ALS-CSF-induced structural changes in spinal motor neurons of rat pups cause deficits in motor behaviour.

Amyotrophic lateral sclerosis (ALS) is a late-onset, neurodegenerative disease associated with the loss of motor neurons in the spinal cord, brain stem and primary motor cortex. Deficit in the motor function is one of the clinical features of this disease. However, the association between adverse morphological alterations in the spinal motor neurons and motor deficit in sporadic ALS (SALS) is still debated. The present study has sought to investigate the effects of serial intrathecal injections of ALS-CSF into rat pups, at post-natal (P) days 3, 9 and 14, on the motor neuronal (MN) morphology at the cervical and lumbar levels of the spinal cord at P16 and P22. The present study used Cresyl violet and Golgi-Cox staining methods to determine the progressive changes in the morphology of spinal MNs in both cervical and lumbar extensions. The study found a loss of motor neurons in the spinal cord (36% for P16 in cervical and 41.7% in P16 lumbar and 49.57% for P22 cervical and 44.63% for P22 lumbar) and reduced choline acetyl transferase (ChAT) expression after repeated infusion of ALS-CSF. Significant increase in the soma area was also found in ALS-CSF rats (around 21% in P22 cervical and 26.4% in P22 lumbar). Soma hypertrophy was associated with increased dendritic arborization of MNs at both cervical and lumbar levels of the spinal cord. The data also showed a direct correlation between ALS-CSF induced changes in the MN number in the spinal cord and motor behavioral deficits. The loss of MNs, reduced ChAT, changes in soma and dendritic morphology with declined rotarod performance, thus, confirming the pathological phenotypes as seen in ALS patients.

Mechanisms underlying remediation of depression-associated anxiety by chronic N-acetyl cysteine treatment.

RATIONALE: Anxiety is one of the most comorbid conditions with major depressive disorder (MDD). Depression-associated anxiety often stems from the dysfunctional hypothalamic-pituitary-adrenal (HPA) axis and its altered regulation by the amygdala. Furthermore, MDD is associated with altered glutamatergic processing leading to anxiety and impaired regulation of the HPA axis. Recent studies have demonstrated that N-acetyl cysteine (NAC), a pleiotropic drug, exerts antidepressant-like effect by modulation of hippocampal functions, periterminal release of glutamate, and/or redox systems. However, the effects of NAC on depression-associated anxiety, HPA axis hyperactivity, and amygdalar dysfunctions are relatively unknown. OBJECTIVES: Accordingly, we evaluated the effect of NAC on neonatal clomipramine (CLI)-induced adulthood anxiety and accompanying changes in plasma corticosterone levels, amygdalar volumes, neuronal/glial densities, levels of monoamines, and their metabolites in the amygdalar complex. RESULTS: We found that chronic treatment with NAC reverses CLI-induced anhedonia and enhanced anxiety. Interestingly, attenuation of CLI-associated anxiety in NAC-treated rats were accompanied by a reversal of adrenal and spleen hypertrophy, and normalization of enhanced plasma corticosterone levels, indicating improved HPA axis functioning. Furthermore, NAC treatment was sufficient to reverse volumetric hypertrophy of basolateral amygdala (BLA), and altered noradrenaline (NA) metabolism in the amygdalar complex. The effects of NAC in the reversal of CLI-induced impairments were similar to that of fluoxetine (FLX). CONCLUSIONS: We suggest that beneficial effects of NAC on antidepressive- and antianxiety-like behaviors are at least in part mediated via restoration of amygdalar and HPA axis functioning. Our results support the hypothesis that NAC might be evolved as a therapeutic strategy for reversal of amygdalar dysfunction in depression.

Brain stimulation rewarding experience attenuates neonatal clomipramine-induced adulthood anxiety by reversal of pathological changes in the amygdala.

