the impact of METH on mice DG stem/progenitor cell self-renewal functions. METH (10nM) decreased DG stem cell self-renewal, while 1nM delayed cell cycle in the G0/G1-to-S phase transition and increased the number of quiescent cells (G0 phase), which correlated with a decrease in cyclin E, pEGFR and pERK1/2 protein levels. Importantly, both drug concentrations (1 or 10nM) did not induce cell death. In accordance with the impairment of self-renewal capacity, METH (10nM) decreased Sox2(+)/Sox2(+) while increased Sox2(-)/Sox2(-) pairs of daughter cells. This effect relied on N-methyl-d-aspartate (NMDA) signaling, which was prevented by the NMDA receptor antagonist, MK-801 (10μM). Moreover, METH (10nM) increased doublecortin (DCX) protein levels consistent with neuronal differentiation. In conclusion, METH alters DG stem cell properties by delaying cell cycle and decreasing self-renewal capacities, mechanisms that may contribute to DG neurogenesis impairment followed by cognitive deficits verified in METH consumers.

  3. Developmental hypothyroidism abolishes bilateral differences in sonic hedgehog gene control in the rat hippocampal dentate gyrus.

    PubMed

    Tanaka, Takeshi; Wang, Liyun; Kimura, Masayuki; Abe, Hajime; Mizukami, Sayaka; Yoshida, Toshinori; Shibutani, Makoto

    2015-03-01

    Both developmental and adult-stage hypothyroidism disrupt rat hippocampal neurogenesis. We previously showed that exposing mouse offspring to manganese permanently disrupts hippocampal neurogenesis and abolishes the asymmetric distribution of cells expressing Mid1, a molecule regulated by sonic hedgehog (Shh) signaling. The present study examined the involvement of Shh signaling on the disruption of hippocampal neurogenesis in rats with hypothyroidism. Pregnant rats were treated with methimazole (MMI) at 0 or 200 ppm in the drinking water from gestation day 10-21 days after delivery (developmental hypothyroidism). Adult male rats were treated with MMI in the same manner from postnatal day (PND) 46 to PND 77 (adult-stage hypothyroidism). Developmental hypothyroidism reduced the number of Mid1(+) cells within the subgranular zone of the dentate gyrus of offspring on PND 21, and consequently abolished the normal asymmetric predominance of Mid1(+) cells on the right side through the adult stage. In control animals, Shh was expressed in a subpopulation of hilar neurons, showing asymmetric distribution with left side predominance on PND 21; however, this asymmetry did not continue through the adult stage. Developmental hypothyroidism increased Shh(+) neurons bilaterally and abolished the asymmetric distribution pattern on PND 21. Adult hypothyroidism also disrupted the asymmetric distribution of Mid1(+) cells but did not affect the distribution of Shh(+) hilar neurons. The results suggest that the hippocampal neurogenesis disruption seen in hypothyroidism involves changes in asymmetric Shh(+) neuron distribution in developmental hypothyroidism and altered Mid1 expression in both developmental and adult-stage hypothyroidism.

  4. Deletion of lysophosphatidic acid receptor LPA1 reduces neurogenesis in the mouse dentate gyrus

    PubMed Central

    Matas-Rico, Elisa; García-Diaz, Beatriz; Llebrez-Zayas, Pedro; López-Barroso, Diana; Santín, Luis; Pedraza, Carmen; Smith-Fernández, Anibal; Fernández-Llebrez, Pedro; Tellez, Teresa; Redondo; Chun, Jerold; De Fonseca, Fernando Rodríguez; Estivill-Torrús, Guillermo

    2013-01-01

    Neurogenesis persists in certain regions of the adult brain including the subgranular zone of the hippocampal dentate gyrus wherein its regulation is essential, particularly in relation to learning, stress and modulation of mood. Lysophosphatidic acid (LPA) is an extracellular signaling phospholipid with important neural regulatory properties mediated by specific G protein-coupled receptors, LPA1-5. LPA1 is highly expressed in the developing neurogenic ventricular zone wherein it is required for normal embryonic neurogenesis, and, by extension may play a role in adult neurogenesis as well. By means of the analyses of a variant of the original LPA1-null mutant mouse, termed the Malaga variant or “maLPA1-null,” which has recently been reported to have defective neurogenesis within the embryonic cerebral cortex, we report here a role for LPA1 in adult hippocampal neurogenesis. Proliferation, differentiation and survival of newly formed neurons are defective in the absence of LPA1 under normal conditions and following exposure to enriched environment and voluntary exercise. Furthermore, analysis of trophic factors in maLPA1-null mice demonstrated alterations in brain-derived neurotrophic factor and insulin growth factor 1 levels after enrichment and exercise. Morphological analyses of doublecortin positive cells revealed the anomalous prevalence of bipolar cells in the subgranular zone, supporting the operation of LPA1 signaling pathways in normal proliferation, maturation and differentiation of neuronal precursors. PMID:18708146

  5. Continuous twin screw granulation: influence of process variables on granule and tablet quality.

    PubMed

    Vercruysse, J; Córdoba Díaz, D; Peeters, E; Fonteyne, M; Delaet, U; Van Assche, I; De Beer, T; Remon, J P; Vervaet, C

    2012-09-01

    The aim of the current study was to screen theophylline (125 mg) tablets manufactured via twin screw granulation in order to improve process understanding and knowledge of process variables that determine granule and tablet quality. A premix of theophylline anhydrate, α-lactose monohydrate and PVP (ratio: 30/67.5/2.5,w/w) was granulated with demineralized water. Experiments were done using the high-shear wet granulation module (based on twin screw granulation) of the ConsiGma™-25 unit (a continuous tablet manufacturing system) for particle size enlargement. After drying, granules were compressed using a MODUL™ P tablet press (compression force: 10 kN, tablet diameter: 12 mm). Using a D-optimal experimental design, the effect of several process variables (throughput (10-25 kg/h), screw speed (600-950 rpm), screw configuration (number (2, 4, 6 and 12) and angle (30°, 60° and 90°) of kneading elements), barrel temperature (25-40°C) and method of binder addition (dry versus wet)) on the granulation process (torque and temperature increase in barrel wall), granule (particle size distribution, friability and flowability) and tablet (tensile strength, porosity, friability, disintegration time and dissolution) quality was evaluated. The results showed that the quality of granules and tablets can be optimized by adjusting specific process variables (number of kneading elements, barrel temperature and binder addition method) during a granulation process using a continuous twin screw granulator.

  6. [Correlation of dry granulation process parameters and granule quality based on multiple regression analysis].

    PubMed

    Cao, Han-Han; Du, Ruo-Fei; Yang, Jia-Ning; Feng, Yi

    2014-03-01

    In this paper, microcrystalline cellulose WJ101 was used as a model material to investigate the effect of various process parameters on granule yield and friability after dry granulation with a single factor and the effect of comprehensive inspection process parameters on the effect of granule yield and friability, then the correlation between process parameters and granule quality was established. The regress equation was established between process parameters and granule yield and friability by multiple regression analysis, the affecting the order of the size of the order of the process parameters on granule yield and friability was: rollers speed > rollers pressure > speed of horizontal feed. Granule yield was positively correlated with pressure and speed of horizontal feed and negatively correlated rollers speed, while friability was on the contrary. By comparison, fitted value and real value, fitted and real value are basically the same of no significant differences (P > 0.05) and with high precision and reliability.

  7. Magnesium carbonate precipitate strengthened aerobic granules.

    PubMed

    Lee, Duu-Jong; Chen, Yu-You

    2015-05-01

    Aerobic granules were precipitated internally with magnesium carbonate to enhance their structural stability under shear. The strengthened granules were tested in continuous-flow reactors for 220 days at organic loadings of 6-39 kg/m(3)/day, hydraulic retention times of 0.44-19 h, and temperatures of 10 or 28°C. The carbonate salt had markedly improved the granule strength without significant changes in granule morphology or microbial communities (with persistent strains Streptomyces sp., Rhizobium sp., Brevundimonas sp., and Nitratireductor sp.), or sacrifice in biological activity for organic degradation. MgCO3 precipitated granules could be used in continuous-flow reactor for wastewater treatment at low cost and with easy processing efforts.

  8. Electrochemical performance of granulated titania nanoparticles

    NASA Astrophysics Data System (ADS)

    Wilhelm, O.; Pratsinis, S. E.; de Chambrier, E.; Crouzet, M.; Exnar, I.

    The electrochemical performance of Li-ion insertion into electrodes made of various sizes of anatase titania nanoparticles embedded in larger granulated entities (1-10 μm) is investigated. The granules are formed by spray drying of a suspension containing titania nanoparticles made by hydrolyzing titanium tetraisopropoxide (TTIP). Depending on the three process steps, i.e. hydrolysis-condensation, hydrothermal processing and spray drying, different properties for the electrode made from these granules can be achieved in terms of phase composition, specific surface area (SSA) and specific charge capacity. Hydrothermally processed (HP) particles are more resistant to calcination than sol-gel precipitated (SGP) ones and have a higher SSA which leads to a better performance with respect to specific charge capacity. Electrodes made from granulated nanoparticles have superior specific charge capacity than from non-granulated ones as the former have more inter-particle contacts.

  9. Maternal exposure to 3,3'-iminodipropionitrile targets late-stage differentiation of hippocampal granule cell lineages to affect brain-derived neurotrophic factor signaling and interneuron subpopulations in rat offspring.

    PubMed

    Itahashi, Megu; Abe, Hajime; Tanaka, Takeshi; Mizukami, Sayaka; Kikuchihara, Yoh; Yoshida, Toshinori; Shibutani, Makoto

    2015-08-01

    3,3'-Iminodipropionitrile (IDPN) causes neurofilament (NF)-filled swellings in the proximal segments of many large-caliber myelinated axons. This study investigated the effect of maternal exposure to IDPN on hippocampal neurogenesis in rat offspring using pregnant rats supplemented with 0 (controls), 67 or 200 ppm IDPN in drinking water from gestational day 6 to day 21 after delivery. On postnatal day (PND) 21, female offspring subjected to analysis had decreased parvalbumin(+), reelin(+) and phospho-TrkB(+) interneurons in the dentate hilus at 200 ppm and increased granule cell populations expressing immediate-early gene products, Arc or c-Fos, at ≥  67 ppm. mRNA expression in the dentate gyrus examined at 200 ppm decreased with brain-derived neurotrophic factor (Bdnf) and very low density lipoprotein receptor. Immunoreactivity for phosphorylated NF heavy polypeptide decreased in the molecular layer of the dentate gyrus and the stratum radiatum of the cornu ammonis (CA) 3, portions showing axonal projections from mossy cells and pyramidal neurons, at 200 ppm on PND 21, whereas immunoreactivity for synaptophysin was unchanged in the dentate gyrus. Observed changes all disappeared on PND 77. There were no fluctuations in the numbers of apoptotic cells, proliferating cells and subpopulations of granule cell lineage in the subgranular zone on PND 21 and PND 77. Thus, maternal IDPN exposure may reversibly affect late-stage differentiation of granule cell lineages involving neuronal plasticity as evident by immediate-early gene responses to cause BDNF downregulation resulting in a reduction in parvalbumin(+) or reelin(+) interneurons and suppression of axonal plasticity in the mossy cells and CA3 pyramidal neurons.

  10. Effect of platelet dense granule contents upon osteoblast viability.

    PubMed

    Mehta, Siddhant K; Tucci, Michelle A; Benghuzzi, Hamed A

    2012-01-01

    The incorporation of platelet-rich plasma (PRP) into scaffolds for application in musculoskeletal injuries has been a topic of recent interest in orthopaedic surgery. Platelets have dense granules containing ADP, ATP, serotonin, and calcium; and alpha granules containing PDGF, VEGF, IGF, TGF-ß, and EGF. Particular focus of previous studies has been on mitogenic effects of alpha granules, but the role of dense granules in PRP therapy currently remains undefined. The objective of the present study was to evaluate the effect of ATP, ADP, and serotonin upon osteoblast viability in vitro. Human osteoblast-like cells (MG-63 cells) were exposed to phosphate buffered saline (control group), ATP (20µM), ADP (10µM), and serotonin (11.75nM) for 24, 48, and 72 hours. Osteoblast viability was evaluated at each timepoint using biochemical assays. When compared to controls, osteoblasts treated with ATP and ADP resulted in a significant reduction in cell number, while serotonin caused an increase at 24 hours. Similar trends were noted at later timepoints. At 48 hours, a trend towards increase in glutathione was observed with ADP and ATP, but was not sustained at 72 hours. No significant differences in membrane damage were detected between groups. At 24 and 48 hours, ADP significantly increased nitric oxide production. Results of this study demonstrate that ATP, ADP, and serotonin induced significant structural adaptive responses to osteoblastic activities. The data revealed minimal functional alteration as evident by biomarker measurements. Overall conclusion: the results provided further insight regarding PRP therapy for traumatized bone.

  11. Neuroprotective Effect of Ginseng against Alteration of Calcium Binding Proteins Immunoreactivity in the Mice Hippocampus after Radiofrequency Exposure

    PubMed Central

    Maskey, Dhiraj

    2013-01-01

    Calcium binding proteins (CaBPs) such as calbindin D28-k, parvalbumin, and calretinin are able to bind Ca2+ with high affinity. Changes in Ca2+ concentrations via CaBPs can disturb Ca2+ homeostasis. Brain damage can be induced by the prolonged electromagnetic field (EMF) exposure with loss of interacellular Ca2+ balance. The present study investigated the radioprotective effect of ginseng in regard to CaBPs immunoreactivity (IR) in the hippocampus through immunohistochemistry after one-month exposure at 1.6 SAR value by comparing sham control with exposed and ginseng-treated exposed groups separately. Loss of dendritic arborization was noted with the CaBPs in the Cornu Ammonis areas as well as a decrease of staining intensity of the granule cells in the dentate gyrus after exposure while no loss was observed in the ginseng-treated group. A significant difference in the relative mean density was noted between control and exposed groups but was nonsignificant in the ginseng-treated group. Decrease in CaBP IR with changes in the neuronal staining as observed in the exposed group would affect the hippocampal trisynaptic circuit by alteration of the Ca2+ concentration which could be prevented by ginseng. Hence, ginseng could contribute as a radioprotective agent against EMF exposure, contributing to the maintenance of Ca2+ homeostasis by preventing impairment of intracellular Ca2+ levels in the hippocampus. PMID:24069603

  12. Linking local circuit inhibition to olfactory behavior: a critical role for granule cells in olfactory discrimination.

    PubMed

    Strowbridge, Ben W

    2010-02-11

    In this issue of Neuron, Abraham et al. report a direct connection between inhibitory function and olfactory behavior. Using molecular methods to alter glutamate receptor subunit composition in olfactory bulb granule cells, the authors found a selective modulation in the time required for difficult, but not simple, olfactory discrimination tasks.

  13. Correlative microscopy of detergent granules.

    PubMed

    van Dalen, G; Nootenboom, P; Heussen, P C M

    2011-03-01

    The microstructure of detergent products for textile cleaning determines to a large extent the physical properties of these products. Correlative microscopy was used to reveal the microstructure by reconciling images obtained by scanning electron microscopy with energy dispersive X-ray analysis, X-ray microtomography and Fourier transform infrared microscopy. These techniques were applied on the same location of a subsample of a spray-dried detergent base powder embedded in polyacrylate. In this way, the three-dimensional internal and external structure of detergent granules could be investigated from milli to nano scale with detailed spatial information about the components present. This will generate knowledge how to design optimal microstructures for laundry products to obtain product properties demanded by the market. This method is also very useful for other powder systems used in a large variety of industries (e.g. for pharmaceutical, food, ceramic and metal industries).

