Whole Body Study of [11C]NNC-112 PET Imaging of Dopamine D1 Receptors

Abnormalities in dopaminergic neurotransmission have been implicated in several neurodegenerative and psychiatric disorders, such as Parkinson's disease, schizophrenia, attention-deficit-hyperactivity disorder and drug dependence. Among the Dopamine (DA) receptors, D1 receptors are understood to be involved in the regulation of motor and cognitive activity by modulating DAergic function. Neuroreceptor imaging with Positron Emission Tomography (PET) and Single Photon Emission Computerized Tomography (SPECT) allows in vivo quantification of the density and distribution of D1 receptors in humans. Recently, a new and superior PET radioligand for in vivo quantification of D1 receptors in extrastriatal regions has been developed. \[11C\]NNC-112 is a D1 radiotracer with high specific to nonspecific binding, making it suitable for imaging low density D1 receptors in extrastriatal regions such as the neocortex. Several studies in humans have confirmed the potential of this radiotracer, however, to date, dosimetry studies of \[11C\]NNC-112 in humans have not been performed. The specific objective of this protocol is to estimate radiation-absorbed doses of \[11C\]NNC-112 in human subjects. For this purpose, we propose to perform a kinetic whole body imaging study of \[11C\]NNC-112 in healthy human subjects. We hypothesize that the level of radiation-absorbed doses of \[11C\]NNC-112 in humans will be within limits, and consequently, we should be able to move to the next stage of our imaging research, where we will use this radioligand to measure the density and distribution of D1 receptors in Parkinson's disease.