ADRENERGIC-STIMULATION OF FERTILIZING ABILITY IN HAMSTER SPERMATOZOA

Hamster spermatozoa, preincubated for 3 h in a culture medium containing bovine serum albumin (BSA) and a protein-free ultrafiltrate of a bovine adrenal cortex preparation, were unable to fertilize cumulus-free eggs. In contrast, if the culture medium also contained a protein-free ultrafiltrate of a bovine adrenal medulla preparation, 92% of the inseminated eggs were fertilized within 2 h. Replacement of the adrenal medulla preparation with 20.0 μM (-)-epinephrine (BSA and the adrenal cortex preparations also present) resulted in 85% of the inseminated eggs being fertilized. If 20.0 μM (-)-phenylephrine, an α-adrenergic agonist or 20.0 μM (-)-isoproterenol, a β-adrenergic agonist, was used in place of epinephrine, the percentage of fertilized eggs was 11% and 50%, respectively. With both phenylephrine and isoproterenol present, 90% of the eggs were fertilized. Furthermore, fertilization in the presence of 20.0 μM (-)-epinephrine could be inhibited by equimolar concentrations of either phentolamine, an α-adrenergic antagonist, (0% fertilization) or (-)-propranolol, a α-adrenergic antagonist, (18% fertilization). These results, together with our previous work, suggest the involvement of adrenergic receptors in the development of the fertilizing ability of hamster spermatozoa in vitro.