  14. NEDDylation promotes stress granule assembly

    PubMed Central

    Jayabalan, Aravinth Kumar; Sanchez, Anthony; Park, Ra Young; Yoon, Sang Pil; Kang, Gum-Yong; Baek, Je-Hyun; Anderson, Paul; Kee, Younghoon; Ohn, Takbum

    2016-01-01

    Stress granules (SGs) harbour translationally stalled messenger ribonucleoproteins and play important roles in regulating gene expression and cell fate. Here we show that neddylation promotes SG assembly in response to arsenite-induced oxidative stress. Inhibition or depletion of key components of the neddylation machinery concomitantly inhibits stress-induced polysome disassembly and SG assembly. Affinity purification and subsequent mass-spectrometric analysis of Nedd8-conjugated proteins from translationally stalled ribosomal fractions identified ribosomal proteins, translation factors and RNA-binding proteins (RBPs), including SRSF3, a previously known SG regulator. We show that SRSF3 is selectively neddylated at Lys85 in response to arsenite. A non-neddylatable SRSF3 (K85R) mutant do not prevent arsenite-induced polysome disassembly, but fails to support the SG assembly, suggesting that the neddylation pathway plays an important role in SG assembly. PMID:27381497

  15. Starch granules: structure and biosynthesis.

    PubMed

    Buléon, A; Colonna, P; Planchot, V; Ball, S

    1998-08-01

    The emphasis of this review is on starch structure and its biosynthesis. Improvements in understanding have been brought about during the last decade through the development of new physicochemical and biological techniques, leading to real scientific progress. All this literature needs to be kept inside the general literature about biopolymers, despite some confusing results or discrepancies arising from the biological variability of starch. However, a coherent picture of starch over all the different structural levels can be presented, in order to obtain some generalizations about its structure. In this review we will focus first on our present understanding of the structures of amylose and amylopectin and their organization within the granule, and we will then give insights on the biosynthetic mechanisms explaining the biogenesis of starch in plants.

  16. Pathophysiological Alterations In The Basolateral Amygdala And Neurodegeneration Of Limbic Structures During Epileptogenesis Induced By Status Epilepticus

    DTIC Science & Technology

    2009-02-05

    Crestani F, Martin JR, Möhler H, and Rudolph U (2000) Mechanism of action of the hypnotic zolpidem in vivo. Br J Pharmacol 131:1251–56...epilepsy laterality and reproductive hormone levels in women. Epilepsy Behav 4:407-13. Houser CR (1990) Granule cell dispersion in the dentate gyrus of...cortex from epileptic patients. Neurobiol Dis 8:459- 68. Kostarczyk EM (1986) The amygdala and male reproductive functions. I. Anatomical and

  17. The effect of Urtica dioica extract on the number of astrocytes in the dentate gyrus of diabetic rats.

    PubMed

    Jahanshahi, M; Golalipour, M J; Afshar, M

    2009-05-01

    Diabetes mellitus is associated with cerebral alterations in both human and animal models of the disease. These alterations include abnormal expression of hypothalamic neuropeptides and hippocampal astrogliosis. Urtica dioica (Nettle) is among several species listed for their use against diabetes in folk medicine. The aim of this study was the evaluation of the astrocyte number in the dentate gyrus of diabetic rats after treatment with nettle. A total of 21 male albino Wistar rats were used in the present study. The animals were divided into three groups: control, nettle-untreated diabetic, and nettle treated diabetic. Hyperglycaemia was induced by streptozotocin (80 mg/kg) in the animals of the diabetic and treatment groups. One week after injection of the streptozotocin, the animals in the treatment group received a hydroalcoholic extract of Urtica dioica (100 mg/kg/day) for 4 weeks intraperitoneally. After a 5-week survival period, all the rats were sacrificed and coronal sections were taken from the dorsal hippocampal formation of the right cerebral hemispheres. The area densities of the astrocytes were measured and compared between the three groups (p < 0.05). The number of astrocytes increased in the diabetic rats (24.06 +/- 9.57) compared with the controls (17.52 +/- 6.66). The densities in the treated rats (19.50 +/- 6.16) were lower than in the diabetic rats. Furthermore, the control and treated rats showed similar densities. We concluded that U. dioica extract helped compensate for astrocytes in the treatment rats dentate gyrus in comparison with diabetic rats.

  18. Impact of screw configuration on the particle size distribution of granules produced by twin screw granulation.

    PubMed

    Vercruysse, J; Burggraeve, A; Fonteyne, M; Cappuyns, P; Delaet, U; Van Assche, I; De Beer, T; Remon, J P; Vervaet, C

    2015-02-01

    Twin screw granulation (TSG) has been reported by different research groups as an attractive technology for continuous wet granulation. However, in contrast to fluidized bed granulation, granules produced via this technique typically have a wide and multimodal particle size distribution (PSD), resulting in suboptimal flow properties. The aim of the current study was to evaluate the impact of granulator screw configuration on the PSD of granules produced by TSG. Experiments were performed using a 25 mm co-rotating twin screw granulator, being part of the ConsiGma™-25 system (a fully continuous from-powder-to-tablet manufacturing line from GEA Pharma Systems). Besides the screw elements conventionally used for TSG (conveying and kneading elements), alternative designs of screw elements (tooth-mixing-elements (TME), screw mixing elements (SME) and cutters) were investigated using an α-lactose monohydrate formulation granulated with distilled water. Granulation with only conveying elements resulted in wide and multimodal PSD. Using kneading elements, the width of the PSD could be partially narrowed and the liquid distribution was more homogeneous. However, still a significant fraction of oversized agglomerates was obtained. Implementing additional kneading elements or cutters in the final section of the screw configuration was not beneficial. Furthermore, granulation with only TME or SME had limited impact on the width of the PSD. Promising results were obtained by combining kneading elements with SME, as for these configurations the PSD was narrower and shifted to the size fractions suitable for tableting.

  19. Asymmetric distribution in twin screw granulation.

    PubMed

    Chan Seem, Tim; Rowson, Neil A; Gabbott, Ian; de Matas, Marcel; Reynolds, Gavin K; Ingram, Andy

    2016-09-01

    Positron Emission Particle Tracking (PEPT) was successfully employed to validate measured transverse asymmetry in material distribution in the conveying zones of a Twin Screw Granulator (TSG). Flow asymmetry was established to be a property of the granulator geometry and dependent on fill level. The liquid distribution of granules as a function of fill level was determined. High flow asymmetry at low fill level negatively affects granule nucleation leading to high variance in final uniformity. Wetting of material during nucleation was identified as a critical parameter in determining final granule uniformity and fill level is highlighted as a crucial control factor in achieving this. Flow asymmetry of dry material in conveying zones upstream of binder fluid injection leads to poor non-uniform wetting at nucleation and results in heterogeneous final product. The granule formation mechanism of 60°F kneading blocks is suggested to be primarily breakage of agglomerates formed during nucleation. Optimisation of screw configuration would be required to provide secondary growth. This work shows how fill dependent flow regimes affect granulation mechanisms.

  20. Granulation of zeolite-containing aluminosilicate hydrogel

    SciTech Connect

    Galimov, Z.F.; Vinkel'man, A.P.

    1987-09-01

    The granulation of aluminosilicate hydrogel as an intermediate for the synthesis of cracking catalysts was investigated from the standpoint of eliminating the splitting cone from the granulator and eliminating coagulation directly on the cone surface. A method for forming the gel without a cone was developed by dispersion of jets of sol issuing directly from the mixer. Gel quality was considerably higher in dispersions of time-constant jets of the sol. The experimental mixer can be used as a design basis for a multijet granulator with a capacity equivalent to one or several splitting cones in commercial units.

  1. Synaptic pathology in the cerebellar dentate nucleus in chronic multiple sclerosis.

    PubMed

    Albert, Monika; Barrantes-Freer, Alonso; Lohrberg, Melanie; Antel, Jack P; Prineas, John W; Palkovits, Miklós; Wolff, Joachim R; Brück, Wolfgang; Stadelmann, Christine

    2016-10-05

    In multiple sclerosis, cerebellar symptoms are associated with clinical impairment and an increased likelihood of progressive course. Cortical atrophy and synaptic dysfunction play a prominent role in cerebellar pathology and although the dentate nucleus is a predilection site for lesion development, structural synaptic changes in this region remain largely unexplored. Moreover, the mechanisms leading to synaptic dysfunction have not yet been investigated at an ultrastructural level in multiple sclerosis. Here, we report on synaptic changes of dentate nuclei in post-mortem cerebella of 16 multiple sclerosis patients and eight controls at the histological level as well as an electron microscopy evaluation of afferent synapses of the cerebellar dentate and pontine nuclei of one multiple sclerosis patient and one control. We found a significant reduction of afferent dentate synapses in multiple sclerosis, irrespective of the presence of demyelination, and a close relationship between glial processes and dentate synapses. Ultrastructurally, we show autophagosomes containing degradation products of synaptic vesicles within dendrites, residual bodies within intact-appearing axons and free postsynaptic densities opposed to astrocytic appendages. Our study demonstrates loss of dentate afferent synapses and provides, for the first time, ultrastructural evidence pointing towards neuron-autonomous and neuroglia-mediated mechanisms of synaptic degradation in chronic multiple sclerosis.

  2. Objective assessment of mastication predominance in healthy dentate subjects and patients with unilateral posterior missing teeth.

    PubMed

    Yamasaki, Y; Kuwatsuru, R; Tsukiyama, Y; Oki, K; Koyano, K

    2016-08-01

    We aimed to investigate mastication predominance in healthy dentate individuals and patients with unilateral posterior missing teeth using objective and subjective methods. The sample comprised 50 healthy dentate individuals (healthy dentate group) and 30 patients with unilateral posterior missing teeth (partially edentulous group). Subjects were asked to freely chew three kinds of test foods (peanuts, beef jerky and chewing gum). Electromyographic activity of the bilateral masseter muscles was recorded. The chewing side (right side or left side) was judged by the level of root mean square electromyographic amplitude. Mastication predominance was then objectively assessed using the mastication predominant score and the mastication predominant index. Self-awareness of mastication predominance was evaluated using a modified visual analogue scale. Mastication predominance scores of the healthy dentate and partially edentulous groups for each test food were analysed. There was a significant difference in the distribution of the mastication predominant index between the two groups (P < 0·05). The mastication predominant score was weakly correlated with self-awareness of mastication predominance in the healthy dentate group, whereas strong correlation was observed in the partially edentulous group (P < 0·05). The results suggest that the individuals with missing unilateral posterior teeth exhibited greater mastication predominance and were more aware of mastication predominance than healthy dentate individuals. Our findings suggest that an objective evaluation of mastication predominance is more precise than a subjective method.

  3. Application of tumbling melt granulation (TMG) method to prepare controlled-release fine granules.

    PubMed

    Maejima, T; Kubo, M; Osawa, T; Nakajima, K; Kobayashi, M

    1998-03-01

    The tumbling melt granulation (TMG) method was applied to prepare controlled-release fine granules of diltiazem hydrochloride (DH). The entire process, from the preparation of the cores by the adherence of DH to the sucrose crystal to the subsequent coating of the controlled-release layer, was performed without using any solvent. A mixture of meltable material, talc, and ethylcellulose was used for the controlled-release layer and controlled-release fine granules approximately 400 microns in diameter were obtained with excellent producibility. The dissolution rate of DH from these fine granules was similar to that of a once-a-day dosage form obtained in the market; further, the dependency of the dissolution profile on pH of the media was less. Thus, it was concluded that this TMG method was very useful for preparing not only controlled-release beads of granule size (usually 500 to 1400 microns) but also fine granules.

  4. Distribution of binder in granules produced by means of twin screw granulation.

    PubMed

    Fonteyne, Margot; Fussell, Andrew Luke; Vercruysse, Jurgen; Vervaet, Chris; Remon, Jean Paul; Strachan, Clare; Rades, Thomas; De Beer, Thomas

    2014-02-28

    According to the quality by design principle processes may not remain black-boxes and full process understanding is required. The granule size distribution of granules produced via twin screw granulation is often found to be bimodal. The aim of this study was to gain a better understanding of binder distribution within granules produced via twin screw granulation in order to investigate if an inhomogeneous spread of binder is causing this bimodal size distribution. Theophylline-lactose-polyvinylpyrrolidone K30 (PVP) (30-67.5-2.5%, w/w) was used as a model formulation. The intra-granular distribution of PVP was evaluated by means of hyperspectral coherent anti-Stokes Raman scattering (CARS) microscopy. For the evaluated formulation, no PVP rich zones were detected when applying a lateral spatial resolution of 0.5 μm, indicating that PVP is homogenously distributed within the granules.

  5. Granulation Properties in DOT Images from Solar Maximum to Minimum

    NASA Astrophysics Data System (ADS)

    Pötzi, W.

    DOT granulation filtergrams in the G-Band from solar maximum to solar minimum (1999 to 2007) were investigated for changes of granulation properties like areas, perimeter, fractal dimension, cell sizes, and life times. Granules seem to become larger during solar minimum, whereas the distances between the granule centres stay constant. Nonetheless, the uncertainties are very high.

  6. RNA Granules and Diseases — A Case Study of Stress Granules in ALS and FTLD

    PubMed Central

    Fan, Alexander C.; Leung, Anthony K. L.

    2017-01-01

    RNA granules are microscopically visible cellular structures that aggregate by protein–protein and protein-RNA interactions. Using stress granules as an example, we discuss the principles of RNA granule formation, which rely on the multivalency of RNA and multi-domain proteins as well as low-affinity interactions between proteins with prion-like/low-complexity domains (e.g. FUS and TDP-43). We then explore how dysregulation of RNA granule formation is linked to neurodegenerative diseases, such as amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration (FTLD), and discuss possible strategies for therapeutic intervention. PMID:27256390

  7. Phasins, Multifaceted Polyhydroxyalkanoate Granule-Associated Proteins

    PubMed Central

    Mezzina, Mariela P.

    2016-01-01

    Phasins are the major polyhydroxyalkanoate (PHA) granule-associated proteins. They promote bacterial growth and PHA synthesis and affect the number, size, and distribution of the granules. These proteins can be classified in 4 families with distinctive characteristics. Low-resolution structural studies and in silico predictions were performed in order to elucidate the structure of different phasins. Most of these proteins share some common structural features, such as a preponderant α-helix composition, the presence of disordered regions that provide flexibility to the protein, and coiled-coil interacting regions that form oligomerization domains. Due to their amphiphilic nature, these proteins play an important structural function, forming an interphase between the hydrophobic content of PHA granules and the hydrophilic cytoplasm content. Phasins have been observed to affect both PHA accumulation and utilization. Apart from their role as granule structural proteins, phasins have a remarkable variety of additional functions. Different phasins have been determined to (i) activate PHA depolymerization, (ii) increase the expression and activity of PHA synthases, (iii) participate in PHA granule segregation, and (iv) have both in vivo and in vitro chaperone activities. These properties suggest that phasins might play an active role in PHA-related stress protection and fitness enhancement. Due to their granule binding capacity and structural flexibility, several biotechnological applications have been developed using different phasins, increasing the interest in the study of these remarkable proteins. PMID:27287326

  8. Culturing of cerebellar granule cells to study neuronal migration: gradient and local perfusion assays.

    PubMed

    Guijarro, Patricia; Jiang, Jian; Yuan, Xiao-bing

    2012-07-01

    Cultures of cerebellar granule cells are a suitable model to analyze the mechanisms governing neuronal migration. In this unit, we describe a protocol to obtain cultures of dissociated granule cells at a low density, where individual cells can be easily observed. In addition, we include a protocol for studying neuronal migration in these cultures, using single, actively migrating cerebellar granule cells. Following this protocol, a factor of interest can be applied either in a gradient concentration by means of a micropipet located near the neuron, or in a homogeneous concentration by locally perfusing a certain region of the neuron. Time-lapse images are taken to analyze changes in the speed and/or directionality of the observed neuron. Overall, the two protocols take more or less a day and a half to perform, and are a useful way to evaluate a certain factor/drug for its chemotactic activity or its capacity to alter migration speed.

