An experimental study of tangzhouling on morphological changes of nissl bodies in the dorsal root ganglion of DM rats / Un estudio experimental de tangzhouling sobre los cambios morfológicos de los cuerpos de nissl en el ganglio de la raíz dorsal de ratas DM

SUMMARY: This study aims to investigate the effect of Tangzhouling on the morphological changes of Nissl bodies in the dorsal root ganglion of DM Rats. In this study, 69 rats were randomly divided into a control group (n = 10) and a model group (n = 59). The rats in the model group were randomly divided into a diabetic group (n = 11), a vitamin C group (n = 12), a low dose Tangzhouling group (n = 12), a medium dose Tangzhouling group (n = 12) and a high dose Tangzhouling group (n = 12). The dose of Tangzhouling in the low dose group was 5 times that of the adult dose, being 0.44g/kg/d. The dose of Tangzhouling in the medium dose group was 10 times that of the adult dose, being 0.88g/kg/d. The dose of Tangzhouling in the high dose group was 20 times that of the adult dose, being 1.75g/kg/d. All doses above are crude drug dosages. Rats in the vitamin C group were given 10 times the dose of an adult, being, 0.05 g/ kg/d. The diabetic group and the control group were given the same amount of distilled water. Drug delivery time is 16 weeks. The dorsal root ganglion was placed in a freezing tube at the end of the experiment. The morphological changes of Nissl bodies in the dorsal root ganglion were detected by HE and Nissl staining. The study results showed that vitamin C had no significant effect on the quantity, size and nucleolus. Tangzhouling can improvee the morphology, quantity and nucleolus of Nissl bodies to a certain extent, and the high dose is better than the lower dose. Tangzhouling capsules can improve the nerve function of DM rats through Nissl bodies.

RESUMEN: Este estudio tuvo como objetivo investigar el efecto de Tangzhouling en los cambios morfológicos de los cuerpos de Nissl en el ganglio de la raíz dorsal de las ratas DM. En este estudio, 69 ratas se dividieron aleatoriamente en un grupo control (n = 10) y un grupo modelo (n = 59). Las ratas del grupo modelo se dividieron aleatoriamente en un grupo diabéticos (n = 11), un grupo vitamina C (n = 12), un grupo de dosis baja de Tangzhouling (n = 12), un grupo de dosis media de Tangzhouling (n = 12) y un grupo de dosis alta de Tangzhouling (n = 12). La dosis de Tangzhouling en el grupo de dosis baja fue 5 veces mayor que la dosis del adulto, siendo 0,44 g/kg/d. La dosis de Tangzhouling en el grupo de dosis media fue 10 veces mayor que la dosis del adulto, siendo 0,88 g/kg/d. La dosis de Tangzhouling en el grupo de dosis alta fue 20 veces mayor que la dosis del adulto, siendo 1,75 g/kg/d. Todas las dosis anteriores son dosis de fármaco crudo. Se les administró 10 veces la dosis de un adulto a las ratas del grupo vitamina C, siendo 0,05 g/kg/d. El grupo de diabéticos y el grupo de control recibieron la misma cantidad de agua destilada. El tiempo de entrega del fármaco fue de 16 semanas. El ganglio de la raíz dorsal se colocó en un tubo de congelación al final del experimento. Los cambios morfológicos de los cuerpos de Nissl en el ganglio de la raíz dorsal se detectaron mediante tinción de HE y Nissl. Los resultados del estudio mostraron que la vitamina C no tuvo un efecto significativo sobre la cantidad, el tamaño y el nucléolo. Tangzhouling puede mejorar la morfología, la cantidad y el nucléolo de los cuerpos de Nissl hasta cierto punto, y es mejor la dosis alta que la dosis baja. Las cápsulas de Tangzhouling pueden mejorar la función nerviosa de las ratas DM a través de los cuerpos de Nissl.

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.

