Dopamine Level In The Stratium Exhibits Circadian Rhythms In The Rat Model Of Tourette Syndrome

Dopamine dysfunction is implicated in the pathogenesis of tic disorders. To explore whether TD symptoms might be related to the circadian variations of dopamine in the striatum, in this study we established rat models of tic disorder (TD) induced by iminodipropionitrile (IDPN). 120 Sprague-Dawley male rats were divided into two groups:control group and IDPN treatment group. The rats in treatment group were injected 150 mg/kg IDPN for 7 consecutive days, while rats in control group were injected saline. The rats in each group were subjected to open field test at daily time points:1:00, 5:00, 9:00, 13:00, 17:00, 21:00, continuously for 7 days. Then the rats were killed at the 6 different time points during the 24 hours period. The rat striatums were quickly removed and the levels of dopamine and 5-HT were measured by high-performance liquid chromatography. The results showed that dopamine level and the excitability of the rats in treatment group exhibited rhythmic features. The peak of DA secretion was at 5 am, when the rats exhibited the highest excitability. Our results suggest that 5 am is an important time point for drug intervention to alleviate the condition of TS.