ABSTRACT
Objective To investigate the effects of low frequency electroacupuncture on the P2X3 receptor expres-sion in dorsal root ganglion ( DRG) of rats with type II diabetic neuropathic pain. Methods Part 1:Fifty normal SD rats were randomly divided into normal group (8 rats) and model group (42 rats). The rat model of type II diabetic neuropathic pain was generated by high fat and high sugar diet with a single intraperitoneal injection of streptozotocin ( STZ, 35 mg/kg) . 2 Hz electroacupuncture was administered at ipsilateral acupoints Zusanli and Kunlun for consecutive 7 days. Insulin sensitivity index ( ISI) was measured at 0 w and 5 w, and fasting plasma glucose ( FPG) was measured at 0 w, 5 w, and 7 w. Paw withdrawal threshold (PWT) was measured by mechanical pain threshold, and P2X3 receptor was determined by immunofluorescence. Part 2:Twelve rats with diabetic neuropathic pain (DNP) were divided into EA + vehicle group (6 rats) and EA + αβ?meATP group (6 rats). Rats in the two groups received the same EA treatment as Part 1. Rats in the EA + αβ?meATP group were injected with P2X3 receptor agonistαβ?meATP (0. 6μmol/L, 100μL) into the ventral sur?face of each hind paw every time before EA treatment. Rats in the EA + vehicle group received the same dose of vehicle ( PBS buffer) as a control. Pain threshold of the rats were measured. Results ① Compared with the normal group, the ISI levels of the rats in DNP group was significantly decreased after 5 weeks of the high?fat high?sugar diet (P < 0. 01). Two weeks after STZ injection, the fasting plasma glucose levels in the rats receiving STZ were significantly elevated ( P <0. 01 ) . The type 2 diabetes model was established with a successful rate of 69. 04%. ②PWTs:The PWTs of rats in DNP group were reduced compared with rats in the normal group (P < 0. 01), indicating that the type 2 DNP model was suc?cessfully established. Compared with the PWTs of DNP?controlled rats, the 2 Hz electroacupuncture significantly increased bilateral PWT of rats subjected to DNP from day 3 after treatment (P < 0. 01). P2X3 receptor agonistαβ?meATP greatly reduced bilateral PWT of EA?treated DNP rats compared with that of the EA + vehicle group (P < 0. 01). ③The immu?nofluorescence essay showed that P2X3 receptor expression in bilateral L5 DRGs in the DNP group was significantly in?creased as compared with that in the normal group ( P < 0. 01 ) . The increases were inhibited by 2 Hz EA in L5 DRGs compared with the DNP group (P < 0. 01). Conclusions 2Hz electroacupuncture can effectively treat the type II diabet?ic neuropathic pain by decreasing the expression of L5 DRG P2X3 receptors in rats.