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Biomedical subjects

G N Moskovkin

Publications and source records attributed to G N Moskovkin.

At least 19 recordsLinked to original sources
PubMed1991

Development of glial fibrillary acidic protein immunoreactivity in thyroidectomized rats.

The majority of astroglia develop postnatally in rats. GFAP (glial fibrillary acidic protein)-immunoreactivity appears mainly during the 2nd and 3rd postnatal weeks throughout the brain. Hypothyroidism inhibits, among others, the cell proliferation, maturation, and migration of neurons. However, hardly any data on the effect of hypothyroidism on GFAP-immunoreactivity are available in the literature. In our experiments, thyroidectomy was performed between the 3rd and 5th postnatal days. Operated and control animals from the same litter were perfused transcardially and processed for immunohistochemistry in parallel after 2, 3, and 4 wk. On the basis of serial sections, the development of GFAP-immunoreactivity was not generally affected by hypothyroidism. We could observe only two phenomena that showed a tendency of retardation in the operated animals: (1) the decrease of the strong GFAP-immunopositivity of white matter tracts (for example, internal capsule and pyramidal tract) and (2) the gradual disappearance of the GFAP-immunoreactive radial fibers (for example, in the neocortex, in the olfactory bulb, and around the 3rd ventricle).

Aging↗
PubMed1989

Effect of triiodothyronine on the muscarinic receptors and acetylcholinesterase activity of developing rat brain.

The effect of triiodothyronine was investigated on the developing muscarinic system in rat cerebral cortex. Triiodothyronine was administered from birth to day 30. In the synaptosomal membrane fraction of the cerebral cortex, acetylcholinesterase activity and the binding of the muscarinic ligand 3H-quinuclidinyl-benzylate increased significantly as compared to the control. An analysis of the binding curve based on Hill plots suggested a positive cooperativity of receptors of the membrane samples obtained from both hormone treated and control animals. The results obtained are in accordance with morphological, biochemical and clinical data on the thyroid hormone effect on central nervous system maturation.

Acetylcholinesterase↗
PubMed1987

[The site (central or peripheral) of the anti-ulcer action of dalargin, a synthetic analog of endogenous opioids in an experimental model of cysteamine-induced duodenal ulcer in rats].

Dalargin injected subcutaneously at a dose of 10 micrograms/kg decreased 4-5 fold ulcer manifestations in rats with cysteamine-induced duodenal ulcers. Intracerebroventricular dose of 2 micrograms diminished the manifestations to a lesser extent Dalargin only at a dose exceeding 500 micrograms intraperitoneally decreased significantly the in vivo binding of 3H-D-Ala2, D-Leu5-enkephalin with brain opiate receptors. We believe that Dalargin injected peripherally in small doses does not penetrate the blood-brain barrier and that its antiulcer activity is due to the interaction with peripheral opioid receptors. It seems possible that the disturbances in the central/peripheral ratio of the opioid activity plays an important role in the pathogenesis of duodenal peptic ulcer.

Animals↗
PubMed1984

DNA synthesis in the Purkinje neurons.

(3H) Thymidine is incorporated into some cerebellar Purkinje cells of 6- to 30-day-old rats. The frequency of labelled neuronal nuclei was higher in the 12- to 30-day old rats than in the 6- to 10-day-old animals. The grain distribution pattern in autoradiographs was mostly nucleolar amounting to three to ten grains. Some other local labels were revealed, too. Only six Purkinje cells among 42,000 studied in 21 rats possessed heavy label (25 to 50 grains) distributed throughout the nucleus. Control estimations with deoxyribonuclease, hot perchloric acid and covering the autoradiographs again established that the Purkinje cells synthesize DNA perhaps for the purpose of DNA surplus accumulation and/or DNA repair in the neurons.

Age Factors↗
PubMed1983

[Labelling of the nuclei of differentiated Purkinje neurons after 3H-thymidine administration to rats].

