DETECTION OF GNRH MOLECULAR-FORMS IN BRAINS AND GONADS OF THE CRESTEDNEWT, TRITURUS-CARNIFEX

Gonadotrophin-releasing hormone (GnRH) immunoreactivity is detectable in the brain, ovary, and testis of the newt, Triturus carnifex, collec ted during February (reproductive phase), May, and July (nonreproducti ve phase). In the brain of May animals, chicken GnRH-II positive cell bodies are located within the terminal nerve, the anterior preoptic ar ea, and the preoptic nucleus, which appears to be devoid of immunoreac tive mammalian GnRH cell bodies. During February and July, both chicke n GnRH-II and mammalian GnRH are detected only within the terminal ner ve and anterior preoptic area. Generally, in the reproductive as well as the nonreproductive periods, chicken GnRH-II fibers are widely dist ributed in the brain; however, the distribution of fibers of both mole cular forms suggests that they exert hypophysiotropic activity. High-p ressure liquid chromatography (HPLC) coupled with radioimmunoassay ind icates the presence of an early-eluting GnRH peak in brains and gonads but not in plasma. Using chicken GnRH-II antiserum, immunoreactivity is observed in spermatocytes, spermatozoa, and the external theca laye r. Seasonal changes of the GnRH-like material are observed in both sex es, and its high concentration detectable during February is in good c orrelation with the timing of reproduction. (C) 1997 Elsevier Science Inc.