Silver Nanoparticles Conjugate Attenuates Highly Active Antiretroviral Therapy-Induced Hippocampal Nissl Substance and Cognitive Deficits in Diabetic Rats.

BACKGROUND: The application of nanomedicine to antiretroviral drug delivery holds promise in reducing the comorbidities related to long-term systemic exposure to highly active antiretroviral therapy (HAART). However, the safety of drugs loaded with silver nanoparticles has been debatable. This study is aimed at evaluating the effects of HAART-loaded silver nanoparticles (HAART-AgNPs) on the behavioural assessment, biochemical indices, morphological, and morphometric of the hippocampus in diabetic Sprague-Dawley rats. METHODS: Conjugated HAART-AgNPs were characterized using FTIR spectroscopy, UV spectrophotometer, HR-TEM, SEM, and EDX for absorbance peaks, size and morphology, and elemental components. Forty-eight male SD rats (250 ± 13 g) were divided into nondiabetic and diabetic groups. Each group was subdivided into (n = 8) A (nondiabetic+vehicle), B (nondiabetic+HAART), C (nondiabetic+HAART-AgNPs), D (diabetic+vehicle), E (diabetic+HAART), and F (diabetic+HAART-AgNPs). Morris water maze, Y-maze test, and weekly blood glucose levels were carried out. Following the last dose of 8-week treatment, the rats were anaesthetized and euthanized. Brain tissues were carefully removed and postfixed for Nissl staining histology. RESULTS: 1.5 M concentration of HAART-AgNPs showed nanoparticle size 20.3 nm with spherical shape. HAART-AgNPs revealed 16.89% of silver and other elemental components of HAART. The diabetic control rats showed a significant increase in blood glucose, reduced spatial learning, positive hippocampal Nissl-stained cells, and a significant decrease in GSH and SOD levels. However, administration of HAART-AgNPs to diabetic rats significantly reduced blood glucose level, improved spatial learning, biochemical indices, and enhanced memory compared to diabetic control. Interestingly, diabetic HAART-AgNP-treated rats showed a significantly improved memory, increased GSH, SOD, and number of positive Nissl-stained neurons compared to diabetic-treated HAART only. CONCLUSION: Administration of HAART to diabetic rats aggravates the complications of diabetes and promotes neurotoxic effects on the experimental rats, while HAART-loaded silver nanoparticle (HAART-AgNP) alleviates diabetes-induced neurotoxicity.

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.

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.

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.

Chelidonic acid evokes antidepressant-like effect through the up-regulation of BDNF in forced swimming test.

Depression is usually accompanied by neuro-inflammatory reactions. Chelidonic acid, in particular, has shown anti-inflammatory effects. The objective of this study was to evaluate the anti-depressant effects of chelidonic acid and to discuss the potential mechanisms of a forced swimming test. Chelidonic acid was administered orally once a day for 14 days. On the 14th day, chelidonic acid resulted in a significant decrease in immobility time during the forced swimming test without alteration of locomotor activity, in an open field test. Chelidonic acid also increased the number of nissl bodies in the hippocampus. Brain-derived neurotrophic factor expression and extracellular signal-regulated protein kinase phosphorylation in the hippocampus were up-regulated by the administration of chelidonic acid. Chelidonic acid administration significantly increased the mRNA expression of hippocampal estrogen receptor-ß. The levels of hippocampal interleukin (IL)-1ß, IL-6, and tumor necrosis factor-α were effectively attenuated by the administration of chelidonic acid. In addition, chelidonic acid significantly increased the levels of 5-hydroxytryptamine (serotonin), dopamine, and norepinephrine compared with those levels for the mice that were administered distilled water in the hippocampus. These results suggest that chelidonic acid might serve as a new therapeutic strategy for the regulation of depression associated with inflammation.

Tualang honey supplement improves memory performance and hippocampal morphology in stressed ovariectomized rats.

