Radioimmunoassay of rabbit luteinizing hormone: serum levels during various reproductive states.

A highly sensitive, 5-day double antibody radioimmunoassay method has been developed to measure rabbit luteinizing hormone (LH), using guinea pig anti-ovine LH serum and radioiodinated ovine LH. In the assay, rabbit serum, rabbit pituitary homogenates and a rabbit pituitary LH standard produce parallel doseresponse curves. Within physiological ranges, the system is free from interference with rabbit follicle stimulating hormone (FSH) or rabbit thyroid stimulating hormone (TSH), and appears quite specific for LH. Reproducibility and precision of the assay are within acceptable limits. In a series of preliminary tests, LH was found to be low in males as well as in females during estrus, anestrus, pregnancy and after hemi-ovariectomy. In rabbits which had been ovariectomized for periods of 4–14 months, mean plasma LH levels were higher than in estrous animals and a circhoral rhythm was suggested by a wide SD which appeared to be unrelated to the duration of ovariectomy. In female rabbits, serum LH levels inc...