Protective effects of hydroxy-α-sanshool from the pericarp of Zanthoxylum bungeanum Maxim. On D-galactose/AlCl3-induced Alzheimer's disease-like mice via Nrf2/HO-1 signaling pathways.

Hydroxy-α-sanshool (HAS) is an unsaturated fatty acid amide from Zanthoxylum bungeanum Maxim. with hypolipidemic, hypoglycemic, anti-inflammatory, and neurotrophic effects, etc. In this study, results indicated that HAS effectively ameliorated spontaneous locomotion deficit of mice induced by D-galactose (D-gal) and AlCl3 treatment in open field test. Results of Morris water maze test (MWM) showed that HAS significantly improved the spatial learning and memory ability of aging mice. Histopathological evaluations revealed that HAS markedly alleviated morphological changes and increased number of Nissl neurons in hippocampus of D-gal/AlCl3-induced Alzheimer's disease (AD)-like mice. HAS markedly reduced malondialdehyde (MDA) production, and increased the activity of antioxidative enzymes including superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT), showing an inhibitory effect on oxidative stress. Furthermore, HAS treatment obviously reversed the inhibitory expressions of mRNA and protein of HO-1 and Nrf2 in the hippocampus of AD mice, suggesting that neuroprotective effects of HAS against oxidative stress might be mediated by the Nrf2/HO-1 pathway. Meanwhile, HAS significantly inhibited neuronal apoptosis by decreasing mRNA and protein expressions of Cyt-c, Bax and Caspase 3, and increasing Bcl-2 expression in the hippocampus of AD mice. These results suggest that HAS have the potential to be developed as antioxidant drug for the prevention and early therapy of AD.

Endoplasmic Reticulum Stress Is Associated with the Mesencephalic Dopaminergic Neuron Injury in Stressed Rats.

An increasing number of people are in a state of stress due to social and psychological pressures, which may result in mental disorders. Previous studies indicated that mesencephalic dopaminergic neurons are associated with not only reward-related behaviors but also with stress-induced mental disorders. To explore the effect of stress on dopaminergic neuron and potential mechanism, we established stressed rat models of different time durations and observed pathological changes in dopaminergic neurons of the ventral tegmental area (VTA) through HE and thionine staining. Immunohistochemistry coupled with microscopy-based multicolor tissue cytometry (MMTC) was employed to investigate the number changes of dopaminergic neurons. Double immunofluorescence labelling was used to investigate expression changes of endoplasmic reticulum stress (ERS) protein GRP78 and CHOP in dopaminergic neurons. Our results showed that prolonged stress led to pathological alteration in dopaminergic neurons of VTA, such as missing of Nissl bodies and pyknosis in dopaminergic neurons. Immunohistochemistry with MMTC indicated that chronic stress exposure resulted in a significant decrease in dopaminergic neurons. Double immunofluorescence labelling showed that the endoplasmic reticulum stress protein took part in the injury of dopaminergic neurons. Taken together, these results indicated the involvement of ERS in mesencephalic dopaminergic neuron injury induced by stress exposure.

Role of melatonin in the dynamics of acute spinal cord injury in rats.

Melatonin is well-documented to have the ability of reducing nerve inflammation and scavenging free radicals. However, the therapeutic effect of melatonin on spinal cord injury has not been fully described. In this study, we assessed the effect of melatonin on T9 spinal cord injury established by Allen method in rats. Melatonin deficiency significantly delayed the recovery of sensory and motor functions in SCI rats. Treatment with melatonin significantly alleviated neuronal apoptosis and accelerated the recovery of spinal cord function. These results suggest that melatonin is effective to ameliorate spinal cord injury through inhibition of neuronal apoptosis and promotion of neuronal repair.

Time-Dependent Memory and Gait Improvement by Intranasally-Administered Extracellular Vesicles in Parkinson's Disease Model Rats.

