title: Identification of A3 adenosine receptor agonists as novel non-narcotic analgesics.
abstract: Chronic pain negatively impacts the quality of life in a variety of patient populations. The current therapeutic repertoire is inadequate in managing patient pain and warrants the development of new therapeutics. Adenosine and its four cognate receptors (A1 , A2A , A2B and A3 ) have important roles in physiological and pathophysiological states, including chronic pain. Preclinical and clinical studies have revealed that while adenosine and agonists of the A1 and A2A receptors have antinociceptive properties, their therapeutic utility is limited by adverse cardiovascular side effects. In contrast, our understanding of the A3 receptor is only in its infancy, but exciting preclinical observations of A3 receptor antinociception, which have been bolstered by clinical trials of A3 receptor agonists in other disease states, suggest pain relief without cardiovascular side effects and with sufficient tolerability. Our goal herein is to briefly discuss adenosine and its receptors in the context of pathological pain and to consider the current data regarding A3 receptor-mediated antinociception. We will highlight recent findings regarding the impact of the A3 receptor on pain pathways and examine the current state of selective A3 receptor agonists used for these studies. The adenosine-to-A3 receptor pathway represents an important endogenous system that can be targeted to provide safe, effective pain relief from chronic pain.
authors.affiliation: Department of Pharmacology and Physiology, Saint Louis University School of Medicine, St. Louis, MO, USA.
authors.forename: K
authors.initials: K
authors.lastname: Janes
authors.affiliation: Department of Pharmacology and Physiology, Saint Louis University School of Medicine, St. Louis, MO, USA.
authors.forename: A M
authors.initials: AM
authors.lastname: Symons-Liguori
authors.affiliation: Molecular Recognition Section, Laboratory of Bioorganic Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA.
authors.forename: K A
authors.initials: KA
authors.lastname: Jacobson
authors.affiliation: Department of Pharmacology and Physiology, Saint Louis University School of Medicine, St. Louis, MO, USA.
authors.forename: D
authors.initials: D
authors.lastname: Salvemini
mesh_terms: D058909:Adenosine A3 Receptor Agonists / Q000737:chemistry / Q000494:pharmacology*; D018712:Analgesics, Non-Narcotic / Q000737:chemistry / Q000494:pharmacology*; D059350:Chronic Pain / Q000188:drug therapy* / Q000378:metabolism; D006801:Humans; D043684:Receptor, Adenosine A3 / Q000378:metabolism*
chemical_list: D058909:Adenosine A3 Receptor Agonists; D018712:Analgesics, Non-Narcotic; D043684:Receptor, Adenosine A3