  9. Ca2+-dependent dephosphorylation of kinesin heavy chain on beta-granules in pancreatic beta-cells. Implications for regulated beta-granule transport and insulin exocytosis.

    PubMed

    Donelan, Matthew J; Morfini, Gerardo; Julyan, Richard; Sommers, Scott; Hays, Lori; Kajio, Hiroshi; Briaud, Isabelle; Easom, Richard A; Molkentin, Jeffery D; Brady, Scott T; Rhodes, Christopher J

    2002-07-05

    The specific biochemical steps required for glucose-regulated insulin exocytosis from beta-cells are not well defined. Elevation of glucose leads to increases in cytosolic [Ca2+]i and biphasic release of insulin from both a readily releasable and a storage pool of beta-granules. The effect of elevated [Ca2+]i on phosphorylation of isolated beta-granule membrane proteins was evaluated, and the phosphorylation of four proteins was found to be altered by [Ca2+]i. One (a 18/20-kDa doublet) was a Ca2+-dependent increase in phosphorylation, and, surprisingly, three others (138, 42, and 36 kDa) were Ca2+-dependent dephosphorylations. The 138-kDa beta-granule phosphoprotein was found to be kinesin heavy chain (KHC). At low levels of [Ca2+]i KHC was phosphorylated by casein kinase 2, but KHC was rapidly dephosphorylated by protein phosphatase 2B beta (PP2Bbeta) as [Ca2+]i increased. Inhibitors of PP2B specifically reduced the second, microtubule-dependent, phase of insulin secretion, suggesting that dephosphorylation of KHC was required for transport of beta-granules from the storage pool to replenish the readily releasable pool of beta-granules. This is distinct from synaptic vesicle exocytosis, because neurotransmitter release from synaptosomes did not require a Ca2+-dependent KHC dephosphorylation. These results suggest a novel mechanism for regulating KHC function and beta-granule transport in beta-cells that is mediated by casein kinase 2 and PP2B. They also implicate a novel regulatory role for PP2B/calcineurin in the control of insulin secretion downstream of a rise in [Ca2+]i.

  10. Ca2+-dependent dephosphorylation of kinesin heavy chain on beta-granules in pancreatic beta-cells. Implications for regulated beta-granule transport and insulin exocytosis

    NASA Technical Reports Server (NTRS)

    Donelan, Matthew J.; Morfini, Gerardo; Julyan, Richard; Sommers, Scott; Hays, Lori; Kajio, Hiroshi; Briaud, Isabelle; Easom, Richard A.; Molkentin, Jeffery D.; Brady, Scott T.; Rhodes, Christopher J.

    2002-01-01

    The specific biochemical steps required for glucose-regulated insulin exocytosis from beta-cells are not well defined. Elevation of glucose leads to increases in cytosolic [Ca2+]i and biphasic release of insulin from both a readily releasable and a storage pool of beta-granules. The effect of elevated [Ca2+]i on phosphorylation of isolated beta-granule membrane proteins was evaluated, and the phosphorylation of four proteins was found to be altered by [Ca2+]i. One (a 18/20-kDa doublet) was a Ca2+-dependent increase in phosphorylation, and, surprisingly, three others (138, 42, and 36 kDa) were Ca2+-dependent dephosphorylations. The 138-kDa beta-granule phosphoprotein was found to be kinesin heavy chain (KHC). At low levels of [Ca2+]i KHC was phosphorylated by casein kinase 2, but KHC was rapidly dephosphorylated by protein phosphatase 2B beta (PP2Bbeta) as [Ca2+]i increased. Inhibitors of PP2B specifically reduced the second, microtubule-dependent, phase of insulin secretion, suggesting that dephosphorylation of KHC was required for transport of beta-granules from the storage pool to replenish the readily releasable pool of beta-granules. This is distinct from synaptic vesicle exocytosis, because neurotransmitter release from synaptosomes did not require a Ca2+-dependent KHC dephosphorylation. These results suggest a novel mechanism for regulating KHC function and beta-granule transport in beta-cells that is mediated by casein kinase 2 and PP2B. They also implicate a novel regulatory role for PP2B/calcineurin in the control of insulin secretion downstream of a rise in [Ca2+]i.

  11. l-DOPA reverses the impairment of Dentate Gyrus LTD in experimental parkinsonism via β-adrenergic receptors.

    PubMed

    Pendolino, Valentina; Bagetta, Vincenza; Ghiglieri, Veronica; Sgobio, Carmelo; Morelli, Emanuela; Poggini, Silvia; Branchi, Igor; Latagliata, Emanuele C; Pascucci, Tiziana; Puglisi-Allegra, Stefano; Calabresi, Paolo; Picconi, Barbara

    2014-11-01

    Parkinson's disease (PD) patients exhibit motor and non-motor symptoms that severely affect quality of life. Cognitive alterations in PD subjects have been related to both structural and functional hippocampal changes. Here we investigated the effects of the 6-hydroxydopamine (6-OHDA) lesion in the Medial Forebrain Bundle (MFB) on the hippocampus focusing on the Dentate Gyrus (DG). In vivo microdialysis measurements revealed that the 6-OHDA injection disrupts both dopaminergic and noradrenergic transmission in rat DG. In vitro electrophysiological recordings showed that these neurochemical alterations were accompanied by impairment of long-term depression (LTD) at medial perforant path/DG synapses. Furthermore, this alteration was reversed by l-DOPA treatment. Notably, the therapeutic effect of l-DOPA on LTD was blocked by the antagonism of β-noradrenergic receptors, but not by dopamine D1 or D2 receptor antagonists. Thus, while the dopaminergic transmission does not seem to be implicated in this therapeutic effect of l-DOPA, the noradrenergic system plays a central role in the synaptic dysfunction of the DG in experimental PD. Our work provides new evidence on the role of catecholamines in DG synaptic plasticity and sheds light on the possible synaptic mechanisms underlying cognitive deficits in PD. Furthermore, our results indicate that l-DOPA exerts a therapeutic effect on the parkinsonian brain through different, coexistent, mechanisms.

  12. Efficacy of doublecortin as a marker to analyse the absolute number and dendritic growth of newly generated neurons in the adult dentate gyrus.

    PubMed

    Rao, Muddanna S; Shetty, Ashok K

    2004-01-01

    Doublecortin (DCX), a microtubule-associated phosphoprotein, has been recently utilized as a marker of newly born neurons in the adult dentate gyrus (DG). Nonetheless, it is unknown whether DCX exclusively labels newly formed neurons, as certain granule cells with the phenotype of differentiated neurons express DCX. We addressed the authenticity of DCX as a marker of new neurons in the adult DG by quantifying cells that are positive for 5'-bromodeoxyuridine (BrdU), DCX and both BrdU and DCX in hippocampal tissues of adult rats treated with daily injections of BrdU for 12 consecutive days. We provide new evidence that neurons visualized with DCX immunostaining in the adult rat DG are new neurons that are predominantly born during the 12 days before euthanasia. This is confirmed by the robust expression of BrdU in 90% of DCX-positive neurons in the DG of animals injected with BrdU for 12 days. Furthermore, DCX expression is specific to newly generated healthy neurons, as virtually all DCX-positive cells express early neuronal antigens but lack antigens specific to glia, undifferentiated cells or apoptotic cells. As DCX expression is also robust in the dendrites, DCX immunocytochemistry of thicker sections facilitates quantification of the dendritic growth in newly born neurons. Thus, both absolute number and dendritic growth of new neurons that are generated in the adult DG over a 12-day period can be quantified reliably with DCX immunostaining. This could be particularly useful for analysing changes in dentate neurogenesis in human hippocampal tissues as a function of ageing or neurodegenerative diseases.

  13. Involvement of over-expressed BMP4 in pentylenetetrazol kindling-induced cell proliferation in the dentate gyrus of adult rats

    SciTech Connect

    Yin Jinbo; Ma Yuxin; Yin Qing; Xu Haiwei . E-mail: haiweixu2001@yahoo.com.cn; An Ning; Liu Shiyong; Fan Xiaotang; Yang Hui . E-mail: huiyang64@yahoo.com

    2007-03-30

    The dentate gyrus (DG) of the hippocampus is one of a few regions in the adult mammalian brain characterized by ongoing neurogenesis. Proliferation of neural precursors in the granule cell layer of the DG has been identified in pentylenetetrazol (PTZ) kindling epilepsy model, however, little is known about the molecular mechanism. We previously reported that the expression pattern of bone morphogenetic proteins-4 (BMP4) mRNA in the hippocampus was developmentally regulated and mainly localized in the DG of the adult. To explore the role of BMP4 in epileptic activity, we detected BMP4 expression in the DG during PTZ kindling process and explore its correlation with cell proliferation combined with bromodeoxyuridine (BrdU) labeling technique. We found that dynamic changes in BMP4 level and BrdU labeled cells dependent on the kindling stage of PTZ induced seizure-prone state. The number of BMP4 mRNA-positive cells and BrdU labeled cells reached the top level 1 day after PTZ kindled, then declined to base level 2 months later. Furthermore, there was a significant correlation between increased BMP4 mRNA expression and increased number of BrdU labeled cells. After effectively blocked expression of BMP4 with antisense oligodeoxynucleotides(ASODN), the BrdU labeled cells in the dentate gyrus subgranular zone(DG-SGZ) and hilus were significantly decreased 16d after First PTZ injection and 1, 3, 7, 14d after kindled respectively. These findings suggest that increased proliferation in the DG of the hippocampus resulted from kindling epilepsy elicited by PTZ maybe be modulated by BMP4 over-expression.

  14. The transcription factor Cux1 in cerebellar granule cell development and medulloblastoma pathogenesis.

    PubMed

    Topka, Sabine; Glassmann, Alexander; Weisheit, Gunnar; Schüller, Ulrich; Schilling, Karl

    2014-12-01

    Cux1, also known as Cutl1, CDP or Cut is a homeodomain transcription factor implicated in the regulation of normal and oncogenic development in diverse peripheral tissues and organs. We studied the expression and functional role of Cux1 in cerebellar granule cells and medulloblastoma. Cux1 is robustly expressed in proliferating granule cell precursors and in postmitotic, migrating granule cells. Expression is lost as postmigratory granule cells mature. Moreover, Cux1 is also strongly expressed in a well-established mouse model of medulloblastoma. In contrast, expression of CUX1 in human medulloblastoma tissue samples is lower than in normal fetal cerebellum. In these tumors, CUX1 expression tightly correlates with a set of genes which, when mapped on a global protein-protein interaction dataset, yields a tight network that constitutes a cell cycle control signature and may be related to p53 and the DNA damage response pathway. Antisense-mediated reduction of CUX1 levels in two human medulloblastoma cell lines led to a decrease in proliferation and altered motility. The developmental expression of Cux1 in the cerebellum and its action in cell lines support a role in granule cell and medulloblastoma proliferation. Its expression in human medulloblastoma shifts that perspective, suggesting that CUX1 is part of a network involved in cell cycle control and maintenance of DNA integrity. The constituents of this network may be rational targets to therapeutically approach medulloblastomas.

  15. Satellite NG2 progenitor cells share common glutamatergic inputs with associated interneurons in the mouse dentate gyrus.

    PubMed

    Mangin, Jean-Marie; Kunze, Albrecht; Chittajallu, Ramesh; Gallo, Vittorio

    2008-07-23

    Several studies have provided evidence that NG2-expressing (NG2(+)) progenitor cells are anatomically associated to neurons in gray matter areas. By analyzing the spatial distribution of NG2(+) cells in the hilus of the mouse dentate gyrus, we demonstrate that NG2(+) cells are indeed closely associated to interneurons. To define whether this anatomical proximity reflected a specific physiological interaction, we performed patch-clamp recordings on hilar NG2(+) cells and interneurons between 3 and 21 postnatal days. We first observed that hilar NG2(+) cells exhibit spontaneous glutamatergic EPSCs (sEPSCs) whose frequency and amplitude increase during the first 3 postnatal weeks. At the same time, the rise time and decay time of sEPSCs significantly decreased, suggesting that glutamatergic synapses in NG2(+) cells undergo a maturation process that is reminiscent of what has been reported in neurons during the same time period. We also observed that hilar interneurons and associated NG2(+) cells are similarly integrated into the local network, receiving excitatory inputs from both granule cells and CA3 pyramidal neurons. By performing pair recordings, we found that bursts of activity induced by GABAergic antagonists were strongly synchronized between both cell types and that the amplitude of these bursts was positively correlated. Finally, by applying carbachol to increase EPSC activity, we observed that closely apposed cells were more likely to exhibit synchronized EPSCs than cells separated by >200 microm. The finding that NG2(+) cells are sensing patterns of activity arising in closely associated neurons suggests that NG2(+) cell function is finely regulated by the local network.

  16. Entorhinal theta-frequency input to the dentate gyrus trisynaptically evokes hippocampal CA1 LTP

    PubMed Central

    Stepan, Jens; Dine, Julien; Fenzl, Thomas; Polta, Stephanie A.; von Wolff, Gregor; Wotjak, Carsten T.; Eder, Matthias

    2012-01-01

    There exists substantial evidence that some forms of explicit learning in mammals require long-term potentiation (LTP) at hippocampal CA3-CA1 synapses. While CA1 LTP has been well characterized at the monosynaptic level, it still remains unclear how the afferent systems to the hippocampus can initiate formation of this neuroplastic phenomenon. Using voltage-sensitive dye imaging (VSDI) in a mouse brain slice preparation, we show that evoked entorhinal cortical (EC) theta-frequency input to the dentate gyrus highly effectively generates waves of neuronal activity which propagate through the entire trisynaptic circuit of the hippocampus (“HTC-Waves”). This flow of activity, which we also demonstrate in vivo, critically depends on frequency facilitation of mossy fiber to CA3 synaptic transmission. The HTC-Waves are rapidly boosted by the cognitive enhancer caffeine (5 μM) and the stress hormone corticosterone (100 nM). They precisely follow the rhythm of the EC input, involve high-frequency firing (>100 Hz) of CA3 pyramidal neurons, and induce NMDA receptor-dependent CA1 LTP within a few seconds. Our study provides the first experimental evidence that synchronous theta-rhythmical spiking of EC stellate cells, as occurring during EC theta oscillations, has the capacity to drive induction of CA1 LTP via the hippocampal trisynaptic pathway. Moreover, we present data pointing to a basic filter mechanism of the hippocampus regarding EC inputs and describe a methodology to reveal alterations in the “input–output relationship” of the hippocampal trisynaptic circuit. PMID:22988432

  17. Scopolamine impairs behavioural function and arginine metabolism in the rat dentate gyrus.

    PubMed

    Knox, Logan T; Jing, Yu; Fleete, Michael S; Collie, Nicola D; Zhang, Hu; Liu, Ping

    2011-12-01

    Alzheimer's disease (AD) is a neurodegenerative disorder with progressive memory loss. It has been shown that the cholinergic neurotransmission deficit is one of the neurochemical characteristics of AD, and that L-arginine and its metabolites also play a prominent role in AD pathogenesis. Scopolamine, a non-selective muscarinic receptor antagonist, blocks cholinergic neurotransmission and impairs behavioural function, including learning and memory. This study investigated the effects of scopolamine on animals' behavioural performance and L-arginine metabolism in the hippocampus and prefrontal cortex. Rats were given intraperitoneal injections of scopolamine (0.8 mg/kg) or saline (1 ml/kg) and tested in the Y-maze, open field, water maze and elevated plus maze 30 min post-treatment. After completion of the behavioural testing, the CA1, CA2/3 and dentate gyrus (DG) sub-regions of the hippocampus and the prefrontal cortex were harvested to measure the activity and protein expression of nitric oxide synthase (NOS) and arginase, and the levels of L-arginine, L-citrulline, L-ornithine, agmatine, putrescine, spermidine, spermine, glutamate and GABA. Scopolamine treated rats displayed reduced alternation and exploratory behaviour, increased swimming speed and impaired spatial learning and memory. There were significantly decreased NOS activity, increased arginase activity, and increased L-ornithine and putrescine levels in the DG, but not other regions examined, in the scopolamine treated rats as compared to the controls. These findings suggest that scopolamine impairs behavioural function and alters L-arginine metabolism in the DG sub-region of the hippocampus specifically. The underlying mechanisms of it remain to be explored further.

