Striatal dopamine D1 and D2 receptors in burning mouth syndrome

Abstract

Animal studies have indicated that the nigrostriatal dopaminergic system is involved in central pain modulation. In a recent positron emission tomography (PET) study, we demonstrated presynaptic dysfunction of the nigrostriatal dopaminergic pathway in burning mouth syndrome, which is a chronic pain state. The objective of the present study was to examine striatal dopamine D1 and D2 receptors in these patients. We used 11C-NNC 756 and 11C-raclopride to study D1 and D2 receptor binding in a PET study in ten burning mouth patients and 11 healthy controls. Patients underwent a structured psychiatric evaluation and an electrophysiological test for the excitability of the blink reflex. The striatal uptake of 11C-NNC 756 did not differ between patients and controls. In a voxel-level analysis, the uptake of 11C-raclopride was statistically significantly higher in the left putamen in burning mouth patients (corrected P-value 0.038 at cluster-level). In the region of interest analysis, the D1/D2 ratio was 7.7% lower in the right putamen (0.64+/-0.04 vs. 0.69+/-0.04, P=0.01) and 6.4 % lower in the left putamen (0.65+/-0.05 vs. 0.70+/-0.05, P=0.05) when compared to controls. Increased 11C-raclopride uptake and the subsequent decrease in the D1/D2 ratio may indicate a decline in endogenous dopamine levels in the putamen in burning mouth patients.

Cortical and Subcortical Connectivity Changes during Decreasing Levels of Consciousness in Humans: A Functional Magnetic Resonance Imaging Study using Propofol

“…Basal ganglia structures are not commonly reported in the acute pain literature (Jones et al, 1991;Casey et al, 1994) but involvement in the processing of nociceptive information (Tracey et al, 2000), including attention to noxious information, motor preparation and response selection are increasingly recognized, and dedicated nociceptive pathways to the striatum have been identified (Braz et al, 2005). Iardola and colleagues have observed bilateral activation of the putamen with capsaicininduced pain and the basal ganglia have also been found to play a role in chronic pain conditions such as atypical facial pain (Hagelberg et al, 2003a) and burning mouth syndrome (Hagelberg et al, 2003b). The reader is referred to an excellent review for further consideration of the role of the basal ganglia in pain perception (Chudler and Dong, 1995).…”

Pain in Parkinson's disease

“…Studies have shown a predominance of pain in the off period and may be related to increase of stiffness 3,4,23 . The onset of pain on the most affected body side does not mean that pain is caused only by stiffness and/or bradykinesia, a hypothesis that could show that both the pain and motor symptoms share similar mechanisms, what means that modulation of pain could be performed by dopaminergic pathways on basal ganglia, where the lack of dopamine leads to a painful condition 10,24,25 .…”

Burning Mouth Syndrome

“…This, plus other data, strongly suggests that there is a dysfunction of the small diameter afferent sensory fibres in burning mouth syndrome. Imaging studies in patients have also suggested central nervous system changes (Jääskeläinen et al, 2001;Hagelberg et al, 2003).…”