We have recently demonstrated that extracellular vesicles (EVs) derived from the human teeth stem cells improve motor symptoms and normalize tyrosine hydroxylase (TH) expression in the nigrostriatal structures of Parkinson's disease (PD) model rats obtained by 6-hydroxydopamine (6-OHDA) unilateral injection into the medial forebrain bundle (MFB). The aim of this study was to clarify: (1) how long therapeutic effects persist after discontinuation of 17-day intranasal administration of EVs in 6-OHDA rats; (2) may EVs reverse cognitive (learning/memory) dysfunction in these PD model rats; (3) whether and how the behavioral improvement may be related to the expression of TH and Nissl bodies count in the nigrostriatal structures. Our results demonstrated that in 6-OHDA rats, gait was normalized even ten days after discontinuation of EVs administration. EVs successfully reversed 6-OHDA-induced impairment in spatial learning/memory performance; however, the beneficial effect was shorter (up to post-treatment day 6) than that revealed for gait improvement. The shorter effect of EVs coincided with both full normalization of TH expression and Nissl bodies count in the nigrostriatal structures, while slight but significant increase in the 6-OHDA-decreased Nissl count persisted in the substantia nigra even on the post-treatment day 20, supposedly due to the continuation of protein synthesis in the living cells. The obtained data indicate the usefulness of further studies to find the optimal administration regimen which could be translated into clinical trials on PD patients, as well as to clarify other-apart from dopaminergic-neuromodulatory pathways involved in the EVs mechanism of action.

The Human and Mouse Enteric Nervous System at Single-Cell Resolution.

The enteric nervous system (ENS) coordinates diverse functions in the intestine but has eluded comprehensive molecular characterization because of the rarity and diversity of cells. Here we develop two methods to profile the ENS of adult mice and humans at single-cell resolution: RAISIN RNA-seq for profiling intact nuclei with ribosome-bound mRNA and MIRACL-seq for label-free enrichment of rare cell types by droplet-based profiling. The 1,187,535 nuclei in our mouse atlas include 5,068 neurons from the ileum and colon, revealing extraordinary neuron diversity. We highlight circadian expression changes in enteric neurons, show that disease-related genes are dysregulated with aging, and identify differences between the ileum and proximal/distal colon. In humans, we profile 436,202 nuclei, recovering 1,445 neurons, and identify conserved and species-specific transcriptional programs and putative neuro-epithelial, neuro-stromal, and neuro-immune interactions. The human ENS expresses risk genes for neuropathic, inflammatory, and extra-intestinal diseases, suggesting neuronal contributions to disease.

Cortex Mori Radicis extract promotes neurite outgrowth in diabetic rats by activating PI3K/AKT signaling and inhibiting Ca2+ influx associated with the upregulation of transient receptor potential canonical channel 1.

Cortex Mori Radicis extract (CMR) has various pharmacological properties, such as anti­inflammatory, anti­allergic and anti­hyperglycemic effects. However, the effects and mechanisms of CMR in the neuroregeneration of diabetic peripheral neuropathy (DPN) are unclear. In the present study, the effects of CMR on neurite outgrowth of dorsal root ganglia (DRG) neurons in diabetic rats were investigated and its underlying mechanisms were explored. SD rats were subjected to a high­fat diet with low­dose streptozotocin to induce a Type II diabetes model with peripheral neuropathy. CMR was then applied for four weeks continuously with or without injection of small interfere (si)RNA targeting the transient receptor potential canonical channel 1 (TRPC1) via the tail vein. Blood glucose levels, the number of Nissl bodies, neurite outgrowth and growth cone turning in DRG neurons were evaluated. The expression of TRPC1 protein, Ca2+ influx and activation of the PI3K/AKT signaling pathway were also investigated. The results of the present study showed that CMR significantly lowered blood glucose levels, reversed the loss of Nissl bodies, induced neurite outgrowth and restored the response of the growth cone of DRG neurons in diabetic rats. CMR exerted neurite outgrowth­promoting effects by increasing TRPC1 expression, reducing Ca2+ influx and enhancing AKT phosphorylation. siRNA targeting TRPC1 in the CMR group abrogated its anti­diabetic and neuroregenerative effects, suggesting the involvement of TRPC1 in the biological effects of CMR on DPN.

