Concentrations of Prolactin, Luteinizing Hormone and Follicle Stimulating Hormone in Pituitary and Serum of Horses: Effect of Sex, Season and Reproductive State

Publisher Website
Google Scholar
Abstract
Pituitary and serum from 86 male or female horses of various reproductive states were collected in the normal breeding season (summer) and in the nonbreeding season (winter) at a commercial slaughterhouse. Concentrations of prolactin (PRL), luteinizing hormone (LH) and follicle stimulating hormone (FSH) were measured by radioimmunoassay. Concentrations of pregnant mare serum gonadotropin and reproductive steroids in serum and gross appearance of the reproductive tract and gonads were used to catagorize reproductive state. Concentrations of PRL were higher (P<.01) in summer than in winter in pituitary and serum of mares, stallions and geldings. In summer, mares had higher (P<.01) concentrations of PRL in serum than stallions. In mares, concentrations of LH in pituitary were higher (P<.05) in summer than in winter. Concentrations of LH in serum were 1) higher (P<.01) in summer than in winter in mares and geldings, 2) higher (P<.01) in mares than in stallions in summer, 3) higher (P<.01) in geldings than in stallions in summer and 4) higher (P<.01) in mares with low serum progesterone (P) concentrations than in mares with high P concentrations in summer. Concentrations of FSH in pituitary and serum did not differ between summer and winter for any type of horse. Concentrations of FSH in pituitary were 1) higher in mares than in stallions in both summer (P<.01) and winter (P<.07), 2) higher (P<.01) in mares with high serum P concentrations than in mares with low P concentrations in summer and 3) higher in pregnant (greater than approximately 40 d) mares than nonpregnant mares with high serum P concentrations in both summer (P<.06) and winter (P<.07). Concentrations of FSH in serum were higher in geldings than in stallions in both summer (P<.01) and winter (P<.03) and were higher (P<.01) in mares with low serum P concentrations than in mares with high P concentrations in summer.

This publication has 10 references indexed in Scilit: