The Effects of Exogenous ACTH on 5-3b-hydroxysteroid Dehydrogenase Activity in the Embryonic Avian Adrenal Gland

TLDR: The occurrence of JB-HSD activity in the adrenala of the chick embryo lead to the conclusion that the adrenocortical cells have the capacity tor steroid hormone syntheSis b.Y stage 23 (day 4).

Abstract: This investigation concerned itself primarily with the development ot adrenal d-JB-hydr0JE;Y8teroid dehydrogenase (d-3B-HSD) aotivity and the effects of exogenous ACTH on this activity in the embryonic chicken. A prel1m1nary investigation was wxiertaken to determine the norul development of the adrenal of brown and white Legborn chick embryos. Since chronological and morphological ages are not alvays clo.el3 oorrelated, morphologi-cal chara cterietics. as .. tabl1shed 1>7 Hamburger and Hamilton (, 51) , were employed to determine developmental age. There wae no s1gn1ticant difference in development ot the adrenal glands in the two yari.ties ot Leghorn studied. Only minor variations between our observations and those ot other investigators were observed. A moditication ot the histochemical technique of Levy and ooworkers (t.59 was used to detel"'1'ld.ne d.JB-HSD aotivity. Such BoUnty was observed in the primordial adrenocortical cells ot stage 2J (day 4) brown and white Leghorn embl7Os. There was a s1gn1ticant difterence in the development of ~.s -JB-HSD activity between brown and white Leghorn embryos. DUferences in the intensity of the enzyme reaction when sections ot the same embryo were incubated with the two substrates, dehydroepiandrosterone (DHA) and pregnenolone, sugs gest the possibility of two enzyme" rather than one. Brown Leghorn embryos ot stages 2J, 23-24 and 24 showed an increase in enzyme activity after the administration of porcine ACTH. The time interval between the last ACTH injection and the time of sacrifice was found to b. sign1f'icant. Eabryoa sacrificed prior to three hours following injection exix hibited no increase in activity aa did those sacrificed between 21 and 46 hours following injection. A algn1.f'lcant increase in activity was observed in the adrenals ot embryos sacrificed three to 11 hours after the final injection. The occurrence of ,6,..5_JB-HSD activity in the adrenala of the chick embryo lead to the conclusion that the adrenocortical cells have the capacity tor steroid hormone syntheSis b.Y stage 23 (day 4). Treatment of such embryos with exogenous ACTH resulted in an increase in adrenal ,6,..5 -JB-HSD activity indioating that the embryonic chicken adrenal is susceptible to ACTH stimulation in ita early stages ot development.