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 homogenates from adult female Wistar rats with normal cycles and that had been ovariectomized, adrenalectomized, and steroid-treated.

RESULTS

Activities of the two enzymes changed significantly during the normal estrus cycle. Both peaked during metestrus, with COMT showing a secondary peak of activity at proestrus. Progesterone treatment significantly increased and estradiol decreased PNMT activity in comparison to untreated 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 tissues possess the enzymatic machinery to synthesize epinephrine from norepinephrine, and suggest the activity of this pathway may be mediated by variations in the sex hormone environment of the uterus.