Regions Of CNS Research Articles

A Combinatorial Semaphorin Code Instructs the Initial Steps of Sensory Circuit Assembly in the Drosophila CNS

Longitudinal axon fascicles within the Drosophila embryonic CNS provide connections between body segments and are required for coordinated neural signaling along the anterior-posterior axis. We show here that establishment of select CNS longitudinal tracts and formation of precise mechanosensory afferent innervation to the same CNS region are coordinately regulated by the secreted semaphorins Sema-2a and Sema-2b. Both Sema-2a and Sema-2b utilize the same neuronal receptor, plexin B (PlexB), but serve distinct guidance functions. Localized Sema-2b attraction promotes the initial assembly of a subset of CNS longitudinal projections and subsequent targeting of chordotonal sensory afferent axons to these same longitudinal connectives, whereas broader Sema-2a repulsion serves to prevent aberrant innervation. In the absence of Sema-2b or PlexB, chordotonal afferent connectivity within the CNS is severely disrupted, resulting in specific larval behavioral deficits. These results reveal that distinct semaphorin-mediated guidance functions converge at PlexB and are critical for functional neural circuit assembly.

Central leptin and ghrelin signalling: Comparing and contrasting their mechanisms of action in the brain

In the past two decades, two major discoveries have greatly contributed to our current knowledge on the central control of food intake and body-weight; the discovery of the anorexigenic adipocyte derived hormone leptin in 1994 and the orexigenic gut derived hormone ghrelin in 1999. Both hormones act as crucial signals to indicate nutritional status as well as to modulate feeding behaviour through a variety of distinct pathways. They target overlapping CNS regions in order to mediate their obvious opposing effects on energy balance. Here we depict the integral picture of leptin and ghrelin on central regulation of food intake by reviewing their actions across the CNS, in regions of the hypothalamus, brainstem, mesolimbic reward pathway and other higher brain areas.

Administration of anti-c-kit antibody into the cerebrospinal fluid leads to increased cell death in the developing cerebral cortex

It is generally believed that during development, neurons are usually produced in excess. Cell death occurs in the developing nervous system. The survival of the developing neurons depends on many factors derived from the target sites, of which the neuronal trophic factors are by far the best known. Stem cell factor (SCF) and its receptor, c-kit, is expressed in cells of nervous system during development and adulthood. Although the role of SCF/c-kit in the nervous system is so far not clear, in vitro studies indicate that SCF/c-kit is trophic to certain neurons derived from neural crest and cerebral cortex. In this study the effects of anti-c-kit antibody on cell death in the newborn chick cerebral cortex have been investigated. Injection of anti-c-kit antibody into the cisterna magnum increased the number of cell death and resulted in thinning of the cerebral cortex as compared to that from the control group. It is concluded that SCF/c-kit is essential for cortical progenitor cell survival in the cerebral cortex. Moreover, this method may be applied to the other factors and different CNS regions, allowing identification of factors involved in cell death. It additionally re-emphasizes the importance of further investigations into the potential roles of SCF/c-kit signaling in neurodegenerative diseases.

Molecular Annotation of Integrative Feeding Neural Circuits

The identity of higher-order neurons and circuits playing an associative role to control feeding is unknown. We injected pseudorabies virus, a retrograde tracer, into masseter muscle, salivary gland, and tongue of BAC-transgenic mice expressing GFP in specific neural populations and identified several CNS regions that project multisynaptically to the periphery. MCH and orexin neurons were identified in the lateral hypothalamus, and Nurr1 and Cnr1 in the amygdala and insular/rhinal cortices. Cholera toxin β tracing showed that insular Nurr1(+) and Cnr1(+) neurons project to the amygdala or lateral hypothalamus, respectively. Finally, we show that cortical Cnr1(+) neurons show increased Cnr1 mRNA and c-Fos expression after fasting, consistent with a possible role for Cnr1(+) neurons in feeding. Overall, these studies define a general approach for identifying specific molecular markers for neurons in complex neural circuits. These markers now provide a means for functional studies of specific neuronal populations in feeding or other complex behaviors.

Neuroglial Plasticity at Striatal Glutamatergic Synapses in Parkinson's Disease

Striatal dopamine denervation is the pathological hallmark of Parkinson's disease (PD). Another major pathological change described in animal models and PD patients is a significant reduction in the density of dendritic spines on medium spiny striatal projection neurons. Simultaneously, the ultrastructural features of the neuronal synaptic elements at the remaining corticostriatal and thalamostriatal glutamatergic axo-spinous synapses undergo complex ultrastructural remodeling consistent with increased synaptic activity (Villalba and Smith, 2011). The concept of tripartite synapses (TS) was introduced a decade ago, according to which astrocytes process and exchange information with neuronal synaptic elements at glutamatergic synapses (Araque et al., 1999a). Although there has been compelling evidence that astrocytes are integral functional elements of tripartite glutamatergic synaptic complexes in the cerebral cortex and hippocampus, their exact functional role, degree of plasticity and preponderance in other CNS regions remain poorly understood. In this review, we discuss our recent findings showing that neuronal elements at cortical and thalamic glutamatergic synapses undergo significant plastic changes in the striatum of MPTP-treated parkinsonian monkeys. We also present new ultrastructural data that demonstrate a significant expansion of the astrocytic coverage of striatal TS synapses in the parkinsonian state, providing further evidence for ultrastructural compensatory changes that affect both neuronal and glial elements at TS. Together with our limited understanding of the mechanisms by which astrocytes respond to changes in neuronal activity and extracellular transmitter homeostasis, the role of both neuronal and glial components of excitatory synapses must be considered, if one hopes to take advantage of glia–neuronal communication knowledge to better understand the pathophysiology of striatal processing in parkinsonism, and develop new PD therapeutics.

A study of neural-related microRNAs in the developing amphioxus

BackgroundMicroRNAs are small noncoding RNAs regulating expression of protein coding genes at post-transcriptional level and controlling several biological processes. At present microRNAs have been identified in various metazoans and seem also to be involved in brain development, neuronal differentiation and subtypes specification. An approach to better understand the role of microRNAs in animal gene expression is to determine temporal and tissue-specific expression patterns of microRNAs in different model organisms. Therefore, we have investigated the expression of six neural related microRNAs in amphioxus, an organism having an important phylogenetic position in terms of understanding the origin and evolution of chordates.ResultsIn amphioxus, all the microRNAs we examined are expressed in specific regions of the CNS, and some of them are correlated with specific cell types. In addition, miR-7, miR-137 and miR-184 are also expressed in endodermal and mesodermal tissues. Several potential targets expressed in the nervous system of amphioxus have been identified by computational prediction and some of them are coexpressed with one or more miRNAs.ConclusionWe identified six miRNAs that are expressed in the nervous system of amphioxus in a variety of patterns. miR-124 is found in both differentiating and mature neurons, miR-9 in differentiated neurons, miR-7, miR-137 and miR-184 in restricted CNS regions, and miR-183 in cells of sensory organs. Therefore, such amphioxus miRNAs may play important roles in regional patterning and/or specification of neuronal cell types.

Multiple 100 Hz electroacupuncture treatments produced cumulative effect on the suppression of morphine withdrawal syndrome: Central preprodynorphin mRNA and p-CREB implicated

Alleviating opiate withdrawal syndrome in addicts is a critical precondition to break away from drug and further to prevent reuse. Electroacupuncture (EA) was claimed to be effective for alleviating withdrawal syndrome, but the optimal protocol remained unclear. In the present study we found that (1) 100 Hz EA administered 12–24 h after the last morphine injection suppressed the withdrawal syndrome in rats, multiple sessions of EA were more effective than single session, with the after-effect lasting for at least 7 days. (2) A down-regulation of preprodynorphin (PPD) mRNA level was observed in spinal cord, PAG and hypothalamus 60 h after the last morphine injection, which could be reversed by multiple sessions, but not a single session of EA. (3) Accompanied with the decrease of PPD mRNA level, there was an up-regulation of p-CREB in the three CNS regions, which was abolished by 100 Hz EA treatment. The findings suggest that down-regulation of p-CREB and acceleration of dynorphin synthesis in spinal cord, PAG and hypothalamus may be implicated in the cumulative effect of multiple 100 Hz EA treatment for opioid detoxification.

