L-精氨酸对肺动脉高压肉鸡肺小动脉平滑肌细胞凋亡的影响

Effect of L-arginine on Apoptosis of Smooth Muscle Cells in Pulmonary Arterioles in Broilers with Pulmonary Hypertension

将240羽14日龄艾维茵-2000商品代肉鸡于14 d时随机等分为常温对照组(NT组),低温组(LT组)和低温加L-精氨酸组(LA).自14 d起,LT和LA组舍内温度从28℃以1～2C/d的速度下降,至21 d降至12～14℃,并维持到试验结束.此外,LA组自14 d起在饲料中按100 mg/kg剂量添加L-Arg,直至试验结束.记录肺动脉高压综合征(PHS)发病率,并分别于24、32、39和45 d测定右心室/全心室质量比(RV/TV)、血浆NO、肺小动脉管壁面积/管总面积(WA/TA)和平均中膜厚度(mMTPA),并用原位缺口末端标记法(TUNEL法)对肺小动脉凋亡平滑肌细胞进行染色和计数.结果:LT组肉鸡PHS发病率、RV/TV、mMTPA和WA/TA值较NT组升高(P＜0.05);LA组肉鸡PHS发病率较LT组降低(P＜0.05),mMTPA和WA/TA值与LT组相比呈下降趋势,在32d时显著降低(P＜0.05);LT组血浆NO浓度总体上与NT组差异不显著(P＞0.05),仅在39 d时降低(P＜0.05),而LA组血浆NO浓度自32 d时起较NT和LT组显著升高(P＜0.05);LA组肉鸡肺小动脉平滑肌凋亡细胞百分率较NT组和LT组均显著升高(P＜0.05),但LT组与NT组之间相比无显著差异(P＞0.05).上述结果表明,L-Arg/NO通过促进肺小动脉平滑肌细胞凋亡,从而在一定程度上抑制了肺血管重构的形成.

240 Avian-2000 commercial broilers were allocated equally into a normal temperature control group （NT）, a low temperature group （LT） and a low temperature with supplemental L-arginine group （LA） at clay 14 of age. Starting on clay 14, birds in groups LA and LT were subjected to the same low temperature by lowing 1-2 ℃ per day from 28 ℃ （d 14） down to 12-14 ℃ （d 21）, and remained constant until day 49. Starting on day 14, an additional 100 mg/kg L-arginine was added to the basal diets of group LA. Incidence of pulmonary hypertension syndrome （PHS） was recorded. Right/total ventricle ratio （RV/TV）, plasma nitric oxide （NO）, vessel wall area to vessel total area ratio （WA/TA）, and mean media thickness of pulmonary arterioles （mMTPA） were measured at days 24, 32, 39 and 45 of age. Apoptosis of smooth muscle cells in pulmonary arterioles were detected using TdT-mediated dUTP-biotin nick end labeling （TUNEL） kit. It was found that birds in the group LT had increased PHS incidence, RV/ TV, WA/TA and mMTPA compared with those in the group NT. Birds in the group LA tended to have lower WA/TA and mMTPA than those in the group LT, and this tendency was pronounced on day 32. Plasma NO concentration was increased in the group LA compared to that in the groups NT and LT from days 32 to 45, but there were no differences between the groups LT and NT despite an exception on day 39. Birds in the group LA had increased apoptotic to total smooth muscle cells ratio than those in the groups NT and LT; however, there were no differences between the groups LT and NT. It was demonstrated that L-arginine/NO promoted apoptosis in pulmonary smooth muscle cells and thereby prevented pulmonary vascular remodeling to a certain extent.