ARS | Publication request: OREXIN REGULATES APPETITE IN SHEEP

Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: July 20, 1999
Publication Date: N/A

Technical Abstract: Orexin is a hypothalamic neuropeptide that regulates feeding behavior in rats. Orexin-B has recently been cloned in pigs and was shown to stimulate food intake after intramuscular injection. This study was designed to determine whether icv and iv injections of orexin could regulate appetite in sheep. Suffolk wethers were moved to indoor facilities and adapted to diets for 6 wk and trained to stand in stanchions for 3 to 6 h each day fo 2 wk before having lateral ventricle cannulas installed. These sheep were provided water and fed ad libitum. On the day before an experiment, sheep were provided jugular cannulas and on the day of an experiment were placed in stanchions and allowed to stand for 1 h before use. Sheep were then monitored over a 2-h control period prior to iv injection with saline or porcine orexia-B (3 up/kg BW) or IC injection with artificial CSF, orexia-B (0.3 up/kg BW), neuropeptide Y (NPY;0.3 up/kg BW) or orexia and NPY. Food intake was monitored for consecutive 2-h periods. In both iv and IC sheep food intake was increased in the first 2 h by orexia (P<0.05). In the comparison with NPY, orexia had a similar effect to the NPY injection in the first 2 h after injection (.09 kg food intake to .23 and .2 kg respectively). The combination of NPY and orexia had a slightly greater though nonsignificant effect on food intake (to .34 kg). Differences were not apparent in subsequent 2 h interval. These data indicate that orexia stimulates feed intake in sheep after IC stimulation, and as described for the pig, orexia also enhances appetite when administered through a peripheral route.