Radioimmunoassays of Follicle Stimulating Hormone and Luteinizing Hormone in the Dog

Abstract

Heterologous radioimmunoassays for canine FSH and LH were developed and used to quantitate these hormones during proestrus, estrus and diestrus of the bitch. The assay for FSH consists of a rabbit anti-human FSH serum, radioiodinated rat FSH and dog FSH-LER-l685-3A as standard. Inhibition curves produced by the standard, crude extracts of canine pituitary glands and various canine plasma were parallel. Specificity of FSH assay was confirmed by testing for binding inhibition with canine LH (LER-l685-l). Binding was hardly affected by canine LH. The intra- and interassay coefficients of variation was 3.1% and 10.8%. Sensitivity of the FSH assay was 0.20 ng/tube which was adequate to quantify the concentration of FSH in 100 μl or less of canine plasma. The LH assay consists of a rabbit anti-ovine LH serum, radioiodinated rat LH and dog LH-LER-l685-l as standard. Crude extracts of canine pituitary glands and various canine plasma p roduced inhibition curves which were parallel to the standard curve. Binding inhibition was no affected by canine FSH(LER-l685-3A). The intra- and interassay coefficients of variation was 5.8% and 14.3%. Sensitivity of the LH assay was 10.7 pg/tube which allowed estimation of LH concentrations in 100 μl or less of canine plasma. During the reproductive cycle, levels of FSH were lowest during proestrus (51.1 ± 7.4 ng/ml) and increased to 305.5 ± 39.6 ng/ml on a day after LH peak. Levels of FSH declined by Day 4 (63.5 ± 10.4 ng/ml) then increased to 117.4 ± 11.9 ng/ml on Day 18 after LH peak. Levels of LH increased only during preovulatory LH surge, during proestrus and diestrus, were less than 0.5 ng/ml.