[Effect of electroacupuncture on expression of GABAA receptor mRNA in different brain regions in rats with chronic inflammatory pain].

OBJECTIVE: To observe the expression of GABAA receptor mRNA in different brain regions of the central nervous system in chronic inflammatory pain rats and the intervention effect of electroacupuncture (EA). METHODS: A total of 48 SPF male SD rats were randomly divided into a blank control group, a model control group, an EA group and a sham EA group, 12 rats in each group. The model of chronic inflammatory pain was established by injecting Freund's complete adjuvant into the foot. The EA group was treated with EA 28 days after the model establishment. The "Housanli" (ST 36) and "Kunlun" (BL 60) were selected and treated with dilatational wave, 2 Hz/100 Hz in frequency, 0.5-1.5 mA for 30 min; EA was given only once. In the sham EA group, the same acupoints were selected but the needles were only inserted into subcutaneous area; EA was connected for 30 min without electrical stimulation. The behavior changes of mechanical pain threshold and thermal pain threshold before model establishment, 1 day, 3 days, 7 days, 14 days, 21 days and 28 days after the model establishment as well as emotional behavior 29 days after the model establishment were observed; the relative expressions of GABAA receptor mRNA in anterior cingulate cortex, amygdala and hypothalamus were observed. RESULTS: Compared with the blank control group, the change rates of mechanical pain threshold and thermal pain threshold in the model control group were decreased significantly 1 day, 3 days, 7 days, 14 days, 21 days, 28 days after model establishment (P<0.01); 29 days after model establishment, the movement distance and staying time in the central area of open field test in the model control group were decreased significantly (P<0.05). After EA intervention, compared with the model control group and the sham EA group, the change rates of mechanical pain threshold and thermal pain threshold, as well as the movement distance and the staying time of central area were significantly increased in the EA group (P<0.01, P<0.05). Twenty-nine days after model establishment, the expression of GABAA receptor mRNA in anterior cingulate cortex and hypothalamus was not significantly different among all groups (P>0.05). Compared with the blank control group, the expression of GABAA receptor mRNA in the amygdala was decreased significantly in the model control group (P<0.01); compared with the model control group and the sham EA group, the expression of GABAA receptor mRNA in amygdala was increased after intervention in the EA group (P<0.01). CONCLUSION: Single treatment of EA could significantly increase the mechanical pain threshold and thermal pain threshold, improve abnormal emotional behavior in rats with chronic inflammatory pain, which may be related to the increasing of expression of GABAA receptor mRNA in the amygdala.

Effect of Electroacupuncture in "Zusanli" and "Kunlun" Acupoints on TLR4 Signaling Pathway of Adjuvant Arthritis Rats.

BACKGROUND: Rheumatoid arthritis (RA) is a chronic systemic autoimmune disease. Previous study suggested that toll-like receptor (TLR) signaling pathway contributes to the development and progression of RA. In recent years, acupuncture has become one of the most vital treatments of arthralgia. But little is known about the mechanisms of improving RA by acupuncture. STUDY QUESTION: The study studied the effect of electroacupuncture in "Zusanli" and "Kunlun" acupoints on the expression of TLR4, myeloid differentiation factor 88 (MYD88), and NF-κB in adjuvant arthritis rats to clarify the molecular mechanism of acupuncture of RA. STUDY DESIGN: A rat model of adjuvant arthritis was established with injection of 0.1 mL Freund complete adjuvant in the right hindlimb footpad. We next punctured the Zusanli and Kunlun acupoints with 0.25 × 40-mm acupuncture needles to 5-mm depth. Then, we performed electroacupuncture treatment for 28 days with frequency of 2 Hz and intensity of 2 mA, once a day and 30 minutes each time. MEASURES AND OUTCOMES: Arthritis index and paw swelling were measured every week. FQ-PCR and western blot were used to detect the expression of TLR4, MYD88, and NF-κB. RESULTS: Paw swelling of rats injected with Freund complete adjuvant was more serious than that of the normal rats, which illustrated the successful establishment of adjuvant arthritis rat model. After treatment for 14 days, the paw swelling and joint symptoms score decreased, paw tissue inflammation eased in the rats of treatment group compared with the model group during the same period. After treatment for 28 days, the expression of TLR4, MYD88, and NF-κB in the ankle bone tissues decreased at both mRNA and protein levels. CONCLUSIONS: Stimulation with electric needle in Zusanli and Kunlun acupoints can reduce the expression of TLR4, MYD88, and NF-κB, which play an important role in treatment of adjuvant arthritis.