Neuroanatomical distribution and putative functional role of secretoneurin in the CNS of a weakly-pulse type electric fish.

PAULA POUSO; LAURA QUINTANA; GABRIELA C. LÓPEZ; VANCE L. TRUDEAU; GUSTAVO M. SOMOZA; ANA SILVA

Boston

Congreso; The 9th World Congress on Neurohypophysial Hormones; 2011

Secretoneurin (SN) is a secretogranin-II derived neuropeptide found in secretoryvesicles of numerous central and peripheral neuroendocrine cells and neurons. SN isinvolved in neuroinflammation and angiogenesis in mammals. In goldfish, it has beenshown to be both a neuroendocrine and paracrine regulator of luteinizing hormonerelease; yet neuroanatomical evidence suggests numerous other modulatory roles. Inthe weakly electric fish, Brachyhypopomus gauderio basal electromotor output rateshows vasotocin-dependent modulations (daily, seasonal, and social). Here we identifythe presence of SN in the brain of B. gauderio and found that SN may modulateelectrical behavior. SN-immunoreactivity (SN-ir) was evident in both parvocellular andmagnocellular cells of the preoptic nucleus with fibers projecting to theneurohypophysis, suggesting that SN could be released into circulation. Someadenohypophyseal cells also showed SN-ir. SN-ir fibers were detected in the hindbrainwhere the electromotor pacemaker nucleus (PN) lies. In an in vitro preparation (500-m thick brain slice containing the PN), goldfish SN (1µM) affected the spontaneousPN firing rate. Taken together these data show that B. gauderio is an advantageousneuroethological model to test novel functions of SN.Supported by ANII FCE2007_569, CSIC2010I+D, PEDECIBA (Uruguay), ANPCyT, CONICET (Argentina)and NSERC (Canada).