[Influence of connexin 43 gene knockout on the analgesic effect of acupuncture in visceral pain mice].
OBJECTIVE
To explore the possible central and peripheral mechanisms of connexin 43 gene knockout in acupuncture analgesia.


METHODS
Fifty-four wide type (WT) mice and 54 connexin 43 gene knockout (heterozygote, HT) mice were randomly divided into WT control group, WT model group, WT acupuncture group, HT control group, HT model group and HT acupuncture group (n = 18/group). Visceral pain model was established by intraperitoneal injection of 0.6% acetic acid (0. 1 mL/10 g). "Zhongwan" (CV 12) and bilateral "Zusanli" (ST 36) were punctured with filiform needles and stimulated for 30 min by manipulating the needle for 30 s every 5 min. The latency and the number of body-writhing response were observed and the contents of beta-endorphin (beta-EP) in hypothalamus and serum prostaglandin E2 (PGE2) were detected with radioimmunoassay (RIA).


RESULTS
There was no significant difference in the latency and the number of body-writhing response, and contents of hypothalamic beta-EP and serum PGE2 between HT and WT control groups (P > 0.05). Compared with the corresponding control groups, the latency of body-writhing in WT model and HT model groups shortened significantly and the number of body- writhing increased considerably in two model groups (P < 0.01). While in comparison with WT model group, the latency of body-writhing prolonged significantly and the number of body-writhing decreased apparently in WT acupuncture group (P < 0.01); but no marked differences were found between HT model and HT acupuncture groups in these two indexes (P > 0.05). Compared with the corresponding control groups, the contents of both beta-EP and PGE2 increased obviously in WT model and HT model groups (P < 0.05). In comparison with WT model group, beta-EP levels in WT acupuncture group increased further significantly (P < 0.05), and serum PGE2 in WT acupuncture group decreased obviously (P < 0.05); but no significant changes were found between HT model and HT acupuncture groups in beta-EP and PGE2 levels (P > 0.05).


CONCLUSIONS
Acupuncture has a marked antinociceptive effect in WT mice with visceral pain, which may be related to its effects in increasing hypothalamic beta-EP and decreasing serum PGE2; while in connexin 43 gene knockout mice, all the above-mentioned effects of acupuncture are eliminated, indicating an important role of connexin 43 in the analgesic effect of acupuncture.
Yu
Wei-chang
WC
Instituteof Integrated Traditional Chinese Western Medicine, Tongji Hospital Affiliated to Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China.
Huang
Guang-ying
GY
Zhang
Ming-min
MM
D019342:Acetic Acid / Q000494:pharmacology; D015667:Acupuncture Analgesia / Q000379:methods*; D000818:Animals; D018031:Connexin 43 / Q000235:genetics / Q000502:physiology*; D015232:Dinoprostone / Q000097:blood / Q000378:metabolism; D004195:Disease Models, Animal; D005260:Female; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D059408:Pain Management; D011863:Radioimmunoassay; D011897:Random Allocation; D014781:Viscera / Q000503:physiopathology*; D001615:beta-Endorphin / Q000032:analysis
D018031:Connexin 43; D001615:beta-Endorphin; D015232:Dinoprostone; D019342:Acetic Acid