RESUMEN
Plasma 17 beta-estradiol concentrations, thecal estrogen content, and uterine prostaglandin synthetase activity were measured in healthy and prolapsed hens as well as in layers that recovered after exposure to low intensity lighting (250 or 50 lx). The effect of estradiol benzoate injections (100 ng, 3 X per week) in hens exposed to high intensity light (greater than 500 lx) was also studied. Prolapsed hens had significantly lower plasma 17 beta-estradiol concentrations (60 +/- 12 pg/ml; mean +/- SEM) than recovered (374 +/- 40 pg/ml) or healthy hens (475 +/- 45 pg/ml). Theca cells from recovered hens had a significantly higher content of 17 beta-estradiol (.7 ng/5 X 10(5) cells) than theca cells from normal or prolapsed birds (.3 ng/5 X 10(5) cells). Microsomes prepared from the uteri of prolapsed hens converted significantly less arachidonic acid to prostaglandin metabolites (4.4%) than did microsomes from healthy or recovered birds (9.0%). Treatment of prolapsed hens with estradiol benzoate resulted in 89% of the birds recovering within 3 weeks compared to a 4% recovery rate in the controls. We conclude that restoration of peripheral 17 beta-estradiol concentrations to normal levels was concomitant with recovery in prolapsed birds, and suggest that the estrogen exerts its effect by raising the level of prostaglandin synthetase activity in the uterus.