Efekat deksametazonskog tretmana gravidnih ženki pacova na maternalne, fetalne i neonatalne ACTH-ćelije
The effects of dexamethasone treatment of pregnant rats on maternal, fetal and neonatal ACTH-cells
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Adrenocorticotropic hormone (ACTH) is secreted in response to a number of stimuli and it influences growth, differentiation and adrenal steroidogenesis. Rat pituitary ACTH-cells are differentiated at 14-16 days of fetal life, while synthesis of adrenal glucocorticoids starts from the 17th day of gestation as a result of increased synthesis and release of ACTH. The aim of this work was to examine the effect of dexamethasone (Dx), administered to gravid females, on the synthetic ability of their pituitary ACTH-cells as well as those of their fetal and neonatal offspring. The experimental group of pregnant females received Dx (1.5 mg/kg bw) on day 16 of gestation, while the control group received an equal volume of diluent at the same time. Plasma ACTH and cortisol concentrations were determined by RIA. The ACTH-cells were examined under light and electron microscopes. The results obtained indicate that single Dx-treatment of pregnant rats suppresses differentiation of fetal adrenocortical cells and the release of ACTH. However, in neonatal rats the number of ACTH- and precursor cells and their proliferation increased, as well as ACTH and cortisol synthesis and release, i. e. stimulation of synthesis and secretion of ACTH was noticed after suppression in the fetal period. The numerous changes observed in the fetuses and early neonates of dams treated with a single dose of Dx during pregnancy had disappeared in 30-day-old offspring.
Keywords:pituitary; ACTH-cells; fetal period; neonatal period; adult period; dexamethasone
Source:Acta veterinaria, 2000, 50, 4, 195-205