Role of Dopamine D2 Receptor in the Leptin Receptor‐expressing Neurons in Modulation of Compulsive‐like Eating Behavior

Abstract

Leptin, a hormone secreted by adipose tissue, is known to modulate satiety, caloric intake and body weight. There are six alternative spliced isoforms of leptin receptors (LepRa‐f). LepRb is highly expressed in the hypothalamic arcuate nucleus (ARC) which is involved in the regulation of food intake and body weight. Leptin activates pro‐opiomelanocortin‐expressing (POMC) neurons and inhibits agouti‐related peptide (AgRP)‐expressing neurons in the ARC.A recent study shows that dopamine modulates neuronal activities of arcuate POMC neurons and AgRP neurons. Dopamine inhibits arcuate POMC neurons via dopamine D2 receptor but activates AgRP neurons through dopamine D1 receptor. Dopamine is a neurotransmitter that plays a key role in mood, motivation and satiety. Dysregulation of dopamine neurotransmission is involved in the drug addiction. Food addiction is a recently proposed concept and compulsive eating behavior is shown in food addiction as well as an obesity. Negative reinforcement in drug addiction is a concept that negative affect associated with drug withdrawal promotes drug taking to ‘self‐medicate’ or remove those negative states. In the present study, we generated mice lacking D2 receptor in cells expressing LepRb (D2R flox; LepRb‐Cre; D2R cKO). Mice were provided palatable food for more than two weeks to induce food‐addiction like phenotypes in mice. To examine the role of D2 receptor in the leptin receptor‐expressing neurons in modulation of compulsive‐like eating behavior, light‐dark conflict test (LD test) was performed during the palatable food withdrawal period. In addition, palatable food withdrawal‐mediated anxiety/depression‐like behavior were measured during marble burying test (MBT), elevated plus maze (EPM), open filed test (OFT), and forced swim test (FST). No significant changes were found in palatable food (PF) intake in the light box during LD test, suggesting that D2 receptor in cells expressing LepRb would not be involved in the regulation of compulsive eating behavior. Furthermore, there was no significant changes in anxiety/depression‐like behavior measured by MBT, EPM, OPT and FST during the PF withdrawal period.Support or Funding InformationThis research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (2019R1I1A1A01060007).