Pituitary and ovarian hormones in cows with ovarian cysts.

Abstract

Gonadotropin profiles as well as sex steroids in the plasma of cows with ovarian cysts or cystic corpus luteum were examined. Bioactive inhibin levels and concentrations of sex steroids in the individual cystic fluid were determined to analyze the type of ovarian cyst. Plasma concentrations of LH in cows with follicular cysts were generally high as compared with basal LH levels in normal cows during the estrous cycle, though high levels of plasma estradiol-17β were noted. LH levels in cows with follicular cysts and corpus luteum, with luteal cyst or with cystic corpus luteum, however, were low similar to the basal levels of LH in the normal estrous cycle, being associated with high levels of plasma progesterone. Plasma concentrations of FSH in cows with any type of ovarian cyst, on the other hand, were within the range of basal levels of the normal estrous cycle, with no correlation to plasma levels of steroids.These results indicate that elevated levels of LH and basal levels of FSH within the normal range in the estrous cycle are characteristic in cows with follicular cysts. The possibility of involvement of inhibin in lowering FSH to basal levels in these cows with ovarian cysts is discussed.