Global gene expression analysis using microarray to study differential vulnerability to neurodegeneration

Neurodegenerative disorders such as Parkinson’s disease, motor neuron disease and Alzheimer’s disease is characterized by loss of specific cells within certain regions of the brain. One of the most compelling questions is to determine why specific cell populations are vulnerable to neurodegeneration. We addressed this question by studying global gene expression changes using an animal model of neurodegenerative disease. Human ingestion of “chickling peas” from the plant Lathyrus sativus containing an excitatory amino acid, L-?-N-oxalyl amino-L-alanine (L-BOAA) leads to a neurodegenerative disorder, neurolathyrism, a motor neuron disease characterized by spastic paraparesis that targets Betz cells in motor cortex (MC) and the anterior horn cells in the lumbosacral cord (LSC). Our laboratory has earlier shown that L-BOAA toxicity in mice is associated with mitochondrial dysfunction seen as loss of complex I activity in MC and LSC. While MC recovers after an initial insult, sustained injury is seen in LSC. We therefore, profiled global gene expression changes by microarray analyses in mice CNS regions during recovery from L-BOAA toxicity. Mouse cDNA arrays were hybridised with RNA from MC and LSC of control and L-BOAA treated mice. Data was analysed using Array vision and Spot-fire software. In concurrence with earlier results glutaredoxin, a thiol disulfide oxidoreductase was upregulated in both MC and LSC. Glutaredoxin is required for maintenance of complex I function. However, the up-regulation of NADH dehydrogenase (Complex I) was seen only in MC and not in LSC in agreement with the activity of complex I seen earlier. Upregulation of genes related to energy metabolism, antioxidant enzymes, MAP kinases and ubiquitin proteasomal pathways was seen in MC indicating their potential role in the recovery. In contrast in LSC, genes related to MAP kinases and anti-oxidant were not upregulated, instead programmed cell death gene was upregulated. These studies demonstrate the differential responses of CNS regions to a common excitotoxic insult and help identify factors responsible for differential vulnerability of CNS regions often seen in neurodegenerative diseases.

Neuroprotective and neurodegenerative effects of the chronic expression of tumor necrosis factor α in the nigrostriatal dopaminergic circuit of adult mice

Tumor necrosis factor (TNF)-α, a pro-inflammatory cytokine, has been implicated in both neuronal death and survival in Parkinson's disease (PD). The substantia nigra (SN), a CNS region affected in PD, is particularly susceptible to inflammatory insults and possesses the highest density of microglial cells, but the effects of inflammation and in particular TNF-α on neuronal survival in this region remains controversial. Using adenoviral vectors, the CRE/loxP system and hypomorphic mice, we achieved chronic expression of two levels of TNF-α in the SN of adult mice. Chronic low expression of TNF-α levels reduced the nigrostriatal neurodegeneration mediated by intrastriatal 6-hydroxydopamine administration. Protective effects of low TNF-α level could be mediated by TNF-R1, GDNF, and IGF-1 in the SN and SOD activity in the striatum (ST). On the contrary, chronic expression of high levels of TNF-α induced progressive neuronal loss (63% at 20 days and 75% at 100 days). This effect was accompanied by gliosis and an inflammatory infiltrate composed almost exclusively by monocytes/macrophages. The finding that chronic high TNF-α had a slow and progressive neurodegenerative effect in the SN provides an animal model of PD mediated by the chronic expression of a single cytokine. In addition, it supports the view that cytokines are not detrimental or beneficial by themselves, i.e., their level and time of expression among other factors can determine its final effect on CNS damage or protection. These data support the view that new anti-parkinsonian treatments based on anti-inflammatory therapies should consider these dual effects of cytokines on their design.

