[Effect of Electroacupuncture Intervention on Expression of Pain Sensory and Affective Proce- ssing-related µ-opioid Receptor, etc. in the Amygdala in Chronic Neuropathy Pain Rats].Zhen Ci Yan Jiu. 2016 Feb; 41(1):3-10.ZC
To observe the effect of electroacupuncture (EA) on expression of pain sensory and affective processing-related µ-opioid receptor (MOR), glutamatergic AMPA receptor subunit GIuA 1, extracellular signal-regulated kinase (ERK 1/2), cAMP response element binding protein(CREB) in the amygdala in chronic constrictive injury (CC) + negative affection(NA) rats, so as to reveal its mechanism underlying pain relief.
A total of 32 male Wistar rats were randomized into normal control, model, EA, and anesthesia+ EA (AEA) groups (n = 8 in each group). The neuropathic pain NA model was established by ligation of the left sciatic nerve and repeated electrical stimulation of the paw-bottom in the pain-paired compartment. EA was applied to bilateral "Zusanli" (ST 36) and "Yanglingquan" (GB 34) for 30 min, once daily for 7 days. Thermal pain threshold (paw withdrawl latency, PWL) of the bilateral paws was measured by using a Tail-Flick Unit. The expression levels of MOR and p-CREB in the central amygdala (CeA) and those of MOR, GluA 1, p-ERK 1/2 and p-CREB in the right amygdala area were determined using immunofluorescence and Western blot, respectively.
in comparison with the normal group, PWL difference (PWLD) values of the model group were significantly increased (P < 0.001), and the time spent in the CPA-paired. compartment was considerably decreased (P < 0.001). After EA, the PWLD levels of both EA and AEA groups were apparently decreased (P < 0.05), showing a pain relief; and the time spent in the CPA-paired compartment was apparently increased in the EA group (P < 0.05) , rather than in the AEA group (P > 0.05). Additionally , compared to the normal group, the expression level of MOR protein in the amygdala was remarkably increased (P < 0.05) and those of GIuA 1, p-ERK 2 and p-CREB proteins were apparently decreased (P < 0.05). After EA intervention for 7 days, the expression levels of these four proteins in the EA group, and those of MOR, p-ERK 2 and p-CREB in the AEA group were significantly up-regulated (P < 0.001, P < 0.01, P < 0.05). The expression level of GIuA 1 was significantly higher in the EA group than in the AEA group (P < 0.05).
Repeated EA stimulation of ST 36-GB 34 has a definite effect in relieving both sensation and affection dimensions of pain in NA rats, which may be related to its effect in up-regulating the expression of GIuA 1 in the amygdala, but the effects of MOR, p-ERK 2 and p-CREB need being researched further.