Effect of acupuncture on anxiety-like behavior during nicotine withdrawal and relevant mechanisms

Acupuncture, likely the most well-known 'alternative' medical treatment, has been shown to have effects in several types of animal model of drug dependence, including nicotine addiction. We investigated the effect of acupuncture on anxiety-like behavior and corticotrophin-releasing factor (CRF) and neuropeptide Y (NPY) mRNA expression in the amygdala during nicotine withdrawal. Rats were given repeated nicotine injections (0.1mg/kg s.c., once daily for 7 days) or saline. Acupuncture groups were treated with acupuncture at acupoint HT7 or ST36 during withdrawal. The anxiogenic response was measured at 72h after the termination of nicotine injection using an elevated plus maze. CRF and NPY mRNA levels were also evaluated using reverse transcription polymerase chain reaction (RT-PCR) analysis at this time. Rats undergoing nicotine withdrawal (NW) were less likely to explore the open arms of the plus maze compared with the saline-treated controls. The percentage of open arm entries in the HT7 acupuncture group, but not in the ST36 acupuncture group, was significantly increased compared with the NW group. Consistent with this behavior, CRF mRNA levels in the NW group were increased compared with the control group. CRF mRNA levels in the HT7 acupuncture group were significantly decreased compared with the NW group. However, NPY mRNA levels were not different among the groups. These findings indicate that increases in CRF may be involved in the negative affect state associated with nicotine withdrawal and that acupuncture may attenuate anxiety-like behavior following nicotine withdrawal by modulating CRF in the amygdala.