Estradiol regulation of follistatin and inhibin alpha- and beta(B)-subunitmRNA in avian granulosa cells

Estradiol modulation of granulosa cell growth and regulation of follistatin and inhibin alpha- and beta (B)-subunit mRNA were investigated in cultured chicken granulosa cells. Granulosa cells were isolated and pooled accordin g to size from the F-4 + F-5, small yellow (SYF), and large white (LWF) fol licles. Isolated and dispersed granulosa cells were then cultured in the ab sence or presence of 1 x 10(-5) M 17 beta -estradiol. In Experiment 1 (n = 4 replications) the effect of estradiol on the growth of granulosa cells fr om the different-sized follicles was examined at 24 and 48 h of culture. Un treated and treated granulosa cells from all three follicle sizes prolifera ted during culture, and cell viability for all cultures was over 95% throug hout the experiment. After 48 h the untreated cultures for all follicle typ es had 1.6 to 2.2 times (P < 0.05) more cells than the estradiol-treated cu ltures. In Experiment 2 (n 3 replications), the cultures were terminated at 4 and 24 h after plating. Follistatin mRNA levels were higher in estradiol -treated cells at 24 h in F-4 + F-5 follicles, at 4 and 24 h in the SYF, an d at 4 h in the LWF. <beta>(B)-subunit mRNA levels were also increased by e stradiol at 4 h in F-4 + F-5 cells and at 4 and 24 h in the LWF. Steady sta te mRNA levels for the alpha -subunit were higher (P < 0.05) in estradiol-t reated cultures at dr and 24 h in F-4 + F-5 follicles and at 24 h in the SY F. Immunoreactive <alpha>-subunit protein, however, was not increased by es tradiol treatment. Thus, whereas estradiol inhibited granulosa cell growth, it exerted a generally stimulatory effect on the expression of FS and the inhibin alpha- and beta (B)-subunit mRNA. (C) 2000 Academic Press.