Major depressive disorder (MDD) is associated with enhanced anxiety and reduced reward processing leading to impaired cognitive flexibility. These pathological changes during depression are accompanied by dysfunctional hypothalamic-pituitary-adrenal (HPA) axis and its impaired regulation by the amygdala. Notably, the electrical stimulation of brain reward areas produces an antidepressant effect in both MDD patients and animal models of depression. However, the effects of chronic electrical self-stimulation of lateral hypothalamus - medial forebrain bundle (LH-MFB) on depression-associated anxiety and accompanying changes in plasma corticosterone levels, structural, and neurochemical alterations in the amygdala are unknown. Here, we used the neonatal clomipramine (CLI) model of depression. During adulthood, neonatal CLI and vehicle administered rats were subjected to bilateral electrode implantation at LH-MFB and trained to receive intracranial self-stimulation (ICSS) for 14 days. Rats were then tested for anhedonic and anxiety-like behaviors, followed by estimation of plasma corticosterone levels, assessment of amygdalar volumes and neuronal/glial numbers, levels of monoamines and their metabolites in the amygdala. We found that chronic ICSS of LH-MFB reverses CLI-induced anhedonia and anxiety. Interestingly, amelioration of CLI-induced enhanced anhedonia and anxiety in ICSS rats was associated with partial reversal of enhanced plasma corticosterone levels, hypertrophy of basolateral amygdala (BLA), and altered noradrenaline (NA) metabolism in the amygdalar complex. We suggest that beneficial effects of ICSS on CLI-induced anxiety at least in part mediated by the restoration of amygdalar and HPA axis functioning. Our results support the hypothesis that brain stimulation rewarding experience might be evolved as a therapeutic strategy for reversal of amygdalar dysfunction in depression.

N-acetyl cysteine ameliorates depression-induced cognitive deficits by restoring the volumes of hippocampal subfields and associated neurochemical changes.

Depression is highly comorbid with anxiety disorders and associated with profound cognitive impairment. Moreover, cognitive deficits associated with hippocampal dysfunction are central in depression and anxiety disorders. Furthermore, depression is accompanied by glutamatergic dysfunction which can further impair the functioning of the hippocampus. Recent studies have shown that N-acetyl cysteine (NAC), a glutamate modulator produces an antidepressant-like effect by normalization of the periterminal release of glutamate and/or antioxidant effects. However, the effects of repeated NAC treatment on depression-induced anxiety, cognitive deficits, and associated neurochemical and structural alterations are relatively unknown. Accordingly, we investigated whether chronic NAC treatment could reverse cognitive deficits, and associated hippocampal volume loss and monoaminergic alterations in the neonatal clomipramine (CLI) model of depression. We found that chronic NAC treatment produces antidepressive and antianhedonic-like effects. NAC treatment also reversed CLI-induced anxiety. Interestingly, repeated NAC treatment improved the performance of CLI rats in rewarded alternation task in T-maze. The antidepressive-like and procognitive effects of NAC was associated with normalization of volume loss in CA1, dentate gyrus (DG) and hilar subfields of the hippocampus. Furthermore, NAC restored CLI-induced decrease in levels of monoamines and normalized enhanced metabolism in the hippocampus. Taken together, chronic NAC treatment ameliorates depressive and anxiety-like behavior, spatial learning deficits, and reverses CLI-induced pathological alterations at structural and neurochemical levels in the hippocampus. Our findings might help in evolving NAC as a viable pharmacotherapy for reversal of cognitive deficits in depression and associated disorders.

Chronic brain stimulation rewarding experience ameliorates depression-induced cognitive deficits and restores aberrant plasticity in the prefrontal cortex.

