Preface [Hot Topic: Cannabinoid Receptors (Guest Editor: Maria L. Lopez-Rodriguez)]

Central nervous system (CNS)-related pathologies have been one of the most ongoing challenges for scientists. Traditionally, these disorders have been studied from the point of view based on the therapeutic control of the classical and oldknown neurotransmitter systems. However, neurodegenerative diseases, pain and neuroprotection are examples of disorders which still need important efforts and better solutions for their management. In this context, the recent characterization of the endogenous cannabinoid system (ECS), widely -although not exclusivelydistributed throughout the CNS, represents an important focus of attention due to its therapeutic potential. To date, the ECS is constituted by two G-protein coupled receptors, the central CB1 and the peripheral CB2; its endogenous ligands (anandamide, 2-arachidonoylglycerol, 2-arachidonyl glyceryl ether, virodhamine) and an inactivation system that degrades these endocannabinoids. This termination system is thought to consist, in the case of anandamide, of a process of facilitated diffusion and an intracellular membrane bound enzyme termed fatty acid amide hydrolase (FAAH). The ECS is involved in the regulation of a variety of central processes such as antinociception, brain development, memory, retrograde neural communication and control of movement, among others. All these effects have attracted a renewed interest about the therapeutic applications to a broad number of pathologies including pain relief, traumatic brain injury and neurodegenerative diseases such as multiple sclerosis or Huntington's chorea. In this respect, we present a monographic hot topic providing the most recent therapeutic implications of ECS in CNS. This issue contains five reviews contributed by leading experts in the field. Drs. R. Maldonado, O. Valverde and P. Robledo review the participation of the opioid system in the acute and chronic effects induced by cannabinoids. Dr. Baker summarises the potential role of the ECS in the control of multiple sclerosis. The review contributed by Drs. J. Fernez-Ruiz, I. Lastres-Becker, A. Cabrales, E. de Lago and J.A. Ramos is focused on the involvement of the ECS in motor disorders. In our review, we offer a perspective about the potential implications of the anandamide transport in several CNS-related pathologies, together with the current hypothesis under investigation about its therapeutic applications as well as the most recent additions to the family of compounds able to inhibit the anandamide uptake. Finally, Dr. Fowler gives a complete revision about FAAH inhibitors and their therapeutic utility for the treatment of pain and neurodegenerative disorders. I am very grateful to all the above contributors for their excellent reviews and I hope readers will enjoy this issue which represents deep insights and excellent understanding of the subject.