Inhibition of the preovulatory LH surge after a catecholestrogen (2-hydroxyestrone) antiserum injection in the third ventricle of cycling female rats.

Administration of a catecholestrogen (2-hydroxyestrone, 2-OHE1) antiserum (2-OHE1-AS) in the third ventricle of cycling female rats, on the morning of proestrus, leads to a significant reduction in the afternoon LH surge. These responses are dose-dependent and can be observed even when the 2-OHE1-AS is injected on the diestrus morning. Almost similar results were obtained with an antiserum against 17 beta-estradiol (17 beta-E2). Nevertheless, the fact that the central immunoneutralization of 2-OHE1 impedes the preovulatory surge of LH at a time of high peripheral levels of 17 beta-E2 strengthens the idea of a specific role for 2-OHE1 in the control of cycling LH release.