Stimulation of in vitro ovulation and contraction of brook trout (Salvelinus fontinalis) follicles by adrenaline through alpha-adrenoreceptors.

The effects of adrenaline and adrenoreceptor antagonists on ovulation and follicle wall contraction were investigated in brook trout (Salvelinus fontinalis) follicles using in vitro incubation systems. Adrenaline significantly stimulated a dose-dependent increase in ovulation and follicle contraction at concentrations between 1.0 and 100 mumol l-1. The ovulatory and contractile effects of 10 mumol adrenaline l-1 could be blocked by the alpha 1-adrenoreceptor antagonists WB-4101 and benoxathian, and by the alpha 2-antagonist yohimbine. WB-4101 was the most potent blocker, significantly inhibiting ovulation and contraction at 1.0 mumol l-1. In contrast, the beta-antagonist propranolol (100-0.001 mumol l-1) was totally ineffective in blocking adrenaline-induced ovulation and follicle contraction. The results indicate that there is a strong correlation between the effects of adrenaline on ovulation and contraction. In addition, the antagonist studies indicate that adrenaline stimulates ovulation and follicle contraction of brook trout follicles through alpha-adrenoreceptors.