Release of β-endorphin from adrenal gland to lower plasma glucose by the electroacupuncture at Zhongwan acupoint in rats

Abstract

We found that electroacupuncture (EA) at the Zhongwan acupoint released β-endorphin to induce an insulin-dependent hypoglycemia in rats. The present study investigated the source of β-endorphin. EA at 2 Hz for 30 min in rats decreased plasma glucose that could be abolished by naloxone. A similar effect of EA was also observed in wild-type mice but disappeared in μ-opioid receptor knockout mice. Mediation of the μ 1-opioid receptor is considered from the blockade of response to EA by naloxonazine in rats. Otherwise, adrenalectomy abolished not only the hypoglycemic response to EA in rat and mouse but also the increase of plasma β-endorphin and insulin by EA in rats. In conclusion, the increase of plasma β-endorphin by EA at 2 Hz is mainly from the adrenal gland.