Relationship between the concentration of cholecystokinin-like immunoreactivity in plasma and food intake in male rats.
In food-deprived male rats IP injection of cholecystokinin octapeptide (CCK-8, 5 micrograms), ingestion of food or ejaculation caused a comparable increase in plasma concentrations of CCK-8 and inhibited food intake. IV injection of 0.1 microgram CCK-8 interrupted ongoing feeding and greatly increased plasma CCK-8 levels. Osmotic minipumps delivering 0.5 micrograms CCK-8/h implanted IP reduced meal size and caused a modest increase in plasma CCK-8 levels. Injection of 5 micrograms CCK-8 IP produced an abrupt but transient increase in plasma CCK-8 concentrations whereas plasma concentrations of CCK-8 increased gradually with feeding. Injection of 5 micrograms CCK-8 IP, but not feeding, caused a marked increase in plasma oxytocin levels. The suppression of feeding, but not the increase in oxytocin, induced by IP CCK-8 was reversed by ICV injection of the CCK antagonist proglumide in a dose (100 micrograms) which failed to affect food intake if injected IP. Deprivation of food decreased and feeding increased the concentration of CCK-like immunoreactivity in the CSF. It is suggested that CCK-8 inhibits feeding in physiological doses by a specific mechanism in which peripheral as well as central neural CCK is involved.
Lindén
A
A
Department of Psychiatry, Karolinska Institute, Huddinge, Sweden.
Södersten
P
P
D000818:Animals; D001921:Brain / Q000187:drug effects / Q000502:physiology; D002766:Cholecystokinin / Q000097:blood*; D004305:Dose-Response Relationship, Drug; D004435:Eating / Q000187:drug effects / Q000502:physiology*; D005247:Feeding Behavior / Q000187:drug effects / Q000502:physiology*; D008297:Male; D051381:Rats; D011949:Receptors, Cholecystokinin / Q000187:drug effects / Q000502:physiology; D012844:Sincalide / Q000494:pharmacology
D011949:Receptors, Cholecystokinin; D002766:Cholecystokinin; D012844:Sincalide