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

Establishment and evaluation of a compound fear behavior model of Tourette's syndrome in rats

Background

Tourette syndrome (TS) is a common childhood disorder characterized by unwanted movements or vocal sounds called tics. It is often accompanied by other psychobehavioral disorders, including fearful behavior. The establishment and evaluation of rat models of TS and comorbid fear can provide an experimental basis for the treatment of TS and its comorbid fear disorder.

Methods

Sixteen rats were randomly divided into a model group (n=8) and control group (n=8). In the model group, rats were injected intraperitoneally with iminodipropionitrile (IDPN) for 1 week to establish the TS model, which was followed by acoustic and electrical stimulation for 3 weeks to establish the rat models of TS and comorbid fear. The control group received intraperitoneal injection of saline for 1 week, and no further intervention was given in the last 3 weeks. The behavioral changes of the rats were observed and analyzed by the open field test (OFT). Protein kinase A (PKA), cyclic adenosine monophosphate (cAMP), and dopamine (DA) were measured by enzyme-linked immunosorbent assay (ELISA), and tyrosine hydroxylase (TH) and microRNA-134 (miRNA-134) in the brain tissue were detected by using polymerase chain reaction (PCR).

Results

One rat in the model group died on the 24th day. Compared with the control group, the model group had significantly higher scores of locomotor activity, stereotyped behavior, and motor behavior, along with prolonged freezing time and significantly lower expression of miRNA-134. The differences in the expressions of PKA, cAMP, DA, and TH in brain tissue were not statistically significant.

Conclusions

The rat models of TS and comorbid fear have similar changes in behaviors and miRNA-134 level to those in clinical settings and therefore can be used as a reliable animal model to study the mechanism of action of TS and comorbid fear.

Ningdong Granule Upregulates the Striatal DA Transporter and Attenuates Stereotyped Behavior of Tourette Syndrome in Rats

This study aimed to evaluate the possible mechanism of Ningdong granule (NDG) for the treatment of Tourette syndrome (TS). The rats with stereotyped behavior were established by microinjection with TS patients' sera; then, the model rats were divided into NDG and haloperidol (Hal) group, and the nonmedication model rats were regarded as treatment control (TS group). The stereotyped behavior of the rats was recorded, the level of dopamine (DA) in striatum, and the content of homovanillic acid (HVA) in sera were tested, and dopamine transporter (DAT) expression was measured in the study. The experimental results showed that NDG effectively inhibited the stereotyped behavior (P < 0.01), decreased the levels of DA in the striatum (P < 0.05), increased the content of sera HVA (P < 0.01), and enhanced the protein and mRNA expression of DAT in the striatum (P < 0.01). Additionally, the results also revealed Hal could improve the stereotyped behavior as well but had no remarkable influence on DAT expression and DA metabolism. In conclusion, NDG attenuates stereotyped behavior, and its mechanism of action might be associated with the upregulation of DAT expression to regulate DA metabolism in the brain.