Development and Preclinical Evaluation of PET Radiotracers Targeting Adenosine A Receptors.

Several adenosine A receptor (AR) radiotracers for positron emission tomography (PET) have been developed to study their neuromodulatory functions and role in brain disorders. While two xanthine-based radiotracers ([C]-MPDX and [F]-CPFPX) have been used in humans, we aimed to improve the metabolic stability and specific binding. Guided by structure-activity relationship (SAR) studies, 10 derivatives were synthesized with binding affinities up to 0.

Naloxone's dose-dependent displacement of [C]carfentanil and duration of receptor occupancy in the rat brain.

The continuous rise in opioid overdoses in the United States is predominantly driven by very potent synthetic opioids, mostly fentanyl and its derivatives (fentanyls). Although naloxone (NLX) has been shown to effectively reverse overdoses by conventional opioids, there may be a need for higher or repeated doses of NLX to revert overdoses from highly potent fentanyls. Here, we used positron emission tomography (PET) to assess NLX's dose-dependence on both its rate of displacement of [C]carfentanil ([C]CFN) binding and its duration of mu opioid receptor (MOR) occupancy in the male rat brain.

Discovery of Highly Potent Adenosine A Receptor Agonists: Targeting Positron Emission Tomography Probes.

Adenosine receptor (AR) radiotracers for positron emission tomography (PET) have provided knowledge on the biodistribution of ARs in the central nervous system (CNS), which is of therapeutic interest for various neuropsychiatric disorders. Additionally, radioligands that can image changes in endogenous adenosine levels in different physiological and pathological conditions are still lacking. The binding of known antagonist adenosine A receptor (AR) radiotracer, [C]MDPX, failed to be inhibited by elevated endogenous adenosine in a rodent PET study.