A FLUORESCENT DOUBLE LABELED OBSERVATION OF NMDAR1 AND BSI-B4 IN THE SPINAL DORSAL HORN OF THE INFLAMMATION-INDUCED RAT AND ITS ELECTROACUPUNCTURE MODULATION

Objective Glutamate, acting at a spinal N-methyl-D-aspartate(NMDA) receptor has been implicated in development of central sensitization. The goal of the present study was to provide morphological evidences for the relation of NR1 to primary afferent C fiber in the spinal dorsal horn of the rat following inflammatory pain. Methods The Sprague-Dawley rats were divided into control group(n=12), inflammation group(n=12) and electroacupuncture(EA) treatment group(n=12). EA was done in acuponints “Huan Tiao”(GB30) and “Yang Lin Quan” (GB34) (stimulation indices: 0.5-1.5V, 4-16Hz, 30min ) following injection of Complete Freund’s adjuvant(CFA). Using immunofluoresence histochemical double-staining technique, we examined the distributions and relationships between Banderaea Simplicifolia Isolectin B4(BSI-B4) labeled primary afferent C fibers and terminals and NR1 in the dorsal root ganglion(DRG) and superficial laminae of the spinal dorsal horn following CFA-induced inflammation and EA treatment. Results NR1 was located in primary afferent C fibers and terminals of both DRG and superficial laminae of the spinal dorsal horn. In addition, we also found in the DRG that, at 3rd d and 7th d following injection of CFA, the percentages of the number of double-labeled cells to the total number of the BSI-B4 labeled cells and NR1 immunoreactive cells, respectively, all showed that: inflammation groupEA treatment group control group(P0.01), and 3rd group7th group(P0.05). Conclusion NR1 was located in primary afferent C fibers and terminals, and the up-regulation and activation of this presynaptic NR1 may contribute significantly to the hyperalgesia that accompanies persistent inflammation. Moreover, EA treatment could down-regulate the NR1 expression following inflammation to analgesia consequently.