Oestrogen-induced increase in uterine cgmp content in vitro: Effects of inhibitors of protein and rna synthesis

Abstract

We have shown previously that oestradiol elevates the cGMP content of isolated uterine horns incubated for 2 h with the hormone. Cycloheximide (30 Mg/ml) or actinomycin D (100 μg/ml), at concentrations which markedly inhibit protein and RNA synthesis, blocked the oestrogen-induced increase in cGMP. These agents do not inhibit the rise in uterine cGMP content provoked by sodium nitroprusside, thus arguing against a direct toxic effect on the enzyme guanylate cyclase. α-Amanitin, even at very high concentrations (80 Jug/ml), interfered much less efficiently with total RNA and protein synthesis and also failed to prevent the oestrogen-induced increase in cGMP content. Taken together, these observations indicate that oestrogen action on uterine cGMP concentration in vitro depends on an RNA and/or a protein biosynthetic event that takes places in the uterus. This therefore confirms and extends analogous observations made previously under conditions in vivo.