成年大鼠脑桥三叉神经束局部脱髓鞘诱发三叉神经痛样行为

Focal demyelination in the pontine trigeminal tracts induces trigeminal neuralgia-like behaviors in adult rats

目的探究成年大鼠脑桥三叉神经束(pontine trigeminal tract,PTT)局部脱髓鞘能否诱发三叉神经痛样行为。方法利用脑立体定位微量注射技术向250~270 g雄性SD大鼠PTT区域注射1%溶血磷脂酰胆碱(lysophosphatidylcholine,LPC)或1×PBS,分别建立PTT脱髓鞘模型组(LPC组)和对照组。通过髓鞘荧光染色评估PTT区域脱髓鞘改变情况。采用行为学实验检测大鼠缩头反应机械刺激阈值、单侧眼睑缩窄时间和快速抚面次数。通过腹腔注射给予大鼠卡马西平(50 mg/kg)药物处理,评估其行为学改变。结果以Bregma为坐标原点,于前后径(axterior-posterior,AP)-9.86 mm、内外径(medial-lateral,ML)0 mm和背腹径(dorsal-ventral,DV)0 mm处左侧18°倾斜脑立体定位仪的操作臂,使玻璃微电极下行9.22 mm后,以250 nL/min的速度注射250 nL的1%LPC,能够稳定可靠地建立成年大鼠PTT局部脱髓鞘模型。髓鞘荧光染色结果显示成年大鼠PTT局部脱髓鞘模型中脱髓鞘峰点为造模后第7天。行为学实验发现,与对照组相比,引发LPC组大鼠缩头反应的Air-puff气体刺激阈值和von Frey纤维丝刺激阈值显著降低(P<0.01);微量注射后第7天,LPC组大鼠的左侧单侧眼睑缩窄时间和快速抚面次数在不同强度的机械刺激下均显著增加(P<0.01)。卡马西平可显著减少机械刺激触发的左侧单侧快速抚面次数(P<0.01)。结论成年大鼠PTT局部脱髓鞘可以诱发三叉神经痛样行为。

Objective To investigate whether focal demyelination in the pontine trigeminal tracts(PTTs)can induce trigeminal neuralgia-like behaviors in adult rats.Methods Brain stereotaxic microinjection technology was used to inject 1%lysophosphatidylcholine(LPC)or 1×PBS into the PTT region of male SD rats(weighing 250~270 g)to establish the PTT demyelination model group(LPC group)and control group,respectively.Myelin fluorescent staining was employed to evaluate the demyelination changes in the PTT region.Behavioral experiments were performed to measure the mechanical stimulation threshold of head withdraw response,unilateral eyelid contraction duration and numbers of fast face stroking in rats.Intraperitoneal injection of 50 mg/kg carbamazepine was given to the rats to evaluate their behavioral changes.Results A stable local demyelination model of PTT in adult rats was successfully established by,with the coordinate origin at Bregma,descending glass microelectrode for 9.22 mm with a left-side 18°tilt path from axterior-posterior(AP)-9.86 mm,medial-lateral(ML)0 mm and dorsal-ventral(DV)0 mm,and then 250 nL 1%LPC was injected at a rate of 250 nL/min.Myelin fluorescent staining demonstrated that the peak of demyelination was observed at the 7th day after modeling.Behavioral experiments showed that compared with the control group,the air-puff gas stimulation threshold and von Frey filament stimulation threshold that triggered the head withdraw response were significantly reduced in the LPC group(P<0.01).At the 7th day after modeling,there were significant increases in the unilateral eyelid contraction duration and the numbers of unilateral fast face stroking only in the adult rats from the LPC groups(P<0.01).Carbamazepine significantly decreased the numbers of unilateral fast face stroking evoked by mechanical stimulation(P<0.01).Conclusion Focal demyelination in the PTTs can induce trigeminal neuralgia-like behaviors in adult rats.