Failure of High Dietary Fat to Influence Serum Prolactin Levels during the Estrous Cycle in Female Sprague-Dawley Rats 1

Abstract

Abstract

The influence of a 20% high-fat and a 4.5% control fat diet on circulating prolactin levels was determined during the estrous cycle of intact female rats, and during a progesteroneinduced surge of prolactin in ovariectomized, estrogen-primed rats. An indwelling right atrial cannula was implanted into each rat to facilitate repeated blood sampling in conscious, undisturbed animals. No differences in serum prolactin levels were observed at any time during the estrous cycle or in the progesterone-induced surge of prolactin in rats fed either the high-fat or control fat diet. There also were no differences in the estrous cycles of rats on high- or low-fat diets. It is concluded that high dietary fat promotes mammary tumor development by a mechanism that does not involve alterations in circulating prolactin levels or of estrous cycles.