A person develops tolerance to an opioid drug. Which mechanism within the brain's reward circuit explains this adaptation?

💡 Explanation

Tolerance occurs due to receptor desensitization and downregulation in the mesolimbic pathway because the brain attempts to maintain homeostasis in response to chronic opioid exposure. Therefore, higher doses are needed to achieve the same effect, rather than an increase in receptor number or activity of inhibitory neurotransmitters.

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