Secretoneurin in the brain of an electric fish: localization and putative functional role.

P. POUSSO; L. QUINTANA; G, C. LÓPEZ; G. M. SOMOZA; V. L. TRUDEAU; A. SILVA

Ciudad Autonóma de Cuenos Aires

Congreso; 7th International Symposium on Fish Endocrinology; 2012

Secretoneurin (SN) is a secretogranin-II derived neuropeptide found in centraland peripheral neuroendocrine cells and neurons. In goldfish, SN is present in theCNS and it has been shown to be both a neuroendocrine and paracrine regulatorof luteinizing hormone release. In the weakly electric fish, Brachyhypopomusgauderio basal electromotor output rate shows vasotocin-dependent modulations.Here we identify the presence of SN in the brain of B. gauderio and found that SNmay modulate electrical behavior. SN-immunoreactivity (SN-ir) was evident in bothparvocellular and magnocellular cells of the preoptic nucleus with fibers projectingto the neurohypophysis suggesting that SN could be released into circulation.These SN-ir fibers colocalize with isotocin (fish homolog of mammalian oxytocin)and suggest that both neuropeptides are co-released. Some adenohypophysealcells also showed SN-ir. SN-ir fibers were detected in the hindbrain where theelectromotor pacemaker nucleus (PN) lies. In an in vitro preparation (500-μm thickbrain slice containing the PN), goldfish SN (1μM) affected the spontaneous PN firing.These data show that B. gauderio is an advantageous neuroethological model to testnovel functions of SN