Chlorpyrifos Induced Region Specific Vulnerability in Rat CNS and Modulation by Age and Cold Stress: An Interactive Study

Chlorpyrifos (CPF), an organophosphorus insecticide is known to cause ill health in non-target animals by inducing oxidative stress. In this study influence of cold stress (15°C and 20°C) and age as modulating factors on CPF induced oxidative stress was addressed to assess age-related differences and vulnerability in central nervous system of rats. The results indicated an interaction with age and cold exposure resulting in marked decreased activity levels of SOD (P < 0.05), CAT (P < 0.05), GPx (P < 0.05), GST (P < 0.05) followed by increased MDA (P < 0.05) and decreased GSH levels (P < 0.05). The ANOVA and Post-hoc analysis showed that antioxidant enzymes decreased significantly (P < 0.05) on CPF exposure. Moreover synergistic action of CPF and cold stress at 15°C caused higher inhibition on comparison with CPF and cold stress alone and together at 20°C indicating the extent of peroxidative damage in discrete regions of CNS. Further this study showed young individuals to be more sensitive than adults.

The role of endocannabinoids in visceral hyposensitivity induced by rapid eye movement sleep deprivation in rats: Regional differences

Visceral hypersensitivity is one of the most important mechanisms of functional gastrointestinal diseases. Our previous studies have shown that rapid eye movement (REM) sleep deprivation (REMSD) decreases visceral sensitivity in rats, but the mechanisms involved in this effect, have not yet been clarified. In this study, we investigated the role of the CNS and peripheral endocannabinoids in visceral hyposensitivity induced by REMSD. Animals were randomly divided into the cage-yoked (YC), the REMSD group, which suffered from REMSD for 48 h, and the group with the interventions of Rimonabant after REMSD. The visceral sensitivity of all the groups was assessed, and the expressions of cannabinoid receptor (CB1R), fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MGL) in the CNS and gut regions, were detected. We demonstrate that REMSD decreases visceral sensitivity in rats and that the Rimonabant intervention antagonizes this effect. The expression of CB1R in the CNS region was significantly higher in the REMSD compared to the YC group. We did not see similar results in the gut. At the same time, the expressions of FAAH and MGL in the CNS and colon, excluding the iliac terminus, were lower in the REMSD compared to the YC group. Endocannabinoids are involved in the mechanism of visceral hyposensitivity in rats induced by REMSD. Possibly those in the CNS play the main role in this activity.

Immunohistochemical localization of the neuropeptide S receptor in the rat central nervous system

The neuropeptide S receptor (NPSR) is a G-protein coupled receptor that is potently activated by the linear 20 amino acid peptide, neuropeptide S (NPS). Central administration of NPS promotes arousal and anxiolytic-like effects in rodents, and fails to promote such effects in NPSR knockout animals or in the presence of NPSR-selective antagonists. In situ hybridization (ISH) studies in rat brain have revealed that the mRNAs encoding the NPS precursor and the NPS receptor are expressed at high levels in discrete regions of the rat CNS. The distribution of the NPSR protein in brain has not been reported due to a lack of available antibodies. We have generated and validated a NPSR-specific antibody and used it to determine the distribution of the NPSR in male Sprague–Dawley (SD) rat brain. The anti-NPSR antibody identified a single protein by Western blot with an estimated molecular weight of 65 kD, which was prevented by pre-incubation of the antibody with the immunizing peptide. The protein distribution identified with this antibody in rat brain was consistent both with the mRNA distribution identified by in situ hybridization, and to the localization pattern identified by a second NPSR-specific antibody against a distinct NPSR epitope. NPSR protein was identified in the medial amygdala (MeA), substantia nigra pars compacta, subiculum, dorsal raphe, and several hypothalamic and thalamic regions. Additionally, NPSR protein was localized in the pyramidal cell layer of the ventral hippocampus, the medial habenula (MHb), and was widely distributed in the cortex. The distribution of NPSR protein provides further insight into the organization of the NPS system and may guide future studies on the role of the NPSR in brain.

