Endogenous ghrelin tone influences feeding responses to exogenous ghrelin

Program: Abstracts - Orals, Featured Poster Presentations, and Posters
Session: MON 676-684-Central Regulation of Appetite & Feeding
Monday, June 17, 2013: 1:45 PM-3:45 PM
Expo Halls ABC (Moscone Center)

Poster Board MON-683
Virginie Tolle*1, Rim Hassouna2, Philippe Zizzari2, Catherine Tomasetto3 and Jacques P Epelbaum2
1UMR894 Inserm, Paris, France, 2UMR894 INSERM, Paris, France, 3I.G.B.M.C., U964 INSERM UMR-7104 CNRS, ILLKIRCH, France
Ghrelin is the only orexigenic hormone originating from the gastrointestinal tract and its actions on appetite are relayed through the Growth Hormone Secretagogue Receptor 1a. However, feeding responses to intraperitoneal ghrelin injections vary considerably from one C57BL/6 mouse to the other (Hassouna et al. PLoS One 2012). Interindividual variability is observed amongst animals within the same experimental group, suggesting that environmental factors alone (nutrition, stress,...) cannot explain this variability.

In the present study, each mouse received three ghrelin injections (30 nmol, ip) in the early light phase followed by 2 washout days over a 2-weeks period to test the reproducibility of the response. Mice that were clearly high responders (60%, ie increased food intake over a threshold of 0.42 g 4 hours after the injection) retained the capacity to respond to ghrelin throughout the experimental period, thereby suggesting that an endogenous factor determines the sensitivity to this orexigenic signal. However, ghrelin-induced feeding response did not correlate with the amount of food consumed within 15 minutes prior to the injections (R2=0,001, P=0,887), suggesting that immediate feeding status prior to the injection was not causal in the variability of responses. Ghrelin response was next measured in a group of mice after a 30 minutes restraint-stress. Following restraint-stress, animals divided into both low (50%) and high-responders (50%), indicating that psychological stress does not interfere with ghrelin-induced feeding response. We then hypothesized that endogenous ghrelin tone may differentiate high and low responders and compared food intake in wild-type and ghrl -/- mice. Interestingly, whereas only 60% of wild-type injected mice increased food intake over the threshold, 100% of ghrl -/- mice responded to ghrelin.

These data demonstrate that feeding response to ghrelin varies with individual animals and suggest that endogenous ghrelin tone influences the response to exogenous ghrelin. Whether this variability is purely dependent on the individual, or on the individual under a specific environment only, still needs to be investigated

Nothing to Disclose: VT, RH, PZ, CT, JPE

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