PROPRANOLOL INDUCES POLYSPERMY DURING SEA-URCHIN FERTILIZATION

Propranolol, a beta-adrenergic receptor blocker, is found to induce po lyspermy in sea urchin eggs. Unfertilized sea urchin eggs treated for 10 min with 50 mu M of propranolol, and then inseminated, become polys permic and show a fertilization envelope which is barely visible to th e light microscope. Examination of treated eggs by transmission and sc anning electron microscopy shows that the drug does not alter the cort ex of the unfertilized egg. However, after insemination an incomplete cortical reaction occurs. This might well account for both polyspermy and the defective elevation of the fertilization envelope. Since the e ffects of the drug are reversed by simultaneous treatment with adrenal in, perhaps propranolol interferes with the monoaminergic system that has been proposed to be active. The involvement of the monoaminergic s ystem in the fertilization process is present in the sea urchin egg. ( C) 1996 Wiley-Liss, Inc.