Close association of gonadotropin-releasing hormone fibers and gonadotropin, growth hormone, somatolactin and prolactin expressing cells in pejerrey,Odontesthes bonariensis

The purpose of this study was to determine if there is any association betw een immunoreactive (ir) gonadotropin-releasing hormone (GnRH) fibers with d ifferent pituitary endocrine cell types in the pejerrey, Odontesthes bonari ensis. Using a monoclonal antibody raised against mammalian GnRH (mGnRH) (L RH13), ir-GnRH fibers were observed passing through the pituitary stalk and reaching the three areas of the pituitary gland: rostral (RPD) and proxima l pars distalis (PPD) and pars intermedia (PI). Double labeled immunocytoch emistry showed ir-GnRH fibers in close association with prolactin (PRL)-pro ducing cells in the RPD, growth hormone (GH)-producing cells in the PPD, go nadotropin (GtH)-producing cells in the PPD and the external border of the PI, and with somatolactin (SL)-producing cells in the PI. Our results show, direct morphological evidences of a close association of GnRH fibers with GH, PRL, GtH and SL-expressing cells. These results would suggest that GnRH has a broad role in the regulation of the secretion of different pituitary hormones.