Effect of meta-chlorophenylpiperazine and cholecystokinin on food intake of Osborne-Mendel and S5B/P1 rats.
OBJECTIVE
To investigate whether there is a difference in sensitivity to a serotonin agonist, meta-chlorophenylpiperazine (mCPP), or cholecystokinin (CCK-8), an intestinal hormone that inhibits food intake, between the Osborne-Mendel (OM) rat, which becomes obese eating a high-fat diet, and the S5B/Pl (S5B) rat, which is resistant to dietary-induced obesity.


METHODS
OM and S5B rats were adapted to either a high-saturated-fat diet (56% energy as fat) or a low-fat diet (10% energy as fat) or to both for 14 days and then treated with several doses of mCPP or CCK-8.


RESULTS
Treatment with mCPP reduced food intake in both strains of rats. The dose-response curve showed that the OM rats had an increased sensitivity to the serotonergic agonist. Animals eating the high-fat diet had less response to mCPP; and in the S5B rats, the response was significantly reduced. After treatment with CCK-8, there was a similar dose-related suppression of food intake in both the OM and S5B rats.


CONCLUSIONS
These data are consistent with the hypothesis that the serotonin system in the S5B rat has a greater activity that could act to inhibit fat intake. The response to CCK was not significantly affected by strain or diet.
White
Christy L
CL
Pennington Biomedical Research Center, 6400 Perkins Road, Baton Rouge, LA 70808, USA. Whitecl@pbrc.edu
Ishihara
Yuri
Y
York
David A
DA
Bray
George A
GA
D000818:Animals; D002766:Cholecystokinin / Q000494:pharmacology*; D004036:Diet, Atherogenic; D018752:Diet, Fat-Restricted; D004305:Dose-Response Relationship, Drug; D004435:Eating / Q000187:drug effects*; D005765:Gastrointestinal Agents / Q000494:pharmacology; D008297:Male; D010879:Piperazines / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D058826:Serotonin 5-HT2 Receptor Agonists
D005765:Gastrointestinal Agents; D010879:Piperazines; D058826:Serotonin 5-HT2 Receptor Agonists; D002766:Cholecystokinin; C015068:1-(3-chlorophenyl)piperazine