Incorporation of 3H-thymidine into Purkinje's cells of the cerebellum of rats aged 6, 10, 12, 15 and 30 days has been demonstrated. As regards the distribution of silver granules, the nuclei can be divided into two groups--with a local label in the nucleolic zone or in the extranucleolic chromatin and with a uniform labeling. The nuclei with an intense uniform label are encountered rarely, i.e. 1-2 nuclei per 10000 cells. The frequency of the nuclei with local labeling of the nucleolus is higher than that with an extranucleolic local label. In 12--30-day-old rats, the number of labeled nuclei exceeded that in 6--10-day-old animals.

Animals↗
PubMed1982

[Action of hypothyroidism on the metabolic maturation of the pyramidal neurons of the rat hippocampus].

Interference microscopy was used to measure dry mass of pyramidal neurones of hippocampal CA1 and CA3 areas in control and hypothyroid rats aged 14 and 21 days and 2 months. Hypothyrosis was induced in the newborn by intraperitoneal injection of methylthiouracil to the lactating female during the lactation period (for 1 month). Hypothyrosis caused a considerable retardation of the animals' growth. A significant decrease in he concentration of dry substances was detected only in the cytoplasm of Ca1 area neurones in the group of 2-month-old hypothyroid animals. The measurements have demonstrated that hypothyrosis gives rise to pronounced retardation of the neuronal build-up and accumulation of protein products in the cytoplasma of hippocampal pyramidal cells in all the animal groups examined. The size and dry weight of neuronal nuclei of both the hyppocampal areas substantially diminish in the group of 2-month-old hypothyroid animals.

Aging↗
PubMed1978

[Differentiation of astroglial cells of the cerebellar cortex in the postnatal development of the rat: a morphological and histochemical study].

The morphological autoradiographic and cytospectrophotometric analysis of proliferation and differentation of the cerebellar cortex astroglial cells has been carried out during the rat early postnatal development. The proliferating astroglial cells constitute a major part of the whole cell population of the internal granular layer during the first week. It was proved by means of double labelling (3H- and 14C-thymidine) that these cells synthesize DNA and divide repeatedly, their division proceeding without preliminary morphological dedifferentiation, i. e. with the preservation of plasmatic processes. A suggestion is put forward that the precursors of the cerebellar cortex astroglial cells under study take their origin from the subependymal zone during the prenatal development. The results obtained allow to identify the proliferating glial cells as the Bergman's glia.

Age Factors↗
PubMed1978

Origin and proliferation of astroglia in the immature rat cerebellar cortex. A double label autoradiographic study.

The proliferating astroglia cells of the cerebellar internal granular layer (IGL) were studied by a 3H--14C double label autoradiographic technique in 1 mu thick sections of the resin embedded cerebellum of 6-7 day old rats. It was concluded that the proliferating cells undergo repeated mitotic cycles inside the IGL. Thus claims of their acquisition from the external granular layer could be disproved. Calculated from the ratio of 3H- and 3H + 14C-labelled cells, the length of the S phase was 6 hours.

Animals↗
PubMed1976

[Thyroid hormones in the early postnatal development of the CNS: effect of hyperthyroidism on proliferative activity of white matter cells of rat cerebellum].

The effect of triiodothyronin on the proliferative activity of the white matter cells has been studied by means of radioautography in the cerebellum vermis and hemisphere of developing rats. The index of labelled nuclei and the mitotic index of the white matter glial elements in both the cerebellum regions of 7 and 10 days old hyperthyroid animals are markedly reduced. Besides, the general tendency was found towards the increase of the mitotic cycle duration in the white matter cells due to the lengthening of S and G2 + 1/2 M periods. The data obtained are discussed with respect to the importance of thyroid hormones for the CNS development.

Animals↗
PubMed1976

[Local cambial zones in the brain of mammals in the postnatal period].

On the basis of both the authors' and published data, the structure and morphogenetic functions are analyzed for two zones of mammal brain during postnatal period: fascia dentata of hippocampus and cerebellar cortex. A conclusion is drawn that the local cambial zones arise in those brain regions which acquire in the process of morphogenesis a high degree of spatial separation from the ventricular zone. The main function of the cambial zones in question is the formation of a large number of microneurons during postnatal period.

Age Factors↗