Central neuropeptide Y enhances bile secretion through vagal and muscarinic but not nitric oxide pathways in rats.
Neuropeptide Y (NPY) acts in the central nervous system to regulate gastrointestinal functions in rats and dogs. The effects of intracisternal injection of NPY on bile secretion and biliary components were investigated in urethane-anesthetized rats with bile duct cannula. Intracisternal NPY (0.02-0.12 nmol) dose-dependently increased bile secretion by 9.2-19.5%. The secretory response occurred within the first 20-40 min and lasted for the 120-min observation period. Intravenous injection of NPY (0.12 nmol) did not modify bile secretion under identical conditions. Biliary bile acid, phospholipid, and cholesterol secretion were not modified by intracisternal injection of NPY (0.12 nmol), whereas bicarbonate was increased by 19.0 +/- 1.7% from 40 to 120 min after NPY injection. Cervical cord transection at the C6 level, acute bilateral adrenalectomy (-120 min), or injection of NG-nitro-L-arginine methyl ester (10 mg/kg, IV, -15 min), an inhibitor of nitric oxide biosynthesis, did not alter intracisternal NPY (0.12 nmol)-induced stimulation of bile secretion. Atropine (2.0 mg/kg, IP, -30 min) and bilateral cervical vagotomy (-120 min) completely abolished the stimulatory effect of intracisternal NPY (0.12 nmol) on bile secretion. These findings indicate that NPY acts in the brain to stimulate bicarbonate-dependent bile secretion through vagal and muscarinic pathways and suggest that peptides in the central nervous system may be involved in the vagal regulation of bile secretion.
D000109:Acetylcholine / Q000502:physiology; D000818:Animals; D001639:Bicarbonates / Q000378:metabolism; D001646:Bile / Q000378:metabolism*; D002946:Cisterna Magna; D004305:Dose-Response Relationship, Drug; D007267:Injections; D050356:Lipid Metabolism; D008297:Male; D009434:Neural Pathways / Q000187:drug effects; D009478:Neuropeptide Y / Q000494:pharmacology*; D009569:Nitric Oxide / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D011976:Receptors, Muscarinic / Q000187:drug effects*; D014630:Vagus Nerve / Q000187:drug effects*
D001639:Bicarbonates; D009478:Neuropeptide Y; D011976:Receptors, Muscarinic; D009569:Nitric Oxide; D000109:Acetylcholine