Decoding the Influence of Central LEAP2 on Hedonic Food Intake and its association with Dopaminergic Reward Pathways

The gut-brain peptide ghrelin and its receptor (GHSR) are established as a regulator of hunger and reward-processing. However, the recently recognized GHSR inverse agonist, liver-expressed antimicrobial peptide 2 (LEAP2), is less characterized. Given the role of GHSR in many central processes, and in particular reward, understanding the central effects of LEAP2 is of high interest to understand reward-related behaviors and disorders, including hedonic feeding in eating disorders. The present study aimed to elucidate LEAP2s central effect on reward-related behaviors through hedonic feeding and its mechanism. LEAP2 was administrated centrally in male mice and effectively reduced hedonic feeding but had no or little effect on homeostatic chow intake when a more palatable option was available. Strikingly, the effect on hedonic feeding was correlated to the preference of the palatable food option, where peanut butter showed the highest preference and the greatest reduction by LEAP2. Further, LEAP2 reduced the rewarding memory of high-preference foods, as well as attenuated the accumbal dopamine release associated with peanut butter exposure and eating. Interestingly, LEAP2 was widely expressed in the brain, and in particular in reward-related brain areas such as the laterodorsal tegmental area (LDTg). The expression in this area was also markedly altered when given free access to peanut butter. Accordingly, infusion of LEAP2 into the LDTg was sufficient to attenuate acute peanut butter eating. Taken together, the present results show that central LEAP2 has a profound effect on central dopaminergic reward signaling and affects several aspects of hedonic eating. The present study highlights LEAP2s effect on reward, which may have application not only for hedonic feeding, but for other reward-related psychiatric disorders as well.