Effects of intracerebroventricular injection of dynorphin, leumorphin and alpha neo-endorphin on operant feeding in pigs.
Young pigs, which are useful experimental animals for biomedical research, were prepared with lateral intracerebroventricular (ICV) cannulae and housed individually in cages fitted with operant panels, with food and water ad lib. ICV injection of 200 micrograms of dynorphin A 1-17 or 1-13 resulted in a significant meal commencing within 2-5 min. Shorter fragments of dynorphin (1-10, 1-9, 1-8) were ineffective at inducing feeding as was dynorphin B (rimorphin). In the same situation, leumorphin and alpha neo-endorphin (200 micrograms) elicited significant feeding but beta neo-endorphin did not. Dynorphin 1-17 or 1-13, administered 5 min before feeding started, increased meal size when pigs were fed after 4-h deprivation. Naloxone ICV (0.4 mg) significantly reduced food intake in pigs feeding after 4-h deprivation and its main effect was in the second half of the meal. Naloxone also abolished the effect of ICV dynorphin. It is concluded that dynorphin and related endogenous opioids are involved in the regulation of food intake in pigs.
Baldwin
B A
BA
AFRC Institute of Animal Physiology and Genetics Research, Babraham, Cambridge, UK.
de la Riva
C
C
Ebenezer
I S
IS
D000818:Animals; D001070:Appetitive Behavior / Q000187:drug effects*; D001921:Brain / Q000187:drug effects*; D003216:Conditioning, Operant / Q000187:drug effects*; D004399:Dynorphins / Q000494:pharmacology*; D004723:Endorphins / Q000494:pharmacology*; D004745:Enkephalins / Q000494:pharmacology*; D005247:Feeding Behavior / Q000187:drug effects*; D005260:Female; D007276:Injections, Intraventricular; D008297:Male; D009042:Motivation; D009270:Naloxone / Q000494:pharmacology; D010446:Peptide Fragments / Q000494:pharmacology; D011498:Protein Precursors / Q000494:pharmacology*; D011957:Receptors, Opioid / Q000187:drug effects*; D013552:Swine
D004723:Endorphins; D004745:Enkephalins; D010446:Peptide Fragments; D011498:Protein Precursors; D011957:Receptors, Opioid; D009270:Naloxone; C025681:alpha-neoendorphin; D004399:Dynorphins; C033660:preproenkephalin