PHENYLETHANOLAMINE-N-METHYL TRANSFERASE AND CATECHOL-O-METHYL TRANSFERASE-ACTIVITY IN RAT UTERUS - CYCLIC AND STEROID-INDUCED CHANGES

Purpose. The activity of phenylethanolamine-N-methyl-transferase (PNMT ) and catechol-O-methyl-transferase (COMT) was studied in uterine homo genates from adult female Wistar rats with normal cycles and that had been ovariectomized, adrenalectomized, and steroid-treated. Results. A ctivities of the two enzymes changed significantly during the normal e strus cycle. Both peaked during metestrus, with COMT showing a seconda ry peak of activity at proestrus. Progesterone treatment significantly increased and estradiol decreased PNMT activity in comparison to untr eated controls. Hydrocortisone administration had no effect on uterine PNMT activity. COMT activity was not affected significantly by any of the steroid treatments. Conclusion. The data confirm that uterine tis sues possess the enzymatic machinery to synthesize epinephrine from no repinephrine, and suggest the activity of this pathway may be mediated by variations in the sex hormone environment of the uterus.