  18. Granule size control and targeting in pulsed spray fluid bed granulation.

    PubMed

    Ehlers, Henrik; Liu, Anchang; Räikkönen, Heikki; Hatara, Juha; Antikainen, Osmo; Airaksinen, Sari; Heinämäki, Jyrki; Lou, Honxiang; Yliruusi, Jouko

    2009-07-30

    The primary aim of the study was to investigate the effects of pulsed liquid feed on granule size. The secondary aim was to increase knowledge of this technique in granule size targeting. Pulsed liquid feed refers to the pump changing between on- and off-positions in sequences, called duty cycles. One duty cycle consists of one on- and off-period. The study was performed with a laboratory-scale top-spray fluid bed granulator with duty cycle length and atomization pressure as studied variables. The liquid feed rate, amount and inlet air temperature were constant. The granules were small, indicating that the powder has only undergone ordered mixing, nucleation and early growth. The effect of atomizing pressure on granule size depends on inlet air relative humidity, with premature binder evaporation as a reason. The duty cycle length was of critical importance to the end product attributes, by defining the extent of intermittent drying and rewetting. By varying only the duty cycle length, it was possible to control granule nucleation and growth, with a wider granule size target range in increased relative humidity. The present study confirms that pulsed liquid feed in fluid bed granulation is a useful tool in end product particle size targeting.

  19. Prenatal alcohol exposure reduces the proportion of newly produced neurons and glia in the dentate gyrus of the hippocampus in female rats

    PubMed Central

    Uban, Kristina A.; Sliwowska, Joanna H.; Lieblich, Stephanie; Ellis, Linda A.; Yu, Wayne L.; Weinberg, Joanne; Galea, Liisa A. M.

    2010-01-01

    Prenatal alcohol exposure (PAE) alters adult neurogenesis and the neurogenic response to stress in male rats. As the effects of stress on neurogenesis are sexually dimorphic, the present study investigated the effects of PAE on adult hippocampal neurogenesis under both non-stressed and stressed conditions in female rats. Pregnant females were assigned to one of three prenatal treatments: 1) Alcohol (PAE) - liquid alcohol (ethanol) diet ad libitum (36% ethanol-derived calories); 2) Pair-fed - isocaloric liquid diet, with maltose-dextrin substituted for ethanol, in the amount consumed by a PAE partner (g/kg body wt/day of gestation); and 3) Control - lab chow ad libitum. Female offspring were assigned to either non-stressed (undisturbed) or stressed (repeated restraint stress for 9 days) conditions. On day 10, all rats were injected with bromodeoxyuridine (BrdU) and perfused either 24 hours (cell proliferation) or 3 weeks (cell survival) later. We found that PAE did not significantly alter cell proliferation or survival, whereas females from the Pair-fed condition exhibited elevated levels of cell survival compared to Control females. Importantly, however, the proportion of both new neurons and new glial cells in the hippocampal dentate gyrus was reduced in PAE compared to Control females. Exposure to stress did not alter neurogenesis in any of the prenatal treatment groups. In summary, compared to females from the Control condition, prenatal dietary restriction enhanced the survival of new neurons, whereas PAE altered the differentiation of newly produced cells in the adult dentate gyrus. Alterations in hippocampal neurogenesis following PAE may contribute to learning and memory deficits seen in individuals with fetal alcohol spectrum disorders. PMID:20736015

  20. Prenatal alcohol exposure reduces the proportion of newly produced neurons and glia in the dentate gyrus of the hippocampus in female rats.

    PubMed

    Uban, Kristina A; Sliwowska, Joanna H; Lieblich, Stephanie; Ellis, Linda A; Yu, Wayne K; Weinberg, Joanne; Galea, Liisa A M

    2010-11-01

    Prenatal alcohol exposure (PAE) alters adult neurogenesis and the neurogenic response to stress in male rats. As the effects of stress on neurogenesis are sexually dimorphic, the present study investigated the effects of PAE on adult hippocampal neurogenesis under both nonstressed and stressed conditions in female rats. Pregnant females were assigned to one of three prenatal treatments: (1) alcohol (PAE)-liquid alcohol (ethanol) diet ad libitum (36% ethanol-derived calories); (2) pair-fed-isocaloric liquid diet, with maltose-dextrin substituted for ethanol, in the amount consumed by a PAE partner (g/kg body wt/day of gestation); and (3) control-lab chow ad libitum. Female offspring were assigned to either nonstressed (undisturbed) or stressed (repeated restraint stress for 9 days) conditions. On day 10, all rats were injected with bromodeoxyuridine (BrdU) and perfused either 24 hours (cell proliferation) or 3 weeks (cell survival) later. We found that PAE did not significantly alter cell proliferation or survival, whereas females from the pair-fed condition exhibited elevated levels of cell survival compared to control females. Importantly, however, the proportion of both new neurons and new glial cells in the hippocampal dentate gyrus was reduced in PAE compared to control females. Exposure to stress did not alter neurogenesis in any of the prenatal treatment groups. In summary, compared to females from the control condition, prenatal dietary restriction enhanced the survival of new neurons, whereas PAE altered the differentiation of newly produced cells in the adult dentate gyrus. Alterations in hippocampal neurogenesis following PAE may contribute to learning and memory deficits seen in individuals with fetal alcohol spectrum disorders.

  1. Monitoring high-shear granulation using sound and vibration measurements.

    PubMed

    Briens, L; Daniher, D; Tallevi, A

    2007-02-22

    Sound and vibration measurements were investigated as monitoring methods for high-shear granulation. Five microphones and one accelerometer were placed at different locations on a 10 and a 25 l granulator and compared to find the optimum location and the effect of scale. The granulation process could be monitored using the mean frequency and root mean square sound pressure levels from acoustic emissions measured using a microphone in the filtered air exhaust of the granulators. These acoustic monitoring methods were successful for both the 10 and the 25 l granulation scales. The granulation phases, however, were more clearly defined for the larger scale granulation. The root mean square acceleration level from vibration measurements was also able to monitor the granulation, but only for the larger 25 l granulator.

  2. Diffusion tensor MRI shows progressive changes in the hippocampus and dentate gyrus after status epilepticus in rat - histological validation with Fourier-based analysis.

    PubMed

    Salo, Raimo A; Miettinen, Tuukka; Laitinen, Teemu; Gröhn, Olli; Sierra, Alejandra

    2017-03-04

    Imaging markers for monitoring disease progression, recovery, and treatment efficacy are a major unmet need for many neurological diseases, including epilepsy. Recent evidence suggests that diffusion tensor imaging (DTI) provides high microstructural contrast even outside major white matter tracts. We hypothesized that in vivo DTI could detect progressive microstructural changes in the dentate gyrus and the hippocampal CA3bc in the rat brain after status epilepticus (SE). To test this hypothesis, we induced SE with systemic kainic acid or pilocarpine in adult male Wistar rats and subsequently scanned them using in vivo DTI at five time-points: prior to SE, and 10, 20, 34, and 79 days post SE. In order to tie the DTI findings to changes in the tissue microstructure, myelin- and glial fibrillary acidic protein (GFAP)-stained sections from the same animals underwent Fourier analysis. We compared the Fourier analysis parameters, anisotropy index and angle of myelinated axons or astrocyte processes, to corresponding DTI parameters, fractional anisotropy (FA) and the orientation angle of the principal eigenvector. We found progressive detectable changes in DTI parameters in both the dentate gyrus (FA, axial diffusivity [D||], linear anisotropy [CL] and spherical anisotropy [CS], p<0.001, linear mixed-effects model [LMEM]) and the CA3bc (FA, D||, CS, and angle, p<0.001, LMEM; CL and planar anisotropy [CP], p<0.01, LMEM) post SE. The Fourier analysis revealed that both myelinated axons and astrocyte processes played a role in the water diffusion anisotropy changes detected by DTI in individual portions of the dentate gyrus (suprapyramidal blade, mid-portion, and infrapyramidal blade). In the whole dentate gyrus, myelinated axons markedly contributed to the water diffusion changes. In CA3bc as well as in CA3b and CA3c, both myelinated axons and astrocyte processes contributed to water diffusion anisotropy and orientation. Our study revealed that DTI is a promising method

  3. Manipulation of starch granule size distribution in potato tubers by modulation of plastid division.

    PubMed

    de Pater, Sylvia; Caspers, Martien; Kottenhagen, Marijke; Meima, Henk; ter Stege, Renaldo; de Vetten, Nick

    2006-01-01

    Starch granule size is an important parameter for starch applications in industry. Starch granules are formed in amyloplasts, which are, like chloroplasts, derived from proplastids. Division processes and associated machinery are likely to be similar for all plastids. Essential roles for FtsZ proteins in plastid division in land plants have been revealed. FtsZ forms the so-called Z ring which, together with inner and outer plastid division rings, brings about constriction of the plastid. It has been shown that modulation of the expression level of FtsZ may result in altered chloroplast size and number. To test whether FtsZ is also involved in amyloplast division and whether this, in turn, may affect the starch granule size in crop plants, FtsZ protein levels were either reduced or increased in potato. As shown previously in other plant species, decreased StFtsZ1 protein levels in leaves resulted in a decrease in the number of chloroplasts in guard cells. More interestingly, plants with increased StFtsZ1 protein levels in tubers resulted in less, but larger, starch granules. This suggests that the stoichiometry between StFtsZ1 and other components of the plastid division machinery is important for its function. Starch from these tubers also had altered pasting properties and phosphate content. The importance of our results for the starch industry is discussed.

  4. Granulostasis: Protein Quality Control of RNP Granules

    PubMed Central

    Alberti, Simon; Mateju, Daniel; Mediani, Laura; Carra, Serena

    2017-01-01

    Ribonucleoprotein (RNP) granules transport, store, or degrade messenger RNAs, thereby indirectly regulating protein synthesis. Normally, RNP granules are highly dynamic compartments. However, because of aging or severe environmental stress, RNP granules, in particular stress granules (SGs), convert into solid, aggregate-like inclusions. There is increasing evidence that such RNA-protein inclusions are associated with several age-related neurodegenerative diseases, such as amyotrophic lateral sclerosis (ALS), fronto-temporal dementia (FTD) and Alzheimer’s disease (AD). Thus, understanding what triggers the conversion of RNP granules into aggregates and identifying the cellular players that control RNP granules will be critical to develop treatments for these diseases. In this review article, we discuss recent insight into RNP and SG formation. More specifically, we examine the evidence for liquid-liquid phase separation (LLPS) as an organizing principle of RNP granules and the role of aggregation-prone RNA-binding proteins (RBPs) in this process. We further discuss recent findings that liquid-like SGs can sequester misfolded proteins, which promote an aberrant conversion of liquid SGs into solid aggregates. Importantly, very recent studies show that a specific protein quality control (PQC) process prevents the accumulation of misfolding-prone proteins in SGs and, by doing so, maintains the dynamic state of SGs. This quality control process has been referred to as granulostasis and it relies on the specific action of the HSPB8-BAG3-HSP70 complex. Additional players such as p97/valosin containing protein (VCP) and other molecular chaperones (e.g., HSPB1) participate, directly or indirectly, in granulostasis, and ensure the timely elimination of defective ribosomal products and other misfolded proteins from SGs. Finally, we discuss recent findings that, in the stress recovery phase, SGs are preferentially disassembled with the assistance of chaperones, and we discuss

  5. Denitrification in USB reactor with granulated biomass.

    PubMed

    Pagácová, P; Galbová, K; Drtil, M; Jonatová, I

    2010-01-01

    Denitrification of low concentrations of NO(3)-N (20 mg L(-1)), with methanol as an organic carbon source (COD:NO(3)-N=6) in laboratory upflow sludge bed reactor (USB), was tested as a possibility for wastewater post-treatment. By gradual increase of volumetric loading (Bv) and hydraulic loading (gamma), anoxic biomass spontaneously granulated out even from flocculate activated sludge and from anaerobic granulated sludge as well. Anaerobic granulated biomass derived from high-rate anaerobic IC reactor was a far better inoculum for anoxic granulation and for denitrification in the USB reactor. The maximum level of Bv and gamma was remarkably higher with the use of anaerobic granulated inoculum, (19-22 kg COD m(-3)d(-1); 3.2-3.7 kg NO(3)-Nm(-3)d(-1); 2.8-3.2m(3)m(-2)h(-1); SVI=15 mL g(-1)) in comparison to inoculum from flocculate activated sludge (4.2-8.1 kg CO Dm(-3)d(-1); 0.7-1.4 kg NO(3)-Nm(-3)d(-1); 0.7-1.15m(3)m(-2)h(-1); SVI=40-95 mL g(-1)).

  6. Granulation in saturnian rings and atmosphere

    NASA Astrophysics Data System (ADS)

    Kochemasov, G. G.

    2008-09-01

    The third theorem of the wave planetary tectonics [1-3 & others] states: "Celestial bodies are granular". It means that inertia-gravity waves appearing in bodies due to their movements in non-circular keplerian orbits and propagating in them in four interfering orthogonal and diagonal directions produce tectonic granules. They are of three kinds: uprising (+), subsiding (-) and neutral (0). Their sizes are inversely proportional to bodies orbital frequencies. Higher frequency - smaller granule, lower frequency - larger granule. The inertia-gravity waves warp all spheres of celestial bodies: solid, liquid, gaseous, and act in stars, planets, asteroids, comets and satellites. The Cassini data provide numerous excellent images of saturnian rings and show that wave processes are ordinary also in them - in disperse solid environment. To illustrate dependence between orbital frequencies and granule sizes we provide the following geometrical representation of the planetary row starting from the solar photosphere also having a certain orbital frequency about the center of the Solar system (Fig. 1). This row can be extended in domain of the outer planets by the same algorithm: Jupiter 3πR, Saturn 7.5πR, Uranus 21πR, Neptune 41πR, Pluto 62πR. One cannot directly observe these huge waves in the planets but they are needed for wave modulation procedures very important for satellites and rings having two orbital frequencies: around the star and planets. A recent support for the wave structurization in the Solar system came from Saturn where 22 year long ground-based temperature observations discovered a wave-like oscillation: hotcold pattern switches every Saturn half-year = 15 Earth's years [4]. Like in the radio-wave physics the lower orbiting frequency of the Saturn's system around Sun modulates the higher orbiting frequencies of the system satellites, rings and the planet's upper atmosphere about the Saturn `s system center. . The higher frequency is multiplied and

  7. Formation of volutin granules in Corynebacterium glutamicum.

    PubMed

    Pallerla, Srinivas Reddy; Knebel, Sandra; Polen, Tino; Klauth, Peter; Hollender, Juliane; Wendisch, Volker F; Schoberth, Siegfried M

    2005-02-01

    Volutin granules are intracellular storages of complexed inorganic polyphosphate (poly P). Histochemical staining procedures differentiate between pathogenic corynebacteria such as Corynebacterum diphtheriae (containing volutin) and non-pathogenic species, such as C. glutamicum. Here we report that strains ATCC13032 and MH20-22B of the non-pathogenic C. glutamicum also formed subcellular entities (18-37% of the total cell volume) that had the typical characteristics of volutin granules: (i) volutin staining, (ii) green UV fluorescence when stained with 4',6-diamidino-2-phenylindole, (iii) electron-dense and rich in phosphorus when determined with transmission electron microscopy and X-ray microanalysis, and (iv) 31P NMR poly P resonances of isolated granules dissolved in EDTA. MgCl2 addition to the growth medium stimulated granule formation but did not effect expression of genes involved in poly P metabolism. Granular volutin fractions from lysed cells contained polyphosphate glucokinase as detected by SDS-PAGE/MALDI-TOF, indicating that this poly P metabolizing enzyme is present also in intact poly P granules. The results suggest that formation of volutin is a more widespread phenomenon than generally accepted.

