Study of the neurobiological mechanisms which regulate reward eating behaviors during caloric restriction: role of the hormone ghrelin and its receptor GHSR

DANIELA CASSANO, FRANCO BARRILE, MIRTA REYNALDO, GUADALUPE GARCÍA ROMERO, MARIO PERELLÓ.

Buenos Aires

Congreso; XXXVII SAN 2022 Annual Meeting; 2022

Ghrelin is a stomach-derived hormone that acts via growth hormone secretagogue receptor (GHSR). GHSR is expressed in the arcuate nucleus (ARC), in the lateral hypothalamic area (LHA) and in the dopamine neurons of the ventral tegmental area (VTA) that innervates the nucleus accumbens (Acb). Since plasma ghrelin levels increase under calorie restriction (CR), GHSR signaling could act in the mesolimbic pathway and affect reward-related behaviors. During our CR protocol mice were daily exposed to 40% of their daily ad libitum food intake for 5 days and were daily exposed to a saccharine solution, for 4h, a non-caloric purely rewarding stimulus before the meal. As previous results showed that GHSR is required for the increase of saccharine consumption observed in CR mice, we studied the neurobiological mechanisms which control the consummatory behavior of palatable stimuli under CR. We found that the ARC is not required for the increase of saccharine consumption or the LHA and Acb activation observed in CR mice. Also, we showed that GHSR in dopamine neurons is not required for the increased of saccharine consumption in CR mice, and dopamine neurons lack c-Fos induction in CR mice. Furthermore, the block of orexin receptor 1 did not show any changes in saccharine consumption. On the other hand, the GHSR expression exclusively in the LHA shows a tendency to restore the consummatory behaviors. Thus, we conclude that the LHA could coordinate the consumption of saccharine under CR.