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, 2018, 8041820
eCollection

Electroacupuncture at Hua Tuo Jia Ji Acupoints Reduced Neuropathic Pain and Increased GABA A Receptors in Rat Spinal Cord

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Electroacupuncture at Hua Tuo Jia Ji Acupoints Reduced Neuropathic Pain and Increased GABA A Receptors in Rat Spinal Cord

Siao-Wei Jiang et al. Evid Based Complement Alternat Med.

Abstract

Chronic constriction injury- (CCI-) induced neuropathic pain is the most similar model to hyperalgesia in clinical observation. Neuropathic pain is a neuronal dysfunction in the somatosensory system that may lead to spontaneous pain. In this study, electroacupuncture (EA) was applied at bilateral L4 and L6 of Hua Tuo Jia Ji points (EX-B2) for relieving neuropathic pain in rats. Eighteen Sprague-Dawley rats were randomly assigned to three groups: sham, 2-Hz EA, and 15-Hz EA groups. Following von Frey and cold plate tests, both the 2- and the 15-Hz EA groups had significantly lower mechanical and thermal hyperalgesia than the sham group. Western blot analysis results showed that γ-aminobutyric acid A (GABAA), adenosine A1 receptor (A1R), transient receptor potential cation channel subfamily V member 1 (TRPV1), TRPV4, and metabotropic glutamate receptor 3 (mGluR3) were similar in the dorsal root ganglion of all three groups. Furthermore, levels of GABAA receptors were higher in the spinal cord of rats in the 2- and 15-Hz EA groups compared with the sham control group. This was not observed for A1R, TRPV1, TRPV4, or mGluR3 receptors. In addition, all the aforementioned receptors were unchanged in the somatosensory cortex of the study rats, suggesting a central spinal effect. The study results provide evidence to support the clinical use of EA for specifically alleviating neuropathic pain.

Figures

Figure 1
Figure 1
Withdrawal thresholds and hind paw lifting of rats in the sham (n = 6), 2-Hz EA (n = 6), and 15-Hz EA (n = 6) groups (N = 18) after CCI induction at days 7 to 9. (a) Mechanical forces of neuropathic pain rats on days 7 (7), 8 (8), and 9 (9). (b) Hind paw lifting of neuropathic pain rats on days 7 (7), 8 (8), and 9 (9). ∗p < 0.01 versus sham group. CCI: chronic constriction injury; EA: electroacupuncture.
Figure 2
Figure 2
Expression levels of GABAA, A1R, TRPV1, TRPV4, and mGluR3 receptors in rat DRG. (a) GABAA, (b) A1R, (c) TRPV1, (d) TRPV4, and (e) mGluR3 expression levels in DRG from the sham, 2-Hz EA, and 15-Hz EA groups (from left to right). Sham: neuropathic pain rats with sham EA; 2 Hz: neuropathic pain rats that received 2-Hz EA; 15 Hz: neuropathic pain rats that received 15-Hz EA. ∗p < 0.05 compared with the sham group. The Western blot bands at the top of each panel show the target protein. The lower bands are internal controls (β-actin). A1R: adenosine A1 receptor; DRG: dorsal root ganglion; EA: electroacupuncture; GABA: γ-aminobutyric acid; TRPV1: transient receptor potential cation channel subfamily V member 1; mGluR3: metabotropic glutamate receptor 3; TRPV4: transient receptor potential cation channel subfamily V member 4.
Figure 3
Figure 3
Expression levels of GABAA, A1R, TRPV1, TRPV4, and mGluR3 receptors in rat SC. (a) GABAA, (b) A1R, (c) TRPV1, (d) TRPV4, and (e) mGluR3 expression levels in the SC of the rats from the sham, 2-Hz EA, and 15-Hz EA groups (from left to right). Sham: neuropathic pain rats with sham EA; 2 Hz: neuropathic pain rats that received 2-Hz EA; 15 Hz: neuropathic pain rats that received 15-Hz EA. ∗p < 0.05 compared with the sham group. The Western blot bands at the top of each panel show the target protein. The lower bands are internal controls (β-actin). A1R: adenosine A1 receptor; DRG: dorsal root ganglion; EA: electroacupuncture; GABA: γ-aminobutyric acid; TRPV1: transient receptor potential cation channel subfamily V member 1; mGluR3: metabotropic glutamate receptor 3; TRPV4: transient receptor potential cation channel subfamily V member 4.
Figure 4
Figure 4
Expression levels of GABAA, A1R, TRPV1, TRPV4, and mGluR3 receptors in rat SSC. (a) GABAA, (b) A1R, (c) TRPV1, (d) TRPV4, and (e) mGluR3 expression levels in the SSC of rats from the sham, 2-Hz EA, and 15-Hz EA groups (from left to right). Sham: neuropathic pain rats with sham EA; 2 Hz: neuropathic pain rats that received 2-Hz EA; 15 Hz: neuropathic pain rats that received 15-Hz EA. ∗p < 0.05 compared with the sham group. The Western blot bands at the top of each panel show the target protein. The lower bands are internal controls (β-actin). A1R: adenosine A1 receptor; DRG: dorsal root ganglion; EA: electroacupuncture; GABA: γ-aminobutyric acid; TRPV1: transient receptor potential cation channel subfamily V member 1; mGluR3: metabotropic glutamate receptor 3; TRPV4: transient receptor potential cation channel subfamily V member 4.

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