BACKGROUND: Major depressive disorder (MDD) is a multifactorial disease which often coexists with cognitive deficits. Depression-induced cognitive deficits are known to be associated with aberrant reward processing, neurochemical and structural alterations. Recent studies have shown that chronic electrical stimulation of brain reward areas induces a robust antidepressant effect. However, the effects of repeated electrical self-stimulation of lateral hypothalamus - medial forebrain bundle (LH-MFB) on depression-induced cognitive deficits and associated neurochemical and structural alterations in the prefrontal cortex (PFC) are unknown. OBJECTIVES: We investigated the effect of chronic rewarding self-stimulation of LH-MFB in neonatal clomipramine (CLI) model of depression. During adulthood, neonatal CLI and saline administered rats were implanted with bilateral electrodes stereotaxically in the LH-MFB and trained to receive intracranial self-stimulation (ICSS) for 14 days. The rats were tested for depressive-like behaviors, learning and memory followed by estimation of PFC volumes, levels of monoamines and its metabolites in the PFC. RESULTS: We found that chronic ICSS of LH-MFB reverses CLI-induced behavioral despair and anhedonia. Interestingly, self-stimulation normalizes the impaired novel object and location recognition memory in CLI rats. The amelioration of learning impairments in CLI rats was associated with the reversal of volume loss and restoration of monoamine metabolism in the PFC. CONCLUSION: We demonstrated that repeated intracranial self-stimulation of LH-MFB ameliorates CLI-induced learning deficits, reverses altered monoamine metabolism and the atrophy of PFC. Our results support the hypothesis that chronic brain stimulation rewarding experience might be evolved as a potential treatment strategy for reversal of learning deficits in depression and associated disorders.

Neural functions of the aging brain: Daily living, developmental and geriatric disabilities.

Neuronal, microglial, astrocytic and oligodendrocytic functions of the brain are significantly affected during normal aging, and more so if inflicted with neurological diseases. Aging is a consistent risk factor for many neurodegenerative diseases that are sporadic in nature, whereas developmental neurological disabilities stem from errors in brain development. The neuronal functions are affected in both developmental disabilities and geriatric diseases. This special issue, is based on the two-days meeting at Thiruvanathapuram, India on 'Neural Functions of Aging Brain', which had several original presentations, as well as full reviews by neurobiologists and clinicians from India. Out of these, thirteen peer reviewed contributions are published in the present Special Issue of this Journal. This 'Foreword' is also a brief overview on the current scenario of neurobiology research on developmental disabilities and ageing in India based on the manuscripts included in the special issue, vis-s-vis the global scenario. Apparently, there is a void in geriatric and developmental neuroscience research in India since huge data mining and translation, concerted efforts on clinical neuroscience research, and consistent efforts on pure basic research resulting in 'first in the field' novelty are largely missing. Overall, Indian neuroscience excels in making meaningful relevance of contemporary discoveries in neuroscience and contributing towards advances in their applications.

Inactivation of Basolateral Amygdala Prevents Stress-Induced Astroglial Loss in the Prefrontal Cortex.

Repeated stress causes cognitive decline and decreases the expression of glial fibrillary acidic protein (GFAP)+ astroglial cells in the prefrontal cortex (PFC). The stress-induced alterations in astroglial density and morphology might significantly contribute to cognitive impairments. Apart from PFC, a key region involved in modulation of repercussions of stress is basolateral amygdala (BLA), which undergoes hypertrophy following chronic immobilization stress (CIS) and has intense reciprocal connections to the PFC. Interestingly, inactivation of BLA precludes stress-induced learning deficits. However, the modulatory role of BLA on CIS-induced alterations in GFAP+ astroglial density and associated learning deficits are presently unknown. Accordingly, we present two sets of experiments evaluating the effects of BLA inactivation either permanently or temporarily on CIS-induced changes in learning and astroglial expression in the PFC. CIS causes impairment in novel object recognition memory and astroglial loss in the PFC. In experiment I, we permanently inactivated the BLA by ibotenate lesion prior to CIS and observed a significant improvement in learning. Surprisingly, BLA lesion also prevented the stress-induced astroglial loss in the PFC. Furthermore, in the experiment II, we analyzed whether the effects of permanent inactivation could be mirrored by the temporary blockage of BLA specifically during stress. Interestingly, temporary inactivation of BLA mimics the effects of lesion. There was a notable prevention of learning impairment and astroglial loss in the PFC following BLA inactivation during stress. The present study emphasizes that stress-induced astroglial loss might contribute to cognitive deficits and modulation of BLA activity might be a viable strategy for management of stress-related PFC dysfunctions.

Prevention of chronic immobilization stress-induced enhanced expression of glucocorticoid receptors in the prefrontal cortex by inactivation of basolateral amygdala.

