Validation of an Ovine-Ovine LH Radioimmunoassay for Use in the Hamster1

The 00 LH double-antibody RIA system developed by Niswender at al. (1968a) has been tested to show its specificity for LH in the hamster. In this system hamster sera, hamster pituitary homogenates, sheep pituitary LH standard, and rat pituitary LH standard all show parallel dose-response curves. Hamster sera, TSH, and FSH do not appear to interfere with the assay of LII. Reproducibility and precision of the assay are within acceptable limits. The system reveals highly signfficant increases in serum LH after ovariectomy, during the course of proestrus and after in vivo administration of purified LH-releasing hormone. Blood samples were collected at different times up to 1 hr after a single iv, ip, or im injection of synthetic LH-RH. Only iv administration of the releasing hormone caused a rapid rise in circulating LH. At all times up to 1 hr the response seen after an im injection was contained within the dome of the curve representing the response observed after iv administration. Responses seen after ip and im injections were similar.