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: 1.0 ± 0.2 vs. 1.9 ± 0.3 g, p = 0.017; second day: 0.4 ± 0.2 vs.1.1 ± 0.3 g, p = 0.010). However, EA at 10 Hz/1.2 msec was ineffective on both days. 2) Subdiaphragmatic vagotomy significantly reduced cisplatin-induced kaolin intake (1.1 ± 0.3 vs. 2.2 ± 0.3 g, p = 0.014) 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.