# Neurotransmitter release

PET radiopharmaceuticals are used for measuring in vivo the receptor density (concentration) as Bmax or Binding potential. These methods actually do not assess the total concentration of receptors, but the concentration of available receptors, that is, receptors that have not been occupied by endogenous ligands or drugs. This has been utilized for measurement of drug-induced receptor occupancy in drug development, and for measuring the changes in endogenous synaptic neurotransmitter concentrations (Fisher et al., 1995; Friston et al., 1997; Endres and Carson, 1998; Laruelle, 2000; Laruelle and Huang, 2001; Alpert et al., 2003; Finnema et al., 2015).

PET methods for assessing neurotransmitter concentrations have been developed for dopamine (Volkow et al., 1994; Ginovart et al., 1997; Badgaiyan, 2013; Lippert et al., 2019), opioids (Bartenstein et al., 1993; Mitchell et al., 2012; Colasanti et al., 2012), serotonin (Paterson et al., 2010; Tyacke and Nutt, 2015), GABA (Frankle et al., 2012; Stokes et al., 2014), and noradrenaline (Lehto et al., 2016).

Common methodologies should be applied, and simulated open datasets can be used to benchmark analysis pipelines to improve reproducibility (Veronese et al., 2021).