Recently, our research team has reported that Tualang honey was able to improve immediate memory in postmenopausal women comparable with that of estrogen progestin therapy. Therefore the aim of the present study was to examine the effects of Tualang honey supplement on hippocampal morphology and memory performance in ovariectomized (OVX) rats exposed to social instability stress. Female Sprague-Dawley rats were divided into six groups: (i) sham-operated controls, (ii) stressed sham-operated controls, (iii) OVX rats, (iv) stressed OVX rats, (v) stressed OVX rats treated with 17ß-estradiol (E2), and (vi) stressed OVX rats treated with Tualang honey. These rats were subjected to social instability stress procedure followed by novel object recognition (NOR) test. Right brain hemispheres were subjected to Nissl staining. The number and arrangement of pyramidal neurons in regions of CA1, CA2, CA3 and the dentate gyrus (DG) were recorded. Two-way ANOVA analyses showed significant interactions between stress and OVX in both STM and LTM test as well as number of Nissl-positive cells in all hippocampal regions. Both E2 and Tualang honey treatments improved both short-term and long-term memory and enhanced the neuronal proliferation of hippocampal CA2, CA3 and DG regions compared to that of untreated stressed OVX rats.

Systematic administration of B vitamins attenuates neuropathic hyperalgesia and reduces spinal neuron injury following temporary spinal cord ischaemia in rats.

BACKGROUND: B vitamins have been demonstrated to be effective in treating chronic pain due to peripheral nerve injury. We investigated whether B vitamins could alleviate neuropathic pain and reduce neuron injury following temporary ischaemia in a rat model of spinal cord ischaemia-reperfusion injury (SCII). METHODS: SCII was produced by transiently blocking the unilateral lumbar arteries in adult male Sprague-Dawley rats. Behavioural and neurochemical signs of neuropathic pain and spinal neuron injury were analysed with and without B vitamin treatment. RESULTS: SCII caused behavioural thermal hyperalgesia and mechanical allodynia and neurochemical alterations, including increased expression of the vanilloid receptor 1 (VR1) and induction of c-Fos, as well as activation of the astrocytes and microglial cells in the spinal cord. Repetitive systemic administration of vitamin B complex (B1/B6/B12 at 33/33/0.5 mg/kg, i.p., daily, for 7-14 consecutive days) significantly reduced thermal hyperalgesia and the increased expression of VR1 and c-Fos, as well as activation of the astrocytes and microglial cells. SCII caused a dramatic decrease of the expression of the rate-limiting enzyme glutamic acid decarboxylase-65 (GAD65), which synthesizes γ-aminobutyric acid (GABA) in the axonal terminals, and ß-III-tubulin, and also caused loss of Nissl bodies in the spinal cord. These alterations were largely prevented and rescued by the B vitamin treatment. CONCLUSIONS: These findings support the idea that the B vitamins are capable of neuroprotection and antinociception during spinal cord injury due to temporary ischaemia. Rescuing the loss of inhibitory GABAergic tone may reduce spinal central sensitization and contribute to B vitamin-induced analgesia.

Proteasome inhibition induces DNA damage and reorganizes nuclear architecture and protein synthesis machinery in sensory ganglion neurons.

Bortezomib is a reversible proteasome inhibitor used as an anticancer drug. However, its clinical use is limited since it causes peripheral neurotoxicity. We have used Sprague-Dawley rats as an animal model to investigate the cellular mechanisms affected by both short-term and chronic bortezomib treatments in sensory ganglia neurons. Proteasome inhibition induces dose-dependent alterations in the architecture, positioning, shape and polarity of the neuronal nucleus. It also produces DNA damage without affecting neuronal survival, and severe disruption of the protein synthesis machinery at the central cytoplasm accompanied by decreased expression of the brain-derived neurotrophic factor. As a compensatory or adaptive survival response against proteotoxic stress caused by bortezomib treatment, sensory neurons preserve basal levels of transcriptional activity, up-regulate the expression of proteasome subunit genes, and generate a new cytoplasmic perinuclear domain for protein synthesis. We propose that proteasome activity is crucial for controlling nuclear architecture, DNA repair and the organization of the protein synthesis machinery in sensory neurons. These neurons are primary targets of bortezomib neurotoxicity, for which reason their dysfunction may contribute to the pathogenesis of the bortezomib-induced peripheral neuropathy in treated patients.

