C57BL/6哮喘小鼠细胞内镁含量与肺组织β2受体mRNA表达的相关性研究

目的：探讨细胞内镁含量对C57BL/6哮喘小鼠肺组织β₂受体mRNA表达的影响。方法:健康4－6周龄清洁级雌性C57BL/6小鼠96只，体重(12±2)g，随机数字表法分为A、B、C、D 4组，每组各24只。应用鸡卵蛋白(OVA)建立哮喘小鼠模型。A、B组予低镁饲料喂食，C、D组予正常镁饲料喂食。B、D组腹腔内注射沙丁胺醇诱导β₂受体低调节，A、C组腹腔内注射生理盐水作对照。第1 d、21 d、34 d各组分别随机抽取8只检测血浆Mg2+、红细胞内Mg2+、肺组织β₂受体mRNA及蛋白表达。 结果:1 d血浆Mg2+、红细胞内Mg2+、肺组织β₂AR mRNA及蛋白表达各组间差异无显著（均P>0.05）。21 d、34 d C组血浆Mg2+、红细胞内Mg2+、肺组织β₂AR mRNA及蛋白表达均显著高于A组［21 d：(0.84±0.09)mmol/L vs （0.57±0.10)mmol/L、(2.39±0.14)mmol/L vs （2.11±0.08)mmol/L、(0.75±0.09)mmol/L vs （0.59±0.06)pmol/g、（88.50±8.50)pmol/g vs （60.10±7.70)pmol/g，均P<0.05；34 d：(0.67±0.10)mmol/L vs (0.51±0.09)mmol/L、(2.17±0.08)mmol/L vs (2.05±0.09)mmol/L、(0.61±0.05)pmol/g vs (0.53±0.06)pmol/g、(76.60±7.10)pmol/g vs (58.00±7.60)pmol/g，均P<0.05］；21 d、34 d D组血浆Mg2+、红细胞内Mg2+、肺组织β₂AR mRNA及蛋白表达亦显著高于B组［21 d：(0.95±0.33)mmol/L vs (0.46±0.09)mmol/L、(2.32±0.18)mmol/L vs (1.87±0.14)mmol/L、(0.73±0.10)pmol/g vs (0.43±0.07)pmol/g、(96.90±8.00)pmol/g vs (47.90±4.90)pmol/g，均P<0.05；34 d：(0.71±0.10)mmol/L vs (0.31±0.08)mmol/L、(1.66±0.13)mmol/L vs (1.45±0.16)mmol/L、(0.40±0.07)pmol/g vs (0.33±0.05)pmol/g、(61.50±3.20)pmol/g vs (35.30±7.10)pmol/g，均P<0.05］。结论:细胞内镁缺乏的C57BL/6哮喘小鼠肺组织β₂受体表达减少，在激动剂作用下更易发生β₂受体低调节。

Correlation between intracellular magnesium and expression of beta 2-adrenergic receptor mRNA in the lung of C57BL/6 asthmatic mice

AIM: To explore the effect of intracellular magnesium on expression of beta 2-adrenergic receptor mRNA in the lung of C57BL/6 asthmatic mice. METHODS: Ninety-six healthy, 4-6 weeks old and female C57BL/6 mice, weighting (12±2) g, were randomly divided into the following A, B, C, D groups with 24 mice in each group. The mice were sensitized and challenged by ovalbumin to establish the asthmatic model. A and B groups were fed with magnesium deficient diet. C and D groups were fed with normal magnesium level diet. B and D groups were injected intraperitoneally with 0.2 mL sulphate salbutamol solution after OVA provocation. A and C groups were injected intraperitoneally with 0.2 mL saline as control. Eight mice in each group were randomly taken out at 1 d, 21 d, 34 d to detect plasma Mg2+, intracellular Mg2+, the beta 2-AR mRNA and protein in lung tissue. RESULTS: No significant difference in plasma Mg2+, intracellular Mg2+, the beta 2-AR mRNA and protein in lung tissue among all groups at 1st d was observed (P>0.05, respectively). Plasma Mg2+, intracellular Mg2+, the beta 2-AR mRNA and protein in lung tissue in group C at 21st d and 34th d were significantly higher than those in group A at 21st d and 34th d ［21st d:(0.84±0.09)mmol/L vs 0.57±0.10)mmol/L, (2.39±0.14)mmol/L vs (2.11±0.08) mmol/L,(0.75±0.09)pmol/g vs (0.59±0.06)pmol/g, (88.50±8.50)pmol/g vs (60.10±7.70)pmol/g, P<0.05, respectively; 34th d:(0.67±0.10)mmol/L vs (0.51±0.09)mmol/L, (2.17±0.08)mmol/L vs (2.05±0.09)mmol/L,(0.61±0.05)pmol/g vs (0.53±0.06)pmol/g, (76.60±7.10)pmol/g vs (58.00±7.60)pmol/g, P<0.05, respectively］. Also, plasma Mg2+, intracellular Mg2+, the beta 2-AR, mRNA and protein of lung tissue in group D at 21st d and 34th d were significantly higher than those in group B at 21st d and 34th d ［21st d:(0.95±0.33)mmol/L vs (0.46±0.09)mmol/L,(2.32±0.18)mmol/L vs (1.87±0.14)mmol/L,(0.73±0.10)pmol/g vs (0.43±0.07)pmol/g, (96.90±8.00)pmol/g vs (47.90±4.90)pmol/g, P<0.05, respectively; 34th d:(0.71±0.10)mmol/L vs (0.31±0.08)mmol/L, (1.66±0.13)mmol/L vs (1.45±0.16)mmol/L,(0.40±0.07)pmol/g vs (0.33±0.05)pmol/g, (61.50±3.20)pmol/g vs (35.30±7.10)pmol/g, P<0.05, respectively］.CONCLUSION: The expression of β2-adrenergic receptor mRNA in the lung of C57BL/6 asthmatic mice with deficient intracellular magnesium is suppressed and C57BL/6 asthmatic mice with deficient intracellular magnesium are even easier to induce downregulation of β2-adrenergic receptor when β2-AR agonist is administered.