Endocrine Abstracts

In our in-vitro experiments we examined the involvement of insulin-like growth factor type II (IGF-II) in the control of ovarian function in domestic fowl, together with the intracellular mechanisms of IGF-II action. Fragments of ovarian follicles were cultured with and without IGF-II (1-100 ng/ml), blockers of protein kinase A (PAK, KT5820, 10 mg/ml), tyrosine kinase (TK, AG1024, 1mg/ml), mitogen-activated protein konase (MAPK, PD98059, 10 mg/ml), cyclin-dependent protein kinase (CDC2, olomoucine, 1 mg/ml) and their combinations. The production of progesterone (P), testosterone (T), estradiol (E), arginine-vasotocin (AVT), proliferation-associated (PCNA) and apoptosis-associated (bax) peptides, PKA, TK (phosphotyrosine), MAPK(ERK1,2), CDC2 (p34/cdc2), PKA- amd MAPK-stimulated transcription factor CREB-1 were evaluated by using RIA, EIA, Western immunobloting and immunocytochemistry. It was observed that IGF-II increased the expression of PCNA, TK, MAPK, CREB, T, E and AVT and decreased the production of bax, p34/p34 and P. The blockers of PKA, MAPK, CDC2 inhibited expreession of the corresponding kinases. Furthermore, these kinase blockers were able to prevented or even to reverse the IGF-II effects.

Our observations demonstrate the production of PCNA, TK, MAPK, CDC2, CREB, steroid and nanopeptide hormones by avian ovarian cells. Furthermore, they suggest the involvement of IGF-II in the control of avian ovarian cell proliferation, apoptosis, secretry activity, protein kinases and transcription factor. Moreover, our data suggest that IGF-II action on ovarian cells is mediated through the PKA-, TK-, MAPK- and CDC2-dependent intracellular mechanisms.