Chemotherapy-Induced Pica in Rats Reduced by Electroacupuncture

Objectives: Acupuncture or electroacupuncture (EA) has been applied for treating chemotherapy-induced emesis with limited success. The aims of this study were to investigate the anti-emetic effect of EA and to explore underlying anti-emetic mechanisms. Materials and Methods: Rats were chronically implanted with a pair of stainless steel leads at acupoint pericardium 6 (PC6). Effects of EA with different parameters on cisplatin-induced nausea were assessed by pica (intake of kaolin, a surrogate of nausea in species without vomiting reflex). C-fos expressions in the area postrema (AP) and nucleus tractus solitarii (NTS) were analyzed. Subdiaphragmatic vagotomy was used to study involvement of the vagal pathway. Results: 1) EA at 20 Hz/0.6 msec reduced kaolin intake in the first and second days after cisplatin injection compared with the sham-EA group (first day: 1.06 +/- 0.2 vs. 1.96 +/- 0.3 g, p=50.017; second day: 0.46 +/- 0.2 vs. 1.16 +/- 0.3 g, p=50.010). However, EA at 10 Hz/1.2 msec was ineffective on both days. 2) Subdiaphragmatic vagotomy significantly reduced cisplatin-induced kaolin intake (1.16 +/- 0.3 vs. 2.26 +/- 0.3 g, p=50.014) and also blocked the inhibitory effect of EA on kaolin intake in the first day. 3) Cisplatin significantly increased the expression of c-fos in the NTS and AP. Vagotomy greatly reduced c-fos expression in both NTS and AP. EA reduced the cisplatin-induced c-fos expression in the AP but not the NTS. Conclusions: EA at PC6 with appropriate parameters has an inhibitory effect on cisplatin-induced nausea. The anti-emetic effect of the EA is centrally medicated involving the AP via the vagal pathway as well as the potential effect on AP by reducing the release of hormones.