Antinociception Of Intrathecal Dexmedetomidine In The Mouse Formalin Test

Objective The purpose of this study was to determine if intrathecal dexmedetomidine can modulate formalin-induced nociception and spinal nNOS mRNA expression in dorsal horn of spinal cord in the mouse formalin test.Methods The experiment was performed in two parts: In part one,we determine if intrathecal dexmedetomidine can modulate formalin-induced nociception in the mouse formalin test; In part two,we detect with Real Time PCR the spinal nNOS mRNA expression in dorsal horn of spinal cord in the mouse formalin test of the intrathecal dexmedetomidine .Twenty four adult male SD rats are randomly assigned to the S group - sham operation group(anesthesia,disinfection,not to inject 5%formaldehyde at the foot plates,only intrathecal physiological saline 20μl in preanesthesia 10 min . O group- operation group, D1 group-Dex 5μg/kg group,D2 group-Dex 10μg/kg group. All of the rats O group,D1 group and D2 group are injected 5%formaldehyde 40μl at the foot plates, the rats of D1 group and D2 group are intrathecaled dexmedetomidine and the rats of S group and O group are intrathecaled 0.9%Sodium Chloride Solution 20μl 10min befor operation. The nociceptive behaviours including licking,biting and lifting of the injected paw were cumulatively recorded during phase I(0-5min)and phaseⅡ(15-50min),and then we score it by Dubuisson'S method.。To put to death the rats after inject formalin,and open the lamina of vertebra to expose the spinal cord of the intumescentia lumbalis,and then cut the spinal cord with an operating knife. We dip the myeloid tissue in RNAfixer, abstracte the rats myeloid tissue total RNA with Trizol method, and measure the total RNA density in Beckman nucleic acid-protein analyzer,and then reverse transcription the total RNA into cDNA, to maintain it in 4℃. We detect the cornu dorsale medullae spinalis L4一5nNOS mRNA expression with Real Time PCR. Results The pain score discrepancy during phase I is not statistically significant in all groups(P>O.05), but during phaseⅡ, compared to O group ,the S,D1,D2 groups pain score grow downwards significantly, and the distinction is statistically significant(P