Longitudinal PET Imaging of α7 Nicotinic Acetylcholine Receptors with [18F]ASEM in a Rat Model of Parkinson's Disease.

Abstract

The nicotinic acetylcholine alpha-7 receptors (α7R) are involved in a number of neuropsychiatric and neurodegenerative brain disorders such as Parkinson's disease (PD). However, their specific pathophysiologic roles are still unclear. In this context, we studied the evolution of these receptors in vivo by positron emission tomography (PET) imaging using the recently developed tracer 3-(1,4-diazabicyclo[3.2.2]nonan-4-yl)-6-[18F]fluorodibenzo[b,d]thiophene-5,5-dioxide) in a rat model mimicking early stages of PD. PET imaging of α7R was performed at 3, 7, and 14days following a partial striatal unilateral lesion with 6-hydroxydopamine in adult rats. After the last imaging experiments, the status of nigro-striatal dopamine neurons as well as different markers of neuroinflammation was evaluated on brain sections by autoradiographic and immunofluorescent experiments. We showed an early and transitory rise in α7R expression in the lesioned striatum and substantia nigra, followed by over-expression of several gliosis activation markers in these regions of interest. These findings support a longitudinally follow-up of α7R in animal models of PD and highlight the requirement to use a potential neuroprotective approach through α7R ligands at the early stages of PD.