본 연구는 흰쥐 발바닥에 Complete Freund’s Adjuvant (CFA)를 투여하는 염증모델에서 통증반응과 척수신경절내 zinc (Zn2±) 변화의 연관성을 autometallography (AMG) 조직화학법으로 확인하였다. 행동검사에서 CFA투여 후 1일에 이미 통증반응의 역치가 유의한 수준으로 감소되었으며, 3일 및 1주에 걸쳐 가장 예민한 통증반응을 보였으며, 이러한 경향은 3주까지 지속되었다. 대조군의 AMG 염색표본에서는 소수의 작은신경절세포에서 미약한 양성반응이 관찰되었으며, 큰신경절세포의 경우 AMG 염색에 양성반응을 보인 세포가 전혀 관찰되지 않았다. 척수신경절내 Zn2±변화를 보면 실험 1일군 이후에는 대부분의 작은신경절세포들이 강한 염색반응을 보였으며, 3일과 7일군에서 그 수가 최대였으며, 3주군에서는 오히려 그 수가 감소하였다. 반면 실험 3일군 이후에 큰 신경절세포가 AMG에 양성반응을 띠었으며, 척수신경절세포를 둘러싸는 위성세포에서도 AMG 염색성이 관찰되었다. 본 연구의 결과는 염증성 통증의 발달, 유지, 회복 등 복잡한 병리기전에 Zn2±가 관여되어 있음을 시사한다.
This study was designed to investigate any correlation between the mechanism of pain development and changes of histochemically reactive zinc contents in the rat spinal ganglion following complete Freund’s Adjuvant(CFA) injection, as an inflammatory pain model. Male Sprague-Dawley rats (270~290 g) were used for this study. Surgeries were done under anesthesia using pentobarbital (30 mg/kg). we injected 200 μL of CFA subcutaneously in the dorsal aspect of one hind paw using a 30-gauge needle and an 1 mL syringe. Semmes-Weinstein monofilaments was used to test for mechanical hyperalgesia. Finally, zinc selenite autometallography (AMG) was done by Danscher’s method. The rat suffered from severe painful swelling of the hindpaw 1 day after a CFA inoculation. Changes in pain threshold were significantly changed on 1 day, and lasted during experiment period of 3 weeks after the CFA inoculation. In control group, ganglion cells vary in size from 15 to 100 μm. The smaller neurons are strongly stained with AMG, whereas the larger cells are not almostly stained. Each large ganglion cell is surrounded by perineuronal satellite cells, showing apparent AMG stainity. In experiment group, AMG-positive small ganglion cells increased on 1 day after CFA inoculation, and showed a peak in cell number at 3days group, and decreased gradually after 7 days. We found a small number of large-sized ganglion cells with AMG stainity 7 days and 3 weeks after CFA inoculation. Our results indicate that zinc may be involved in pain mechanism in the spinal ganglion level.
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