Neurophysiological evidence for muscle tone reduction by intrathecal baclofen at the brainstem level

Objective Intrathecal baclofen (ITB) is an efficient treatment modality for severe spasticity that is considered to act at the spinal level. Its influence on phasic spasticity is usually determined clinically by testing muscle reflexes, and on tonic spasticity by using scores such as the Modified Ashworth Scale (MAS). Neurophysiological techniques, e.g., soleus H reflex, may provide additional information regarding ITB efficacy. There is, however, only scarce information available on time–response relationships of clinical and neurophysiological measures of spasticity obtained at different levels along the neuroaxis. Methods Fourteen patients with severe spastic paraparesis underwent serial evaluation of MAS in upper and lower limbs and serial testing of H reflex in soleus and flexor carpi radialis muscles, T wave in quadriceps and biceps brachii muscles, and blink reflex (BR) with and without prepulse, at baseline, and 15, 30, 60, 90, 120, and 180 min following ITB bolus application. Results ITB bolus application caused significant suppression of soleus H reflex after 15 min and of quadriceps T wave after 30 min, while MAS dropped significantly after 60 min together with significant suppression of BR R2 area without and with prepulse stimulation. H reflex in flexor carpi radialis and T wave in biceps brachii were not significantly suppressed by ITB. The time course of early changes in soleus H max/ M max ratio and quadriceps T wave indicates a suppression of hyperreflexia at the spinal level, while a later reduction of MAS synchronously with suppression of BR with and without prepulse concurs with a brainstem effect of ITB. Conclusion Temporal concurrence between suppression of brainstem reflexes and desired suppression of lower limb muscle hypertonia after ITB bolus application suggests that both may be at least partially mediated from a common CNS region of activity. Significance Our data concur with a significant brainstem action of ITB.

Magnetic Resonance Imaging-Guided Delivery of Adeno-Associated Virus Type 2 to the Primate Brain for the Treatment of Lysosomal Storage Disorders

Gene replacement therapy for the neurological deficits caused by lysosomal storage disorders, such as in Niemann-Pick disease type A, will require widespread expression of efficacious levels of acid sphingomyelinase (ASM) in the infant human brain. At present there is no treatment available for this devastating pediatric condition. This is partly because of inherent constraints associated with the efficient delivery of therapeutic agents into the CNS of higher order models. In this study we used an adeno-associated virus type 2 (AAV2) vector encoding human acid sphingomyelinase tagged with a viral hemagglutinin epitope (AAV2-hASM-HA) to transduce highly interconnected CNS regions such as the brainstem and thalamus. On the basis of our data showing global cortical expression of a secreted reporter after thalamic delivery in nonhuman primates (NHPs), we set out to investigate whether such widespread expression could be enhanced after brainstem infusion. To maximize delivery of the therapeutic transgene throughout the CNS, we combined a single brainstem infusion with bilateral thalamic infusions in naive NHPs. We found that enzymatic augmentation in brainstem, thalamic, cortical, as well subcortical areas provided convincing evidence that much of the large NHP brain can be transduced with as few as three injection sites.

