[Serotonin inhibits phorbol ester-induced oocyte maturation in the green toad (Bufo viridis)]

The activator of protein kinase C phorbol-12-myristat-13-acetate (PMA) induces maturation of the definitive intact (coated with the follicular envelopes) and defolliculated oocytes of the green toad. This effect is more pronounced in case of defolliculated oocytes. The amount of matured oocytes depends on the PMA concentration in solution. Serotonin (5-HT) inhibits or blocks maturation of the oocytes induced either by progesterone or by PMA. A possible mechanism of this effect is discussed with special reference to its role in regulation of oocyte maturation.