Editorial [Hot topic: Endocannabinoid Receptor System (Guest Editor: Robyn A. Puffenbarger)]

As I reflected about the progress in the endocannabinoid field for this Hot Topics issue, I cannot help but think of the recent losses to our community. In 2008, we were stunned by the untimely passing of two leaders in our field, Billy Martin (1943- 2008) and Mike Walker (1950-2008). I had the privilege of seeing both give lectures, and their research legacy is apparent from the tremendous impact they each had on endocannabinoid research. What is not as visible is the number of lives both Drs. Martin and Walker touched as mentors and “builders” of the next generation of scientists. As I think about Dr. Martin's contributions, the tetrad of cannabinoid effects comes to mind as a critical moment for our field. As the authors in this volume write about pain and CNS diseases in particular, I can see the links of those ideas to Dr. Martin's tetrad. From the tetrad of cannabinoid effects, particularly antinocipception, entire lab careers have sought to understand the role of cannabinoids in prevention of pain perception. In this edition, Drs. Guinnon and Hohmann's review of the pain literature focuses on two endocannabinoids, 2-arachidonyl glycerol and anandamide. Dr. Walker's lab also sought to understand the role of endocannabinoids in pain and his lab's website continues to proclaim that “pain kills.” It is fitting that the first review here also examines the role of endocannabinoids as potential therapies for pain perception. Critical to the understanding of the endocannabinoid involvement in pain perception and the linked-diseases is the ability of cannabinoids to change cellular responses. In the second paper, Drs. Dalton, Bass, Van Horn, and Howlett review the growing literature on endocannabinoid signal transduction pathways. From the receptors to the proteins to the nucleus, and back to the responses of the cell, these authors clearly lay out the molecular implications for endocannabinoids and their related compounds. This area is far from complete in terms of understanding, and our authors point out the newest research in the hepatocytes and adipose tissue, hinting at the relevance of endocannabinoids to appetite and obesity research.