[Effect of connexin 43 knockout on acupuncture-induced down-regulation of c-fos expression in spinal dorsal horn in visceral pain mice].

OBJECTIVE

To explore the effect of connexin 43 gene knockout on acupuncture analgesia.

METHODS

Seventy-two wide type (WT) and connexin 43 gene knockout mice were separately and randomly divided into: WT control group, WT model group, WT acupuncture group, heterozygous (HT) control group, HT model group and HT acupuncture group, with 12 cases in each. Visceral pain model was established by intraperitoneal administration of acetic acid. "Zhongwan" (CV 12) and bilateral "Zusanli" (ST 36) were punctured with a filiform needle for 30 min and stimulated by manipulating the needle 30 s every 5 min. The expression of c-fos in the spinal dorsal horn was assayed by using RT-PCR and western blot techniques.

RESULTS

There was no significant difference between HT and WT control mice in relative grey value of spinal c-fos mRNA expression (P>0.05), in which few c-fos mRNA and protein expressed. The expression of c-fos mRNA and protein was increased significantly following intraperitoneal acetic acid injection compared with control groups in both HT and WT mice (P<0.01). And no significant difference was found between HT and WT model groups in c-fos mRNA expression (P>0.05). Compared with WT model group, the expression of both c-fos mRNA and c-fos protein in WT acupuncture group was down-regulated significantly (P<0.01). In comparison with HT model group, the expression of both c-fos mRNA and protein in HT acupuncture group was down-regulated but without statistically significant difference (P>0.05). And the expression of c-fos mRNA and protein in HT acupuncture group was significantly higher than that in WT acupuncture group (P<0.05, 0.01).

CONCLUSION

Acupuncture has a marked antinociceptive effect in visceral pain mice, and simultaneously suppresses the expression of c-fos mRNA and protein evoked by noxious stimulation in the spinal dorsal horn. Connexin 43 gene knockout may weaken acupuncture analgesia and reduce EA-induced down-regulation of c-fos expression, suggesting an involvement of connexin 43 in the analgesic effect of acupuncture.