  8. Cerebralcare Granule® attenuates cognitive impairment in rats continuously overexpressing microRNA-30e

    PubMed Central

    XU, YONG; LIU, ZHIFEN; SONG, XI; ZHANG, KERANG; LI, XINGRONG; LI, JIANHONG; YAN, XU; LI, YUAN; XIE, ZHONGCHEN; ZHANG, HUI

    2015-01-01

    Previous studies have demonstrated that dysregulation of micro (mi)RNAs is associated with the etiology of various neuropsychiatric disorders, including depression and schizophrenia. Cerebralcare Granule® (CG) is a Chinese herbal medicine, which has been reported to have an ameliorative effect on brain injury by attenuating blood-brain barrier disruption and improving hippocampal neural function. The present study aimed to evaluate the cognitive behavior of rats continuously overexpressing miRNA-30e (lenti-miRNA-30e), prior to and following the administration of CG. In addition, the mechanisms underlying the ameliorative effects of CG were investigated. The cognitive ability of the rats was assessed using an open-field test and a Morris water maze spatial reference/working memory test. A terminal deoxynucleotidyl transferase dUTP nick end labeling assay was used to detect neuronal apoptosis in the dentate gyrus of the hippocampus. Immunohistochemical analysis and western blotting were conducted to detect the expression levels of B-cell lymphoma 2 (BCL-2) and ubiquitin-conjugating enzyme 9 (UBC9), in order to examine neuronal apoptosis. The lenti-miRNA-30e rats exhibited increased signs of anxiety, depression, hyperactivity and schizophrenia, which resulted in a severe impairment in cognitive ability. Furthermore, in the dentate gyrus of these rats, the expression levels of BCL-2 and UBC9 were reduced and apoptosis was increased. The administration of CG alleviated cognitive impairment, enhanced the expression levels of BCL-2 and UBC9, and reduced apoptosis in the dentate gyrus in the lenti-miRNA-30e rats. No significant differences were detected in behavioral indicators between the lenti-miRNA-30e rats treated with CG and the normal controls. These findings suggested that CG exerts a potent therapeutic effect, conferred by its ability to enhance the expression levels of BCL-2 and UBC9, which inhibits the apoptotic process in neuronal cells. Therefore, CG may be

  9. The combined effect of wet granulation process parameters and dried granule moisture content on tablet quality attributes.

    PubMed

    Gabbott, Ian P; Al Husban, Farhan; Reynolds, Gavin K

    2016-09-01

    A pharmaceutical compound was used to study the effect of batch wet granulation process parameters in combination with the residual moisture content remaining after drying on granule and tablet quality attributes. The effect of three batch wet granulation process parameters was evaluated using a multivariate experimental design, with a novel constrained design space. Batches were characterised for moisture content, granule density, crushing strength, porosity, disintegration time and dissolution. Mechanisms of the effect of the process parameters on the granule and tablet quality attributes are proposed. Water quantity added during granulation showed a significant effect on granule density and tablet dissolution rate. Mixing time showed a significant effect on tablet crushing strength, and mixing speed showed a significant effect on the distribution of tablet crushing strengths obtained. The residual moisture content remaining after granule drying showed a significant effect on tablet crushing strength. The effect of moisture on tablet tensile strength has been reported before, but not in combination with granulation parameters and granule properties, and the impact on tablet dissolution was not assessed. Correlations between the energy input during granulation, the density of granules produced, and the quality attributes of the final tablets were also identified. Understanding the impact of the granulation and drying process parameters on granule and tablet properties provides a basis for process optimisation and scaling.

  10. Antimicrobial-Coated Granules for Disinfecting Water

    NASA Technical Reports Server (NTRS)

    Akse, James R.; Holtsnider, John T.; Kliestik, Helen

    2011-01-01

    Methods of preparing antimicrobialcoated granules for disinfecting flowing potable water have been developed. Like the methods reported in the immediately preceding article, these methods involve chemical preparation of substrate surfaces (in this case, the surfaces of granules) to enable attachment of antimicrobial molecules to the surfaces via covalent bonds. A variety of granular materials have been coated with a variety of antimicrobial agents that include antibiotics, bacteriocins, enzymes, bactericides, and fungicides. When employed in packed beds in flowing water, these antimicrobial-coated granules have been proven effective against gram-positive bacteria, gram-negative bacteria, fungi, and viruses. Composite beds, consisting of multiple layers containing different granular antimicrobial media, have proven particularly effective against a broad spectrum of microorganisms. These media have also proven effective in enhancing or potentiating the biocidal effects of in-line iodinated resins and of very low levels of dissolved elemental iodine.

  11. Molecular defects that affect platelet dense granules.

    PubMed

    Gunay-Aygun, Meral; Huizing, Marjan; Gahl, William A

    2004-10-01

    Platelet dense granules form using mechanisms shared by melanosomes in melanocytes and by subsets of lysosomes in more generalized cells. Consequently, disorders of platelet dense granules can reveal how organelles form and move within cells. Models for the study of new vesicle formation include isolated delta-storage pool deficiency, combined alphadelta-storage pool deficiency, Hermansky-Pudlak syndrome (HPS), Chediak-Higashi syndrome, Griscelli syndrome, thrombocytopenia absent radii syndrome, and Wiskott-Aldrich syndrome. The molecular bases of dense granule deficiency are known for the seven subtypes of HPS, as well as for Chediak-Higashi syndrome, Griscelli syndrome, and Wiskott-Aldrich syndrome. The gene products involved in these disorders help elucidate the generalized process of the formation of vesicles from extant membranes such as the Golgi.

  12. Measuring stellar granulation during planet transits

    NASA Astrophysics Data System (ADS)

    Chiavassa, A.; Caldas, A.; Selsis, F.; Leconte, J.; Von Paris, P.; Bordé, P.; Magic, Z.; Collet, R.; Asplund, M.

    2017-01-01

    Context. Stellar activity and convection-related surface structures might cause bias in planet detection and characterization that use these transits. Surface convection simulations help to quantify the granulation signal. Aims: We used realistic three-dimensional (3D) radiative hydrodynamical (RHD) simulations from the Stagger grid and synthetic images computed with the radiative transfer code Optim3D to model the transits of three prototype planets: a hot Jupiter, a hot Neptune, and a terrestrial planet. Methods: We computed intensity maps from RHD simulations of the Sun and a K-dwarf star at different wavelength bands from optical to far-infrared that cover the range of several ground- and space-based telescopes which observe exoplanet transits. We modeled the transit using synthetic stellar-disk images obtained with a spherical-tile imaging method and emulated the temporal variation of the granulation intensity generating random images covering a granulation time-series of 13.3 h. We measured the contribution of the stellar granulation on the light curves during the planet transit. Results: We identified two types of granulation noise that act simultaneously during the planet transit: (i) the intrinsic change in the granulation pattern with timescale (e.g., 10 min for solar-type stars assumed in this work) is smaller than the usual planet transit ( hours as in our prototype cases); and (ii) the fact that the transiting planet occults isolated regions of the photosphere that differ in local surface brightness as a result of convective-related surface structures. First, we showed that our modeling approach returns granulation timescale fluctuations that are comparable with what has been observed for the Sun. Then, our statistical approach shows that the granulation pattern of solar and K-dwarf-type stars have a non-negligible effect of the light curve depth during the transit, and, consequentially on the determination of the planet transit parameters such as the

  13. Synaptic Changes in the Dentate Gyrus of APP/PS1 Transgenic Mice Revealed by Electron Microscopy

    PubMed Central

    Merino-Serrais, Paula; Gonzalez, Santiago; DeFelipe, Javier

    2013-01-01

    Abstract Numerous studies have reported widespread synaptic dysfunction or loss in early stages of both Alzheimer disease (AD) patients and animal models; it is widely accepted that synapse loss is the major structural correlate of cognitive dysfunction. Elucidation of the changes that may affect synapses is crucial for understanding the pathogenic mechanisms underlying AD, but ultrastructural preservation of human postmortem brain tissue is often poor, and classical methods for quantification of synapses have significant technical limitations. We previously observed changes in dendritic spines in plaque-free regions of the neuropil of the dentate gyrus of double-transgenic APP/PS1 (amyloid precursor protein/presenilin 1) model mice by light microscopy. Here, we used electron microscopy to examine possible synaptic alterations in this region. We used standard stereologic techniques to determine numbers of synapses per volume. We were able to reconstruct and analyze thousands of synapses and their 3-dimensional characteristics using a focused ion beam/scanning electron microscope and 3-dimensional reconstruction software (EspINA), which performs semiautomated segmentation of synapses. Our results show that both numbers of synapses per volume and synaptic morphology are affected in plaque-free regions of APP/PS1 mice. Therefore, changes in the number and morphology of synapses seem to be widespread alterations in this animal model. PMID:23584198

  14. Characterization of physiological phenotypes of dentate gyrus synapses of PDZ1/2 domain-deficient PSD-95-knockin mice.

    PubMed

    Nagura, Hitoshi; Doi, Tomoko; Fujiyoshi, Yoshinori

    2016-03-01

    The hippocampal formation is involved in several important brain functions of animals, such as memory formation and pattern separation, and the synapses in the dentate gyrus (DG) play critical roles as the first step in the hippocampal circuit. Previous studies have reported that mice with genetic modifications of the PDZ1/2 domains of postsynaptic density (PSD)-95 exhibit altered synaptic properties in the DG and impaired hippocampus-dependent behaviors. Based on the involvement of the DG in the regulation of behaviors, these data suggest that the abnormal behavior of these knockin (KI) mice is due partly to altered DG function. Precise understanding of the phenotypes of these mutant mice requires characterization of the synaptic properties of the DG, and here we provide detailed studies of DG synapses. We have demonstrated global changes in the PSD membrane-associated guanylate kinase expression pattern in the DG of mutant mice, and DG synapses in these mice exhibited increased long-term potentiation under a wide range of stimulus intensities, although the N-methyl-d-aspartic acid receptor dependence of the long-term potentiation was unchanged. Furthermore, our data also indicate increased silent synapses in the DG of the KI mice. These findings suggest that abnormal protein expression and physiological properties disrupt the function of DG neurons in these KI mice.

  15. Similar distribution changes of GABAergic interneuron subpopulations in contrast to the different impact on neurogenesis between developmental and adult-stage hypothyroidism in the hippocampal dentate gyrus in rats.

    PubMed

    Shiraki, Ayako; Akane, Hirotoshi; Ohishi, Takumi; Wang, Liyun; Morita, Reiko; Suzuki, Kazuhiko; Mitsumori, Kunitoshi; Shibutani, Makoto

    2012-10-01

    Hypothyroidism affects neurogenesis. The present study was performed to clarify the sensitivity of neurogenesis-related cellular responses in the hippocampal dentate gyrus between developmental and adult-stage hypothyroidism. An exposure study of methimazole (MMI) as an anti-thyroid agent at 0, 50, 200 ppm in the drinking water was performed using pregnant rats from gestation day 10 to postnatal day (PND) 21 (developmental hypothyroidism) and adult male rats by setting an identical exposure period from PND 46 through to PND 77 (adult-stage hypothyroidism). Offspring with developmental hypothyroidism were killed at PND 21 or PND 77, and animals with adult-stage hypothyroidism were killed at PND 77. Proliferation and apoptosis were unchanged in the dentate subgranular zone by either developmental or adult-stage hypothyroidism. With regard to precursor granule cells, a sustained reduction of paired box 6-positive stem or early progenitor cells and a transient reduction of doublecortin-positive late-stage progenitor cells were observed after developmental hypothyroidism with MMI at 50 and 200 ppm. These cells were unchanged by adult-stage hypothyroidism. With regard to γ-aminobutyric acid (GABA) ergic interneuron subpopulations in the dentate hilus, the number of parvalbumin-positive cells was decreased and the number of calretinin-positive cells was increased after both developmental and adult-stage hypothyroidism with MMI at 50 and 200 ppm. Fluctuations in GABAergic interneuron numbers with developmental hypothyroidism continued through to PND 77 with 200 ppm MMI. Considering the roles of GABAergic interneuron subpopulations in neurogenesis and neuronal differentiation, subpopulation changes in GABAergic interneurons by hypothyroidism may be the signature of aberrant neurogenesis even at the adult stage.

  16. Chronic 835-MHz radiofrequency exposure to mice hippocampus alters the distribution of calbindin and GFAP immunoreactivity.

    PubMed

    Maskey, Dhiraj; Pradhan, Jonu; Aryal, Bijay; Lee, Chang-Min; Choi, In-Young; Park, Ki-Sup; Kim, Seok Bae; Kim, Hyung Gun; Kim, Myeung Ju

    2010-07-30

    Exponential interindividual handling in wireless communication system has raised possible doubts in the biological aspects of radiofrequency (RF) exposure on human brain owing to its close proximity to the mobile phone. In the nervous system, calcium (Ca(2+)) plays a critical role in releasing neurotransmitters, generating action potential and membrane integrity. Alterations in intracellular Ca(2+) concentration trigger aberrant synaptic action or cause neuronal apoptosis, which may exert an influence on the cellular pathology for learning and memory in the hippocampus. Calcium binding proteins like calbindin D28-K (CB) is responsible for the maintaining and controlling Ca(2+) homeostasis. Therefore, in the present study, we investigated the effect of RF exposure on rat hippocampus at 835 MHz with low energy (specific absorption rate: SAR=1.6 W/kg) for 3 months by using both CB and glial fibrillary acidic protein (GFAP) specific antibodies by immunohistochemical method. Decrease in CB immunoreactivity (IR) was noted in exposed (E1.6) group with loss of interneurons and pyramidal cells in CA1 area and loss of granule cells. Also, an overall increase in GFAP IR was observed in the hippocampus of E1.6. By TUNEL assay, apoptotic cells were detected in the CA1, CA3 areas and dentate gyrus of hippocampus, which reflects that chronic RF exposure may affect the cell viability. In addition, the increase of GFAP IR due to RF exposure could be well suited with the feature of reactive astrocytosis, which is an abnormal increase in the number of astrocytes due to the loss of nearby neurons. Chronic RF exposure to the rat brain suggested that the decrease of CB IR accompanying apoptosis and increase of GFAP IR might be morphological parameters in the hippocampus damages.

  17. The granulation of binary mixtures: the effects of the properties of the component powders on granules.

    PubMed

    Opakunle, W O; Spring, M S

    1976-12-01

    Sulphanilamide and citric acid individually and in various proportions with lactose, have been granulated by massing and screening. There was an optimum blend, that produced granules of maximum mean size and strength, for each binary system examined. The proportion of the components of this optimal blend was dependent on the physical properties of the second component in a mixture with lactose. Results from three systems, lactose:boric acid, lactose:sulphanilamide and lactose:citric acid indicate that although part dissolution of powder during granulation is a factor affecting granule properties, in some systems other physical properties of the second component may become dominant. It is suggested that the combined effect of cohesiveness and wettability of the powders may make the major contribution to granule strength with the sulphanilamide systems. The ultimate mean granule size produced is determined by the wettability or solubiluty of the powders, or both, in all cases examined. The great affinity of citric acid for aqueous binder solution was the dominant factor determining the properties of granules prepared from lactose:citric acid mixtures.

