Abstract

Scientific progress in the biological sciences increasingly relies on an integration of behavioral, pharmacological, cellular, and molecular approaches, particularly in translating basic research observations into therapeutic potential. The strength of in vivo model systems lies in the direct assessment of physiological function. However, they only allow indirect evidence for mechanism of action. Frequently, in vitro models provide just the opposite. A combination of both in vitro and in vivo approaches are often essential for establishing the underlying mechanisms of a specific pharmacological effect. In recent times, an endogenous cannabinoid system has been characterized due to the combined efforts of chemists, pharmacologists, molecular and cellular biologists, and biochemists. This endogenous cannabinoid system is providing a basis for systematically addressing the pharmacological controversies surrounding marijuana. The description of this endogenous cannabinoid system and the strategies for establishing the physiological function of this system are the subjects of this article.