Antioxidant role of oleuropein on midbrain and dopaminergic neurons of substantia nigra in aged rats.

BACKGROUND: Oleuropein is a phenolic compound which is present in the olive leaf extract. The purpose of the present study was to investigate the neuroprotective effect of oleuropein as an antioxidant agent on the substantia nigra in aged rats. METHODS: Twenty 18-month-old Wistar rats (450-550 g) were randomly divided into control and experimental groups. The experimental group received a daily single dose of 50 mg/kg of oleuropein by oral gavage for 6 months. The control group received only distilled water. All rats were sacrificed two hours after the last gavage and the brains were removed and midbrains were cut. One part of the midbrains were homogenized and centrifuged. The tissue supernatant was assayed for lipid peroxidation (LPO) and antioxidant enzyme activities. The other part of midbrains fixed and embedded in paraffin, then processed for Nissl and immunohistochemistry (IHC) staining. Data was analyzed using SPSS by t-test. Differences were considered significant for P<0.05. RESULTS: The level of LPO in midbrain of the rats was decreased significantly in the experimental group, but superoxide dismutase, catalase and glutathione peroxidase activities were increased in experimental group compared to control group (P<0.05). Morphometric analyses showed significantly that the experimental group had more neurons in substantia nigra pars compacta (SNc) either in Nissl or IHC staining when compared to control (P<0.05). CONCLUSION: The results of the present study indicate that treatment of the old rats with oleuropein reduces the oxidative damage in SNc by increasing the antioxidant enzyme activities.

[Effect of erythropoietin on activities of antioxidant enzymes in the brain tissue of aged rats].

OBJECTIVE: To study the effect of erythropoietin (EPO) on the activities of antioxidant enzymes, namely catalase (CAT) and glutathione peroxidase (GSH-Px) in the brain tissues of aged rats. METHODS: Thirty SD rats were randomly divided into normal control, aging model, and recombinant human erythropoietin (rhEPO) treatment groups (n=10). Morris water maze was used to compare the behavioral indexes. The rats were then sacrificed to observe Nissl bodies in the hippocampal neurons with Nissl staining and test the activities of CAT and GSH-Px in the brain tissues. RESULTS: Compared with the control group, the aging rats showed significantly deteriorated learning and memory abilities (P<0.05), which were improved obviously by rhEPO treatment (P<0.05). The number of Nissl bodies in the neurons was reduced in the aging rats compared with that in the control group, and rhEPO treatment increased the number of Nissle bodies but failed to restore the control level. The aging rats also showed significantly lowered activities of CAT and GSH-Px in the brain tissue (P<0.05), which were increased significantly after rhEPO treatment (P<0.05). CONCLUSION: EPO can enhance the activities of the antioxidant enzymes in the brain tissues of aged rats to increase the antioxidant capacity and produces an anti-aging effect.

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.

[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.

Neurotoxicological evaluation of long-term lanthanum chloride exposure in rats.