  18. Toxoplasma secretory granules: one population or more?

    PubMed

    Mercier, Corinne; Cesbron-Delauw, Marie-France

    2015-02-01

    In Toxoplasma gondii, dense granules are known as the storage secretory organelles of the so-called GRA proteins (for dense granule proteins), which are destined to the parasitophorous vacuole (PV) and the PV-derived cyst wall. Recently, newly annotated GRA proteins targeted to the host cell nucleus have enlarged this view. Here we provide an update on the latest developments on the Toxoplasma secreted proteins, which to date have been mainly studied at both the tachyzoite and bradyzoite stages, and we point out that recent discoveries could open the issue of a possible, yet uncharacterized, distinct secretory pathway in Toxoplasma.

  19. Formulation of custom sized LX-15 granules

    SciTech Connect

    Stull, T.W.

    1980-04-01

    LX-15 is a booster explosive formulation consisting of 95% HNS I and 5% Kel F-800 developed by Lawrence Livermore Laboratory. The purpose of this effort was to develop formulation techniques for the production of custom size granules that are amenable for processing in automatic weighing equipment. This report details processes whereby 0.4 and 1.5 kg size batches are produced, meeting those requirements. Efforts to date have found that granule size is dependent on batch/vessel size, water-to-solvent ratio and the degree of vessel agitation.

  20. Process for producing zirconium based granules

    SciTech Connect

    Jade, S.S.

    1990-05-22

    This patent describes a process for the production f amorphous zirconium based granules. It comprises: adding about 2--15 wt % of a suitable phase stabilizer to an aqueous solutio, based upon the total weight of ZrO{sub 2} in solution, to produce an aqueous solution having a pH in the range of about 4 to 7 comprising a zirconium based complex and phase stabilizer and thereafter; drying the aqueous solution comprising the zirconium based complex and the phase stabilizer at a temperature below about 180{degrees} C. for a time sufficient to evaporate the aqueous solution thereby forming amorphous zirconium based granules containing the phase stabilizer.

  1. Continuous melt granulation: Influence of process and formulation parameters upon granule and tablet properties.

    PubMed

    Monteyne, Tinne; Vancoillie, Jochem; Remon, Jean-Paul; Vervaet, Chris; De Beer, Thomas

    2016-10-01

    The pharmaceutical industry has a growing interest in alternative manufacturing models allowing automation and continuous production in order to improve process efficiency and reduce costs. Implementing a switch from batch to continuous processing requires fundamental process understanding and the implementation of quality-by-design (QbD) principles. The aim of this study was to examine the relationship between formulation-parameters (type binder, binder concentration, drug-binder miscibility), process-parameters (screw speed, powder feed rate and granulation temperature), granule properties (size, size distribution, shape, friability, true density, flowability) and tablet properties (tensile strength, friability, dissolution rate) of four different drug-binder formulations using Design of experiments (DOE). Two binders (polyethylene glycol (PEG) and Soluplus®) with a different solid state, semi-crystalline vs amorphous respectively, were combined with two model-drugs, metoprolol tartrate (MPT) and caffeine anhydrous (CAF), both having a contrasting miscibility with the binders. This research revealed that the granule properties of miscible drug-binder systems depended on the powder feed rate and barrel filling degree of the granulator whereas the granule properties of immiscible systems were mainly influenced by binder concentration. Using an amorphous binder, the tablet tensile strength depended on the granule size. In contrast, granule friability was more important for tablet quality using a brittle binder. However, this was not the case for caffeine-containing blends, since these phenomena were dominated by the enhanced compression properties of caffeine Form I, which was formed during granulation. Hence, it is important to gain knowledge about formulation behavior during processing since this influences the effect of process parameters onto the granule and tablet properties.

  2. Granule size distributions after twin-screw granulation - Do not forget the feeding systems.

    PubMed

    Meier, R; Thommes, M; Rasenack, N; Moll, K-P; Krumme, M; Kleinebudde, P

    2016-09-01

    The aim of this study was to investigate the influence of qualitatively different powder feeder performances on resulting granule size distributions after twin-screw granulation of a highly drug loaded, hydrophobic mixture and a mannitol powder. It was shown that powder feeder related problems usually cannot be identified by trusting in the values given by the feeder. Therefore, a newly developed model for the evaluation of the performance of powder feeders was introduced and it was tried to connect this model to residence time distributions in twin-screw granulation processes. The influence of feeder performances on resulting granule size distributions varied, depending on the applied screw configuration and the used powder. Regarding the hydrophobic and highly drug loaded formulation, which was granulated at an L/S-ratio of 0.5, a pure conveying screw and a medium kneading configuration, consisting of 60° kneading blocks were negatively influenced by poor feeder settings. For optimal settings more narrow distributions could be obtained. For an extensive kneading configuration good and poor settings resulted in mono-modal granule size distributions but were differing in the overall size. Mannitol, a model substance for a liquid sensitive formulation was granulated at an L/S-ratio of 0.075. It was even more important to maintain optimal feeding as mannitol was highly affected by poor feeder performances. Even an extensive kneading configuration could not level the errors in powder feeder performance, resulting in qualitatively different granule size distributions. The results of this study demonstrate the importance of detailed knowledge about applied feeding systems to gain optimal performance in twin-screw granulation.

  3. Defective synaptic transmission and structure in the dentate gyrus and selective fear memory impairment in the Rsk2 mutant mouse model of Coffin-Lowry syndrome.

    PubMed

    Morice, Elise; Farley, Séverine; Poirier, Roseline; Dallerac, Glenn; Chagneau, Carine; Pannetier, Solange; Hanauer, André; Davis, Sabrina; Vaillend, Cyrille; Laroche, Serge

    2013-10-01

    The Coffin-Lowry syndrome (CLS) is a syndromic form of intellectual disability caused by loss-of-function of the RSK2 serine/threonine kinase encoded by the rsk2 gene. Rsk2 knockout mice, a murine model of CLS, exhibit spatial learning and memory impairments, yet the underlying neural mechanisms are unknown. In the current study, we examined the performance of Rsk2 knockout mice in cued, trace and contextual fear memory paradigms and identified selective deficits in the consolidation and reconsolidation of hippocampal-dependent fear memories as task difficulty and hippocampal demand increase. Electrophysiological, biochemical and electron microscopy analyses were carried out in the dentate gyrus of the hippocampus to explore potential alterations in neuronal functions and structure. In vivo and in vitro electrophysiology revealed impaired synaptic transmission, decreased network excitability and reduced AMPA and NMDA conductance in Rsk2 knockout mice. In the absence of RSK2, standard measures of short-term and long-term potentiation (LTP) were normal, however LTP-induced CREB phosphorylation and expression of the transcription factors EGR1/ZIF268 were reduced and that of the scaffolding protein SHANK3 was blocked, indicating impaired activity-dependent gene regulation. At the structural level, the density of perforated and non-perforated synapses and of multiple spine boutons was not altered, however, a clear enlargement of spine neck width and post-synaptic densities indicates altered synapse ultrastructure. These findings show that RSK2 loss-of-function is associated in the dentate gyrus with multi-level alterations that encompass modifications of glutamate receptor channel properties, synaptic transmission, plasticity-associated gene expression and spine morphology, providing novel insights into the mechanisms contributing to cognitive impairments in CLS.

  4. Effects of Melissa officinalis L. (lemon balm) extract on neurogenesis associated with serum corticosterone and GABA in the mouse dentate gyrus.

    PubMed

    Yoo, Dae Young; Choi, Jung Hoon; Kim, Woosuk; Yoo, Ki-Yeon; Lee, Choong Hyun; Yoon, Yeo Sung; Won, Moo-Ho; Hwang, In Koo

    2011-02-01

    Lemon balm, leaves of Melissa officinalis L., has been used for anti-anxiety and spasmolytics. We observed the extract of Melissa officinalis L. (MOE) on cell proliferation and neuroblast differentiation in the hippocampal dentate gyrus (DG) of middle-aged mice (12 months of age) using Ki67 and doublecortin (DCX), respectively. We also observed changes in corticosterone, GAD67 and GABA-transaminase (GABA-T) to check their possible mechanisms related to neurogenesis. We administered 50 or 200 mg/kg MOE to the animals once a day for 3 weeks. For labeling of newly generated cells, we also administered 5-bromodeoxyuridine (BrdU) twice a day for 3 days from the day of the first MOE treatment. Administration of 50 or 200 mg/kg MOE dose-dependently increased Ki67 positive nuclei to 244.1 and 763.9% of the vehicle-treated group, respectively. In addition, 50 or 200 mg/kg MOE significantly increased DCX positive neuroblasts with well-developed (tertiary) dendrites. Furthermore, MOE administration significantly increased BrdU/calbindin D-28 k double labeled cells (integrated neurons into granule cells in the DG) to 245.2% of the vehicle-treated group. On the other hand, administration of MOE reduced corticosterone levels in serum and decreased GABA-T levels in the DG homogenates. These results suggest that MOE increases cell proliferation, neuroblast differentiation and integration into granule cells by decreasing serum corticosterone levels as well as by increasing GABA levels in the mouse DG.

  5. Amyotrophic lateral sclerosis-linked mutations increase the viscosity of liquid-like TDP-43 RNP granules in neurons.

    PubMed

    Gopal, Pallavi P; Nirschl, Jeffrey J; Klinman, Eva; Holzbaur, Erika L F

    2017-03-21

    Ribonucleoprotein (RNP) granules are enriched in specific RNAs and RNA-binding proteins (RBPs) and mediate critical cellular processes. Purified RBPs form liquid droplets in vitro through liquid-liquid phase separation and liquid-like non-membrane-bound structures in cells. Mutations in the human RBPs TAR-DNA binding protein 43 (TDP-43) and RNA-binding protein FUS cause amyotrophic lateral sclerosis (ALS), but the biophysical properties of these proteins have not yet been studied in neurons. Here, we show that TDP-43 RNP granules in axons of rodent primary cortical neurons display liquid-like properties, including fusion with rapid relaxation to circular shape, shear stress-induced deformation, and rapid fluorescence recovery after photobleaching. RNP granules formed from wild-type TDP-43 show distinct biophysical properties depending on axonal location, suggesting maturation to a more stabilized structure is dependent on subcellular context, including local density and aging. Superresolution microscopy demonstrates that the stabilized population of TDP-43 RNP granules in the proximal axon is less circular and shows spiculated edges, whereas more distal granules are both more spherical and more dynamic. RNP granules formed by ALS-linked mutant TDP-43 are more viscous and exhibit disrupted transport dynamics. We propose these altered properties may confer toxic gain of function and reflect differential propensity for pathological transformation.

  6. Quantal regulation and exocytosis of platelet dense-body granules.

    PubMed

    Ge, Shencheng; Woo, Emily; Haynes, Christy L

    2011-11-16

    This study reports how quantal size, or the quantity of chemical messengers within a storage granule, is regulated in platelet dense-body granules via dynamic adaption of granule size according to changing levels of granule contents. Mechanistic studies using carbon-fiber microelectrode fast-scan cyclic voltammetry and amperometry methods correlated with transmission electron microscopy analysis reveal the impact of granule structural changes on granular content secretion kinetics and highlight the dynamic interplay between soluble granule contents and membrane components in exocytosis. Despite the distinct chemical profile of platelet dense-body granules, these secretory granules act according to general biochemical/biophysical phenomena using charge-charge interactions to sequester chemical messengers and employ known conserved exocytotic machinery to deliver them; therefore, the mechanistic information obtained herein further advances the general understanding of exocytosis while revealing fundamental details about blood platelets.

  7. Vaccine adjuvants: Tailor-made mast-cell granules

    NASA Astrophysics Data System (ADS)

    Gunzer, Matthias

    2012-03-01

    Mast cells induce protective immune responses through secretion of stimulatory granules. Microparticles modelled after mast-cell granules are now shown to replicate and enhance the functions of their natural counterparts and to direct the character of the resulting immunity.

  8. THE NUMBER OF CATECHOLAMINE STORAGE GRANULES IN ADRENAL MEDULLA

    DTIC Science & Technology

    A method is described for counting the catecholamine-containing heavy granules of adrenal glands. There are 5.0 ! 0.8 (S. E.) x 10 to the 12th power... granules /gram wet weight of fowl adrenal gland. Individual heavy granules contain about 8 million molecules of catecholamines (1.4 x 10 to the 17th...power mole). Reference to published electron microphotographs of adrenal medulla cells allows estimation of the average volume of heavy granules and

  9. Flow rates and repose angles of wet-processed granulations.

    PubMed

    Carstensen, J T; Chan, P C

    1977-09-01

    The equation of McDougall and Evans was found not to apply to granulations. The functional relationships among volumetric powder flow rates, angles of repose, and particle size were demonstrated to exhibit maxima (rather than minima) in five common pharmaceutical granulations produced by wet processing. The angular behavior of granules (such as the experienced range of angles) is explained via supported stacking geometries, and the shallow maxima in the angle of repose versus granule diameter was derived from this model.

  10. ALS mutant SOD1 interacts with G3BP1 and affects stress granule dynamics.

    PubMed

    Gal, Jozsef; Kuang, Lisha; Barnett, Kelly R; Zhu, Brian Z; Shissler, Susannah C; Korotkov, Konstantin V; Hayward, Lawrence J; Kasarskis, Edward J; Zhu, Haining

    2016-10-01

    Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease. Mutations in Cu/Zn superoxide dismutase (SOD1) are responsible for approximately 20 % of the familial ALS cases. ALS-causing SOD1 mutants display a gain-of-toxicity phenotype, but the nature of this toxicity is still not fully understood. The Ras GTPase-activating protein-binding protein G3BP1 plays a critical role in stress granule dynamics. Alterations in the dynamics of stress granules have been reported in several other forms of ALS unrelated to SOD1. To our surprise, the mutant G93A SOD1 transgenic mice exhibited pathological cytoplasmic inclusions that co-localized with G3BP1-positive granules in spinal cord motor neurons. The co-localization was also observed in fibroblast cells derived from familial ALS patient carrying SOD1 mutation L144F. Mutant SOD1, unlike wild-type SOD1, interacted with G3BP1 in an RNA-independent manner. Moreover, the interaction is specific for G3BP1 since mutant SOD1 showed little interaction with four other RNA-binding proteins implicated in ALS. The RNA-binding RRM domain of G3BP1 and two particular phenylalanine residues (F380 and F382) are critical for this interaction. Mutant SOD1 delayed the formation of G3BP1- and TIA1-positive stress granules in response to hyperosmolar shock and arsenite treatment in N2A cells. In summary, the aberrant mutant SOD1-G3BP1 interaction affects stress granule dynamics, suggesting a potential link between pathogenic SOD1 mutations and RNA metabolism alterations in ALS.