Repeated exposure to stress precipitates anxiety, depression and cognitive deficits. Stress-induced activation of the hypothalamus-pituitary-adrenal (HPA) axis is modulated by the prefrontal cortex (PFC) and basolateral amygdala (BLA). It is well established that BLA positively regulates the HPA axis and undergoes hypertrophy following chronic immobilization stress (CIS). However, it is not known whether inactivation of the BLA can modulate the stress-induced changes in the expression of glucocorticoid receptors (GRs) in the PFC. To address this, we stereologically estimated GR+ cell densities in the prelimbic (PrL) and anterior cingulate cortex (ACC). Following ibotenate lesioning of the BLA, rats were subjected to CIS and GR+ cell densities were assessed. CIS increases the GR+ cell densities in PrL and ACC. BLA lesion prior to CIS abolished the CIS-induced increase in GR+ cell densities in both regions. In the second part of experiments, we evaluated whether selective inactivation of BLA during CIS would mimic the effects of BLA lesion. Interestingly, the BLA inactivation specifically during CIS prevented the increase in GR+ cell densities in the PrL and ACC. The findings of our study suggest that BLA regulates the stress-induced increase in prefrontal GR expression, which might be crucial in the emergence of affective and cognitive symptoms following stress. We speculate that modulation of BLA during stress might prevent HPA axis dysfunctions and GR resistance in stress-related disorders, and could assist in the development of novel therapeutic strategies to treat stress and associated disorders like depression. Further, molecular studies are warranted for the understanding of stress-induced GR resistance and its prevention via BLA inactivation.

Basolateral amygdalar inactivation blocks chronic stress-induced lamina-specific reduction in prefrontal cortex volume and associated anxiety-like behavior.

Chronic exposure to stress causes cognitive deficits, anxiety and depression. Earlier studies have suggested that the prefrontal cortex (PFC) and basolateral amygdala (BLA) can differentially modulate the stress-induced alterations either by their action on HPA axis or via direct reciprocal connections between them. The PFC dysfunction and BLA hypertrophy following stress are known to cause anxiety and affective symptoms. Recent studies indicate that inactivation of BLA projections to PFC remarkably decreases anxiety. However, the effect of BLA inactivation on stress-induced anxiety and associated volume loss in prelimbic (PrL) and anterior cingulate (ACC) subregions of PFC is not known. Accordingly, we evaluated the effect of BLA lesion or inactivation during chronic immobilization stress (CIS) on an approach-avoidance task and associated volume loss in the PFC. The stressed rats showed a significant volumetric reduction in layer I and II of the PrL and ACC. Interestingly, BLA lesion prior to stress prevented the volume loss in PrL and ACC. Further, BLA lesion blocked the anxiety-like behavior in stressed rats. However, in the absence of stress, BLA lesion increased the number of shocks as compared to controls. As BLA lesion produced an anticonflict effect, we performed temporary inactivation of BLA specifically during stress. Similar to BLA lesion, lidocaine-induced inactivation prevented the stress-induced volume loss and anxiety-like behavior. We demonstrate that inactivation of BLA during stress prevents CIS-induced anxiety and associated structural correlates in the PFC. The present study extends the hypothesis of amygdalar silencing as a possible management strategy for stress and associated disorders.

Admixing MPTP-resistant and MPTP-vulnerable mice enhances striatal field potentials and calbindin-D28K expression to avert motor behaviour deficits.

