NITRIC-OXIDE SYNTHASE IN THE CAUDAL NEUROSECRETORY-SYSTEM OF THE TELEOST OREOCHROMIS-NILOTICUS

This study provides evidence that, within the caudal neurosecretory sy stem of the teleost Oreochromis niloticus, neurons express nitric oxid e synthase (NOS)-like molecules. The presence of NOS-like molecules wa s demonstrated by means of NADPH-diaphorase (NADPHd) staining and NOS immunohistochemistry. In the caudal spinal cord, NOS-positive neurosec retory cell bodies and neurosecretory fibers were observed. in additio n, NOS-positive structures were found in the urophysis which correspon d to neurosecretory axon terminals. Cellular co-localization of NOS an d ovine corticotropin-releasing factor (oCRF) immunoreactivities confi rmed that the NOS-positive structures belong to the caudal neurosecret ory system. The present results suggest that NO may participate in the caudal neuroendocrine function. (C) 1997 Elsevier Science Ireland Ltd .