With their widespread application in industry, agriculture, medicine, and daily life, rare earth elements (REEs) are widely used in various fields and eventually accumulated in human body. Therefore, understanding the effects of REEs on health has become more and more important. In this work, the neurotoxicity of lanthanum (La) was evaluated. Wistar rats were exposed to lanthanum chloride through oral administration at 0, 0.1, 2, and 40 mg/kg doses from gestation day 0 through 6 months of age. Experiments were carried out to reveal the effects of La exposure on brain functions from four aspects including behavioral performance, [Ca2+](i) level and the activity of Ca2+-ATPase (adenosine triphosphatase) in hippocampal cells, oxidative stress, and Nissl staining. Adverse effects were observed in 2 and 40 mg/kg dose groups and increased with dose. Morris water maze test showed that La exposure at 2 and 40 mg/kg could significantly impair the behavioral performance. (The preference for the target quadrant decreased by 16.6% and 19.4% versus control, respectively.) The neurotoxicological consequences demonstrated that the alteration in homeostasis of [Ca2+](i)/Ca2+-ATPase (the ratio of [Ca2+](i) vs. Ca2+-ATPase activity increased by 44% in rats of 40 mg/kg group), the inhibition to activities of antioxidant enzymes, and the subsequent cell damage (18% and 23% cell loss in CA3 subregion of rats in 2 and 40 mg/kg group, respectively) might be involved in the neurological adverse effects of REEs exposure.

Neuroprotective effects of lactation against kainic acid treatment in the dorsal hippocampus of the rat.

Marked hippocampal changes in response to excitatory amino acid agonists occur during pregnancy (e.g. decreased frequency in spontaneous recurrent seizures in rats with KA lesions of the hippocampus) and lactation (e.g. reduced c-Fos expression in response to N-methyl-d,l-aspartic acid but not to kainic acid). In this study, the possibility that lactation protects against the excitotoxic damage induced by KA in hippocampal areas was explored. We compared cell damage induced 24 h after a single systemic administration of KA (5 or 7.5 mg/kg bw) in regions CA1, CA3, and CA4 of the dorsal hippocampus of rats in the final week of lactation to that in diestrus phase. To determine cellular damage in a rostro-caudal segment of the dorsal hippocampus, we used NISSL and Fluorojade staining, immunohistochemistry for active caspase-3 and TUNEL, and we observed that the KA treatment provoked a significant loss of neurons in diestrus rats, principally in the pyramidal cells of CA1 region. In contrast, in lactating rats, pyramidal neurons from CA1, CA3, and CA4 in the dorsal hippocampus were significantly protected against KA-induced neuronal damage, indicating that lactation may be a natural model of neuroprotection.

A method for peripheral chromatolysis in neurons of trigeminal and dorsal root ganglia, produced in rats by lithium.

In classical chromatolysis, Nissl bodies are initially lost centrally with subsequent progression to the periphery of the neuron. Peripheral chromatolysis has the opposite pattern; it is less common and more difficult to produce. We describe a new method for producing peripheral chromatolysis in neurons of trigeminal ganglia and dorsal root ganglia that requires only injection of large doses of lithium chloride (LiCl) for two, three or four consecutive daily doses. This method may be useful for elucidating the intraneuronal mechanisms that control the location and structure of the Nissl bodies.

Neuroprotective effect of riluzole in a primate model of Parkinson's disease: behavioral and histological evidence.

Our study aimed to determine whether riluzole, which has shown efficacy as a disease-modifying agent in amyotrophic lateral sclerosis (ALS), is neuroprotective in a marmoset model of Parkinson's disease (PD). Reduction of energy demand by riluzole could be a rational neuroprotective strategy with good tolerability. The efficacy of riluzole was evaluated in marmosets by testing its ability to reduce MPTP-induced behavioral deficits and loss of dopaminergic nigral neurons. Marmosets were divided into two groups of four animals each: animals in Group 1 were injected twice with MPTP (2 mg/kg subcutaneous) and treated with riluzole (10 mg/kg per os b.i.d.), animals in Group 2 (controls) were injected with MPTP and with the vehicle of riluzole. A third group of marmosets which did not receive MPTP or riluzole drug was introduced for neurohistopathological studies (normal animals). Marmosets treated with riluzole preserved a better motor function and neurological performance through the 26 days of assessment when compared with the controls. Histologically, there was sparing of TH- and Nissl-stained nigral neurons and of TH-stained terminals in the striatum and the putamen in the group treated with riluzole compared to the controls. We conclude that riluzole protects dopaminergic neurons and reduces behavioral deficits in a marmoset model of PD.