Evid Based Complement Alternat Med. 2012;2012:568273. doi: 10.1155/2012/568273. Epub 2011 Aug 8.
Effect of Electroacupuncture on Activation of p38MAPK in Spinal Dorsal Horn in Rats with Complete Freund's Adjuvant-Induced Inflammatory Pain.
Liang Y1, Fang JQ, Du JY, Fang JF.
The Third Clinical Medical College, Zhejiang Chinese Medical University, 548 Binwen Road, Binjiang District, Hangzhou City, Zhejiang Province 310053, China.
Activation of mitogen-activated protein kinases (MAPKs), especially p38 MAPK, plays an important role in the development of central sensitization related to persistent inflammatory pain. Electroacupuncture (EA) is well known to relieve persistent inflammatory pain. However, little is known about relationship between EA and p38 MAPK. Inflammatory pain rat model was induced by intraplantar injection of complete Freund's adjuvant (CFA). Male adult SD rats were randomly divided into the saline group, CFA group, and CFA + EA group. EA (constant saquare wave, 2 Hz and 100 Hz alternating frequencies, intensities ranging from 1 to 2 mA) was applied to bilateral "Zusanli" (ST 36) and "Kunlun" acupoints (BL 60) for 30 min, once per day. The paw edema and paw withdrawal threshold (PWT) were measured at preinjection and days postinjection 1, 3, and 14. Spinal p-p38MAPK- immunoreactivty (p-p38MAPK-IR) cells were detected by immunohistochemistry at postinjection day 3 and 14. EA significantly inhibited paw edema at postinjection days 14 and increased PWT at postinjection days 3 and 14. Moreover, the increasing number of spinal p-p38MAPK-IR cells which was induced by CFA injection was suppressed by EA stimulation. These results indicate that anti-inflammatory and analgesic effect of EA might be associated with its inhibition of spinal p38 MAPK activation and thereby provide a potential mechanism for the treatment of inflammatory pain by EA.
Effect of electroacupuncture (EA) on ipsilateral paw edema at different time points in complete Freund's adjuvant (CFA) rats. Values are mean ± SD, n = 10 animals per experimental group. **P < 0.01 versus saline group; ▲▲ P < 0.01 versus CFA group at corresponding time points.
Evid Based Complement Alternat Med. 2012;2012:568273.
Effect of EA on ipsilateral paw withdrawal thresholds (PWTs) at different time points in CFA rats. Values are mean ± SD, n = 10 animals per experimental group. *P < 0.05, **P < 0.01 versus saline group; ▲▲ P < 0.01 versus CFA group at corresponding time points.
Effect of EA on phosphor-p38MAPK-immunoreactivty (p-p38MAPK-IR) expression in the ipsilateral spinal dorsal horn induced in CFA rats. (a) Representative sections of p-p38MAPK-IR cells in the ipsilateral spinal dorsal horn at postinjection days 3 and 14. (section 1, saline group; sections 2 and 4, CFA group, sections 3 and 5, CFA + EA group; sections 2 and 3, postinjection day 3; sections 4 and 5, postinjection day 14; Bars = 50 μm; section thickness = 30 μm). (b) Quantification of p-p38MAPK-IR showing that EA suppressed p-p38MAPK-IR expression in the ipsilateral spinal dorsal horn. Values are mean ± SD, n = 3 animals per experimental group. **P < 0.01 versus saline group; ▲▲ P < 0.01 versus CFA group at corresponding time points.