ABSTRACT
In a series of publications, W. R. Martin and his associates have developed a theory of chronic tolerance and physical dependence. A more elaborate theory of “new receptors” to explain tolerance and physical dependence has been proposed by H. O. Collier. Collier also discusses the possible roles played by the transmitter substances, acetylcholine and norepinephrine, in connection with morphine tolerance and physical dependence. The type of morphine-”dependence” described by W. D. M. Paton is more difficult to relate to physical dependence in organisms with a central nervous system. The survey of “theories related to physical dependence” should include at least brief mention of the possible role of physical dependence in the perpetuation of drug-seeking behavior and in relapse. The role of altered serotonin metabolism in the development of tolerance to and physical dependence on opioids has been called into question by the results of further investigations.