Asian-Indians are less vulnerable to Parkinson's disease (PD) than the Caucasians. Their admixed populace has even lesser risk. Studying this phenomenon using 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-susceptible C57BL/6J, MPTP-resistant CD-1 and their resistant crossbred mice revealed differences in the nigrostriatal cyto-molecular features. Here, we investigated the electrophysiological and behavioural correlates for differential MPTP-susceptibility and their outcome upon admixing. We recorded local field potentials (LFPs) from dorsal striatum and assessed motor co-ordination using rotarod and grip strength measures. Nigral calbindin-D28K expression, a regulator of striatal activity through nigrostriatal projections was evaluated using immunohistochemistry. The crossbreds had significantly higher baseline striatal LFPs. MPTP significantly increased the neuronal activity in delta (0.5-4 Hz) and low beta (12-16 Hz) ranges in C57BL/6J; significant increase across frequency bands till high beta (0.5-30 Hz) in CD-1, and caused no alterations in crossbreds. MPTP further depleted the already low nigral calbindin-D28K expression in C57BL/6J. While in crossbreds, it was further up-regulated. MPTP affected the rotarod and grip strength performance of the C57BL/6J, while the injected CD-1 and crossbreds performed well. The increased striatal ß-oscillations are comparable to that in PD patients. Higher power in CD-1 may be compensatory in nature, which were also reported in pre-symptomatic monkeys. Concurrent up-regulation of nigral calbindin-D28K may assist maintenance of striatal activity by buffering calcium overload in nigra. Thus, preserved motor behaviour in PD reminiscent conditions in CD-1 and crossbreds complement compensated/unaffected striatal LFPs. Similar electrophysiological correlates and cytomorphological features are envisaged in human phenomenon of differential PD prevalence, which are modulated upon admixing.

Influence of age and gender on blood pressure variability and baroreflex sensitivity in a healthy population in the Indian sub-continent.

Background The current exploratory study was aimed at estimating measures of blood pressure variability (BPV) and baroreflex sensitivity (BRS) in a healthy population in the Indian sub-continent. Methods One hundred and forty-two healthy subjects were recruited for the study. Blood pressure (BP) was recorded continuously for 15 min using the Finometer (Finapres Medical Systems, The Netherlands). For offline analysis, Nevrokard cardiovascular parameter analysis (CVPA) software (version 2.1.0) was used for BPV analysis. BRS was determined by spectral and sequence methods. One-way ANOVA and Bonferroni's test were used to compare parameters. Pearson's correlation coefficient was employed to look for possible associations between age and other continuous variables. Results Out of 196 screened volunteers, 54 were excluded and 142 subjects were grouped based on ages as 10-19 years (group 1), 20-29 years (group 2), 30-39 years (group 3), 40-49 years (group 4), and 50-59 years (group 5). Within groups, body mass index (BMI, p=0.000) and BP (systolic and diastolic) were significantly different. Post hoc analysis showed mean blood pressure (MBP) and diastolic blood pressure (DBP) differing significantly between groups 1 and 4 (p<0.05 for both) along with other cardiovascular parameters. Age correlated positively with BMI and all parameters of BP. Significant gender differences were observed for stroke volume, cardiac output, up BRS, total BRS, peripheral resistance (PR), and aortic impedance. Conclusions Our study has provided reference values for BPV and BRS in an Indian population. It also indicates age-related neurocardiac imbalance and possible utility of these tests for screening at the start of neurocardiac damage in a healthy population.

Etiogenic factors present in the cerebrospinal fluid from amyotrophic lateral sclerosis patients induce predominantly pro-inflammatory responses in microglia.

BACKGROUND: Microglial cell-associated neuroinflammation is considered as a potential contributor to the pathophysiology of sporadic amyotrophic lateral sclerosis. However, the specific role of microglia in the disease pathogenesis remains to be elucidated. METHODS: We studied the activation profiles of the microglial cultures exposed to the cerebrospinal fluid from these patients which recapitulates the neurodegeneration seen in sporadic amyotrophic lateral sclerosis. This was done by investigating the morphological and functional changes including the expression levels of prostaglandin E2 (PGE2), cyclooxygenase-2 (COX-2), TNF-α, IL-6, IFN-γ, IL-10, inducible nitric oxide synthase (iNOS), arginase, and trophic factors. We also studied the effect of chitotriosidase, the inflammatory protein found upregulated in the cerebrospinal fluid from amyotrophic lateral sclerosis patients, on these cultures. RESULTS: We report that the cerebrospinal fluid from amyotrophic lateral sclerosis patients could induce an early and potent response in the form of microglial activation, skewed primarily towards a pro-inflammatory profile. It was seen in the form of upregulation of the pro-inflammatory cytokines and factors including IL-6, TNF-α, iNOS, COX-2, and PGE2. Concomitantly, a downregulation of beneficial trophic factors and anti-inflammatory markers including VEGF, glial cell line-derived neurotrophic factor, and IFN-γ was seen. In addition, chitotriosidase-1 appeared to act specifically via the microglial cells. CONCLUSION: Our findings demonstrate that the cerebrospinal fluid from amyotrophic lateral sclerosis patients holds enough cues to induce microglial inflammatory processes as an early event, which may contribute to the neurodegeneration seen in the sporadic amyotrophic lateral sclerosis. These findings highlight the dynamic role of microglial cells in the pathogenesis of the disease, thus suggesting the need for a multidimensional and temporally guarded therapeutic approach targeting the inflammatory pathways for its treatment.