Activation of the MAPK signaling pathway induces upregulation of pro-apoptotic proteins in the hippocampi of cold stressed adolescent mice.

Stress induces many non-specific responses in the hippocampus, especially during adolescence. Low environmental temperature is known to induce stress, but its influence on the hippocampus, especially in adolescent mice is not clear. We compared apoptotic-related protein levels and MAPK signaling pathway activation in hippocampal neurons of adolescent mice under low temperature conditions (4 °C for 12 h) with western blotting and immunohistochemistry. Western bolt results demonstrated that the levels of phospho-JNK, phospho-p38, and cleaved-caspase 3 significantly increased, while the ratio of Bcl-XL/Bax decreased, in the cold stress group. The results of immunohistochemistry (IHC) and Nissl staining demonstrated that the protein optical density of caspase 3 increased and Nissl bodies decreased in the cold stress group compared with controls. Thus, we conclude that cold exposure initiates activation of the MAPK signaling pathway and subsequently induces the upregulation of pro-apoptotic proteins in the hippocampi of adolescent mice. Overall our study reveals the relationship between cold stress and apoptosis in adolescent mice.

Dendrobium officinale polysaccharides attenuate learning and memory disabilities via anti-oxidant and anti-inflammatory actions.

The aim of this study was to explore the therapeutic effect and underling mechanism of Dendrobium officinale polysaccharides (DOPS) on two well-established animal models of learning and memory disabilities. Model of estrogen deficiency caused learning and memory disability can be induced by ovariectomy in mice, and mice were injected subcutaneously with d-galactose, which can also cause cognitive decline. H&E staining and Nissl staining were employed to confirm the protective effect of DOPS on hippocampal neuron. Morris water maze test, biochemical analysis, immunohistochemistry and immunofluorescence assay were used to study the effect and underlying mechanism of DOPS on two different learning and memory impairment models. Administration of DOPS significantly improved learning and memory disability in both models. Further studies showed that DOPS could attenuate oxidative stress and reduce neuro-inflammation via up-regulating expressions of Nrf2/HO-1 pathway and inhibiting activation of astrocytes and microglia in ovariectomy- and d-galactose-induced cognitive decline. These findings suggest that DOPS have an appreciable therapeutic effect on learning and memory disabilities and its mechanism may be related to activate Nrf2/HO-1 pathway to reduce oxidative stress and neuro-inflammation.

Corilagin Reduces the Frequency of Seizures and Improves Cognitive Function in a Rat Model of Chronic Epilepsy.

BACKGROUND Worldwide, epilepsy is an important chronic neurological condition. The aim of this study was to evaluate the effects of corilagin, an ellagitannin extracted from medicinal plants, on the frequency of seizures and cognitive function in a rat model of chronic epilepsy. MATERIAL AND METHODS Chronic epilepsy was induced in male Wistar rats by intraperitoneal (IP) injection of pentylenetetrazol (PTZ) for 36 days. Corilagin, 10 mg/kg and 20 mg/kg, was injected IP into treated rats, 24 days before the start of PTZ treatment, until the end of the protocol. The effects of corilagin were assessed by the pattern of epileptic seizures; cognitive function was assessed using the Morris water maze (MWM) navigation test. The mechanism of action of corilagin was investigated by measuring cytokine levels and oxidative stress parameters, including reactive oxygen species (ROS) production, and carbonic anhydrase inhibitory (CAI) activity. Histological analysis of fixed brain tissue sections included cresyl violet acetate staining (Nissl staining) for Nissl substance in the neuronal cytoplasm. RESULTS The corilagin-treated rats, compared with the control group, showed a significantly lower rate of epileptic events, improved cognitive function, reduced level of cytokines, reduced ROS production reduced CAI activity in the brain tissues (P<0.01). Histology of the rat brain tissues study showed that corilagin treatment maintained the neuronal cellular structure and number of surviving cells compared with the control group of rats. CONCLUSIONS The findings of this study showed that corilagin reduced the frequency of seizures and improved the cognitive function in a rat model of chronic epilepsy.

