**Part 7**

**Future Applications** 

624 Pharmacology

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**28** 

*Brazil* 

Francisney Pinto Nascimento1,2,

*1Department of Pharmacology;* 

**The Involvement of Purinergic System in** 

Sérgio José Macedo Jr.2 and Adair Roberto Soares Santos1,2

*2Laboratory of Neurobiology of Pain and Inflammation,* 

**Pain: Adenosine Receptors and Inosine as** 

*Department of Physiological Sciences; Universidade Federal de Santa Catarina* 

 During the recent years, the interest in the purinergic system has been gaining importance, and this interest is not accidental. The purinergic system is so far known to be involved in several physiological conditions in mammals, becoming a potential therapeutic target for the treatment of many pathologies and disorders. One of the physiological roles is the control of pain. This chapter will emphasize adenosine receptors (P1) and its activation and inhibition by adenosine and by specific agonists or antagonists in the treatment of pain. Although most of the studies quoted in this chapter were performed in animals, in this chapter we will use the expression *analgesia* instead of *antinociception* (term used to report pain in animals) to simplify our communication. Some drugs that act on adenosine receptors have presented interesting results in clinical studies of pain and other drugs are under investigation. Of note, it has recently been shown that inosine, a metabolite of adenosine, has significant analgesic effects in several pre-clinical models of pain. Thus, the inosine can be an important tool in this area of study or even a molecule of interest for future pharmacological approaches, knowing that such as adenosine, it is produced endogenously and devoid of side effects in normal doses. In addition, new approaches using enzyme inhibitors of the purinergic system or supplies of adenosine suggest alternatives to potentiate and lasting analgesic effects of adenosine or analogs. Moreover, the release of purines and the adenosine A1 receptor activation are essential to analgesia by acupuncture in mice. Thus, purinergic system will be the target of many future pain-treatment researches. After all, it is indispensable to students and biomedical professionals to know

Purinergic receptors history began when Drury and Szent-Györgi described the potent actions of purines adenine and adenosine on the heart and blood vessels (Drury & Szent-

and understand basic concepts about this endogenous system.

**2.1 Purinergic receptors: History and involvement in pain** 

**2. Involvement of purinergic system in pain** 

**1. Introduction** 

**Pharmacological Tools in Future Treatments** 
