Endorphins in psychiatry: an overview and a hypothesis.

This article presents an overview of the biochemistry, pharmacology, and physiology of endogenous opioid peptides (endorphins). Clinical psychopharmacology of exogenous opiate agonists and antagonists is reviewed. The evidence presented in the review is compatible with a hypothesis that the level of functional endorphins may be related to psychological events, with a normal level needed for psychological homeostasis. One corollary of this hypothesis is that the level of opioids in the brains of the mentally ill may be disturbed. Therapeutic implications of this hypothesis are considered.