The study on the mechanism of voltage gated calcium channels on 2, 4, 6-trinitrobenzene sulfonic acid induced inflammatory visceral hypersensitivity / 中华消化杂志

ABSTRACT

Objective To screen the difference of gene expression in dorsal root ganglia (DRG)of inflammatory visceral hypersensitivity rats and to explore the role of voltage gated calcium channel (VGCC) in inflammatory visceral hypersensitivity. Methods Total 180 male Sprague-Dawley rats were in this study,the weight varied from 200 gram to 300 gram. 2,4,6-trinitrobenzenesulfonic acid (TNBS) model group was maken by 2. 0% TNBS slowly injection,the dosage was 100mg per kilogram. The normal control group was only injected with same volume of 0. 9% sodium chloride solution. After the model had been maken for four days,gene expression profiles of L6-S2 DRGs were tested by rat cDNA microarray chips. And the result was verified by RT-PCR and Western blot. The changes of intracellular Ca2+ and the voltage gated calcium currents were recorded by patch-clamp.The special Ca2+ channel blockers were given by intrathecal injection,and then the changes of visceral sensitivity were observed. The visceral sensitivity was measured by abdominal withdrawal reflex (AWR). Results There were significant changes of 172 genes expression in L6-S2 DRGs of TNBS model rats,which included Ca2+ channel,membrane receptor and intracellular second messenger. Of those,L-type Ca2+ channel (Cav1. 2) and R-type Ca2+ channel (Cav2. 3) were significantly up-regulated. The results of gene microarray chips were further confirmed by RT-PCR and Western blot.The intracellular Ca2+ testing indicated that there was no statistical significant of resting intracellular Ca2+ in colonic special sensory neuron between TNBS group and normal control group (P＞0. 05);while the evoked transients [Ca2+] significantly increased compared with normal control group (P＜0. 05). The whole cell patch clamp recording showed that the L-type and R-type calcium current were significantly increased in colonic primary sensory neurons of TNBS group compared with normal control group (P＜0. 05). The inflammatory visceral hypersensitivity was significantly reduced by intrathecal injection of nimodipine and SNX-482 (P＜0. 05). Conclusion The up-regulation of Cav1. 2and Cav2. 3 play an important role in inflammatory visceral hyperalgesia,which may be the possible potential therapeutic targets for visceral inflammatory hyperalgesia.