Effect of estradiol and testosterone on catechol-O-methyl transferase activity of rat superior cervical ganglion, pineal gland, anterior hypophysis and hypothalamus.

The effect of estradiol and testosterone on the activity of catechol-O- methyl transferase (COMT) of the superior cervical ganglion, pineal gland, anterior hypophysis and hypothalamus were examined in castrated rats. In female rats a single injection of 2 mug of estradiol caused a significant 25% increase of hypothalamic COMT, whereas after 3 daily injections no differences in enzyme activity were observed between hormone- and vehicle-injected controls. In male rats testosterone propionate (0.5 mg) increased hypothalamic COMT by 53%; this effect was not detectable in animals treated with the androgen for 3 days. COMT activity of the superior cervical ganglion, pineal gland and anterior hypophysis did not exhibit significant changes after any of the hormone schedules used.