Prolactin in Male and Female Reproduction

Abstract

In female rats prolactin levels in plasma remained very low until puberty at which time a sharp rise may occur beginning the day before vaginal opening. It is possible that this may be induced by estrogen secretion resulting from the action of FSH and LH on the ovary since estrogen injections can produce a similar rise in prepubertal rats. Similar changes were found in male rats with prolactin secretion paralleling plasma testosterone levels and a sharp elevation just preceding the rapid growth of seminal vesicles at puberty. In young heifers pituitary prolactin content paralleled mammary development, rising rapidly in the first three months and then more slowly until nine months. In humans in contrast, prolactin levels are higher in children than in adults. Levels are very high in cord blood and in infant blood in the first day of life, but then rapidly decline. Prolactin can be detected in the infant’s urine in the first few days of life and it has been suggested that this prolactin may be the cause of the “witch’s milk” phenomenon when infants lactate in the first few days of life. (Clemens, Minaguchi, Storey, Voogt, Meites, 1969: Dowd, Bartke, 1972: Frantz, Kleinberg, Noel, 1972b: Friesen, Belanger, Guyda, Hwang, 1972: Friesen, Hwang, Guyda, Tolis, Tyson, Myers, 1972: Lyons, 1937: Minaguchi, Clemens, Meites, 1968: Sinha, Tucker, 1969: Voogt, Chen, Meites, 1970: Yamamoto, Taylor, Cole, 1970.)