IDENTIFICATION OF IMMUNOREACTIVE MAMMALIAN GONADOTROPIN-RELEASING-HORMONE IN THE BRAIN OF METAMORPHIC LARVAE OF BUFO-ARENARUM HENSEL (AMPHIBIA, ANURA)

Gonadotropin-releasing hormone (GnRH) immunoreactivity in brain extrac ts of Bufo arenarum tadpoles were investigated by high-performance liq uid chromatography, followed by radioimmunoassay analysis using two di fferent antisera raised against different GnRH variants. Only one immu noreactive peak was identified, eluting in the same position as synthe tic mammalian GnRH. This result was further confirmed by serial diluti on studies using more specific mammalian GnRH antisera. Our results su ggest that mammalian GnRH is most Likely an endogenous peptide in the brain of the developing larvae and froglets of Bufo arenarum and quite likely it is the only GnRH variant present during those development s tages. The distribution and density of cell bodies and fibers were ana lysed by immunocytochemical procedures. Immunoreactive cell bodies app eared in the olfactory epithelium and across the olfactory nerve at la te prometamorphic larval stages. Near the metamorphic climax and in fr oglets, perikarya and fibers were detected in basal forebrain, preopti c and hypothalamic areas. No immunoreaction was observed at midbrain, hindbrain and spinal cord levels. This study suggests that mammalian G nRH is most likely an endogenous peptide and is probably the only GnRH variant in the brain of the developing larvae and froglets of Bufo ar enarum. Copyright (C) 1996 ISDN.