DISTRIBUTION AND ACTIVITY OF DOGFISH NPY AND PEPTIDE YY IN THE CARDIOVASCULAR-SYSTEM OF THE COMMON DOGFISH

Neuropeptide Y is present in sympathetic nerves in the mammalian cardiovascular system. This study has investigated the distribution of neuropeptide Y in the cardiovascular and gastrointestinal systems and the effect of dogfish neuropeptide Y and related peptides on cardiovascular tissue of an elasmobranch fish, the common dogfish (Scyliorhinus canicula). Neuropeptide Y-like immunoreactivity is present in varicose nerve fibers innervating dogfish gut and cardiovascular tissue and in endocrine cells of the dogfish spiral intestine. Dogfish neuropeptide Y, dogfish peptide YY, and porcine neuropeptide Y contract the dogfish afferent branchial artery in a concentration-dependent manner. The effect is not inhibited by the presence of tetrodotoxin or by removal of the endothelium. The mammalian Yl receptor selective agonist [Leu31Pro34]NPY but not the mammalian Y2 receptor selective agonist neuropeptide Y-(13-36) peptide has vasoconstrictor properties in this system, suggesting that the receptor mediating the vasoconstriction resembles the mammalian Yl receptor more than the Y2 receptor.