Imaging of adenosine receptors

Over the last decades adenosine receptor ligands, agonists as well as antagonists, have been developed. The requirements for compounds suitable for non-invasivein vivo imaging of adenosine receptors (radiopharmaceuticals, radiotracers) with positron emission tomography (PET) are in several aspects different from thosefor therapeutic drugs. This difference will be elucidated for radiotracers involved in human neurotransmission research.In humans theA1 adenosine receptor (A1AR) shows themost abundant distribution and highest concentrations in brain cortical and subcortical areas, whereas theA2Aadenosine receptor (A2AAR) can be found in selected regions like striatum, nucleus accumbens, olfactory tubercle. A2B adenosine receptors (A2BAR) and A3 adenosinereceptors (A3ARs) are expressed in low levels in the brain.Most of the imaging probes therefore target the A1AR and A2AAR. The talk will give an overview of currentlyused imaging probes and applications. The neuroreceptor imaging technique has been used for example to investigate physiological mechanisms of the sleep wakeregulation or pathophysiological conditions like cerebral ischemia, ethanol intoxication, epilepsy or Alzheimer’s disease in humans and animal models. Pharmacokineticanalysis of PET experiments allow additionally to investigate drug action in the human brain, like for example the impact of caffeine on A1AR availability