Purification and characterization of luteinizing hormone from pituitary glands of rockfish, Sebastes schlegeli

Abstract

To acquire greater knowledge of the reproductive function of luteinizing hormone (LH) in the viviparous rockfish Sebastes schlegeli, LH from the pituitary glands of mature rockfish was isolated, purified, and localized and its biological activity was characterized. The molecular mass of purified LH was estimated to be approximately 33 kDa, similar to that of known LH. When rockfish LH was purified by reverse-phase high-performance liquid chromatography, its N-terminal amino acid sequences were found to coincide with those of predicted cDNA sequences of rockfish gonadotropin alpha (ssGTH alpha) and ssLH beta mature peptides. Immunocytochemical analysis using antisera against ssGTH alpha (molecular weight [MW], similar to 14.5 kDa) and ssLH beta (MW, similar to 18.5 kDa) indicated that the LH-producing cells are mainly distributed throughout the proximal pars distalis and along the periphery of the pars intermedia. Further, in vitro ovarian follicle analysis demonstrated that purified intact rockfish LH significantly enhances E(2) secretion in a dose-dependent manner. This is the first report on the purification and characterization of LH from a viviparous teleost, and these results will enable future research and increase our understanding of the mechanisms underlying the maturation of such fish. (C) 2011 Elsevier Inc. All rights reserved.