Reproductive Hormone and Transcriptomic Responses of Pituitary Tissue in Anestrus Gilts Induced by Nutrient Restriction

The onset of estrus is a critical sign of female sexual maturity. The pituitary plays a vital role in this process by the secretion of reproductive hormones. To investigate the effects of nutrient restriction on reproductive function and the underlying mechanisms involved, deep RNA sequencing of pituitary gland tissue was carried out to determine the differentially expressed genes (DEGs) between gilts in normal estrus, and gilts in which anestrus was induced by nutrient restriction. Gilts which had gone through two estrus cycles were fed a normal (CON, 2.86kg/d, n = 10) or nutrient restricted (NR, 1kg/d, n = 10) diet. The NR gilts experienced another three estrus cycles, but did not express estrus symptoms at the anticipated 6th and 7th cycles. Body weight gain in NR gilts was significantly decreased by nutrient restriction. Gilts were considered as anestrus when blood progesterone concentrations lower than 1.0 ng/mL from three consecutive blood samples were recorded. Circulating concentrations of progesterone (