Session: MON 676-684-Central Regulation of Appetite & Feeding
Poster Board MON-684
Food restricted GHSR-KO (n=10) and wild-type (WT) rats (n=10) were trained to bar press on a fixed ratio 1 (FR1) schedule of reinforcement, followed by FR4, and finally a progressive ratio (PR) schedule for purified grain-based pellets. The procedure was repeated for purified chocolate-flavored, sugar, and high-fat chocolate pellets, respectively. We hypothesized that an absence of intact ghrelin signaling in KO rats would attenuate the amount of effort produced to obtain reinforcers, an effect that is likely to be exaggerated when the pellet is highly palatable. An analysis of the cost-benefit ratio as measured by breakpoint was conducted. Results show that while the KO and WT rats performed similarly to eachother on a PR schedule to obtain grain, chocolate flavor and high-fat chocolate pellets, when pressing for sugar pellets, the KO rats failed to increase their rate of bar pressing. Interestingly, both WT and KO rats exhibited less effort to obtain the high-fat chocolate reinforcer (though the amount of calories earned was comparable). In the presence of a sweet reinforcer the GHSR KO rat does not escalate its responding as is typical for a hungry animal. As sugar is known to be a highly palatable reinforcer, these results highlight that the absence of GHSR can influence the incentive value attributed to food rewards.
Nothing to Disclose: SJK, LS, AA
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