THE MECHANISM OF THE ANTI-GONAD ACTION OF PROLACTIN IN ADULT PIGEONS

Abstract

The pronounced anti-gonad action of prolactin in adult birds is an indirect effect of its action on the bird''s own pituitary, where it stops the release of F.S.H.; thereafter the gonad undergoes the rapid and extensive atrophy which likewise follows complete hypophysectomy or sex hormone administration. The ability of estrone, progesterone and testosterone to suppress the F.S.H. output of the pituitary has been observed in adult J1 ring doves. A measure of the normal daily output of F.S.H. from the pituitary of the adult S dove indicates this is equivalent to one minimum ovulation dose in the 4-month New Zealand rabbit. Prolactin induced an increase in body weight in the several groups of adult [male] doves and ? pigeons tested; in other similar groups such weight increase was partly or entirely overcome by preparations containing thyrotropic hormone. Thus 29 pigeons were dosed with an insoluble pituitary fraction; the 12 birds of this group given also 15 to 60 units of prolactin daily for 6 days had livers 44% larger than the 17 given the isosoluble fraction only. In 12 adult S doves liver size was increased 100% or more by 50 units of prolactin daily for 10 days.