The last few years have produced exciting and important new developments in opiate research as the result of various outstanding studies by investigators in a number of different laboratories. The seemingly puzzling demonstration that electrical stimulation-produced analgesia in rats could be counteracted by injection of the narcotic antagonist naloxone, in the absence of any exogenous narcotic, was one of the first suggestions of an endogenous opioid action. In vitro binding studies with radioactively labeled potent narcotics and narcotic antagonists were found to provide an effective technique for determining the tissue distribution and concentration of the opiate receptors. Probably the most active and fascinating new avenue of research has been in the multidisciplinary area of the isolation, synthesis, and pharmacological characterization of the various endogenous peptides, such as the enkephalins and other endorphins, which apparently act as ligands for opiate receptors. Although at the present time it appears that the endorphins probably produce tolerance and dependence similar to morphine itself, and from a practical standpoint would lead only to a more expensive morphine-like substance, the vast potential of molecular modification may still allow for the synthesis of new derivatives with less addictiveness, greater resistance to hydrolytic or other types of inactivation, longer duration of action, and improved effectiveness by intravenous and other routes of administration outside the central nervous system. Recent work suggests that some of the beneficial analgesic effect of acupuncture may be related to the action of the endogenous opioids, as indicated by the fact that naloxone has been reported to decrease acupuncture analgesia. The expanding studies in the field of the endogenous opioids may lead to the elucidation of many mechanisms of action which are of fundamental pharmacological importance.

Other recent studies have resulted in advances in the understanding of opiate neurochemistry, the nature and purification of opiate receptors, possible differences in opiate receptors, the complex effects of narcotics on behavior, and metabolic aspects of opiate agonists and antagonists. The following articles present new contributions in many of these areas of opiate research and provide additional scientific knowledge which should assist in the efforts to achieve solutions to the problems of opiate abuse and addiction, and at the same time improve the safety of the valuable legitimate medical uses of the opiates and opioid narcotics.

HAROLD BLUMBERG Department of Pharmacology New York Medical College Valhalla, New York 10595