Porcine theca cells produce immunoreactive beta-endorphin and change steroidogenesis in response to opioid agonist

In earlier in vitro experiments opioids affected steroidogenesis in porcine luteal and granulosa cells. The present studies were undertaken to examine the effects of FK 33-824 (opioid agonist) alone or in combination with LH, PRL or naloxone (NAL, opioid antagonist) on steroidogenesis in cultured po rcine theca cells. Moreover, we have tested beta -endorphin-like immunoreac tivity (beta -END-LI) concentrations in culture media under control conditi ons and following treatments of theca cells with LH, PRL, progesterone (P-4 ), oestradiol (E-2) or testosterone (T). FK 33-824 and NAL significantly in creased P-4 release by theca cells and inhibited stimulatory effect of LH o n this steroid output. PRL-induced P-4 secretion from the cells was blunted only by FK 33-824. Secretion of androstenedione (A(4)) and T was essential ly elevated in the presence of FK 33-824 and this potentiation of both andr ogen release was completely abolished by PRL. NAL blocked stimulatory effec t of the opioid agonist only in case of T. Secretion of oestradiol and oest rone was completely free from the influence of both the opioid agonist and antagonist. Pig theca cells were able to produce beta -END-LI but none of t ested hormones (LH, PRL, P-4, E-2 and T alone or in combination) significan tly affected this production. In conclusion, these data indicate that porci ne theca cells may produce beta -END-LI and change their steroidogenesis in response to opioid peptides.