The effect of short-term starvation on pituitary and plasma LH, plasma estradiol and progesterone, and on pituitary response to LH-RH in the laying hen ( Gallus domesticus)

Abstract

The effect of starvation on pituitary and plasma LH, plasma estradiol and progesterone levels, and pituitary response to LH-RH in the laying hen were studied. Deprivation of food for 7 days prevented egg laying and significantly decreased plasma LH, estradiol, and progesterone concentrations, but did not significantly change pituitary LH concentration. Resumption of feeding raised plasma LH and progesterone to their initial levels, but increased plasma estradiol to a higher level than its initial level within 3–4 days of refeeding. A single injection of 20 μg LH-RH to intact laying hens before starvation significantly increased plasma LH. LH-RH at 20-μg dose failed to increase plasma LH on the third day of food withdrawal, but increased it to some extent on the seventh day. The hen recovered initial sensitivity to LH-RH in increasing plasma LH after 7 days of refeeding. These results indicate that starvation caused follicular atresia in the hen probably due to the decrease of gonadotrophin secretion from the pituitary, and that starvation may reduce pituitary gonadotrope sensitivity to LH-RH in the hen at least in the early stage of fasting.