A Study Of Transcranial Direct Current Stimulation In Improving Behavioral Symptoms Of A Rat Model Of Parkinson’s Disease

In this study, a simple and effective tDCS (Transcranial Direct Current Stimulation)protocol applied in SD rats is developed. Comsol is applied to verify the current hasbeen injected into the cortex. After that, the6-OHDA unilateral lesioned PD(Parkinson’s Disease) rats are involved into behavioral tests, which are used to assessthe effects of tDCS in PD like symptoms. In the digital simulation, a geometrical solidmodel (length:6mm, Width:10mm, High:8mm) is extracted from the head of the rat,the electrode that attached onto the skull is a cylinder with a diameter of2mm, and ahigh:3mm. The test current is40μA, the highest current density is found at theboundary of cerebrospinal fluid and endocranium, which is12.74μA/mm2, the currententered into the cortex is61.4%. Therefore, this tDCS protocol is valid. Then, rotationalbehavior, corridor test, gait test, and MEP test are conducted.32PD rats were involvedinto the rotational test. Different current amplitude (20μA，80μA，200μA) are appliedto the rat groups respectively. The latency and the speed of the rotational behavior aredifferent significantly (P<0.05) after tDCS when compared to themselves. There is nosignificant difference between the4groups in latency and the rotational duration(P>0.05). After tDCS, there appears a significant difference (P<0.05) in rotational speedwhen compared to the sham group except for the20μA group; But there is nodifference between the80μA group and the200μA group (P>0.05). Additionally,26PDrats and12healthy rats are involved into corridor test, gait test, and MEP test. tDCSrelieve the symptoms that in the corridor test and in the gait test significantly (P<0.001).The amplitude of MEP from the contralateral forelimb is enhanced significantly aftertDCS (P<0.001), in which the enhancement lasted for more than10minutes; the MEPdetected from the ipsilateral forelimb decreased because of the inter-hemisphereinhibition which lasted for no more than20minutes. Therefore, the tDCS protocol forPD rats are valid and effective for the studies in tDCS for animal model in the future.