Involvement of Gap Junctions in Stimulation of in vitro Maturation of the Common Frog Oocytes by Low Progesterone Concentrations

Abstract

The inhibitor of gap junctions 18alpha-glycerretinic acid inhibits the maturation of follicle-enclosed common frog oocytes stimulated by low progesterone concentrations. The inhibitory effect of 18alpha-glycerretinic acid does not depend on concentrations within the limits of 5-40 microM. The inhibitory progesterone concentrations differ markedly in different females. The inhibitory effects of actinomycin D (5 microg/ml) and 18alpha-glycerretinic acid (5 microg/ml) were expressed when the same progesterone concentrations were used. When injected in an intact oocyte, Lucifer yellow was transported into the follicle cells, thus suggesting the presence of gap junction between these latter and the oocyte. The data obtained suggest that the previously described transcription-dependent factor formed in the follicle cells under the influence of low progesterone concentrations and stimulating oocyte maturation is transported in the oocyte along gap junctions.