Electro-acupuncture Pretreatment at Zusanli (ST36) Acupoint Attenuates Lipopolysaccharide-Induced Inflammation in Rats by Inhibiting Ca Influx Associated with Cannabinoid CB2 Receptors.

In this study, we aimed to investigate the effect of electro-acupuncture (EA) pretreatment at zusanli (ST36) acupoint on lipopolysaccharide (LPS)-induced endotoxemic rat model and explore the underlying molecular mechanisms. Rats were treated with EA at ST36 for 7 days before being subjected to LPS. Two hours post-LPS, samples such as serum, local acupoint tissues, and spleens were collected and processed for investigations including cytokine production, cytosolic calcium (Ca) concentration, Ca influx, cannabinoid CB2 receptor (CB2R) expression, and TLR4/NF-κB signaling. Our results showed EA pretreatment significantly attenuated LPS-induced inflammatory cytokine production, such as TNF-α, IL-1β, and IL-6. EA also enhanced CB2R expression, inhibited Ca influx, and inactivated TLR4/NF-κB signaling, subsequently resulting in a substantial reduction of Ca concentration. Importantly, CB2R antagonist AM630 effectively abrogated the suppressive effect of EA at ST36 on the endotoxemic rats, suggesting CB2R was involved in the anti-inflammatory effect of EA. EA pretreatment could enhance CB2R expression, inhibit Ca influx, and inactivate TLR4/NF-κB signaling, which contributes to the alleviation of LPS-induced inflammation in rats.