Sequential and opposing alterations of 5-HT1A receptor function during withdrawal from chronic morphine

Addiction is a brain chronic relapsing disorder associated with emotional distress. The serotonergic system and especially the 5-HT1A receptor crucially regulate emotional behaviors both in humans and rodents. Using [35S]GTPγS autoradiography in mice, we show that 5-HT1A receptor function is enhanced by chronic morphine treatment in the medial prefrontal cortex, and decreased in dorsal raphe nucleus one week later, two regions involved in emotional processing. These molecular adaptations could contribute to the development of emotional disorders experienced by former opiate addicts.