Effects of Ethanol on Synthesis of Prostaglandin F2α in Bovine Females

Ethanol stimulates the production of prostaglandins in many species. The purpose of this study was to verify the effect of ethanol on the production of prostaglandin F2α (PGF2α) and luteolysis in bovine females. In the first experiment, Holstein cows at day 17 of the oestrous cycle were treated with 100% ethanol (0.05 ml/kg of body weight, IV; n = 5), saline (0.05 ml/kg of body weight, IV; n = 4) or synthetic prostaglandin (150 μg of D‐cloprostenol/cow, IM; n = 4). The plasma concentrations of 13, 14‐dihydro‐15‐keto PGF2α (PGFM; the main metabolite of PGF2α measured in the peripheral blood) were assessed by radioimmunoassay (RIA). There was an acute release of PGFM in response to ethanol comparing to other treatments (p ≤ 0.05). However, only cows treated with PGF2α underwent luteolysis. In the second experiment, endometrial explants of cross‐bred beef cows (n = 4) slaughtered at day 17 of the oestrous cycle were cultured for 4 h. During the last 3 h, the explants were cultured with medium supplemented with 0, 0.1, 1, 10 or 100 μl of 100% ethanol/ml. Medium samples were collected at hours 1 and 4 and concentrations of PGF2α were measured by RIA. Ethanol did not induce PGF2α production by the endometrium. In conclusion, ethanol does not cause luteolysis in cows because it stimulates production of PGF2α in extra‐endometrial tissues.