  11. MMP-13 Regulates Growth of Wound Granulation Tissue and Modulates Gene Expression Signatures Involved in Inflammation, Proteolysis, and Cell Viability

    PubMed Central

    Toriseva, Mervi; Laato, Matti; Carpén, Olli; Ruohonen, Suvi T.; Savontaus, Eriika; Inada, Masaki; Krane, Stephen M.; Kähäri, Veli-Matti

    2012-01-01

    Proteinases play a pivotal role in wound healing by regulating cell-matrix interactions and availability of bioactive molecules. The role of matrix metalloproteinase-13 (MMP-13) in granulation tissue growth was studied in subcutaneously implanted viscose cellulose sponge in MMP-13 knockout (Mmp13−/−) and wild type (WT) mice. The tissue samples were harvested at time points day 7, 14 and 21 and subjected to histological analysis and gene expression profiling. Granulation tissue growth was significantly reduced (42%) at day 21 in Mmp13−/− mice. Granulation tissue in Mmp13−/− mice showed delayed organization of myofibroblasts, increased microvascular density at day 14, and virtual absence of large vessels at day 21. Gene expression profiling identified differentially expressed genes in Mmp13−/− mouse granulation tissue involved in biological functions including inflammatory response, angiogenesis, cellular movement, cellular growth and proliferation and proteolysis. Among genes linked to angiogenesis, Adamts4 and Npy were significantly upregulated in early granulation tissue in Mmp13−/− mice, and a set of genes involved in leukocyte motility including Il6 were systematically downregulated at day 14. The expression of Pdgfd was downregulated in Mmp13−/− granulation tissue in all time points. The expression of matrix metalloproteinases Mmp2, Mmp3, Mmp9 was also significantly downregulated in granulation tissue of Mmp13−/− mice compared to WT mice. Mmp13−/− mouse skin fibroblasts displayed altered cell morphology and impaired ability to contract collagen gel and decreased production of MMP-2. These results provide evidence for an important role for MMP-13 in wound healing by coordinating cellular activities important in the growth and maturation of granulation tissue, including myofibroblast function, inflammation, angiogenesis, and proteolysis. PMID:22880047

  12. The Stress Granule RNA-Binding Protein TIAR-1 Protects Female Germ Cells from Heat Shock in Caenorhabditis elegans.

    PubMed

    Huelgas-Morales, Gabriela; Silva-García, Carlos Giovanni; Salinas, Laura S; Greenstein, David; Navarro, Rosa E

    2016-04-07

    In response to stressful conditions, eukaryotic cells launch an arsenal of regulatory programs to protect the proteome. One major protective response involves the arrest of protein translation and the formation of stress granules, cytoplasmic ribonucleoprotein complexes containing the conserved RNA-binding proteins TIA-1 and TIAR. The stress granule response is thought to preserve mRNA for translation when conditions improve. For cells of the germline-the immortal cell lineage required for sexual reproduction-protection from stress is critically important for perpetuation of the species, yet how stress granule regulatory mechanisms are deployed in animal reproduction is incompletely understood. Here, we show that the stress granule protein TIAR-1 protects the Caenorhabditis elegans germline from the adverse effects of heat shock. Animals containing strong loss-of-function mutations in tiar-1 exhibit significantly reduced fertility compared to the wild type following heat shock. Analysis of a heat-shock protein promoter indicates that tiar-1 mutants display an impaired heat-shock response. We observed that TIAR-1 was associated with granules in the gonad core and oocytes during several stressful conditions. Both gonad core and oocyte granules are dynamic structures that depend on translation; protein synthesis inhibitors altered their formation. Nonetheless, tiar-1 was required for the formation of gonad core granules only. Interestingly, the gonad core granules did not seem to be needed for the germ cells to develop viable embryos after heat shock. This suggests that TIAR-1 is able to protect the germline from heat stress independently of these structures.

  13. The Stress Granule RNA-Binding Protein TIAR-1 Protects Female Germ Cells from Heat Shock in Caenorhabditis elegans

    PubMed Central

    Huelgas-Morales, Gabriela; Silva-García, Carlos Giovanni; Salinas, Laura S.; Greenstein, David; Navarro, Rosa E.

    2016-01-01

    In response to stressful conditions, eukaryotic cells launch an arsenal of regulatory programs to protect the proteome. One major protective response involves the arrest of protein translation and the formation of stress granules, cytoplasmic ribonucleoprotein complexes containing the conserved RNA-binding proteins TIA-1 and TIAR. The stress granule response is thought to preserve mRNA for translation when conditions improve. For cells of the germline—the immortal cell lineage required for sexual reproduction—protection from stress is critically important for perpetuation of the species, yet how stress granule regulatory mechanisms are deployed in animal reproduction is incompletely understood. Here, we show that the stress granule protein TIAR-1 protects the Caenorhabditis elegans germline from the adverse effects of heat shock. Animals containing strong loss-of-function mutations in tiar-1 exhibit significantly reduced fertility compared to the wild type following heat shock. Analysis of a heat-shock protein promoter indicates that tiar-1 mutants display an impaired heat-shock response. We observed that TIAR-1 was associated with granules in the gonad core and oocytes during several stressful conditions. Both gonad core and oocyte granules are dynamic structures that depend on translation; protein synthesis inhibitors altered their formation. Nonetheless, tiar-1 was required for the formation of gonad core granules only. Interestingly, the gonad core granules did not seem to be needed for the germ cells to develop viable embryos after heat shock. This suggests that TIAR-1 is able to protect the germline from heat stress independently of these structures. PMID:26865701

  14. Starch Granule Variability in Wild Solanum Species

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Because most of the dry matter of potato tubers is starch, an understanding of starch properties is important in potato improvement programs. Starch granule size is considered to influence tuber processing quality parameters such as gelatinization temperature, viscosity, and water holding capacity. ...

  15. 21 CFR 520.1468 - Naproxen granules.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.1468 Naproxen granules. (a... pain and lameness exhibited with arthritis, as well as myositis and other soft tissue diseases of...

  16. 21 CFR 520.1468 - Naproxen granules.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.1468 Naproxen granules. (a... pain and lameness exhibited with arthritis, as well as myositis and other soft tissue diseases of...

  17. 21 CFR 520.1468 - Naproxen granules.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS ORAL DOSAGE FORM NEW ANIMAL DRUGS § 520.1468 Naproxen granules. (a... pain and lameness exhibited with arthritis, as well as myositis and other soft tissue diseases of...

  18. Secretory granule biogenesis: rafting to the SNARE.

    PubMed

    Tooze, S A; Martens, G J; Huttner, W B

    2001-03-01

    Regulated secretion of hormones occurs when a cell receives an external stimulus, triggering the secretory granules to undergo fusion with the plasma membrane and release their content into the extracellular milieu. The formation of a mature secretory granule (MSG) involves a series of discrete and unique events such as protein sorting, formation of immature secretory granules (ISGs), prohormone processing and vesicle fusion. Regulated secretory proteins (RSPs), the proteins stored and secreted from MSGs, contain signals or domains to direct them into the regulated secretory pathway. Recent data on the role of specific domains in RSPs involved in sorting and aggregation suggest that the cell-type-specific composition of RSPs in the trans-Golgi network (TGN) has an important role in determining how the RSPs get into ISGs. The realization that lipid rafts are implicated in sorting RSPs in the TGN and the identification of SNARE molecules represent further major advances in our understanding of how MSGs are formed. At the heart of these findings is the elucidation of molecular mechanisms driving protein--lipid and protein--protein interactions specific for secretory granule biogenesis.

  19. Changes in the bucco-lingual thickness of the mandibular alveolar process and skeletal bone mineral density in dentate women: a 5-yr prospective study.

    PubMed

    Jonasson, Grethe; Kiliaridis, Stavros

    2005-04-01

    After tooth extraction there is a great interindividual variation in the remodelling pattern of the alveolar process in edentulous areas, with some individuals losing little bone and others undergoing extensive resorption. However, little is known about possible longitudinal changes in the dentate region of the alveolar process of adults and if these are related to alterations in the skeletal bone mineral density (BMD). In a prospective study, on two occasions, 5-yr apart, the BMD of 117 women was determined in the distal forearm by using dual-energy X-ray absorptiometry, and the bucco-lingual thickness of the mandibular alveolar process was measured on dental casts by using a dial calliper. A decrease in the mean alveolar thickness, exceeding a cut-off value of 0.1 mm, was found in 60% of the women and an increase was found in 3% of the individuals. This decrease was 0.22 +/- 0.20 mm in the posterior region and 0.16 +/- 0.19 mm in the anterior region. The changes in alveolar thickness in the posterior region were significantly correlated to the BMD changes both on the mid-crestal level site and on the cervical level site. We conclude that the bucco-lingual thickness decreases with age in the dentate alveolar process, possibly owing to periosteal resorption related to skeletal bone loss.

  20. The coexpression of reelin and neuronal nitric oxide synthase in a subpopulation of dentate gyrus neurons is downregulated in heterozygous reeler mice.

    PubMed

    Romay-Tallón, Raquel; Dopeso-Reyes, Iria G; Lussier, April L; Kalynchuk, Lisa E; Caruncho, Hector J

    2010-01-01

    Reelin is an extracellular matrix protein expressed in several interneuron subtypes in the hippocampus and dentate gyrus. Neuronal nitric oxide synthase (nNOS) is also expressed by interneurons in these areas. We investigated whether reelin and nNOS are co-localized in the same population of hippocampal interneurons, and whether this colocalization is altered in the heterozygous reeler mouse. We found colocalization of nNOS in reelin-positive cells in the CA1 stratum radiatum and lacunosum moleculare, the CA3 stratum radiatum, and the dentate gyrus subgranular zone, molecular layer, and hilus. In heterozygous reeler mice, the colocalization of nNOS in reelin-positive cells was significantly decreased only in the subgranular zone and molecular layer. The coexpression of reelin and nNOS in several hippocampal regions suggests that reelin and nNOS may work synergistically to promote glutamatergic function, and the loss of this coexpression in heterozygous reeler mice may underlie some of the behavioral deficits observed in these animals.

  1. Role of Dentate Gyrus in Aligning Internal Spatial Map to External Landmark

    ERIC Educational Resources Information Center

    Lee, Jong Won; Kim, Woon Ryoung; Sun, Woong; Jung, Min Whan

    2009-01-01

    Humans and animals form internal representations of external space based on their own body movement (dead reckoning) as well as external landmarks. It is poorly understood, however, how different types of information are integrated to form a unified representation of external space. To examine the role of dentate gyrus (DG) in this process, we…

  2. Developmental profiling of postnatal dentate gyrus progenitors provides evidence for dynamic cell-autonomous regulation

    PubMed Central

    Gilley, Jennifer A.; Yang, Cui-Ping; Kernie, Steven G.

    2009-01-01

    The dentate gyrus of the hippocampus is one of the most prominent regions in the postnatal mammalian brain where neurogenesis continues throughout life. There is tremendous speculation regarding the potential implications of adult hippocampal neurogenesis, though it remains unclear to what extent this ability becomes attenuated during normal aging, and what genetic changes in the progenitor population ensue over time. Using defined elements of the nestin promoter, we developed a transgenic mouse that reliably labels neural stem and early progenitors with green fluorescent protein (GFP). Using a combination of immunohistochemical and flow cytometry techniques, we characterized the progenitor cells within the dentate gyrus and created a developmental profile from postnatal day 7 (P7) until 6 months of age. In addition, we demonstrate that the proliferative potential of these progenitors is controlled at least in part by cell-autonomous cues. Finally, in order to identify what may underlie these differences, we performed stem cell-specific microarrays on GFP-expressing sorted cells from isolated P7 and postnatal day 28 (P28) dentate gyrus. We identified several differentially expressed genes that may underlie the functional differences that we observe in neurosphere assays from sorted cells and differentiation assays at these different ages. These data suggest that neural progenitors from the dentate gyrus are differentially regulated by cell-autonomous factors that change over time. PMID:20014381

  3. Neurotoxic Doses of Chronic Methamphetamine Trigger Retrotransposition of the Identifier Element in Rat Dorsal Dentate Gyrus

    PubMed Central

    Moszczynska, Anna; Burghardt, Kyle J.; Yu, Dongyue

    2017-01-01

    Short interspersed elements (SINEs) are typically silenced by DNA hypermethylation in somatic cells, but can retrotranspose in proliferating cells during adult neurogenesis. Hypomethylation caused by disease pathology or genotoxic stress leads to genomic instability of SINEs. The goal of the present investigation was to determine whether neurotoxic doses of binge or chronic methamphetamine (METH) trigger retrotransposition of the identifier (ID) element, a member of the rat SINE family, in the dentate gyrus genomic DNA. Adult male Sprague-Dawley rats were treated with saline or high doses of binge or chronic METH and sacrificed at three different time points thereafter. DNA methylation analysis, immunohistochemistry and next-generation sequencing (NGS) were performed on the dorsal dentate gyrus samples. Binge METH triggered hypomethylation, while chronic METH triggered hypermethylation of the CpG-2 site. Both METH regimens were associated with increased intensities in poly(A)-binding protein 1 (PABP1, a SINE regulatory protein)-like immunohistochemical staining in the dentate gyrus. The amplification of several ID element sequences was significantly higher in the chronic METH group than in the control group a week after METH, and they mapped to genes coding for proteins regulating cell growth and proliferation, transcription, protein function as well as for a variety of transporters. The results suggest that chronic METH induces ID element retrotransposition in the dorsal dentate gyrus and may affect hippocampal neurogenesis. PMID:28272323

  4. Dentate Gyrus Is Necessary for Disambiguating Similar Object-Place Representations

    ERIC Educational Resources Information Center

    Lee, Inah; Solivan, Frances

    2010-01-01

    Objects are often remembered with their locations, which is an important aspect of event memory. Despite the well-known involvement of the hippocampus in event memory, detailed intrahippocampal mechanisms are poorly understood. In particular, no experimental evidence has been provided in support of the role of the dentate gyrus (DG) in…

  5. Tanshinone I Enhances Neurogenesis in the Mouse Hippocampal Dentate Gyrus via Increasing Wnt-3, Phosphorylated Glycogen Synthase Kinase-3β and β-Catenin Immunoreactivities.

    PubMed

    Chen, Bai Hui; Park, Joon Ha; Cho, Jeong Hwi; Kim, In Hye; Lee, Jae Chul; Lee, Tae-Kyeong; Ahn, Ji Hyeon; Tae, Hyun Jin; Shin, Bich Na; Kim, Jong-Dai; Kang, Il Jun; Won, Moo-Ho; Lee, Yun Lyul

    2016-08-01

    Tanshinone I (TsI), a lipophilic diterpene extracted from Danshan (Radix Salvia miltiorrhizae), exerts neuroprotection in cerebrovascular diseases including transient ischemic attack. In this study, we examined effects of TsI on cell proliferation and neuronal differentiation in the subgranular zone (SGZ) of the mouse dentate gyrus (DG) using Ki-67, BrdU and doublecortin (DCX) immunohistochemistry. Mice were treated with 1 and 2 mg/kg TsI for 28 days. In the 1 mg/kg TsI-treated-group, distribution patterns of BrdU, Ki-67 and DCX positive ((+)) cells in the SGZ were similar to those in the vehicle-treated-group. However, in the 2 mg/kg TsI-treated-group, double labeled BrdU(+)/NeuN(+) cells, which are mature neurons, as well as Ki-67(+), DCX(+) and BrdU(+) cells were significantly increased compared with those in the vehicle-treated-group. On the other hand, immunoreactivities and protein levels of Wnt-3, β-catenin and serine-9-glycogen synthase kinase-3β (p-GSK-3β), which are related with morphogenesis, were significantly increased in the granule cell layer of the DG only in the 2 mg/kg TsI-treated-group. Therefore, these findings indicate that TsI can promote neurogenesis in the mouse DG and that the neurogenesis is related with increases of Wnt-3, p-GSK-3β and β-catenin immunoreactivities.

