INTERACTION OF THE OPIATE AND NEUROENDOCRINE SYSTEMS

Opiates are known to produce various physiological effect s. Ou r understanding of these effects has been greatly increased by the discovery of the opiat e receptor and the endogenous opioid peptides. Recent investigation has demonstrat ed that th ree dist inct receptor subtypes exist; their function is currently being activel y investigated. Receptor theory holds that a drug's actions are the result of interactions between that drug and specific receptor molecules on the cell 's surface. The location of the receptors in the body and the number of drug molecules that inter act with them are important in determining the drug's effects. Vari ations in the dru g's chemical structure will vary its affinity for the receptor. Thi s relationship is the basis of st ructure activity relationships (SAR), a tool used by medicinal chemists when designing drugs. Ideally a drug will have high specificity and affinity for one type of recept or. In the field of psychopharmacology this ideal has not been achieved. Chlorpromazine, for example, interacts with cholinergic and alpha-adrenergic receptors to produce anti-cholinergic and orthostatic hypotensive effects as well as dopamine receptors to produce its desired antipsychotic effects. The challenge to drug designers is th