TTX对糖尿病大鼠机械刺激诱发C纤维高频放电的抑制作用  

TTX inhibited the high frequency firing from C-fiber evoked by mechanical stimulation in diabetic rats

作　　者：王秀超[1] 段建红[1] 胡三觉[1] 

机构地区：[1]第四军医大学神经科学研究所,西安710032

出　　处：《神经解剖学杂志》2011年第2期124-128,共5页Chinese Journal of Neuroanatomy

基　　金：国家自然科学基金重点项目(305302600)

摘　　要：目的:探讨糖尿病大鼠机械刺激诱发C纤维高频放电的机制。方法:24只SD大鼠随机分为对照组和模型组,模型组腹腔注射70 mg/kg链脲菌素制作糖尿病模型,对照组腹腔注射相同剂量的生理盐水。造模前48 h、造模后48 h和4周分别取尾静脉血测血糖浓度;造模前3 d,造模后3、7、14、21、28 d通过刺激后爪,采用vonFrey法测定大鼠50%机械缩爪阈值(PWT)。取造模后4周的大鼠,分离尾神经,测定传导速度以确定纤维类型,并给予60 s的阈上(100 g)机械刺激,记录单根C纤维的放电。在糖尿病大鼠的尾巴上暴露尾神经,给予100nmol/L的TTX 10 min后施加60 s阈上(100 g)机械刺激,观察并记录其放电。结果:造模后48 h模型组(n=12)随机血糖浓度高于16.7 mmol/L的比率为91.7%,与对照组(n=12)比较,模型组在48 h、4周时血糖明显增高;造模后3周模型组PWT明显低于对照组(P<0.05);糖尿病组大鼠C纤维对60 s阈上(100 g)机械刺激诱发的放电数明显高于对照组;加100 nmol/L低浓度的TTX后,糖尿病大鼠中C纤维对机械刺激的放电数明显减少(P<0.01)。结论:低浓度的TTX可以抑制糖尿病大鼠机械诱发的C纤维高频放电。Objective：To investigate the mechanism of high frequency firing from C-fiber evoked by mechanical stimulation in diabetic rats.Methods：Twenty-four SD rats were randomly divided into control group and diabetic group.Rats in diabetic group were performed intraperitoneally streptozotocin（STZ） injection at a dose of 70 mg/kg,while the same volume of saline was injected in control rats.Blood samples from tail vein were collected to determine the concentration of blood glucose at 48 h,and 4 weeks after STZ or saline injection respectively.Von Frey filaments were applied to measure the 50% paw withdraw threshold（PWT） by stimulating the hind paw at 3 days before and 3,7,14,21,28 days after injection.Single fibers of coccygeal nerve were separated and the conduction velocity of these fibers was measured to determine the type.Then we recorded the evoked firing stimulated by sustained suprathreshold mechanical stimulation in rats after 4 weeks injection.Furthermore,in diabetic rats,we exposed another pool on the coccygeal nerve in the tail,and applied 100 nmol/L TTX to this pool.After 10 min,we stimulated the same C fiber by the same stimulus（100 g） and recorded the firing.Results：The ratio of random blood sugar higher than 16.7 mmol/L reached 91.7% at 48 h after STZ injection.The level of blood sugar in diabetic group was significantly higher than that of control group at 48 h,4 w after STZ injection.PWT was decreased dramatically in diabetic rats at 3 w after STZ injection（P〈0.05）.The numbers of firing evoked by sustained suprathreshold（100 g） stimulation was significantly higher for the whole population of C-fibers from diabetic animals than that in C-fibers from controls.After the application of 100 nmol/L TTX in diabetic rats,the numbers of firing evoked by the same stimulus was dramatically reduced（P〈0.01）.Conclusion：Low concentration TTX can attenuate high frequency firing evoked by mechanical simulation C-fibers in diabetic rats.

关 键 词：糖尿病 C纤维 机械刺激 大鼠 

分 类 号：R587.1[医药卫生—内分泌]