鞘内注射血管紧张素Ⅱ对大鼠痛阈的影响

Effect of intrathecal injection of angiotensin Ⅱ on pain threshold in rats

目的探讨鞘内注射不同剂量的血管紧张素Ⅱ(AngⅡ)对大鼠机械痛阈(MWT)和热痛阈(TWL)的影响。方法 30只雄性鞘内置管后无神经症状的SD大鼠,随机均分为AngⅡ0.065nmol组(A1组)、AngⅡ0.65nmol组(A2组)、AngⅡ6.5nmol组(A3组)、生理盐水组(NS组)和正常对照组(C组)。鞘内置管成功后给予A1、A2和A3组大鼠相应剂量的AngⅡ(容量均为27μl),NS组给予相同容剂的生理盐水,C组不作任何处理,测量各组大鼠鞘内给药前120min(T0)、给药后15min(T1)、30min(T2)、60min(T3)、90min(T4)、120min(T5)的MWT和TWL。结果 T1～T4时A2、A3组MWT明显低于T0时和C组,T2、T3时A1组MWT明显低于T0时和C组(P<0.05或P<0.01)。T2时A1组,T1～T3时A2、A3组,T4时A3组TWL明显低于T0时和C组(P<0.05或P<0.01)。T1～T4时,MWT和TWL的组间变化趋势为A3<A2<A1,T5时各组大鼠MWT和TWL均恢复至给药前水平。结论鞘内注射AngⅡ可使大鼠MWT和TWL降低,随着注射剂量增加,MWT和TWL下降幅度增加。

Objective To investigate the effect of intrathecal injection of angiotensin Ⅱ with different doses on hindpaw withdrawal mechanical threshold （MWT） and thermal latency （TWL） in rats. Methods Thirty health adult male Sprague-Dawley rats were randomly divided into 5 groups： group NS receiving saline （27μl） via intrathecal injection; groups A1, A2 andA3 receiving intrathecal angiotensin Ⅱ at the dose of 0. 065 nmol, 0. 65 nmol and 6.5 nmol respectively; group C receiving nothing. MWT and TWL was assessed at 120 min（T0）before injection, 15 min（T1 ）, 30 min（T2）, 60 min（T3）, 90 min（T4） and 120 min（T5） after intrathecal injection. Results In groups A2 and A3, MWT at T1-T4 decreased significantly（P〈0. 05 or P〈O. 01） compared with T0 or those in group Z. In group A1 at T2, T3, group A2 at T1-T3 and group A3 at T4, TWL was significantly lower than those in group Z and those at To （P〈0.05 or P〈0.01）. The MWT and TWL in group A1,A2,A3 were A3%A2%A1 at T1-T4. At the time of T5, the MWT and TWL recovered to the level of pre- injection in all groups. Conclusion Intrathecal injection of Ang Ⅱ could dose-dependently reduce the MWT and TWL in rats.