DIFFERENCES IN THE EXPRESSION OF NEUROTRANSMITTERS, METABOLIC TRANSPORT, POSTSYNAPTIC RECEPTORS, AND SIGNALLING PROTEINS IN THE DOPAMINERGIC TWITCH MODEL INDUCED BY DOI

Feng Wang^#, Wenxiang Wang^#, Bei Song^*, Xiaomin Wen^*

Department of Pediatrics, Xiangyang NO.1 peoples Hospital, Affiliated Hospital of Hubei University of Medicine, Xiangyang 441000, PR China

Objective: To analyse the differences in the expression of neurotransmitters, metabolic transport, postsynaptic receptors, and signalling proteins in the dopamine system of DOI-induced twitching young mouse model.

Methods: Twenty SD rats were randomly allocated to either the model group or control group, which consisted of ten rats each. The model group received intraperitoneal injections of DOI at 1 mg/kg/day to establish the rat twitch model, and the control group received intraperitoneal injections with normal saline for 21 days. RP-HPLC was used to detect the dopamine and vanillic acid content in the brain tissue and plasma of the rats. Radioimmunoassay was used to detect the dopamine transporter (DAT) levels in the brain tissue. DRD1 and DRD2 mRNA expression in the prefrontal lobe and striatum of cerebral cortex. The Western blot method was used to detect phosphorylation of the DARPP-32 protein.

Results: The levels of dopamine and vanillic acid in the brain tissue of the model group were significantly higher than those of the control group (p<0.05). There was no significant difference in the levels of plasma dopamine between the two groups of rats (p>0.05). The DAT content of the striatum, cerebral cortex, and hippocampus of the model group was significantly higher than that of the control group (p<0.01). The expression of DRD1 mRNA in the prefrontal lobe of the model group was significantly higher than that of the control group (p<0.01), and the expression of DRD1 mRNA in the striatum was not significantly different between the two groups (p>0.05). The total protein expression of DARPP-32 in the model group was significantly higher than that of the control group (p<0.01). The expression of the p-DARPP-32 protein was not significantly different between the two groups (p>0.05).

Conclusion: The neurotransmitter content of the dopamine system in the brain tissue of rats with multiple tic disorder was significantly increased, the metabolic index activity was increased, and the expression of the postsynaptic receptors and signalling molecules DARPP-32 was increased. These findings suggest that hyperfunction of the dopamine system is involved in the pathophysiology and pathogenesis of multiple tic disorder.