Ontogeny of the adrenal gland in the spiny mouse, with particular reference to production of the steroids cortisol and dehydroepiandrosterone.
Synthesis of the androgen dehydroepiandrosterone (DHEA) by the fetal adrenal gland is important for placental estrogen production and may also be important for modulating the effects of glucocorticoids on the developing brain. The presence of cortisol in spiny mouse (Acomys cahirinus) blood led us to determine whether the adrenal gland of this precocial rodent also synthesized DHEA. Cytochrome P450 enzyme 17α-hydroxylase/17,20-lyase (P450c17), cytochrome-b5 (Cytb5), and 3β-hydroxysteroid dehydrogenase (3βHSD) were detected in the adrenal gland from 30 days gestation (term = 39 days), and DHEA, cortisol, and aldosterone were detected in fetal plasma from this time. Plasma DHEA concentrations increased 4-fold, whereas cortisol concentrations decreased from day 30 of gestation until the day of birth. Explant culture of fetal adrenal tissue showed that DHEA was produced from exogenous pregnenolone, and thus, the DHEA in the fetal circulation is likely to be of fetal origin. Clear zonation of the fetal adrenal cortex was evident by 38 days gestation when expression of Cytb5 was present throughout the cortex, and coexpression of P450c17 and Cytb5 occurred in the zona reticularis and fasciculata. 3βHSD was expressed in the cortex from at least 30 days gestation and decreased as term approached, consistent with the fall of cortisol in late gestation in this species. These results show that the spiny mouse adrenal gland, like that of the human fetus, can synthesize and secrete DHEA from at least 30 days (relative gestation length, 30 days of a 39-day gestation, 0.76) of gestation, and DHEA may have important roles in placental biosynthesis of estrogens and in modulating the actions of glucocorticoids in the developing brain in this species.
The Ritchie Centre, Monash Institute of Medical Research, 27-31 Wright Street, Clayton, Melbourne, Victoria, Australia 3168.
Tracey A
TA
Quinn
Udani
U
Ratnayake
Hayley
H
Dickinson
Tri-Hung
TH
Nguyen
Michelle
M
McIntosh
Margie
M
Castillo-Melendez
Alan J
AJ
Conley
David W
DW
Walker
D015096:3-Hydroxysteroid Dehydrogenases / Q000378:metabolism; D000311:Adrenal Glands / Q000196:embryology* / Q000254:growth & development / Q000378:metabolism*; D000818:Animals; D000831:Animals, Newborn; D015786:Cytochromes b5 / Q000378:metabolism; D003687:Dehydroepiandrosterone / Q000096:biosynthesis* / Q000097:blood; D005260:Female; D005312:Fetal Blood / Q000378:metabolism; D005865:Gestational Age; D006801:Humans; D006854:Hydrocortisone / Q000096:biosynthesis* / Q000097:blood; D007150:Immunohistochemistry; D008297:Male; D051189:Murinae / Q000097:blood / Q000196:embryology* / Q000378:metabolism*; D011247:Pregnancy; D013254:Steroid 17-alpha-Hydroxylase / Q000378:metabolism
D003687:Dehydroepiandrosterone; D015786:Cytochromes b5; D015096:3-Hydroxysteroid Dehydrogenases; D013254:Steroid 17-alpha-Hydroxylase; D006854:Hydrocortisone