Biological and immunological characterization of human luteinizing hormone discharged by the stimulation of synthetic luteinizing hormone-releasing hormone (LH-RH) in normal and anovulatory women.

Abstract

Plasma samples were obtained by repeated venopunctures immediately before, and at 15, 30, 60, 120 and 180 min after intravenous bolus administration of 100 micrograms synthetic LH-RH in normal and various anovulatory women. Plasma hLH levels were determined by an in vitro bioassay and a radioimmunoassay with improved reagents. The LH-RH stimulation induced an abrupt elevation of both biological and immunological hLH activities in normal and anovulatory women, although the responsiveness to LH-RH differed from case to case. Both elevated biological and immunological hLH activities decreased gradually with a half disappearance time of 122.4 +/- 27.9 min and 112.5 +/- 25.4 min, respectively (Mean +/- S.D.). A transient and significant depression in the ratio of biological to immunological hLH activities (B/I ratio) was observed at 15 min after the LH-RH administration in normal subjects. This depression is attributable to the cross-contamination of an increased amount of hLH subunits induced by LH-RH stimulation. The B/I ratios were significantly elevated throughout the investigation period in the anovulatory patients when compared with those in the normal subjects. This elevation appears to indicate the increased discharge of special type(s) of hLH subpopulations of high biological potency in the anovulatory cases.