Editorial

Serotonin (5-HT) is a widely distributed neurotransmitter and hormone in the mammalian central nervous system and periphery. In 1957 Gaddum and Picarelli reported the characterization of two distinct receptors for serotonin, namely M and D receptors. Since then, several other serotonin receptors have been identified and characterized. Starting from 1988, with the advent of molecular cloning techniques, fourteen receptors of serotonin have been cloned from several species. After nearly fifty years of intense research efforts, witnessed by the introduction into the market of serotonergic drugs such as buspirone, ondansetron, ketanserine, and paroxetine among many others, one could ask whether it is still worth studying the serotonin system. Clearly, the answer is yes. From a search of Scifinder® database on July 2005, it emerged that among the 5-HT receptors, the 5-HT2C subtype was the object of intense research. Drs. G. Di Giovanni, V. Di Matteo, M. Pierucci, A. Benigno and E. Esposito present a review on the pharmacological characteristics of this receptor, whereas Drs. E. Lacivita and M. Leopoldo offer an overview on the studies carried out in both pharmaceutical companies and academy aimed to the identification of selective agents for 5-HT2C receptor. The review by Drs. M. J. Bubar and K. A. Cunningham focus on one of the most promising therapeutic application for 5-HT2C and 5-HT2A receptor agents, namely the treatment of psychostimulant addiction in humans. The role of 5-HT in pain mechanisms has been evidence nearly twenty years ago. Recently, several 5-HT receptor subtypes have been localized into the spinal cord. These new findings have supported the involvement of serotonin receptors in pain mechanisms. Dr. J. A. Lopez-Garcia has reviewed electrophysiological observations from spinal neurons using local administration of serotonergic agents. The review by Drs. J. A. Mico, E. Berrocoso, A. Ortega-Alvaro, J. Gibert-Rahola, and M. O. Rojas-Corrales focuses on 5-HT1A receptors as a target in the search of new pharmacological approaches in the augmentation of analgesia. The 5-HT3 receptor has been the target for the develovepment of several drugs for chemotherapy induced emesis therapy. Starting from the clinical use of such agents some other potential therapeutic uses for 5-HT3 receptor antagonist have emerged. Drs. W. Müller, B. L. Fiebich, and T. Stratz have reviewed their physiology–driven studies on new treatment options in rheumatic diseases using 5-HT3 receptor antagonists. The last two reviews are important updates on studies performed in the field of serotonergic agents. In particular, the review by Dr. A. Bojarski provide a detailed overview on the pharmacophore models proposed up-to-date for the serotonergic receptors. The review by A. M. Moresco, M. Materrese, and F. Fazio describes the state of the art in the discovery of PET and SPET radioligands for the in vivo visualization of serotonin receptors