Pathophysiological changes in the cerebellum and brain stem in a rabbit model after superior petrosal vein sacrifice.

In certain surgical procedures, sacrificing the superior petrosal vein (SPV) is required. Previous studies have reported transient cerebellar edema, venous infarction, or hemorrhage that might occur after sectioning of the SPV. The present study investigated the pathophysiological changes in cerebellum and brain stem after SPV sacrifice. Rabbits were divided into the operation group where the SPV was sacrificed and the control group where the SPV remained intact. Each group was further subdivided into 4, 8, 12, 24, 48, and 72 h groups which represented the time period from sacrificing of the SPV to killing of the rabbits. The water content (WC), Na+ content, K+ content, and pathophysiological changes in cerebellum and brain stem tissue were measured. In comparison with the control, the WC and Na+ content of cerebellar tissue were increased in the 4, 8, 12, and 24 h operation subgroups (P<0.05), but only increased in the 4-h subgroup of the brain stem tissue (P<0.05). The K+ content of the cerebellar tissue decreased in the 4, 8, 12, and 24 h operation subgroups (P<0.05) but only decreased in the 4-h subgroup of brain stem tissue (P<0.05). Nissl staining and TEM demonstrated that cerebellar edema occurred in the 4, 8, 12, and 24 h operation subgroups but not in the 48- and 72-h subgroups. Brain stem edema occurred in the 4-h operation subgroup. In summary, cerebellum and brain stem edema can be observed at different time points after sacrificing of the SPV in the rabbit model.

Neuroprotective effect of G14-humanin on global cerebral ischemia/reperfusion by activation of SOCS3 - STAT3 - MCL-1 signal transduction pathway in rats.

OBJECTIVE: Humanin (HN) has been identified to suppress neuron death. Gly14-HN (HNG), as a variant of HN, can decrease infarct volume after ischemia/reperfusion (I/R) injury. This study aimed to investigate the neuroprotective mechanism of HNG on global cerebral I/R (GI) in rats. METHODS: Rats were randomly divided into 13 groups: Sham group, GI groups and HNG groups. Both GI group and HNG groups included six time points (1, 3, 6, 12, 24, and 72 h). At 24 h after reperfusion, Nissl staining was used to observe positive neurons, and p-STAT3, MCL-1, SOCS3, Bax and Caspase-3 in different groups were detected by immunohistochemistry. qRT-PCR and western blot were used to evaluate the expression of STAT3, p-STAT3, MCL-1, and SOCS3. RESULTS: The immunohistochemistry also showed a significant increase in Bax (0.29 ± 0.007 vs. 0.22 ± 0.007, P < 0.01) and Caspase-3 (0.24 ± 0.02 vs. 0.18 ± 0.006, P < 0.01) in GI group compared with Sham group, while Bax (0.26 ± 0.01 vs. 0.29 ± 0.008, P < 0.01) and Caspase-3 (0.20 ± 0.008 vs. 0.24 ± 0.02, P < 0.01) were significantly decreased by HNG-treatment compared with GI group. Along with immunohistochemistry, western blot and qRT-PCR indicated that the protein and mRNA levels of STAT3, MCL-1, and SOCS3 were up-regulated after administration of HNG at six time points after global cerebral I/R in rat. CONCLUSION: HNG might exert neuroprotective effects through alleviating apoptosis and activating of SOCS3 - STAT3 - MCL-1 signal transduction pathway. Highlights (1) Cerebral ischemia led to neuronal loss in hippocampal CA1 region of rats. (2) HNG had neuroprotective effects on ischemia/reperfusion rats. (3) The protective effect of HNG might be related to the SOCS3 - STAT3 - MCL-1 pathway.

Upregulation effects of Tanshinone IIA on the expressions of NeuN, Nissl body, and IκB and downregulation effects on the expressions of GFAP and NF-κB in the brain tissues of rat models of Alzheimer's disease.

