Effect of indomethacin dexamethasone-induced parturition in swine

The hypothesis that corticosteroids induce parturition in swine by stimulating the synthesis of prostaglandins was tested. Twenty Yorkshire sows were treated with indomethacin and(or) dexamethasone or the respective vehicles of the drugs. Only sows treated with dexamethasone alone showed a premature increase in the concentration of prostaglandin F2 alpha-metabolite (PGF2 alpha-M), a decrease in the concentration of progesterone in the peripheral plasma and induction of parturition. Treatment with indomethacin alone or indomethacin plus dexamethasone prolonged gestation and prevented an increase in PGF2 alpha-M and a decrease in progesterone. These results show that the effect of dexamethasone on prepartum luteolysis and induction of parturition is mediated through stimulation of the synthesis or the release of PGF2 alpha.