Early effects of stilboestrol on growth hormone and prolactin secretion and on pituitary mitotic activity in the male rat.

Abstract

SUMMARY The effects of a single injection of 1 mg diethylstilboestrol dipropionate on pituitary mitotic activity and on secretion of growth hormone and prolactin were investigated in male rats on each of the first 15 days following the single dose and then at intervals for a total period of 63 days. Mitotic activity increased to a maximum on day 4 and then gradually diminished. Serum growth hormone was moderately increased during the 2nd week and serum prolactin showed a gradual rise with a return to normal on day 63. In the pituitary gland, growth hormone concentration diminished until day 28, whereas prolactin rose quickly at first, maintained a raised level and increased further on day 43. During the first 12 days, pituitary weight was significantly correlated with serum growth hormone and prolactin concentration. During days 13–28, serum prolactin, but not growth hormone, was significantly correlated with the pituitary mitotic index.