Biological and immunological properties of zebra pituitary gonadotropins: comparison with horse and donkey gonadotropins.

Previous studies from this laboratory have described the properties of purified luteinizing hormone (LH) and follicle-stimulating hormone (FSH) from horse and donkey anterior pituitary glands. The present study afforded the opportunity to further characterize these previously purified hormone preparations and to compare them with enriched gonadotropin fractions from zebra pituitary glands. Although a single LH and FSH fraction was usually obtained for each pool of pituitaries, two separate zebra LH and two donkey FSH preparations were generated. Purified hormone preparations from the horse were designated eLH and eFSH. Preparations zLH-A, zLH-B, and zFSH were obtained from zebra pituitaries, and fractions dLH, dFSH-A, and dFSH-B were prepared from donkey pituitary glands. These preparations were analyzed by LH and FSH radioimmunoassays (RIAs), radioreceptor assays (RRAs), LH bioassay, and chromatofocusing. Clear immunological differences were observed between equid gonadotropins. Homologous RIAs for eLH and eFSH did not cross-react similarly, or in a parallel fashion, with gonadotropins from the donkey and zebra. In contrast, RIAs capable of assessing LH or FSH in a wide number of species showed all equid gonadotropin preparations to have considerable activity and to produce parallel dilution curves. Relative to eLH (1.00), zLH-A was found to have higher LH bioactivity:LH RIA (2.50), LH RRA:LH RIA (1.42), and LH bioactivity: LH RRA (2.21) activity ratios. The dLH and zLH-B fractions only differed from eLH in LH RRA:LH RIA activity (0.69 and 0.62, respectively). Only LH from the horse possessed clear intrinsic FSH-receptor-binding activity.(ABSTRACT TRUNCATED AT 250 WORDS)