Effect of prostaglandins F2alpha and E2 on milk ejection, blood pressure and mammary artery blood flow in the cow

Abstract

Injections of prostaglandins F2alpha (threshold dose: 1 to 5 microgram) and E2 (threshold dose: 1000 to 300 microgram) in the jugular vein or the carotid artery induced milk ejection in lactating cows after a relatively long latency period. In several cases with PGF2alpha and in one case with PGE2, milk ejection was accompanied by a simultaneous increase in blood flow through the mammary artery. Both routes of administration showed the same response. It is suggested that the effect of the prostaglandins on milk ejection is indirect, possibly secondary to a release of oxytocin from the neurohypophysis.