This study aimed to observe the effects of Tanshinone IIA(Tan IIA) treatment on the expression levels of brain tissue NeuN, Nissl body, IκB, GFAP and NF-κB in Alzheimer's disease (AD) rats to explore the possible anti-inflammatory and neuroprotective mechanisms of Tan IIA. Thirty healthy male Sprague-Dawley rats were randomized into three groups: Sham group, AD+vehicle control group, and AD+Tan IIA group. The models of AD were established by injecting Aß1-42 into the hippocampus of rats. Tagged position and the expression levels of Aß1-42 were observed by immunohistochemistry staining to prove the success of the model of AD. Brain tissues of all groups were collected after Tan IIA treatment and paraffin sections were prepared to assess pathological changes and expression levels of GFAP, IκB and NF-κB by both immunohistochemistry and western blotting. After Aß1-42 injection, the expression levels of GFAP and NF-κB were significantly stronger in the AD+vehicle control group than those in the AD+Tan IIA group and the sham group (P<0.05), the IκB expression level and the number of neurons and Nissl bodies of AD+vehicle control group was reduced compared with the sham or the AD+Tan IIA group (P<0.05). In conclusion, Aß induces a cerebral tissue inflammation reaction. Tan IIA treatment can suppress the proliferation of astrocytes in an AD model, lower the level of NF-κB, and increase the level of NeuN, Nissl body, IκB, thus exerting anti-inflammatory and neuroprotective effects.

Subcortical barrelette-like and barreloid-like structures in the prosimian galago (Otolemur garnetti).

Galagos are prosimian primates that resemble ancestral primates more than most other extant primates. As in many other mammals, the facial vibrissae of galagos are distributed across the upper and lower jaws and above the eye. In rats and mice, the mystacial macrovibrissae are represented throughout the ascending trigeminal pathways as arrays of cytoarchitecturally distinct modules, with each module having a nearly one-to-one relationship with a specific facial whisker. The macrovibrissal representations are termed barrelettes in the trigeminal somatosensory brainstem, barreloids in the ventroposterior medial subnucleus of the thalamus, and barrels in primary somatosensory cortex. Despite the presence of facial whiskers in all nonhuman primates, barrel-like structures have not been reported in primates. By staining for cytochrome oxidase, Nissl, and vesicular glutamate transporter proteins, we show a distinct array of barrelette-like and barreloid-like modules in the principal sensory nucleus, the spinal trigeminal nucleus, and the ventroposterior medial subnucleus of the galago, Otolemur garnetti. Labeled terminals of primary sensory neurons in the brainstem and cell bodies of thalamocortically projecting neurons demonstrate that barrelette-like and barreloid-like modules are located in areas of these somatosensory nuclei that are topographically consistent with their role in facial touch. Serendipitously, the plane of section that best displays the barreloid-like modules reveals a remarkably distinct homunculus-like patterning which, we believe, is one of the clearest somatotopic maps of an entire body surface yet found.

Non-invasive remote limb ischemic postconditioning protects rats against focal cerebral ischemia by upregulating STAT3 and reducing apoptosis.

The signal transducer and activator of transcription 3 (STAT3) signaling pathway has been implicated in cell apoptosis and inflammatory processes. Ischemic preconditioning (IPC) and ischemic postconditioning (IPTC) inhibit both of these processes. In the present study, we investigated the role of phosphorylated STAT3 (p-STAT3)-mediated apoptosis and inflammation following non-invasive remote limb IPTC (NRIPoC) using a classic rat model of focal cerebral ischemia. Forty-five adult male Sprague-Dawley rats were divided randomly into 3 groups (n=15 per group): the sham-operated, ischemia/reperfusion (I/R) and NRIPoC groups. NRIPoC was implemented at the beginning of reperfusion. At 24 h after cerebral reperfusion, we evaluated the neurological deficit score (NDS), assessed the cerebral infarct size and tissue morphology, and evaluated neuronal apoptosis. The protein expression levels of Bcl-2, Bax, nuclear factor-κB (NF-κB), tumor necrosis factor-α (TNF-α) and p-STAT3 in the penumbra region were assessed by western blot analysis. The cerebral infarct volume, the number of apoptotic cells and the protein expression levels of Bcl-2, Bax, NF-κB and TNF-α were all found to be increased in the I/R group compared with the sham-operated group. However, these levels were decreased in the NRIPoC group compared with the I/R group. The number of apoptotic cells in the penumbra in the I/R group was increased compared with that in the NRIPoC and sham-operated groups. The protein expression of p-STAT3 was increased in the NRIPoC group compared with the sham-operated and I/R groups. These results indicate that the protective effects of NRIPoC against cerebral I/R injury may be related to the attenuation of neuronal apoptosis and inflammation through the activation of STAT3.

