Morphine desensitization, internalization, and down-regulation of the mu opioid receptor is facilitated by serotonin 5-hydroxytryptamine2A receptor coactivation.

Analysis of the distribution of mRNA encoding the serotonin (5-hydroxytryptamine) 5-HT(2A) receptor and the mu opioid peptide receptor in rat brain demonstrated their coexpression in neurons in several distinct regions. These regions included the periaqueductal gray, an area that plays an important role in morphine-induced analgesia but also in the… CONTINUE READING