Ionic dysregulations typical of ischemia provoke release of glycine and GABA by multiple mechanisms

Energy deprivation during ischemia causes dysregulations of ions, particularly sodium, potassium and calcium. Under these conditions, release of neurotransmitters is often enhanced and can occur by multiple mechanisms. The aim of this work was to characterize the modes of exit of glycine and GABA from nerve endings exposed to stimuli known to reproduce some of the ionic changes typical of ischemic conditions. Their approach was chosen instead of application of ischemic conditions because the release evoked during ischemia is mechanistically too heterogeneous. Mouse hippocampus and spinal cord synaptosomes, pre-labeled with [(3)H]glycine or [(3)H]GABA, were exposed in superfusion to 50 mM KCl or to 10 microM veratridine. The evoked overflows differed greatly between the two transmitters and between the two regions examined. Significant portions of the K(+)- and the veratridine-evoked overflows occurred by classical exocytosis. Carrier-mediated release of GABA, but not of glycine, was evoked by high K(+); GABA and, less so, glycine were released through transporter reversal by veratridine. External calcium-dependent overflows were only in part sensitive to omega-conotoxins; significant portions occurred following reversal of the plasmalemmal Na(+)/Ca(2+) exchanger. Finally, a relevant contribution to the overall transmitter overflows came from cytosolic calcium originating through the mitochondrial Na(+)/Ca(2+) exchanger. To conclude, ionic dysregulations typical of ischemia cause neurotransmitter release by heterogeneous mechanisms that differ depending on the transmitters and the CNS regions examined.

Sex‐dimorphic changes in neuroactive steroid levels after chronic experimental autoimmune encephalomyelitis

Our previous observations have shown that neuroactive steroid levels in the brain are affected by acute experimental autoimmune encephalomyelitis (EAE) with sex and regional specificity (Giatti et al. 2010). To better understand the effect of EAE on neuroactive steroids, we have here assessed the levels of pregnenolone, progesterone and its derivatives (i.e. dihydroprogesterone, tetrahydroprogesterone and isopregnanolone), testosterone and its derivatives (dihydrotestosterone and 5alpha-androstane-3alpha, 17beta-diol) in different CNS regions of male and female rats affected by chronic EAE. Data obtained by liquid chromatography tandem mass spectrometry revealed that chronic EAE results in sex and regional specific alterations in the levels of neuroactive steroids in the brain, which are in many cases different to those produced by acute EAE. The specific changes in neuroactive steroid levels after chronic EAE may be of relevance to design new possible therapeutic strategies for the disease.

A model-based framework for the analysis of miniature post-synaptic currents

Miniature post-synaptic currents (mPSCs) have become a primary measure of synaptic modification during development, plasticity, and disease. ‘Minis’ represent the response of postsynaptic receptors to the spontaneous fusion of vesicles. They are a useful assay for the number and strength of synaptic connections, as mini event frequency is related to the number of functional release sites, and event amplitude is a measure of synapse strength [1]. Thus, accurate characterization of synapse dynamics relies critically on statistical analyses of event frequency and amplitude. We develop a new paradigm for mPSC analysis that uses likelihood methods [2] and formal goodness-of-fit assessments [3] to derive accurate statistical descriptions of their frequency and amplitude properties. In particular, we demonstrate that mPSC inter-event intervals and amplitudes within individual cells are well described by exponential and log-normal models. These characterizations allow us to analyze mPSCs at the single-cell level. We employ a parametric bootstrap based on these models to make accurate assessments of uncertainty within and between groups in the setting of small samples. This enables accurate estimation of responses for individual cells or groups, and paired comparisons of beforeand after- manipulations in single cells. We illustrate this approach in the analysis of excitatory mPSCs from acute slices of sensory midbrain. We show that the method may be broadly applicable to excitatory and inhibitory PSCs in other CNS regions, and is robust to changes in event selection parameters and recording conditions. Our method preserves information about the variability of events within individual cells and allows the summary of information across cells in order to make between-group comparisons. The use of an accurate model maximizes the efficiency of the resulting statistics, by taking advantage of the high degree of structure in the data. The framework allows accurate inferences to be made from studies of spontaneous activity, and for the first time extends analysis of synaptic function to the single cell level.

