Testosterone effects on protein synthesis in the rat pineal gland. Modulation by the sympathetic nervous system

The administration of 0.5 mg of testosterone propionate (TP) for 3 days to castrated male rats caused 3H-leucine incorporation into pineal proteins to increase significantly by 79%. TP effects depended on time of administration; rats receiving TP at 06.00 h exhibited a significant 150% increase in pineal protein synthesis 24 h later whereas rats injected at 14.00 h only showed a 54% increase in 3H-leucine incorporation into proteins. Superior cervical ganglionectomy decreased pineal testosterone uptake in vitro by 21% and pineal protein synthesis by 27%; in addition it blocked the stimulatory effects of TP on protein synthesis. Ganglionectomy also modified the in vitro metabolism of testosterone by pineal cells; it increased the amounts of 3H-androstenedione and decreased 3H-5∝-androstanedione extracted from pineal glands incubated with 3H-testosterone. These results indicate that the sympathetic nervous input reaching the pineal via the superior cervical ganglia is important to modulate the early steps of androgen action on the pinealocytes.