Forebrain mapping of secretoneurin-like immunoreavtivity and its colocalization with isotocin in the preoptic nucleus and pituitary gland of goldfish

LUIS F. CANOSA; GABRIELA C. LÓPEZ; EMILIA SCHARRIG; KRISTINE LESAUX-FARMER; GUSTAVO M. SOMOZA; OLIVIER KAH; VANCE L. TRUDEAU

JOURNAL OF COMPARATIVE NEUROLOGY

WILEY-LISS, DIV JOHN WILEY & SONS INC

Año: 2011 vol. 519 p. 3748 - 3765

0021-9967

Secretoneurin, a 33-34 amino acid neuropeptide derived from the proteolytic processing of thesecretogranin-II precursor protein, is reasonably well conserved in evolution. Goldfish  secretoneurin shares >75% similarity overall with other vertebrate secretoneurin sequences. The secretoneurin peptide has numerous functions that include neuroinflammation, neurotransmitter release and neuroendocrine regulation. A detailed description of the central distribution of secretoneurin immunoreactivity is only known for the rat. Using our polyclonal antibody against the central, conserved core of the secretoneurin peptide we studied the distribution of secretoneurin-like immunoreactivity in the goldfish brain. Secretoneurin-immunoreactivity were found in the olfactory bulb, entopeduncular nucleus, preoptic nucleus, lateral part of the lateral tuberal nucleus, posterior periventricular nucleus, nucleus of the posterior recess, the nucleus of the saccus vasculosus, and nucleus isthmi. Secretoneurin-immunoreactive fibers were found in the dorsal part of the dorsal telencephalon, ventral and lateral parts of the ventral telencephalon, periventricular preoptic nucleus, pituitary and the ventrocaudal aspect of the nucleus of the lateral recess. The most conspicuous secretoneurin-immunoreactivity was found in the magnocellular and parvocellular cells of the preoptic nucleus that project to the pituitary. Double-labeling studies indicated co-expression with isotocin, the fish homolog of mammalian oxytocin. Clear co-labeling for secretoneurin and isotocin in fibers terminating in the neurointermediate lobe suggests that secretoneurin maybe co-released with isotocin.Previous work indicates that secretoneurin stimulates the release of LH from the goldfish anteriorpituitary. Our findings further support a reproductive role for secretoneurin and related peptides, given the importance of oxytocin family peptides in reproductive behavior in vertebrates.