Efekat deksametazonskog tretmana gravidnih ženki pacova na maternalne, fetalne i neonatalne ACTH-ćelije

Abstract

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.

Adrenokortikotropni hormon (ACTH) se oslobađa kao odgovor na brojne stimuluse i utiče na rast, diferencijaciju i sintezu steroidnih hormona adrenalne žlezde. ACTH ćelije u hipofizi pacova diferenciraju se između 14. i 16. dana fetalnog života, dok sinteza glukokortikoidnih hormona nadbubrežne žlezde počinje 17. fetalnog dana kao rezultat povećane sinteze i oslobadanja ACTH. Cilj ovoga rada je bio da se ispita efekat deksametazonskog (Dx) tretmana gravidnih ženki na ACTH ćelije fetusa i potomaka tokom neonatalnog perioda. Paralelno je ispitivana i sintetska aktivnost ACTH ćelija majki. Eksperimentalna grupa gravidnih ženki tretirana je Dx (1.5 mg/kg/tt) 16. dana gestacije, dok je kontrolna grupa u istom periodu primila odgovarajuću količinu fizioloskog rastvora. Koncentracija ACTH u plazmi određena je RIA metodom. ACTH ćelije fetusa, neonatalnih pacova i gravidnih ženki ispitivane su svetlosnom i elektronskom mikroskopijom. Rezultati ovog istraživanja ukazuju da jednokratni Dx tretman gravidnih ženki inhibitorno utiče na diferencijaciju ACTH ćelija hipofize fetusa i oslobađanje ACTH. Međutim, u neonatalnom periodu broj prekursorskih ACTH ćelija i njihova proliferacija su povećani, kao i sinteza i oslobađanje ACTH i kortizola, tj nakon perioda inhibicije u fetalnom dobu dolazi do stimulacije u pogledu sinteze i sekrecija ACTH ćelija tokom neonatalnog perioda. Brojne promene opisane tokom fetalnog i neonatalnog perioda kod potomaka majki jednokratno tretiranih Dx 16. dana gestacije iščezavaju kod potomaka starih mesec dana.