Rat cortex and hippocampus-derived soluble factors for the induction of adipose-derived mesenchymal stem cells into neuron-like cells.

To simulate brain microenvironment, adipose-derived mesenchymal stem cells (AMSC) were induced to differentiate to neuronal-like cells in rat cortex and hippocampus medium (Cox + Hip). First, isolated AMSC were characterized by flow cytometer and the capacity of adipogenesis and osteogenesis. After induction in rat cortex and hippocampus conditioned medium, the cell morphological change was examined and neural marker proteins (ß-Ш-Tubulin, NSE, Nissl body) expression was detected by immunofluorescence staining. A variety of synaptic marker proteins, including GAP43, SHANK2, SHANK3 and Bassoon body, were detected. ELISA was used to measure brain derived neurotrophic factor (BDNF) and nerve growth factor (NGF) secretion at different time-points. AMSCs positively expressed CD13, CD44 and CD90 and could differentiate into osteoblasts or adipocytes. After induction in Cox + Hip medium for 14 days, cells had a typical neuronal perikaryal appearance, which was suggestive of neuronal differentiation. After 14 days of Cox + Hip treatment, the percentage of cells expressing ß-Ⅲ-Tubulin, NSE and Nissl was 53.9 ± 0.8%, 51.3 ± 1.7% and 16.4 ± 2.1%, respectively. Expression of GAP43, SHANK2, SHANK3 and Bassoon body was detected, indicating synapse formation after treatment in Cox + Hip medium. Differentiated AMSCs secreted neurotrophic factors NGF and BDNF. Thus rat cortex and hippocampus-derived soluble factors can induce AMSCs to a neuronal-like phenotype, suggesting that AMSCs have a dual role in supplementing newborn neurons and secreting neurotrophic factors, and therefore could be help as a potential treatment for nervous system diseases.

Effects of lanthanum chloride on glutamate level, intracellular calcium concentration and caspases expression in the rat hippocampus.

Lanthanum chloride (LaCl(3)) can affect neurobehavioral development and impair cognitive abilities. The mechanism underlying LaCl(3)-induced neurotoxic effects is still unknown. The purpose of this research was to investigate the neuronal impairment induced by LaCl(3) and discuss the possible mechanism from the aspects of the alteration of glutamate level, intracellular calcium concentration ([Ca(2+)](i)), Bax, Bcl-2 and caspases expression in the hippocampus. Lactational rats were exposed to 0, 0.25, 0.50 and 1.0 % LaCl(3) in drinking water, respectively. Their offspring were exposed to LaCl(3) by parental lactation and then administrated with 0, 0.25, 0.50 and 1.0 % LaCl(3) in drinking water for 1 month. The results showed that 0.25, 0.50 and 1.0 % LaCl(3) exposure induced neuronal impairment in the hippocampus of young rat. Hippocampal glutamate level, [Ca(2+)](i) and ratio of Bax and Bcl-2 expression increased significantly after LaCl(3) exposure. Besides, LaCl(3) exposure increased GRP78, GRP94, GADD153 and p-JNK expression, promoted the activation of caspase-3, caspase-9 and caspase-12, induced PARP cleavage and caused excessive apoptosis. These results indicate that LaCl(3) increases glutamate level, [Ca(2+)](i) and ratio of Bax and Bcl-2 expression, which cause excessive apoptosis by the mitochondrial and endoplasmic reticulum stress-induced pathway, and thus neuronal damages in the hippocampus.

