Control of estrogen and androgen receptors in the rat pineal gland by catecholamine transmitter

Sucrose gradient studies of rat pineal cytosol incubated with ³H-estradiol (female pineals) or ³H-5 α -dihydrotestosterone (male pineals) revealed a radioactivity peak in the 8 S region which disappeared after superior cervical ganglionectomy or incubation with excess unlabeled hormone. Ganglionectomy decreased significantly estradiol and testosterone uptake by the pineal gland $\text{in vitro}$ as well as high affinity binding to pineal cytoplasmic and nuclear components. Norepinephrine treatment counteracted all the effects of ganglionectomy but was unable to modify hormone uptake and binding by the pineal gland of sham-operated controls. Pre-treatment with actinomycin D or propranolol but not with phentolamine impaired norepinephrine effects; propranolol blockage however was only partial. Administration of isoproterenol, L-dopa or phentolamine increased hormone uptake by denervated pineals. The effects of isoproterenol were also observed $\text{in vitro}$ and were blocked by propranolol. These results indicate that sex steroid receptors in the pinealocytes are controlled by norepinephrine via beta-adrenergic receptors and that depletion of neural norepinephrine enhanced responsiveness of pineal hormone receptors to exogenous catecholamines.