Forebrain Mapping of Secretoneurin-Like Immunoreactivity and Its Colocalization With Isotocin in the Preoptic Nucleus and Pituitary Gland of Goldfish

CANOSA LF; LOPEZ GC; SCHARRIG E; LESAUX-FARMER K; SOMOZA GM; KHA O; TRUDEAU VL

JOURNAL OF COMPARATIVE NEUROLOGY

WILEY-LISS, DIV JOHN WILEY & SONS INC

Año: 2011 vol. 519 p. 3748 - 3765

0021-9967

ABSTRACTSecretoneurin, a 33–34 amino acid neuropeptidederived from the proteolytic processing of the secretogranin-II precursor protein, is reasonably well conservedin evolution. Goldfish secretoneurin shares >75% similarityoverall with other vertebrate secretoneurinsequences. The secretoneurin peptide has numerousfunctions that include neuroinflammation, neurotransmitterrelease, and neuroendocrine regulation. Adetailed description of the central distribution of secretoneurinimmunoreactivity is only known for the rat.Using our polyclonal antibody against the central, conservedcore of the secretoneurin peptide we studiedthe distribution of secretoneurin-like immunoreactivityin the goldfish brain. Secretoneurin immunoreactivitywas found in the olfactory bulb, entopeduncular nucleus,preoptic nucleus, lateral part of the lateraltuberal nucleus, posterior periventricular nucleus, nucleusof the posterior recess, the nucleus of the saccusvasculosus, and nucleus isthmi. Secretoneurin-immunoreactivefibers were found in the dorsal part of the dorsaltelencephalon, ventral and lateral parts of theventral telencephalon, periventricular preoptic nucleus,pituitary, and the ventrocaudal aspect of the nucleus ofthe lateral recess. The most conspicuous secretoneurinimmunoreactivity was found in the magnocellular andparvocellular cells of the preoptic nucleus that projectto the pituitary. Double-labeling studies indicated coexpressionwith isotocin, the fish homolog of mammalianoxytocin. Clear colabeling for secretoneurin and isotocinin fibers terminating in the neurointermediate lobe suggeststhat secretoneurin maybe coreleased with isotocin.Previous work indicates that secretoneurinstimulates the release of luteinizing hormone from thegoldfish anterior pituitary. Our findings further supporta reproductive role for secretoneurin and related peptides,given the importance of oxytocin family peptidesin reproductive behavior in vertebrates