Influence of a physiological infusion of prostaglandin F 2α into postpartum cows with partially suppressed endogenous production of prostaglandins. 1. Uterine and ovarian morphological responses

Abstract

On day of parturition (day 0), Brown Swiss cows were assigned to either a control untreated group (n=6) or one of two groups (n = 6/group) in which cows were treated twice daily from days 0 to 6 postpartum with Flunixin Meglumine (FM; 1 g/i.m. injection), a prostaglandin synthetase inhibitor. Cows treated with FM received a continuous infusion of either 0.9% saline (FM + saline; days 1 to 10: 46.5 ml/day) or prostaglandin F 2α (PGF 2α) Tham salt (FM + PGF 2α; days 1 to 3 and 7 to 10: 33.8 mg/day; days 4 to 6: 67.7 mg/day) into the descending aorta via a catheter inserted into the costoabdominal artery. Rectal palpation was thrice weekly from days 5 to 60 postpartum to assess utero-ovarian morphological changes. Profile of 15-keto-13, -14-dihydro-PGF 2α (PGFM) concentrations in peripheral plasma collected between days 1 and 11 was lower (p<0.01) in the FM + saline than in the control group animals. IN contrast, following replacement with PGF 2α, profiles of PGFM were similar in the FM + PGF 2α and control groups although peak concentrations were delayed by 2 days in the FM + PGF 2α group. Postpartum decrease in cervical and uterine horn diameter and location of the uterus in the pelvic canal did not differ (P>0.1) among groups. Compared to control cows, ovarian activity of both ovaries was reduced (p<0.01) following partial suppression of prostaglandin synthesis early postpartum. However, replacement with PGF 2α increased (p<0.01) ovarian activity of ovaries ipsilateral to the previously gravid uterine horn. We concluded that partial suppression of prostaglandin synthesis early postpartum did not alter rate of uterine involution in cattle and that PGF 2α may be implicated in the resumption of ovarian activity.