Secretory activity of bovine ovarian granulosa cells transfected with sense and antisense insulin-like growth factor (IGF) binding protein-3 and the response to IGF-I, GH, LH, oxytocin and oestradiol

The aim Of Our in vitro experiments was to examine if IGF binding protein ( IGFBP)-3 is involved in control of bovine ovarian secretory activity. For t his purpose we performed the transfection of bovine granulosa cells with cD NA sense and antisense constructs increasing or inhibiting IGFBP-3 synthesi s. The release of IGFBP-3, progesterone, oxytocin, IGF-I and prostaglandins F (PGF) and E (PGE) by control and transfected cells was compared. The tra nsfected ovarian cells were cultured with and without bLH (100 ng/ml), bGH (100 ng/ml), IGF-I (10 ng/ml), oxytocin (10 ng/ml) and oestradiol-17 beta ( 100 ng/ml). The concentration of IGFBP-3 produced was assessed using ligand and western blotting and secretion of progesterone, oxytocin, IGF-I, PGF a nd PGE was evaluated using RIA/IRIMA techniques. Transfection of cells with the sense IGFBP-3 cDNA construct resulted in the expected increase in IGFBP-3 release, whereas the antisense IGFBP-3 constr uct induced the expected reduction in IGFBP-3 output. The granulosa cells t ransfected to overexpress IGFBP-3 had an increase in IGF-I, PGF and PGE rel ease, and a decrease in basal and hormone- or growth factor-induced accumul ation of progesterone and oxytocin. The granulosa cells transfected to have reduced IGFBP-3 expression gave primarily significant opposite findings. T he present results suggest the involvement of IGFBP-3 in control of bovine ovarian steroid, peptide hormone, growth factor and prostaglandin release. IGFBP-3 is a physiological stimulator of IGF-I and prostaglandin release an d an inhibitor of steroid and peptide hormone output.