AGI January 41/1

Fujimiya, Mineko, Etsuro Itoh, Naoki Kihara, Ikuo Yamamoto, Masaki Fujimura, and Akio Inui. Neuropeptide Y induces fasted pattern of duodenal motility via Y2 receptors in conscious fed rats. Am. J. Physiol. Gastrointest. Liver Physiol. 278: G32–G38, 2000.—Neuropeptide Y (NPY), a 36-amino acid peptide abundantly expressed in the brain, has been implicated in the regulation of feeding and visceral functions. The present study was designed to investigate whether or not NPY specifically regulates duodenal motility. The manometric method was used to measure duodenal motility in conscious, freely moving rats. The rat duodenum showed phasic contractions mimicking the migrating motor complex in the fasted state that were replaced by irregular contractions after the ingestion of food. NPY powerfully affected the contractile activity after intracerebroventricular (icv) administration, changing fed (postprandial) patterns into phasic contractions characterized as fasted (interdigestive) patterns. This effect was mediated via receptors with pharmacological profiles similar to rat Y2 and Y4 receptors, although neither Y1 nor Y5 agonists had any effects on motility despite potent feeding-stimulatory effects. Immunoneutralization with anti-NPY antiserum administered icv abolished fasted patterns and induced fed-like motor activities. An icv dose of peptide YY produced a different effect from NPY, with increase in the motor activities of both fed and fasted patterns. These results indicate that fasted and fed motor activities are regulated processes and that NPY induces fasted activity through Y2, and possibly Y4, receptors, which may represent an integrated mechanism linked to the onset of feeding behavior.