Effect of herbal-partitioned moxibustion at Tianshu (ST 25) and Qihai (CV 6) on pain-related behavior and emotion in rats with chronic inflammatory visceral pain

Abstract

To observe the effect of herbal-partitioned moxibustion (HPM) on pain-related behavior and emotion in a rat model of chronic inflammatory visceral pain, and to investigate the mechanism. Twenty-four male Sprague-Dawley (SD) rats were randomly divided into three groups: a normal group, a model group and an HPM group. Except for the normal group, rats in the other two groups were clystered with mixed liquor of Trinitrobenzene Sulfonic Acid (TNBS) and 50% ethanol to induce the chronic inflammatory visceral pain model. After the models were established successfully, rats in the HPM group were treated with HPM at bilateral Tianshu (ST 25) and Qihai (CV 6). Rats in the normal group and the model group were only fixed as those in the HPM group without treatment. Abdominal withdrawal reflex (AWR) score, mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) were adopted to detect the visceral and somatic pain; meanwhile, open field test (OFT) and elevated plus maze test (EPMT) were employed to evaluate pain emotions such as depression and anxiety. Compared with the normal group, AWR scores of the model group were significantly increased under different stimulus expansion pressure level (P<0.01), MWT and TWL were significantly decreased (P<0.05); in OFT, the values of horizontal activities and vertical activities were significantly decreased (P<0.01); in EPMT, the proportion of the number of entry into the open arms (OE%) and that of residence time in the open arms (OT%) significantly decreased (P<0.01), indicating that the model was successful. Compared with the model group, the AWR score of the HPM group was decreased significantly (P<0.05), MWT and TWL were significantly increased (P<0.05), the values of horizontal activities and vertical activities in the model group were significantly increased (P<0.01); in OFT and EPMT, OE% and OT% were significantly increased (P<0.01). HPM has analgesic effect on chronic inflammatory visceral pain. It can reduce the visceral and somatic pain in rats and markedly improve the emotions such as anxiety and depression induced by chronic visceral pain.