从血管活性肠肽、酪氨酸羟化酶研究电针抑制左旋多巴诱发大鼠膀胱机能亢进的神经生物学机制

目的:通过观察电针对排尿频率、骶髓背角血管活性肠肽(VIP)和脑桥蓝斑酪氨酸羟化酶(TH)表达的影响,探讨针刺抑制左旋多巴诱发的大鼠膀胱机能亢进的神经生物学机制。方法:44只雌性SD大鼠随机分成正常组、对照组、模型组、针刺组,其中模型组和针刺组动物腹腔内先后注射卡比多巴和左旋多巴引起大鼠膀胱机能亢进。在动物清醒和自由活动状态下,应用连续膀胱测压技术动态观察电针“中膂俞”对排尿频率的影响;应用免疫组织化学的方法,观察电针后骶髓背角的VIP和脑桥排尿中枢蓝斑TH的动态变化,并用图像分析技术进行定量分析。结果:模型组在腹腔注射左旋多巴后排尿频率迅速增加(P<0.05),针刺组在腹腔注射左旋多巴后15~75 min时段排尿频率较处理前增加(P<0.05),76~105 min时段排尿频率接近处理前水平(P>0.05)。针刺组在腹腔注射左旋多巴后3 h时骶髓背角的VIP阳性纤维和终末比模型组、正常组显著增加(P<0.05)。在腹腔注射左旋多巴后8 h时模型组骶髓背角的VIP阳性纤维和终末较正常组显著增加(P<0.05);针刺组与正常组骶髓背角的VIP阳性纤维和终末比较无明显差别(P>0.05)。针刺组腹腔注射左旋多巴后3 h时TH在脑桥蓝斑核内的表达较正常组显著减少(P<0.05)。模型组腹腔注射左旋多巴后8 h时TH在脑桥蓝斑核内的表达较正常组显著增加(P<0.05);针刺组腹腔注射左旋多巴后8 h时TH在脑桥蓝斑核内的表达较正常组减少(P<0.05)。结论:电针可部分促进L-多巴引起的膀胱机能亢进大鼠的躯体传入神经释放VIP,抑制脑桥排尿中枢TH的合成,从而降低排尿频率。

Effect of Electroacupuncture on Bladder Hyperactivity and Its Relation with the Activity of the Spinal Vasoactive Intestinal Peptide and Pontine Tyrosine Hydroxylase in the Rat

Objective: To observe the effect of electroacupuncture(EA) on micturition frequency(MF),and the activity of pontine tyrosine hydroxylase(TH) and vasoactive intestinal peptide(VIP) in the sacral dorsal horn of the spinal cord in L-dopa induced bladder hyperactivity rats so as to investigate its neurobiological mechanism.Methods: A total of 44 female SD rats were randomized into normal(n=6),saline control(n=10),model(n=13) and EA(n=15) groups.Bladder hyperactivity model was established by intraperitoneal injection(i.p.i) of Carbidopa((5 mL/kg)) first and L-dopa((5 mL/kg)) 15 min later.Continuous cystometry was performed in conscious rats without any restraint for detecting MF.EA((5 Hz),4-(6 V),continuous waves) was applied to bilateral "Zhonglushu"(BL 29) for(30 min).At the end of the experiments,the rats were transcardiacally perfused with 4% paraformaldehyde under deep anesthesia(10% chloral hydrate),followed by sampling the pons and the sacral cord tissues and cutting into sections ((50 μm and 30 μm respectively)).The activity of TH in pontine tissue and VIP in the sacral dorsal horn of the spinal cord was assayed with immunohistochemical method(ABC method).Results: In comparison with control group,ratios of MF in model group increased significantly(15-45 min),(46-75 min) and(76-105 min) after injection of L-dopa(P<0.05),while compared with model group,MF values of EA group declined considerably(4675 min) and(76-105 min) after injection of L-dopa(P<0.05),suggesting an improvement of L-dopa-induced bladder hyperactivity by EA.Compared with normal group and control group,the relative area values of VIP immunoreaction(IR)-positive fibers and terminals in the sacral cord and TH in pontine tissue increased slightly((3 h)) and significantly((8 h),(P<0.05)) after i.p i.of L-dopa;while compared with model group,the value of VIP increased notably(3 h) after i.p.i.and those of VIP(8 h) after i.p.i.of L-dopa, and TH(3 h) and(8 h) after i.p.i.of L-dopa decreased markedly((P<0.05)),suggesting that EA could promote the release of VIP from the somatic afferent and inhibit the synthesis of TH in pontine micturition center.Conclusion: EA can inhibit L-dopa induced bladder hyperactivity,raise the VIP activity of sacral cord(3 h) after i.p.i.of L-dopa,and reduce VIP activity(8 h) after i.p.i.and TH activity(3 h) and(8 h) after i.p.i.,which maybe the underlying mechanism of EA in inhibiting bladder hyperactivity by reducing the release of TH from pontine micturition center and promoting the release of VIP from the sacral cord dorsal horn.