Regional differences in nerve terminal Na+ channel subtype expression and Na+ channel‐dependent glutamate and GABA release in rat CNS

We tested the hypothesis that expression of pre-synaptic voltage-gated sodium channel (Na(v)) subtypes coupled to neurotransmitter release differs between transmitter types and CNS regions in a nerve terminal-specific manner. Na(v) coupling to transmitter release was determined by measuring the sensitivity of 4-aminopyridine (4AP)-evoked [(3)H]glutamate and [(14)C]GABA release to the specific Na(v) blocker tetrodotoxin (TTX) for nerve terminals isolated from rat cerebral cortex, hippocampus, striatum and spinal cord. Expression of various Na(v) subtypes was measured by immunoblotting using subtype-specific antibodies. Potencies of TTX for inhibition of glutamate and GABA release varied between CNS regions. However, the efficacies of TTX for inhibition of 4AP-evoked glutamate release were greater than for inhibition of GABA release in all regions except spinal cord. The relative nerve terminal expression of total Na(v) subtypes as well as of specific subtypes varied considerably between CNS regions. The region-specific potencies of TTX for inhibition of 4AP-evoked glutamate release correlated with greater relative expression of total nerve terminal Na(v) and Na(v)1.2. Nerve terminal-specific differences in the expression of specific Na(v) subtypes contribute to transmitter-specific and regional differences in pharmacological sensitivities of transmitter release.

Transcriptome profiling analysis reveals region‐distinctive changes of gene expression in the CNS in response to different moderate restraint stress

It is generally believed that temporary moderate stress to a living organism has protective and adaptive effects, but little is known about the responses of CNS to the moderate stresses at molecular level. This study aims to investigate the gene expression changes induced by moderate stress in CNS stress- and nociception-related regions of rats. Moderate restraint was applied to rats for 50 min and cDNA microarrays were used to detect the differential gene expression in different CNS regions. Transcriptome profiling analysis showed that at acute stage stress-related genes were up-regulated in arcuate nucleus; fight-or-flight behavior-related genes were up-regulated in periaqueductal gray, while nitric oxide and GABA signal transmission-related genes were up-regulated in spinal dorsal horn. In addition, immune-related genes were broadly regulated, especially at the late stage. These results suggested that specific genes of certain gene ontology categories were spatiotemporally regulated in specific CNS regions related to relevant functions under moderate external stimuli at acute stage, while immune response was broadly regulated at the late stage. The co-regulated genes among the three different CNS regions may play general roles in CNS when exposed to moderate stress. Furthermore, these results will help to elucidate the physiological processes involved in moderate stress in CNS.

Prevention of apnea-induced apoptosis in NREM- and REM-generating nuclei of adult guinea pigs

The present study was designed to investigate the effects of recurrent periods of apnea/hypoxia on the morphology of neurons in sites that control NREM and REM sleep. In addition, we determined whether the administration of a GABA agonist, eszopiclone, was capable of preventing the degenerative, i.e., apoptotic, sequelae of hypoxia in these sleep-promoting neurons. Adult guinea pigs were divided into control (normoxic) and hypoxic groups; a separate group of hypoxic animals was administered eszopiclone. Recurrent periods of hypoxia and normoxia lasted for a duration of 3 h. Subsequently, the brains were sectioned, and areas in the CNS that control NREM sleep as well as REM sleep were examined after staining with an antibody raised against single-stranded DNA, which labels apoptotic neurons. In the group of control (normoxic) animals, apoptotic neurons were not observed in CNS regions that control NREM or REM sleep. In hypoxic animals, a large number of apoptotic neurons were found in the preceding regions. In the hypoxic animals that were administered eszopiclone, there were almost no apoptotic neurons in the brain regions that control NREM or REM sleep. These results demonstrate that recurrent periods of apnea induce extensive apoptosis in CNS nuclei that control NREM and REM sleep and that eszopiclone is capable of preventing neuronal degeneration in these sites. We suggest that the degeneration of neurons in sites that control the states of sleep is responsible for those sleep disturbances that arise as a consequence of hypoxia in individuals with sleep-related breathing disorders.