The Functional Relationship between Priming and Releasing Actions of Luteinizing Hormone-Releasing Hormone*

Abstract

To examine the relationship between the priming and releasing actions of LRFon LH secretion, 14 normal cycling women received 4 different rates of LRF infusion (0.005, 0.01, 0.05, and 0.1 µg/m²·min for 4 h). The releasing action of the infusion was measured as the area under the curve and the priming effect was assessed by the acute LH increment in response to a test pulse of LRF (10 µg) at the end of infusion. At the lower 2 infusion rates, there were only minor changes in releasingfunction, but it increased exponentially (r = 0.986) with higher rates of infusion. In contrast, the priming effect of the lower 2 doses of infusion increased markedly as a function of infusion rate, but no additional priming was found with the higher rates ofinfusion. Thus, over the range of infusion rates employed, the releasing and priming functions of LRF appear to be dose dependent. These results indicate that the interdependent releasing and priming actions of LRFon LK secretion are functionally dissociable and thatlarge elevations of LRF tend to favor release, while small LRF increments seem to promote priming preferentially. (JClin Endocrinol Metab49: 8,1979)