| Abstract: | Levels of luteinizing hormone-releasing factor (LH-RF), the spontane ous preovulatory surge of luteinizing hormone (LH) and the copulatory reflex release of LH were studied by radioimmunoassay in rats. Blood samples were taken at 9.00, 12.00, 15.00, 18.00, and 21.00 hours of proestrus. LH peaks related to LH-RF values were observed at 18.00 hours in 8 of 11 animals. Plasma LH levels were markedly increased in 13 of 22 animals following mating, though there were no parallel increases in LH-RF. It is concluded that the concentration of plasma LH-RF does not reflect the level of LH-RF in hypophysial blood. |
