Regulatory effects of Ningdong granule on dopaminergic and serotonergic neurotransmission in a rat model of Tourette syndrome assessed by PET

Dysfunctions in dopamine (DA) and serotonin (5-HT) metabolism have been widely implicated in Tourette syndrome (TS); however, the exact nature of these dysfunctions remains unclear. The objective of the present study was to investigate the variation in DA and 5-HT metabolism in a rat model of TS, and to evaluate the therapeutic effect of Ningdong granule (NDG), a traditional Chinese medicine (TCM) preparation used specifically for the treatment of TS. Rats were treated with 3,3 '-iminodipropionitrile for 7 days to induce the model of TS, and were then intragastrically administered NDG each day. After 8 weeks of treatment, micro-positron emission tomography was used to measure the binding of DA D-2 receptors (D(2)Rs), DA transporters (DATs), 5-HT2A receptors (5-HT(2A)Rs) and 5-HT transporters (SERTs) in brain regions of interest. The results indicated that NDG could significantly reduce the typical characteristics of TS in the rat model. Decreased D2R binding and increased DAT binding were detected in the striatum compared with the binding activities in untreated rats. The density of 5-HT2AR was also significantly increased in the striatum following NDG treatment; however, SERT levels were decreased in certain brain regions, including the striatum, cortex, nucleus accumbens and amygdala. Taken together, the current results demonstrated that NDG may be effective in treating patients with TS.