Stress and the dopaminergic reward system

Abstract

Dopamine regulates reward-related behavior through the mesolimbic dopaminergic pathway. Stress affects dopamine levels and dopaminergic neuronal activity in the mesolimbic dopamine system. Changes in mesolimbic dopaminergic neurotransmission are important for coping with stress, as they allow adaption to behavioral responses to various environmental stimuli. Upon stress exposure, modulation of the dopaminergic reward system is necessary for monitoring and selecting the optimal process for coping with stressful situations. Aversive stressful events may negatively regulate the dopaminergic reward system, perturbing reward sensitivity, which is closely associated with chronic stress-induced depression. The mesolimbic dopamine system is excited not only by reward but also by aversive stressful stimuli, which adds further intriguing complexity to the relationship between stress and the reward system. This review focuses on lines of evidence related to how stress, especially chronic stress, affects the mesolimbic dopamine system, and discusses the role of the dopaminergic reward system in chronic stress-induced depression.

Neuroscience: finding reward in stressful situations

The brain’s response to stressful conditions is linked to mechanisms for processing rewarding stimuli, but the nature of this connection remains poorly understood. Studies indicate that how animals cope with acute or chronic stress relies in part on dopamine, a neurotransmitter that produces ‘reward’ signals in the brain. Ja-Hyun Baik, Korea University, Seoul, South Korea, reviews how stress influences dopamine-mediated signaling, in particular exploring the hypothesis that the nature of stressful stimuli specifically determines the behavior induced by dopamine and the way signals are perceived in terms of stress or reward. However, the author also notes the many unanswered questions around the neurological mechanisms underlying chronic stress, and the depression and lack of pleasure produced by stress. Further research is needed to understand the role of dopamine signaling.