S2076 A Novel Method of Electrical Stimulation via Electrodes Chronically Implanted at Acupoints and Its Effect on Cisplatin-Induced Emesis in Rats Assessed by Pica

Abstract

Background and Aims: Acupuncture or electroacupuncture (EA) has been applied for treating chemotherapy-induced emesis with limited success. Two major problems with EA include infrequent application of EA and suboptimal stimulation parameters. The aims of this study were to investigate the feasibility of EA using chronically implanted electrodes and the effects of EA with different parameters on cisplatin-induced emesis in rats assessed by pica (intake of kaolin) that has been validated as a surrogate of emesis in rats. Materials and Methods: Under anesthesia, 19 SD rats were chronically implanted with a pair of electrodes at bilateral acupoint PC6 as follows: A 3mm tip of the exposed wire (serving as an electrode) was inserted into the acupoint and the connecting wire was firstly fixed in the muscle layer around the acupoint, then tunneled subcutaneously to the back of the neck and finally exited and protected for EA. After recovery and appropriate acclimation, the rats were treated using a 3×3 Latin Square cross-over design in which each rat received a sequence of 3 treatments in one of 3 assigned orders. The treatments included the following: EA1: 20Hz, 0.6ms, 2mA and continuous stimulation; EA2: 10Hz, 1.2ms, 2mA and continuous stimulation; Control: no stimulation. During each treatment, cisplatin 6mg/kg was injected intraperitoneally at 3PM during the first day and the rats received with one of the three treatments while staying at a rat restrainer for 3 hrs from 6pm-9m daily for 2 days. During the other periods, the rats were housed in their individual cages. There was an interval of 2 weeks between the two consecutive treatments. Results: 1) The implanted electrodes remained secured at the acupoints without infections. 2) Cisplatin induced substantial kaolin intake as well as reduced food intake and body weight; Treatment with EA1 significantly reduced kaolin intake on the first and second day after cisplatin in comparison with the control (first day, EA1 vs. Control, 1.0±0.2 vs.1.9±0.3g, p=0.017; second day, 0.4±0.2 vs.1.1±0.3g, p= 0.010); 3) Treatment with EA2 had no effects on kaolin intake after Cisplatin. Conclusions: Electrical stimulation via chronically implanted electrodes at acupoints is feasible. That is, EA may be performed chronically and continuously using implantable electrodes and pulse generator. EA at PC6 with appropriate parameters is able to reduce Cisplatin-induced kaolin intake in rats, suggesting an ameliorating effect on chemotherapy-induced emesis. The significant difference in the performance of EA with different parameter sets demonstrates the importance of parameter optimization in the application of EA.