Changes in LH and prolactin in arteriosclerotic femal breeder rats.

Serum levels of LH and prolactin were measured in repeatedly-bred, arteriosclerotic female rats. Serum LH was abnormally decreased on the afternoon of proestrus and estrus. The extent of the depression of circulating LH levels parallels the severity of the arteriosclerosis. Serum prolactin was significantly increased above normal at proestrus, and the degree of prolactin increase was also correlated with the degree of severity of arteriosclerosis. It is suggested that frequent and repeated pregnancies affect the hypothalamic-pituitary-adrenal-gonadal axis leading to hormonal and metabolic imbalance, which may play a causal role in the pathogenesis of the spontaneous arteriosclerosis which appears in repeatedly-bred rats.