[Participation of NO-synthase system in the stress-mediated reactions of the brain].

Neurosis-like status developing as a result of the exposure of animals to chronic stress, which is associated with a transitory cerebral hypoxia, could cause significant structural and functional alterations in many brain structures. Realization of humoral stress effects on the brain is mediated by both extra- and intracelullar signal molecules, among which nitric oxide (NO) is considered to be one of the most potent ones. Expression of neuronal constitutive (nNOS) and inducible (iNOS) isoforms of NO-synthase was studied by immunohistochemistry in the neurons of albino rat brain after exposure of animals to chronic stress resulting in the development of neurosis-like status. Chronic stress was shown to result in the increased expression of both nNOS and iNOS in many brain areas with the predominance in neocortex and hippocampus. The administration of nonspecific inhibitor of NOS, Nomega-nitro-1-arginine methyl ester hydrochloride (L-NAME) (10 mg/kg) resulted in the aggravated depression of the animals, associated with a decrease of locomotor and exploring activities that were evaluated using the traditional tests. The application of NOS activity inhibitor caused an insignificant rise only in iNOS expression. Thus the results obtained suggest that NO is involved in the realization of stress effects with the development of a neurosis-like status.

[Neuronal damage in the hippocampus of inbred mouse strains in the models of epilepsy induced by kainic acid and pilocarpine]. / Issledovanie povrezhdenii neironov hippokampa v inbrednykh liniiakh myshei v modeliakh épilepsii s ispol'zovaniem kainovoi kisloty i pilokarpina.

Elucidation of the mechanisms of neuronal damage is an important task of modem neuroscience and is of paramount importance for medicine. Present work compares two models of excitotoxic neuronal damage induced by kainic acid and pilocarpine, in which inbred C57BL/6J (C57BL) and FVB/NJ (FVB) mice were used. Both models produced higher neuronal damage in FVB although mortality was higher in C57BL. No significant differences between two strains of mice were found in seizures severity. Kainic acid demonstrated greater tropism to hippocampus in comparison with pilocarpine. Hsp-70 and Egr-1 expression was not significantly different in C57BL and FVB. Analysis of the isolated mitochondrial fraction has shown different degree of free radical production in the strains studied, that could be one of the reasons for unequal susceptibility of their neurons to excitotoxic cell death.

[Nestin-expressing cells in the human hippocampus]. / Nestin-ékspressiruiushchie kletki v gippokampe cheloveka.

Nestin is a protein that belongs to a family of intermediate filament proteins which are typical for undifferentiated neural stem and progenitor cells. In this work nestin expression was studied in the hippocampus obtained from patients with epilepsy. Immunohistochemical investigation demonstrated five types of nestin-positive cells, differing in morphological and immunological phenotype. These included cell with a radial glia phenotype, bipolar cells, small dendritic cells, subependymal and astrocyte-like cells. Two types of these cells: radial glia of dentate gyrus and bipolar NG2+ cells can be considered as neural progenitor cells possessing different degrees of commitment.