Portal de Periódicos da CAPES

Light and electron microscopic immunohistochemistry of the localization of adrenal steroidogenic enzymes

1997; Wiley; Volume: 36; Issue: 6 Linguagem: Inglês

10.1002/(sici)1097-0029(19970315)36

1097-0029

Kazunori Ishimura, Hisao Fujita,

Hormonal and reproductive studies

Recent immunohistochemical studies have revealed the precise localization of the enzymes involved in adrenal steroidogenesis. Light microscopical investigations showed that cytochromes P450 of cholesterol side-chain cleavage enzyme (P450scc) and of 11β-hydroxylase (P45011β), 3β-hydroxysteroid dehydrogenase/Δ5-4 isomerase (3βHSD), and 21-hydroxylase (P450C21) are localized in all the adrenocortical cells, especially in those of the zona fasciculata-reticularis. 17α-Hydroxylase/C17-20 lyase (P45017α, lyase) is present in the zona fasciculata-reticularis cells of human, bovine, pig, and guinea-pig adrenals, but absent in the adrenals of some rodents such as rat, hamster, and mouse. Aldosterone synthase (P450aldo) is contained only in the zona glomerulosa cells. In the rat adrenal, P45011β, which catalyzes the conversion of deoxycorticosterone to corticosterone, is localized in the zona fasciculata-reticularis cells. Electron microscopic investigations demonstrated that P450scc and P45011β are colocalized in the matrix side of inner mitochondrial membrane including cristae, while 3βHSD, P450C21, and P45017α, lyase are present in the membranes of smooth endoplasmic reticulum (SER). These results clearly indicate that aldosterone, the most potent mineralocorticoid, is synthesized in the zona glomerulosa cells, and glucocorticoids, such as corticosterone and cortisol, are produced in the zona fasciculata-reticularis cells. The conversion of cholesterol to pregnenolone and the final steps of corticosteroid synthesis occur in the mitochondria, while the intermediate steps, leading to the synthesis of deoxycorticosterone or deoxycortisol from pregnenolone, take place in the SER membranes. Microsc. Res. Tech. 36:445–453, 1997. © 1997 Wiley-Liss, Inc.