Inactivation of basolateral amygdala prevents chronic immobilization stress-induced memory impairment and associated changes in corticosterone levels.

Chronic stress causes detrimental effects on various forms of learning and memory. The basolateral amygdala (BLA) not only plays a crucial role in mediating certain forms of memory, but also in the modulation of the effects of stress. Chronic immobilization stress (CIS) results in hypertrophy of the BLA, which is believed to be one of the underlying causes for stress' effects on learning. Thus, it is plausible that preventing the effects of CIS on amygdala would preclude its deleterious cognitive effects. Accordingly, in the first part, we evaluated the effect of excitotoxic lesion of the BLA on chronic stress-induced hippocampal-dependent spatial learning using a partially baited radial arm maze task. The BLA was ablated bilaterally using ibotenic acid prior to CIS. Chronically stressed rats showed impairment in spatial learning with decreased percentage correct choice and increased reference memory errors. Excitotoxic lesion of the BLA prevented the impairment in spatial learning and reference memory. In the retention test, lesion of the BLA was able to rescue the chronic stress-induced impairment. Interestingly, stress-induced enhanced plasma corticosterone levels were partially prevented by the lesion of BLA. These results motivated us to evaluate if the same effects can be observed with temporary inactivation of BLA, only during stress. We found that chronic stress-induced spatial learning deficits were also prevented by temporary inactivation of the BLA. Additionally, temporary inactivation of BLA partially precluded the stress-induced increase in plasma corticosterone levels. Thus, inactivation of BLA precludes stress-induced spatial learning deficits, and enhanced plasma corticosterone levels. It is speculated that BLA inactivation-induced reduction in corticosterone levels during stress, might be crucial in restoring spatial learning impairments. Our study provides evidence that amygdalar modulation during stress might be beneficial for strategic management of stress-related cognitive deficits.

Admixing of MPTP-Resistant and Susceptible Mice Strains Augments Nigrostriatal Neuronal Correlates to Resist MPTP-Induced Neurodegeneration.

Disease genetics in admixed populations like Hispanic-Americans, African-Americans, etc. are gaining importance due to high disease burden in them. Furthermore, epidemiological studies conclusively prove ethnicity-based differential prevalence of Parkinson's disease (PD), since the American-Caucasians are more susceptible than Asian-Indians and Africans. Contradictorily, Anglo-Indians, an admixture of Europeans and Asian-Indians are five-times less susceptible than Indians. We evaluated the neural basis of this phenomenon using the cytomorphological features of susceptibility to nigrostriatal neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). The nigral dopaminergic neuronal numbers, their size and tyrosine hydroxylase (TH), PitX3 and Nurr1 expression were compared in MPTP-susceptible C57BL/6J mice, MPTP-resistant CD-1 mice and their crossbreds using stereology, morphometry and densitometry. Apoptotic index was evaluated by TUNEL-assay and caspase-3 expression. Striatal volume, TH and glial derived neurotrophic factor (GDNF) expression were studied. The normal CD-1 and crossbreds had significantly more, although smaller, nigral dopaminergic neurons than C57BL/6J, and a larger striatum. The crossbreds had higher TH, Nurr1 and PitX3 levels. MPTP administration caused loss of ~50-60 % nigral dopaminergic neurons in C57BL/6J and ~15 % in CD-1, but none in crossbreds. MPTP-induced cellular shrinkage in C57BL/6J was contrasted by nuclear enlargement without somal alterations in resistant strains. MPTP lowered the striatal TH and GDNF in C57BL/6J. Elevated striatal GDNF in CD-1 and crossbreds could be of compensatory nature and complemented the reduced nigral caspase-3 expression to attenuate and/or block apoptosis. Similar neural correlates of resilience are envisaged in the Anglo-Indian population. Thus, we present the core neuroanatomical features of resilience against PD and evidence for ethnicity-based differential prevalence.

