title: The effects of aging on day-night rhythms of kappa opiate-mediated feeding in the mouse.
abstract: Day-night rhythms in feeding behavior and response to the specific kappa opioid agonist U-50,488H (0.10-10. mg/kg) were measured in young (1-2 months), mature (8-12 months) and old (24-30 months) male CF-1 mice. All the mice consumed more food at night than in the day-time, though this nocturnal peak was markedly reduced in old and mature animals. Young mice also displayed a significant, dose-related, nocturnal enhancement in U-50,488H-stimulated feeding. This day-night rhythm was reduced in mature animals and absent in old mice. In old mice, U-50,488H significantly stimulated feeding only after the high dose of 10 mg/kg. Additionally, old animals did not show the dose-dependent latency to initiation of feeding after administration which was observed in young mice and to a lesser extent in mature animals.
mesh_terms: D019900:3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer; D000367:Age Factors; D000375:Aging; D000818:Animals; D002940:Circadian Rhythm / Q000187:drug effects; D005247:Feeding Behavior / Q000187:drug effects / Q000502:physiology*; D008297:Male; D051379:Mice; D011759:Pyrrolidines / Q000494:pharmacology*; D011930:Reaction Time / Q000187:drug effects; D011957:Receptors, Opioid / Q000502:physiology*; D017473:Receptors, Opioid, kappa
chemical_list: D011759:Pyrrolidines; D011957:Receptors, Opioid; D017473:Receptors, Opioid, kappa; D019900:3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer