The presence of peptidases in the rabbit hypothalamus capable of inactivating luteinizing hormone-releasing hormone.

The presence of peptidases in the rabbit hypothalamus capable of inactivating luteinizing hormone-releasing hormone (LH-RH) was investigated with the use of a sensitive and specific radioimmunoassay for the releasing hormone. Enzymes acting on LH-RH were found in two fractions from rabbit hypothalami, a particulate fraction and a supernatant fraction, which very rapidly inactivated the decapeptide. Peptidase activity in the particulate fraction from male and female rabbits was approximately the same, but the supernatant fraction from female animals had significantly greater peptidase activity than that from male animals. These findings confirm the hypothesis that rabbit hypothalamus contains peptidases which inactivate LH-RH, and give some indication that the enzymes may be involved in the control by the central nervous system of reproductive function.