Both animal models and human studies suggest that the endogenous opioid system is involved in mood regulation.1-5
In a human study, PET scans compared opioid system activity in healthy controls vs patients with MDD in response to social rejection.5
In healthy controls, the negative emotional stimuli activated the endogenous opioid system in key brain regions involved in regulating mood.
In patients with MDD, the endogenous opioid system showed significantly less activation, indicating impaired function of this system.
Overall, these studies suggest that the opioid system must be functioning properly to maintain normal mood regulation.1-5
Opioid receptors are generally believed to play a role in the expression of mood, emotion, reward, and motivation. Agonism or antagonism of the different opioid receptors may lead to varying behavioral and/or physiological outcomes.1-4,9,10
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