Effect of luteinizing hormone-releasing hormone antiserum on sexual behavior in the female rat.

Various components of sexual receptivity were measured in ovariectomized, estrone-primed female rats following direct placement of luteinizing hormone releasing hormone (LH-RH) or a LH-RH antiserum into the medial preoptic area. Two hours after treatment with LH-RH antiserum, rats showed a significant increase in lordosis behavior indicative of increased sexual receptivity. When tested 3 and 7 hours after treatment, both LH-RH antiserum and LH-RH-treated rats displayed increased lordosis behavior. Similar treatment with a specific peripheral LH-RH agonist and antagonist had no effect on sexual behavior. Proceptive behavior was absent or minimal in all groups and therefore was not affected by the different treatments. Similarly, there was no difference in the rejection quotients of the females representing the various treatment groups. These results demonstrate that the same behavioral response can be observed in animals treated centrally with LH-RH and a highly specific LH-RH antiserum. Similar treatments with a specific peripheral LH-RH agonist or antagonist were without effect. These results suggest that the characteristics of LH-RH recognition sites in the brain are different from those in the pituitary.