title: Adenosine A(1) receptors in the central nervous system: their functions in health and disease, and possible elucidation by PET imaging.
abstract: Adenosine is a neuromodulator with several functions in the central nervous system (CNS), such as inhibition of neuronal activity in many signaling pathways. Most of the sedating, anxiolytic, seizure-inhibiting and protective actions of adenosine are mediated by adenosine A(1) receptors (A(1)R) on the surface of neurons and glia. Positron Emission Tomography (PET) is a powerful in vivo imaging tool which can be applied to investigate the physiologic and pathologic roles of A(1)R in the human brain, and to elucidate the mechanism of action of therapeutic drugs targeting adenosine receptors, nucleoside transporters and adenosine-degrading enzymes. In this review article, we discuss (i) functions of adenosine and its receptors in cerebral metabolism; (ii) radioligands for A(1)R imaging: xanthine antagonists, non-xanthine antagonists, and agonists; (iii) roles of A(1)R in health and disease, viz. sleep-wake regulation, modulation of memory retention and retrieval, mediating the effects of alcohol consumption, protecting neurons during ischemia and reperfusion, suppression of seizures, modulating neuroinflammation and limiting brain damage in neurodegenerative disorders. The application of PET imaging could lead to novel insights in these areas. Finally (iv), we discuss the application of PET in pharmacodynamic studies and we examine therapeutic applications of adenosine kinase inhibitors, e.g. in the treatment of pain, inflammation, and epilepsy.
authors.affiliation: Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, Hanzeplein 1, 9713GZ Groningen, The Netherlands.
authors.forename: S
authors.initials: S
authors.lastname: Paul
authors.forename: P H
authors.initials: PH
authors.lastname: Elsinga
authors.forename: K
authors.initials: K
authors.lastname: Ishiwata
authors.forename: R A J O
authors.initials: RA
authors.lastname: Dierckx
authors.forename: A
authors.initials: A
authors.lastname: van Waarde
mesh_terms: D058907:Adenosine A1 Receptor Agonists / Q000737:chemistry; D058916:Adenosine A1 Receptor Antagonists / Q000737:chemistry; D002493:Central Nervous System Diseases / Q000175:diagnosis* / Q000378:metabolism / Q000473:pathology; D006801:Humans; D049268:Positron-Emission Tomography; D043682:Receptor, Adenosine A1 / Q000737:chemistry / Q000378:metabolism*
chemical_list: D058907:Adenosine A1 Receptor Agonists; D058916:Adenosine A1 Receptor Antagonists; D043682:Receptor, Adenosine A1