Specific Stimulatory Effect of LH on the Synthesis of delta4 Gestagens and Androgens in Adrenocortical Cells in vitro

: The aim of this study was to answer the question whether gonadotropins are able to stimulate the synthesis of delta4 gestagens and androgens in adrenals by the same way as in gonads. Adrenal cells of male guinea pigs (n=12) and adrenocortical cells of sows (n=2) were isolated with collagenase 1A and DNA-se and used in two separate experiments. Cell suspensions divided in quadruplicate number of aliquots for each test were preincubated (1 h) and then incubated (h) with high purity pLH-USDA, pLH-GPZ (this was used only in one experiment), pFSH-NIH (the residual contamination of this preparation with ACTH was not excluded) and ACTH1-24. The concentrations of progesterone (P), 17alpha-hydroxyprogesterone (OH-P), androstenedione (A), testosterone (T) and cortisol (F) in the incubated cells were estimated by RIA. The stimulatory effect of two high purity pLH preparations on P, A and T synthesis in guinea pig adrenal cells and pig adrenocortical cells was demonstrated. Moreover, the synthesis of OH-P in pig adrenocortical cells was also stimulated. It may be concluded that these results are specific for LH, since the used pLH-USDA was deprived of any residual ACTH contamination and pLH-GPZ was chromatographically homogenous. These preparations also showed indirect evidences of the activation of steroid 3beta-hydroxysteroid dehydrogenase/isomerase (3beta HSD) which catalyses the synthesis of these four delta4 steroids from their delta5 path precursors. The LH dependent activation of this enzyme in adrenals, which was demonstrated in this work, supported the well known observations of its independence of ACTH. As high as 6-times increase of P synthesis and 2-5 times increase of OH-P synthesis under the influence of pLH in pig adrenocortical cells (consistent with the species of LH) needs the induction of the labile protein i synthesis, since the cholesterol transport into mitochondria and the extent of pregnenolone and its derivatives synthesis depends on that protein. The influence of LH on adrenal steroidogenesis indicates that adrenal cells are the target not only for ACTH but also for LH. The influence of the used pFSH specimen on adrenal steroidogenesis resembles that of ACTH, including the increase of cortisol synthesis. Due to this similarity and lack of evidences of excluding residual ACTH contamination of such pFSH specimen, these results are considered nonspecific. Thus, the problem of FSH influence on adrenal steroidogenesis is still open. Regardless of that, the presented demonstration of specific LH effect appears to be an original contribution to the basic knowledge on adrenal steroidogenesis.