Alterations of the Cerebellar Inhibitory Interneurons and Inhibitory Synapse Following KA-induced Seizures / 대한해부학회지

Most epileptic patients have commonly suffered from recurrent seizures for many years. These seizures are usually associated with inhibitory synaptic reorganization of the hippocampal region, but it is not known whether cerebellar inhibitory synaptic changes can be induced by seizure activity. We sought to determine the pattern of cerebellar alterations in the cerebellar inhibitory interneurons (basket and stellate cells) and then tested if the alterations are associated with their synaptic transmission at the cerebellar GABAergic synapses between inhibitory interneurons and Purkinje cells after systemic kainic acid administration by immunohistochemistry, western blot analysis, dot blot analysis and confocal microscopy. A dramatic increase of the intensity of GAP-43 immunostaining was obvious in the pinceau structures following KA-induced seizures and the intense GAP-43 immunoreaction involved in high expression of PKC-sigma. The activation of the presynaptic terminal at the cerebellar inhibitory synapse is accompanied with strong GABA immunoreactivity in pinceau region (especially 48 h) after KA-seizures. These results suggest a possibility that KA-seizures increase the release of GABA at the cerebellar inhibitory presynaptic terminal and it would be contribute to the depression of Purkinje cell activity, disinhibition, during the epileptogenesis.

Roles of Stem Cell Factor and c-kit Receptor in the Development of Cerebellar GABAergic Neurons / 대한해부학회지

Evidence that Stem cell factor (SCF) and c-Kit receptor tyrosine kinase are expressed in the cerebellum during postnatal development, suggests a possible contribution of the SCF/Kit signaling pathway in the cerebellar development. In the present study, we prepared cerebellar cultures from C57Bl/6J mouse at postnatal day 1and 7 to investigate the role of c-kit receptor and SCF in regulation of growth and differentiation in the postnatal cerebellar GABAergic cells. SCF increased the number of survival cerebellar cells and density of glutamic acid decarboxylase 65/67 (GAD65/67) and calbindin D-28K expression in the immunoblot analysis. SCF also improved the neurite extension of the interneuron neuritis and dendritogenesis of Purkinje cells. Treatment with c-Kit antibody accelerated cellular loss in serum-free media and decreased the growth ability and dendritogenesis of Purkinje cells and cerebellar inhibitory interneurons. Our data suggest that SCF and c-kit receptor are required for the normal growth of postnatal cerebellum and a possible involvement of functional regulation through the SCF/c-kit receptor pathways in the postnatal cerebellar development.

Protective Effect of Etomidate on Kainic Acid-induced Neurotoxicity in Rat Hippocampus / 대한마취과학회지

BACKGROUND: The present investigation was undertaken to evaluate the neuroprotective effect of etomidate against kainic acid (KA) induced neurotoxicity in rats by using the immunoreactivity of heat shock protein-70 (HSP-70) and the acid-fuchsin stain. METHODS: Administration of etomidate (20 mg/kg, I.P.) was performed in sequence; first being just one hour after a KA (10 mg/kg, I.P.) injection, then three more times at one hour intervals. Neuronal damages in the hippocampus were evaluated by using the acid-fuchsin stain to detect cell death and HSP-70 induction as an index of cell injury at 24 h after the administration of KA. RESULTS: HSP-70 induction and acid fuchsin positive neurons were increased in the CA1 and CA3 regions of the hippocampus after a KA injection but significantly decreased by an injection of etomidate (P < 0.01). CONCLUSIONS: These results suggest that the etomidate has a potential effect on the protection of neurons against KA-induced neurotoxicity.

Zinc translocation and heat shock protein induction in rat brains following kainate seizures / 대한해부학회지

Translocation of synaptic zinc may mediate neuronal death in pathological conditions. In this study, we examined the possible correlation between zinc translocation and heat shock protein (HSP)72 induction in rat brains following kainate seizures. Zinc accumulation, visualized by Timm's method, occurred in degenerating neurons in hippocampus, amygdala, and cortex 6~24 h after kainate injection. Immunohistochemistry with anti-HSP72 antibody revealed HSP induction largely in areas where zinc accumulation occurred. At the cellular level, however, most HSP72 immunoreac-tive neurons were found to be Timm (-) and morphologically intact. Present results suggest that intense zinc translocation may induce neuronal death before possible HSP induction. However, we could not rule out the possibility that sublethal zinc translocation, below the detection limit by Timm's method, may play a role in HSP72 induction.

Effects of kainic Acid-induced seizures on GABA and GABA transporter in the cerebellum of the rat / 대한해부학회지

The effects of kainic acid-induced seizures on GABA and GABA transporter in the rat cerebellum were examined by means of immunohistochemical and Western blot methods. Immunocytochemical analysis showed that kainic acid-induced seizures led to a decreased immunoreactivity for GABA to 3 weeks after seizures with an slight increase in the immunoreactivity of cerebellum 24 h after treatment. Immunoreactivities of GABA transporters, GAT-1 and GAT-3 which are localized neurons and astrocytes, were increased at 24 and 48h and after that weak immunoreactivites for GABA transporters were shown in the cerebellar tissues. Our results indicate that kainic acid-induced seizures exerts specific effects on GABA contents and the GABA transporters in the cerebellum and a decrease of GABA contents might not always associated with the decrease in the number of GABA transporters in the rat cerebellum.

beta-amyloid Peptides Induced Neuronal Apoptosis without Tau Phosphorylation / 대한해부학회지

beta-amyloid peptide (Abeta) consisting of 40 to 42 amino acid is the principle constituent of senile plaques in Alzheimer's disease. Although, the hypothesis that deposition of AP triggers a cascade of events leading to the pathology of Alzheimer's disease has been widely accepted, direct evidence for triggering accumulation of phosphorylated tau in paired helical filament is rare. In this study, we examined neurotoxicity induced by 3 kinds of beta-amyloid peptides 1 ~28, 25~,35 and 1~40 to elucidate the way of mechanism trading to neuronal cell death caused by Abeta using cultured hippocampal neurons. For this purpose, we measured lactate dehydrogenase (LDH) in the culture media after treatment with Abeta combined with anti-oxidant drug, trolox, or not. By histochemical and TUNEL method, we studied the change of immunoreaction to anti-MAP-2 (microtubule associated protein -2, the main component of neuritis) and detected apoptotic cells, respectively, in the hippocampal neurons treated with Abeta. To investigate whether tau phosphorylation involve neurotoxicity induced by Abeta, we immunostained the neurons with anti-SMI-31 to recognize phosphorylated Ser 396/404 of tau. From our data, we suggested that Abeta1-40 and Abeta25-35 induced marked neurodegenerative changes, and the mechanism responsible for cell death caused by Abeta -neurotoxicity was associated with the apoptosis. Because Abeta-neurotoxicity was not inhibited by anti-oxidant, trolox, we suggested that anti-oxidant did not protect the neuronal cells against the damage induced by Abeta in ou. expo.imental envi.onment. Finally, we suggested that AP treatment did not potentiate the immunoreactivity to anti-phosphorylated tau antibody and we speculated that Abeta-neurotoxicity led hippocampal cells to apoptosis without tau phosphorylation.

c-kit Receptor and Ligand Expression in Developing Nervous System Blocked c-kit Function by ACK2 / 대한해부학회지

The objective of the present study was to investigate the expression of KL ligand and synaptophysin during postnatal development of the cerebellum blocked c-kit function by ACK2 to determine whether the c-kit receptor and KL ligand interacting system could play a role during the migration of cerebellar neuronal cells and during establishment of functional synapses of all cerebellar neurons. In this study, we used in situ hybridization technique in order to examine the expression of KL mRNA in the cerebellar tissue following intraperitoneal injections of ACK2 and to study the localization of synaptophysin and protein products of KL ligand (SCF: Stem Cell Factor) during postnatal development we used immunohistochemical methods. Our findings are that the intensity of immunoreaction to SCF (protein product of KL ligand) antibody is increased while an immunoreactivity to anti-synaptophysin is decreased in the Purkinje cell bodies in the cerebellum of the mouse given ACK2 from the postnatal day 3 (P3) to Pl4. The overexpression of KL mRNA is detected in the Purkinje cell bodies at Pl4 in the cerebellum blocked c-kit function. At postnatal day 21, the period of which establishment of functional connections of all cerebellar neurons is complete, immunoreactivities of SCF and synaptophysin in the ACK2 treated cerebellum is recovered to the same level being observed in the control. With above results, we suggest a role for the c-kit receptor in the synaptogenesis and migration of developing cerebellar neurons with interaction of ckit receptor/KL ligand system. And the overexpression of KL ligand mRNA and protein product in the Purkinje cells is supposed to be one of mechanisms compensate for the lack of c-kit function in the cerebellum induced by ACK2 during postnatal development.