What are the post-climax effects of opioids in the brain?
The endogenous opioid system consists of 3 families of opioid peptides, β-endorphin, enkephalins, and dynorphins, and their receptors. Opioid peptides and their receptors have widespread, but selective, distribution in the central and peripheral nervous systems. They are particularly found in circuits involved in pain modulation, reward, responses to stress, and autonomic control.
It’s believed that one class of opioids (endorphins) is particularly involved with feelings of euphoria during sex, while the other two classes have roles in inhibition of sexual desire and dopamine release.
The mesolimbic system participates in the naltrexone-induced reversal of sexual exhaustion: Opposite effects of intra-VTA naltrexone administration on copulation of sexually experienced and sexually exhausted male rats