STIMULATION OF IN-VITRO OVULATION AND CONTRACTION OF BROOK TROUT (SALVELINUS-FONTINALIS) FOLLICLES BY ADRENALINE THROUGH ALPHA-ADRENOCEPTORS

The effects of adrenaline and adrenoreceptor antagonists on ovulation and follicle wall contraction were investigated in brook trout (Salvel inus fontinalis) follicles using in vitro incubation systems. Adrenali ne significantly stimulated a dose-dependent increase in ovulation and follicle contraction at concentrations between 1.0 and 100 mu mol l(- 1). The ovulatory and contractile effects of 10 mu mol 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 contr action at 1.0 mu mol l(-1). In contrast, the beta-antagonist propranol ol (100-0.001 mu mol l(-1)) was totally ineffective in blocking adrena line-induced ovulation and follicle contraction. The results indicate that there is a strong correlation between the effects of adrenaline o n ovulation and contraction. In addition, the antagonist studies indic ate that adrenaline stimulates ovulation and follicle contraction of b rook trout follicles through alpha-adrenoreceptors.