[Characteristic of serotoninergic neurons of medullary nucleus raphe obscurus in norm and in serotoninergic system deficiency during the prenatal period of development in rats].

Morphological characteristics of the serotoninergic neurons forming nucleus raphe obscurus (NRO), were studied in rats at the early stages (days 5, 10, 12 and 14) of the postnatal period in normal rats and in animals whose prenatal development took place under the conditions of serotonin deficiency. NRO was found to contain three subpopulations serotonin-producing neurons (large, medium and small), which had different sensitivity to serotonin level during development. The results have shown that serotoninergic system deficiency during the prenatal period resulted in the changes of NRO structural organization and in the decrease of the rate of this nucleus formation, serotonin-producing neurons differentiation and the reduction of their total number by approximately a factor of 1.6. At the same time, the significant changes of the dimensions of serotoninergic neurons of all types took place. In control animals, the size of large, medium and small neurons was 1.8, 1.4 and 1.5 times greater than that in experimental animals, respectively. Reduction of the neuron dimensions was associated with the changes of a nucleo-cytoplasmic ratio. The volume of the cytoplasm and of Nissl bodies was significantly decreased. Along with it, the cell destruction was noted that increased with age. Synchronously with it, the marked astrocytic reaction developed, which could further lead to gliosis.

Neurons of the dentate molecular layer in the rabbit hippocampus.

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.

[Participation of serotonin in the mechanisms of the formation of trigeminal motor nucleus].

The formation of trigeminal motor nucleus (TMN) was studied in the early postnatal period in 21 female Wistar rats which received the serotonin biosynthesis inhibitor para-chloro-phenylalanine at prenatal Day 16 (the period of serotoninergic system formation). It was shown that the serotonin deficit during the prenatal period in rats resulted in the changes of TMN structural organization. In the early postnatal period, the delay of neuropil development, the reduction of cell body size with the partial loss of Nissl substance in some of the neurons, the presence of degenerating neurons with the signs of hyperchromatosis in all the parts of the nucleus, especially in TMN ventromedial part, were detected. At later stages, the destruction of motoneurons became slower, though some of them had morphological abnormalities. With the increase of the postnatal age (by Day 20) the number of motor neurons decreased, apparently, as a result of the gradual intensification of cell death. Simultaneously with the motor neuron degeneration in TMN parts studied, the astrocytic gliosis was observed.

Neuroprotective effect of exogenous melatonin on dopaminergic neurons of the substantia nigra in ovariectomized rats.

BACKGROUND: Melatonin has receptors in substantia nigra pars compacta (SNc) and regulates development of dopaminergic (DA) neurons. This study was undertaken to determine ability of melatonin to protect SNc dopaminergic neuron loss induced by estrogen deficiency in ovariectomized rats. METHODS: Female rats were randomized into four groups of seven each: control, ethanol sham, ovariectomy (ovx) and ovx with melatonin (ovx + m). In ovx, ovaries were removed. Ovx + m group was intraperitoneally injected with melatonin for 10 days, while the ethanol sham group received only ethanol. All rats were perfused with 4% paraformaldehyde, midbrains removed, fixed and paraffin embedded, then processed for Nissl and tyrosine hydroxylase staining (IHC). Ten sections of SNc in Nissl and IHC staining were analyzed in each animal, Nissl stained and tyrosine hydroxylase (TH) immunoreactive cells were counted in five experimental groups randomly. Data was analyzed using SPSS by ANOVA and t-test. Differences were considered significant for P<0.05. RESULTS: There was less cell number in ovx compared to control and ethanol sham groups significantly (P<0.001). The ovx + m group had more cells than the ovx group in the SNc significantly (P<0.001). Furthermore, there was significant decrease of TH positive cell number in the ovx group compared to control and ethanol sham groups (P<0.05). The number of TH immunoreactive cells was higher in ovx + m compared to the ovx group (P<0.05). CONCLUSION: These findings can be compared with human and used in clinical application for prevention of DA neuron death of SNc after ovariectomy.