  6. Aerobic granulation of protein-rich granules from nitrogen-lean wastewaters.

    PubMed

    Chen, Yu-You; Ju, Sheau-Pyng; Lee, Duu-Jong

    2016-10-01

    Proteins (PN)-rich granules are stable in structure in long-term reactor operations. This study proposed to cultivate PN-rich granules with PN/polysaccharides (PS) >20 from nitrogen lean wastewater, with ammonia-nitrogen as sole nitrogen source at chemical oxygen demand (COD)/N of 153.8. The yielded granules can sustain their structural stability in sequencing batch reactor mode for sufficient treatment of wastewaters up to 7000mg/L COD and with COD/N<500 and in continuous-flow reactor for successful 216-d treatment of wastewaters up to organic loading rate (OLR) of 39kg/m(3)-d. The produced granules were enriched with Firmicutes and β-proteobacteria as dominating strains. More than 58% of the nitrogen fed in the nitrogen-lean wastewater is converted to the PN in the granules. The replacement of ammonia by nitrate as sole nitrogen source led to granules enriched with γ-proteobacteria which are easily deteriorated at low OLR.

  7. Amylolytic hydrolysis of native starch granules affected by granule surface area.

    PubMed

    Kim, J C; Kong, B W; Kim, M J; Lee, S H

    2008-11-01

    Initial stage of hydrolysis of native starch granules with various amylolytic enzymes, alpha-amylase from Bacillus subtilis, glucoamylase I (GA-I) and II (GA-II) from Aspergillus niger, and beta-amylase from sweet potato showed that the reaction was apparently affected by a specific surface area of the starch granules. The ratios of the reciprocal of initial velocity of each amylolytic hydrolysis for native potato and maize starch to that for rice with the amylolytic enzymes were nearly equivalent to the ratio of surface area per mass of the 2 starch granules to that of rice, that is, 6.94 and 2.25, respectively. Thus, the reciprocal of initial velocity of each enzymatic hydrolysis as expressed in a Lineweaver-Burk plot was a linear function of the reciprocal of surface area for each starch granule. As a result, it is concluded that amylolytic hydrolysis of native starch granules is governed by the specific surface area, not by the mass concentration, of each granule.

  8. Experimental investigation of granule size and shape dynamics in twin-screw granulation.

    PubMed

    Kumar, Ashish; Vercruysse, Jurgen; Bellandi, Giacomo; Gernaey, Krist V; Vervaet, Chris; Remon, Jean Paul; De Beer, Thomas; Nopens, Ingmar

    2014-11-20

    A twin-screw granulator (TSG), a promising equipment for continuous high shear wet granulation (HSWG), achieves the desired level of mixing by a combination of the appropriate screw configuration and a suitable set of process settings (e.g. feed rate, screw speed, etc.), thus producing a certain granule size and shape distribution (GSSD). However, the primary sizing and shaping mechanism behind the resulting distribution is not well understood due to the opacity of the multiphase system in the granulator. This study experimentally characterised the GSSD dynamics along the TSG barrel length in order to understand the function of individual screw modules and process settings, as well as their interaction. Particle size analysis of granules collected at the outlet of the TSG suggested significant interaction between the process and screw configuration parameters influencing the heterogeneity in the GSSD. By characterising the samples collected along the screw length, a variable influence of the screw modules at different process conditions was observed. At low liquid-to-solid ratio (L/S), the first kneading module seemed to play a significant role in mixing, whereas the second kneading module was found to be more involved in reshaping the granules. At high L/S and high throughput, aggregation mainly took place in the second kneading module changing the GSSD. The results obtained from this study will be further used for the calibration and validation of a mechanistic model and, hence, support future development of a more detailed understanding of the HSWG process in a TSG.

  9. Wave granulation in the Venus' atmosphere

    NASA Astrophysics Data System (ADS)

    Kochemasov, G.

    2007-08-01

    In unique venusian planetary system the solid body rotates very slowly and the detached massive atmosphere very rapidly. However both together orbit Sun and their characteristic orbital frequency -1/ 0.62 year - places them in the regular row of planets assigning them characteristic only for Venus wave produced granulation with a granule size πR/6 [1& others]. Remind other bodies in the row with their granule sizes inversely proportional to their orbital frequencies: solar photosphere πR/60, Mercury πR/16, Venus πR/6, Earth πR/4, Mars πR/2, asteroids πR/1 (R-a body radius). Three planets have atmospheres with wave granulations having sizes equal to their lithospheric granules. But Venus, unlike Earth and Mars, has the detached atmosphere that can be considered as a separate body with its own orbital frequency around the center of the Venus' system. According to the correlation between an orbital frequency and a wave granule size the venusian wave granule will be πR/338 (a scale can be Earth: orbital frequency 1/ 1year, granule size πR/4 or Sun: frequency 1/1month, granule size πR/60). So, πR/338 = 57 km. This theoretical size is rather close to that observed by Galileo SC through a violet filter "the filamentary dark features. . . are here revealed to be composed of several dark nodules, like beads on a string, each about 60 miles across" (PIA00072). Actually all Venus' disc seen from a distance π1.7mln.miles is peppered with these fine features seen on a limit of resolution. So, the Venus' atmosphere has two main frequencies in the solar system with corresponding wave granulations: around Sun 1/225 days (granule πR/6) and around Venus 1/ 4 days (granule πR/338). As was done for the Moon, Phobos, Titan and other icy satellites of Saturn [2, 3, 4 & others] one can apply the wave modulation technique also for the atmosphere of Venus. The lower frequency modulates the higher one by dividing and multiplying it thus getting two side frequencies and

  10. Wave granulation in the Venus' atmosphere

    NASA Astrophysics Data System (ADS)

    Kochemasov, G.

    2007-08-01

    In unique venusian planetary system the solid body rotates very slowly and the detached massive atmosphere very rapidly. However both together orbit Sun and their characteristic orbital frequency -1/ 0.62 year - places them in the regular row of planets assigning them characteristic only for Venus wave produced granulation with a granule size πR/6 [1& others]. Remind other bodies in the row with their granule sizes inversely proportional to their orbital frequencies: solar photosphere πR/60, Mercury πR/16, Venus πR/6, Earth πR/4, Mars πR/2, asteroids πR/1 (R-a body radius). Three planets have atmospheres with wave granulations having sizes equal to their lithospheric granules. But Venus, unlike Earth and Mars, has the detached atmosphere that can be considered as a separate body with its own orbital frequency around the center of the Venus' system. According to the correlation between an orbital frequency and a wave granule size the venusian wave granule will be πR/338 (a scale can be Earth: orbital frequency 1/ 1year, granule size πR/4 or Sun: frequency 1/1month, granule size πR/60). So, πR/338 = 57 km. This theoretical size is rather close to that observed by Galileo SC through a violet filter "the filamentary dark features. . . are here revealed to be composed of several dark nodules, like beads on a string, each about 60 miles across" (PIA00072). Actually all Venus' disc seen from a distance ~1.7mln.miles is peppered with these fine features seen on a limit of resolution. So, the Venus' atmosphere has two main frequencies in the solar system with corresponding wave granulations: around Sun 1/225 days (granule πR/6) and around Venus 1/ 4 days (granule πR/338). As was done for the Moon, Phobos, Titan and other icy satellites of Saturn [2, 3, 4 & others] one can apply the wave modulation technique also for the atmosphere of Venus. The lower frequency modulates the higher one by dividing and multiplying it thus getting two side frequencies and

  11. Hydrolysis of native poly(hydroxybutyrate) granules (PHB), crystalline PHB, and artificial amorphous PHB granules by intracellular and extracellular depolymerases.

    PubMed

    Merrick, J M; Steger, R; Dombroski, D

    1999-01-01

    Native poly(hydroxybutyrate) (PHB) granules, purified PHB and artificial amorphous PHB granules were examined as putative substrates for hydrolysis by the intracellular depolymerase system of Rhodospirillum rubrum and the extracellular depolymerase of Pseudomonas lemoignei. The R. rubrum depolymerizing system requires pretreatment of granules with a heat stable 'activator' fraction; the activator can be replaced by mild trypsin treatment. Artificial granules were prepared with a cationic detergent, cetyltrimethylammonium bromide (CTAB) and an anionic detergent, (sodium cholate). Cholate and CTAB PHB granules were hydrolyzed by both enzyme systems; however, some differences were noted. Cholate granules were hydrolyzed in the absence of the R. rubrum activator fraction. Activator was required for the hydrolysis of CTAB granules but could be replaced by heparin in the extracellular depolymerase system but not in the intracellular depolymerase system. A Triton X-114 extract of native PHB granules inhibited the hydrolysis of trypsin-activated granules by the intracellular depolymerase. The inhibition was reversed by the activator fraction. Detergent extracts of granules activated with the R. rubrum activator were unable to inhibit the hydrolysis of trypsin-activated granules. These data suggest that the activator acts to modify an inhibitor present on native granules.

  12. Differential inhibition onto developing and mature granule cells generates high-frequency filters with variable gain

    PubMed Central

    Pardi, María Belén; Ogando, Mora Belén; Schinder, Alejandro F; Marin-Burgin, Antonia

    2015-01-01

    Adult hippocampal neurogenesis provides the dentate gyrus with heterogeneous populations of granule cells (GC) originated at different times. The contribution of these cells to information encoding is under current investigation. Here, we show that incoming spike trains activate different populations of GC determined by the stimulation frequency and GC age. Immature GC respond to a wider range of stimulus frequencies, whereas mature GC are less responsive at high frequencies. This difference is dictated by feedforward inhibition, which restricts mature GC activation. Yet, the stronger inhibition of mature GC results in a higher temporal fidelity compared to that of immature GC. Thus, hippocampal inputs activate two populations of neurons with variable frequency filters: immature cells, with wide‐range responses, that are reliable transmitters of the incoming frequency, and mature neurons, with narrow frequency response, that are precise at informing the beginning of the stimulus, but with a sparse activity. DOI: http://dx.doi.org/10.7554/eLife.08764.001 PMID:26163657

  13. Single-dose and chronic corticosterone treatment alters c-Fos or FosB immunoreactivity in the rat cerebral cortex.

    PubMed

    Szakács, Réka; Fazekas, Ildikó; Mihály, András; Krisztin-Péva, Beáta; Juhász, Anna; Janka, Zoltán

    2010-03-01

    The aim of this study was to examine the effects of single-dose and chronic corticosterone treatment on the inducible transcription factor c-Fos and FosB, and thereby to estimate the effects of high-doses of corticosterone on calcium-dependent neuronal responses in the rat cerebral cortex. At the same time we investigated the distribution of interneurons containing calretinin (CR), vasoactive intestinal polypeptide (VIP) and neuropeptide Y (NPY) in chronically treated animals in order to collect data on the involvement of inhibitory neurons in this process. Adult male rats were injected subcutaneously with 10mg corticosterone, whereas controls received the vehicle (sesame oil). The animals were fixed by transcardial perfusion 12 and 24h following single corticosterone injection, and the brains were processed for c-Fos and FosB immunohistochemistry. To investigate the effects of repeated corticosterone administration, rats were daily treated with the same amount of corticosterone (10mg/animal, subcutaneously) for 21 days. Controls were injected with vehicle. At the end of the experiment, the rats were perfused and immunohistochemistry was used to detect the presence of the FosB protein, CR, VIP and NPY. Quantitative evaluation of immunolabelled cells was performed in the neocortex and the hippocampus. The number of immunoreactive nuclei per unit area was used as a quantitative measure of the effects of corticosterone. It was found that a single-dose administration of corticosterone resulted in a significant, time-dependent increase of c-Fos protein immunoreactivity in the granule cell layer of the dentate gyrus, as well as in regions CA1 and CA3 of the hippocampus 12 and 24h post-injection with respect to control animals. Significant enhancement of c-Fos immunoreactivity was also observed in the neocortex at 12 and 24h post-injection. Single-dose treatment did not significantly alter FosB immunolabelling. Repeated administration of corticosterone produced a complex

  14. Characteristics of aerobic granulation at mesophilic temperatures in wastewater treatment.

    PubMed

    Cui, Fenghao; Park, Seyong; Kim, Moonil

    2014-01-01

    Compact and structurally stable aerobic granules were developed in a sequencing batch reactor (SBR) at mesophilic temperatures (35°C). The morphological, biological and chemical characteristics of the aerobic granulation were investigated and a theoretical granulation mechanism was proposed according to the results of the investigation. The mature aerobic granules had compact structure, small size (mean diameter of 0.24 mm), excellent settleability and diverse microbial structures, and were effective for the removal of organics and nitrification. The growth kinetics demonstrated that the biomass growth depended on coexistence and interactions between heterotrophs and autotrophs in the granules. The functions of heterotrophs and autotrophs created a compact and secure layer on the outside of the granules, protecting the inside sludge containing environmentally sensitive and slow growing microorganisms. The mechanism and the reactor performance may promise feasibility and efficiency for treating industry effluents at mesophilic temperatures using aerobic granulation.

  15. Process to manufacture effervescent tablets: air forced oven melt granulation.

    PubMed

    Yanze, F M; Duru, C; Jacob, M

    2000-12-01

    In the present study we apply melt granulation in an air forced oven, called "are forced oven melt granulation" to the single-stage manufacture of effervescent granules consisting of anhydrous citric acid (43.2%) and sodium bicarbonate (56.8%) in order to make tablets. This study established that process parameters such as concentration of PEG 6000, residence time in the air forced oven, fineness of PEG 6000, fineness of the initial effervescent mix and efficiency of two lubricants markedly influenced several granule and tablet characteristics. The granules ready to be compressed into tablets were stable for 7 days at 60% RH/18 degrees C. It is a dry, simple, rapid, effective, economical, reproducible process particularly well suited to the manufacture of effervescent granules which are easily compressed into effervescent tablets. Of all the formulations tested, only formulations B2 and E2 melt granulated for 30 minutes gave tablets which had optimum compression characteristics without processing problems during compression.

  16. D1/D5 receptors and histone deacetylation mediate the Gateway Effect of LTP in hippocampal dentate gyrus.

    PubMed

    Huang, Yan-You; Levine, Amir; Kandel, Denise B; Yin, Deqi; Colnaghi, Luca; Drisaldi, Bettina; Kandel, Eric R

    2014-02-18

    The dentate gyrus (DG) of the hippocampus is critical for spatial memory and is also thought to be involved in the formation of drug-related associative memory. Here, we attempt to test an aspect of the Gateway Hypothesis, by studying the effect of consecutive exposure to nicotine and cocaine on long-term synaptic potentiation (LTP) in the DG. We find that a single injection of cocaine does not alter LTP. However, pretreatment with nicotine followed by a single injection of cocaine causes a substantial enhancement of LTP. This priming effect of nicotine is unidirectional: There is no enhancement of LTP if cocaine is administrated prior to nicotine. The facilitation induced by nicotine and cocaine can be blocked by oral administration of the dopamine D1/D5 receptor antagonist (SKF 83566) and enhanced by the D1/D5 agonist (SKF 38393). Application of the histone deacetylation inhibitor suberoylanilide hydroxamic acid (SAHA) simulates the priming effect of nicotine on cocaine. By contrast, the priming effect of nicotine on cocaine is blocked in genetically modified mice that are haploinsufficient for the CREB-binding protein (CBP) and possess only one functional CBP allele and therefore exhibit a reduction in histone acetylation. These results demonstrate that the DG of the hippocampus is an important brain region contributing to the priming effect of nicotine on cocaine. Moreover, both activation of dopamine-D1 receptor/PKA signaling pathway and histone deacetylation/CBP mediated transcription are required for the nicotine priming effect in the DG.

  17. Shigella flexneri modulates stress granule composition and inhibits stress granule aggregation.

    PubMed

    Vonaesch, Pascale; Campbell-Valois, François-Xavier; Dufour, Alexandre; Sansonetti, Philippe J; Schnupf, Pamela

    2016-07-01

    Invasion and multiplication of the facultative, cytosolic, enteropathogen Shigella flexneri within the colonic epithelial lining leads to an acute inflammatory response, fever and diarrhea. During the inflammatory process, infected cells are subjected to numerous stresses in