Electrophysiological characterization of Nsc-34 cell line using Microelectrode Array.

Neurons communicate with each other through intricate network to evolve higher brain functions. The electrical activity of the neurons plays a crucial role in shaping the connectivity. With motor neurons being vulnerable to neurodegenerative diseases, understanding the electrophysiological properties of motor neurons is the need of the hour, in order to comprehend the impairment of connectivity in these diseases. NSC-34 cell line serves as an excellent model to study the properties of motor neurons as they express Choline acetyltransferase (ChAT). Although NSC-34 cell lines have been used to study the effect of various toxicological, neurotrophic and neuroprotective agents, the electrical activity of these cells has not been elucidated. In the current study, we have characterized the electrophysiological properties of NSC-34 cell lines using Micro-Electrode Array (MEA) as a tool. Based on the spike waveform, firing frequency, auto- and cross-correlogram analysis, we demonstrate that NSC-34 cell culture has >2 distinct types of neuronal population: principal excitatory neurons, putative interneurons and unclassified neurons. The presence of interneurons in the NSC-34 culture was characterized by increased expression of GAD-67 markers. Thus, finding an understanding of the electrophysiological properties of different population of neurons in NSC-34 cell line, will have multiple applications in the treatment of neurological disorders.

Differential expression of calbindin in nigral dopaminergic neurons in two mice strains with differential susceptibility to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine.

Parkinson's disease (PD) affects the A9 dopaminergic (DA) neurons of substantia nigra pars compacta (SNpc) whereas other DA neuronal subtypes are spared. The role of calbindin in this differential vulnerability has been long elicited, and is seen in the MPTP induced mice models of PD. A peculiar feature of mice models is the strain specific differences in the susceptibility to MPTP. Here, calbindin-D28K expression in DA neurons of SNpc of MPTP susceptible C57BL/6 mice and MPTP resistant CD-1 mice was studied as a susceptibility marker of degeneration. Unbiased stereological estimation of immunoperoxidase stained midbrain sections revealed significantly higher number of calbindin immunoreactive cells in SNpc of CD-1 mice compared to that of C57BL/6 strain. Western blotting showed minimal differences in the levels. Calbindin-tyrosine hydroxylase immunofluorescence co-labeling was performed to map the calbindin immunoreactive DA neurons in SNpc and ventral tegmental area (VTA) and to quantify the calbindin expression at cellular level. While the levels were comparable in VTA of both mice strains, the SNpc of CD-1 mice showed significantly higher calbindin expression. Within the SNpc, the medial and dorsal subdivisions showed higher calbindin expression in CD-1. The expression in the ventrolateral SNpc of both strains remained comparable. Our observations clearly point at overall higher levels and sizeable percentage of cells expressing more calbindin in SNpc of CD-1 mice, which might confer neuroprotection against MPTP, while its lower expression makes C57BL/6 mice more susceptible. Similar mechanism may be attributed to the phenomenon of differential prevalence of PD in different ethnic populations.

The selective noradrenergic reuptake inhibitor reboxetine restores spatial learning deficits, biochemical changes, and hippocampal synaptic plasticity in an animal model of depression.

