Prostaglandin E2 alpha-induced release of oxytocin from ovine corpora lutea in vitro

Abstract Prostaglandin (PG)F 2 alpha, in the dose range 1−10 4 nM, failed to elicit oxytocin secretion in vitro from ovine luteal tissue on day 12 of the estrous cycle (estrus = Day 0), during a 60 minute period. Preincubation of luteal slices for 6 hours prior to treatment suggested that tissue desensitization due to the release of endogenous prostaglandins by tissue preparation is not responsible for this lack of response. However, in luteal tissue collected on day 6 of the ovine estrous cycle, PGF 2 alpha stimulated oxytocin release in a dose-dependent manner. This apparent change in sensitivity of the ovine corpus luteum in vitro may be due to a combination of a reduction in the luteal oxytocin available for release and saturation of PGF 2 alpha receptors in the more mature tissue.