Evaluation of the effect of orexin-1 receptors in the nucleus accumbens shell on cost-benefit decision making in male rats

Background: Cost-benefit decision-making is a one of the decision-making models in which the animal achieves a final benefit (reward) by evaluating the cost (effort or delay). The role of different brain regions such as nucleus accumbens in this process has been proven. Orexin is a neuropeptide expressed exclusively by lateral hypothalamus area neurons and orexin-producing neurons project their axons throughout the brain such as nucleus accumbens. The nucleus accumbens is a region of neural system that serves effort-based decision-making and orexin 1 receptor is distributed extensively throughout nucleus accumbens. Different physiological acts for erixin have been shown including cognitive actions and rewards. Since there is limited knowledge about this subject, this study aimed to examine the effect of orexin 1 receptor in the nucleus accumbens shell on effort-based decision-making. Materials and Methods: In this study, T-maze was used to investigate cost-benefit decision-making based on effort, and the effect of SB334867 (30, 100, 300 nM/0.5µlDMSO), as selective orexin 1 receptor antagonist, within the nucleus accumbens shell was examined. Results: SB334867 300 nM/0.5µl DMSO (injection in the shell of nucleus accumbens) significantly decreased the percentage of high reward choice (P<0.01) than the control group. Conclusion: SB334867 affects the animal's preference for crossing the barrier and achieving more rewards, and the animal chooses to lower reward, without any effort.