Radioimmunoassay of rabbit luteinizing hormone during pregnancy and following immunization with homologous antibodies to bovine LH

A sensitive radioimmunoassay has been developed to measure rabbit LH using guineapig anti-ovine LH serum and radiodinated ovine LH. In the assay, rabbit pituitary LH standard and rabbit serum LH produced parallel dose response curves. Within the physiological ranges, the system was free from interference with oFSH, and o-prolactin. Reproducibility and precision of the assay were within acceptable limits. In female rabbits, there was a significant increase in serum LH levels immediately after mating and it remained so till two hours after mating. The levels came down to basal levels and stayed low throughout pregnancy. The levels of LH were also analysed in animals who received injections of globulin fraction of homologous antiserum to ovine LH(AsoLH) or normal rabbit serum (NRS)+ on every 11th day of their successive pregnancies. There was a significant rise in LH levels (P 0.02) post-treatment with AsoLH when values were compared with pre-treatment levels or with those obtained from animals treated with NRS. The serum levels were also analysed in two rabbits treated with AsoLH and in one rabbit treated with NRS before and immediately after the injections. There was significant rise in LH levels immediately after the AsoLH injection and 15 day post-delivery levels were higher than the preinjection levels. No such rise in LH levels was observed in animal treated with NRS. (auth.)