脱氧鬼臼毒素对大鼠背根神经元电压依赖性钾通道的作用

目的:探讨脱氧鬼臼毒素(DOP)对外周神经系统的毒性作用机制?方法:采用全细胞膜片钳技术研究DOP对急性分离大鼠背根(DRG)神经元电压依赖性钾通道的作用,从离子通道水平探讨其神经毒性作用机制?结果:10?20?40?80 μmol/L的DOP对全钾电流(IK)和延迟整流钾电流(IKDR)均有影响,且能以浓度依赖方式?部分可逆地阻断电压依赖性钾电流,使电流电压曲线向去极化方向移动?同时,DOP对IKDR的抑制率[(43.22 ± 6.85)%]明显高于IK[(27.55 ± 4.65)%]?结论:DOP对钾离子电流的影响可能是鬼臼毒素类化合物引起外周神经病变的机制之一?     

应用ERKO小鼠观察雌激素对痛觉的影响及ERs的作用特点

目的:探讨雌激素通过ERs对痛觉的影响?方法:WT?αERKO和βERKO小鼠随机分为去卵巢加17β-E2组(OVX+17β-E2)和去卵巢组(OVX+Oil),甩尾热痛仪和热痛刺激仪测痛,并应用福尔马林致痛模型评价雌激素对痛觉的影响?结果:将WT小鼠卵巢切除后给予外源性雌激素,发现17β-雌二醇(17β-E2)对甩尾痛阈和缩足痛阈没有影响,敲除ERα或ERβ后甩尾痛阈和缩足痛阈也没有变化;17β-E2能够降低福尔马林炎症性痛实验的Ⅱ相反应,但对Ⅰ相反应无影响?进一步应用ERKO小鼠模型观察ERα和ERβ的作用特点发现,较WT小鼠,βERKO雌性小鼠在福尔马林炎症性痛模型Ⅱ相疼痛反应行为的时间减少,而在Ⅰ相反应中没有差别;αERKO小鼠福尔马林炎症性痛实验与WT比较没有明显差异?结论:雌激素可以影响慢性炎性痛,可能与影响急性痛进程无关?ERβ亚型在雌激素调节痛觉传递和调制过程中发挥着重要作用?     

代森锰锌对小鼠生精细胞T型Ca2+通道的作用

目的:研究农药代森锰锌(mancozeb)对小鼠生精细胞T型钙电流(ICaT)的影响?方法:采用膜片钳全细胞记录技术观察代森锰锌对急性机械分离的小鼠生精细胞ICaT 的影响?结果:Mancozeb(10?20?40?80?120 μmol/L)呈浓度?电压依赖性抑制小鼠生精细胞钙电流,抑制率分别为(9.93±0.90)%?(20.93±2.50)%?(25.92±2.80)%?(42.64±3.10)%?(56.80±3.20)% (n=6,P<0.05)?Mancozeb 对T型钙通道的半数最大抑制浓度(K50)为35.60 μmol/L?120 μmol/L mancozeb显著改变T型Ca2+通道的激活和失活特性:半数激活电压(V1/2a)和激活斜率因子(κa)分别从(-47.09±1.05)mV和(8.67±0.78) mV变为(-51.46±0.84)mV和(10.56±0.619)mV (n=5, P < 0.05);而半数失活电压(V1/2i)和失活斜率因子(κi)分别从(-62.96±3.36)mV和(9.93±1.41)mV变为 (-64.11±5.55)mV和(13.64±1.95)mV (n=5,P < 0.05)?结论:Mancozeb对生精细胞T型钙通道有抑制作用,且呈浓度依赖性?     

加巴喷丁对奥沙利铂诱发神经病理性痛小鼠背根神经节神经元高电压激活钙通道的影响

目的 评价加巴喷丁对奥沙利铂诱发神经病理性痛小鼠背根神经节(DRG)神经元高电压激活钙通道的影响.方法 清洁级雄性昆明小鼠,体重20～25 g,6周龄.采用腹腔注射奥沙利铂3mg/kg的方法制备神经病理性痛模型.取模型制备成功的小鼠41只,采用随机数字表法,将小鼠随机分为神经病理性痛组(NP组,n=20)和加巴喷丁组(G组,n=21),另取10只正常小鼠为正常对照组(C组).G组于奥沙利铂给药后第3天腹腔注射加巴喷丁100mg/kg,NP组及C组给予等容量的生理盐水,每天1次,连续3 d.于加巴喷丁给药前即刻、给药后1～3 d(T1-4)时测定小鼠双后肢机械缩足阈值(MWT).于最后一次MWT测定后,取两侧L4,5节段DRG,分离DRG神经元,采用全细胞膜片钳记录峰电流密度,拟合DRG神经元高电压激活钙通道激活曲线和稳态失活曲线,计算半数激活电位(Va1/2)和半数失活电位(Vi1/2).结果 与C组比较,NP组T1～4时、G组T1时MWT降低,NP组峰电流密度和Vi1/2升高(P＜0.05),Va1/2差异无统计学意义,G组峰电流密度、Vi1/2和Va1/2差异无统计学意义(P＞0.05);与NP组比较,G组T2-4时MWT升高,峰电流密度和Vi1/2降低(P＜0.05).结论 加巴喷丁减轻小鼠奥沙利铂诱发神经病理性痛的机制可能与抑制DRG神经元高电压激活钙通道电流,促进通道失活有关.

Abstract：

Objective To investigate the effects of gabapentin on high-voltage-activated calcium currents in dorsal root ganglion (DRG) neurons in mice with oxaliplatin-induced neuropathic pain (NP). Methods Pathogen-free male Kunming mice aged 6 weeks weighing 20-25 g were used in this study. NP was induced by injection of intraperitoneal oxaliplatin 3 mg/kg. Successful induction of NP was defined as the mechanical paw withdrawal threshold (MWT) measured at 3 d after oxaliplatin administration decreased to 40% of the baseline ( before administration of oxaliplatin). Forty-one mice in which NP was successfully induced were randomly divided into 2 groups: NP group ( n = 20) and gabapentin group (group G, n = 21 ). Another 10 normal mice served as control group (group C). At 3 days after oxaliplatin administration, gabapentin 100 mg/kg was injected intraperitoneally once a day for 3 consecutive days in group G, while C and NP groups received the equal volume of normal saline.MWT to von Fray filament stimulation was measured immediately before and 1-3 days after gabapentin administration (T1-4). After the last measurement of MWT, bilateral L4.5 DRG was collected and neurons were isolated. The high-voltage-activated calcium currents were recorded using whole-cell patch-clamp technique. The peak current density and the voltage where half of the current was activated ( Va1/2 ) or inactivated ( Vi 1/2 ) were calculated. Results Compared with group C, MWT at T1-4 was decreased, the peak current density and Vi1/2 were significantly increased in group NP, and MWT at T1 was decreased in group G ( P ＜ 0.05). There was no significant difference in the peak current density, Vi1/2 and Va1/2 between C and G groups ( P ＞ 0.05). MWT at T2-4 was significantly increased, while the peak current density and Vi1/2 were significantly decreased in group G compared with group NP (P ＜ 0.05). Conclusion Gabapentin can reduce oxaliplatin-induced NP in mice through inhibiting high-voltage-activated calcium currents and promoting the inactivation of the channels in DRG neurons.