Some Thoughts on the Present Status and Future of Opioid Research

Abstract

In 1978, a few years after the identification of opioid receptors and the subsequent isolation of their endogenous ligands, our group published a monograph in which the state of opioid research at that time was represented. In the present work, published some 12 years later, more recent developments in this field are reviewed. The importance of opioids as biologically active peptides is probably reflected in their apparently long evolutionary history: opioids have been identified in a wide variety of species, ranging from primitive multicellular organisms to humans, and in both neural and nonneural tissue systems. At present, there is hardly an area of neurobiology in which opioid actions have not been implicated, and their involvement in nonnervous modulation of physiological processes is also receiving increasing recognition. Nevertheless, despite an immense amount of research, the real functional significance of these peptides, and the mechanisms underlying their actions, remains elusive.