Depression is a major psychiatric illness that is associated with cognitive dysfunctions. The underlying mechanism of depression-associated memory impairment is unclear. Previously, we showed altered hippocampal synaptic plasticity in an animal model of depression. Although several antidepressants are beneficial in the treatment of depression, very little is known about the effects of these drugs on depression-associated learning and memory deficits. Prolonged antidepressant treatment might contribute to neuroplastic changes required for clinical outcomes. Accordingly, we evaluated the effect of chronic reboxetine (a selective noradrenergic reuptake inhibitor) treatment on depression-induced reduced hippocampal synaptic plasticity, neurotransmitter levels, and spatial learning and memory impairments. Depression was induced in male Wistar rats by the administration of clomipramine from postnatal days 8 to 21, and these rats were treated with reboxetine in adulthood. The neonatal clomipramine administration resulted in impaired hippocampal long-term potentiation (LTP), decreased hippocampal cholinergic activity and monoamine levels, and poor performance in a partially baited eight-arm radial maze task. Chronic reboxetine treatment restored the hippocampal LTP, acetylcholinesterase activity, and levels of biogenic amines and ameliorated spatial learning and memory deficits in the depressed state. Thus, restoration of hippocampal synaptic plasticity might be a cellular mechanism underlying the beneficial effect of reboxetine in depression-associated cognitive deficits. This study furthers the existing understanding of the effects of antidepressants on learning, memory, and synaptic plasticity and could ultimately assist in the development of better therapeutic strategies to treat depression and associated cognitive impairments.

Role of VEGF and VEGFR2 Receptor in Reversal of ALS-CSF Induced Degeneration of NSC-34 Motor Neuron Cell Line.

Vascular endothelial growth factor (VEGF), the well-known angiogenic factor is both neurotrophic and neuroprotective. Altered VEGF signalling is implicated in the pathogenesis of amyotrophic lateral sclerosis (ALS), a fatal degenerative disease of motor neurons. We have shown earlier that VEGF protects NSC-34 motor neuronal cell line, when exposed to cerebrospinal fluid (CSF) from sporadic ALS patients (ALS-CSF). Here, we have investigated the consequences of ALS-CSF and VEGF supplementation on the VEGFR2 receptor and endogenous VEGF expression. ALS-CSF caused significant down-regulation of VEGFR2 as well as the Calbindin-D28K levels, but not endogenous VEGF. Exogenous supplementation restored the depletion of VEGFR2 and Calbindin-D28K with a concomitant up-regulation of endogenous VEGF. The up-regulated caspase 3 in the ALS-CSF group was reinstated to basal levels along with a significant reduction in the number of TUNEL-positive cells. Electron photomicrographs of ALS-CSF-exposed cells divulged presence of cytoplasmic vacuoles alongside severe damage to organelles like mitochondria, endoplasmic reticulum, etc. Substantial recovery of most of the damaged organelles was noted in response to VEGF supplementation. While the enhancement in endogenous VEGF levels highlights the autocrine functions, the up-regulation of VEGFR2 receptor emphasizes the paracrine functions of VEGF in modulating its neuroprotective effect against ALS-CSF. The revival of cellular organellar structure, increased calbindin expression and enhanced survival in response to VEGF supplementation consolidates the opinion that VEGF indeed has a therapeutic potential in sporadic ALS.

Reach task-associated excitatory overdrive of motor cortical neurons following infusion with ALS-CSF.

Converging evidence from transgenic animal models of amyotrophic lateral sclerosis (ALS) and human studies suggest alterations in excitability of the motor neurons in ALS. Specifically, in studies on human subjects with ALS the motor cortex was reported to be hyperexcitable. The present study was designed to test the hypothesis that infusion of cerebrospinal fluid from patients with sporadic ALS (ALS-CSF) into the rat brain ventricle can induce hyperexcitability and structural changes in the motor cortex leading to motor dysfunction. A robust model of sporadic ALS was developed experimentally by infusing ALS-CSF into the rat ventricle. The effects of ALS-CSF at the single neuron level were examined by recording extracellular single unit activity from the motor cortex while rats were performing a reach to grasp task. We observed an increase in the firing rate of the neurons of the motor cortex in rats infused with ALS-CSF compared to control groups. This was associated with impairment in a specific component of reach with alterations in the morphological characteristics of the motor cortex. It is likely that the increased cortical excitability observed in the present study could be the result of changes in the intrinsic properties of motor cortical neurons, a dysfunctional inhibitory mechanism and/or an underlying structural change culminating in a behavioral deficit.