牛磺酸锌对染铅大鼠海马NOS活性和nNOS蛋白及基因表达的影响

EFFECT OF TAURINE-ZINC ON NOS ACTIVITY, NEURON NOS PROTEIN AND GENE EXPRESSIONS IN HIPPOCAMPUS OF LEAD-EXPOSED RATS

目的:探讨不同剂量牛磺酸锌(TZC)拮抗铅对大鼠海马一氧化氮合酶(NOS)活性和神经元型一氧化氮合酶(nNOS)蛋白及基因表达的损害。方法:用NADPH-黄递酶(NADPH-d)组化、ABC免疫组化和半定量逆转录-聚合酶链式反应(RT-PCR)法,研究饮用含0.2 g/L醋酸铅(PbAc)饮水和含不同剂量(5.9、17.7g/kg)TZC饲料喂养的大鼠海马NOS活性、nNOS阳性神经元数目以及nNOS基因表达的变化。结果:与对照组大鼠海马CA1区NOS、nNOS阳性神经元数(56.80±6.69,60.67±13.48)和海马nNOS mRNA相对含量(0.454±0.045)相比,染铅组大鼠海马CA1区NOS、nNOS阳性神经元数(42.60±6.1 7,46.67±9.04)和海马nNOS mRNA相对含量(0.071±0.025)明显减少(P<0.05)。而铅加5.9 g/kg TZC 组大鼠海马CA1区NOS、nNOS阳性神经元数(61.60±7.30,56.87±6.64)和海马nNOSmRNA相对含量(0.412±0.061)均较染铅组明显增加(P<0.05)。铅加牛磺酸(Tau)组和铅加17.7 g/kgTZC组海马nNOS mRNA相对含量(0.138±0.026和0.137±0.019)较染铅组明显增加(P<0.05)。各组大鼠海马齿状回NOS和nNOS阳性细胞数的变化与CA1区变化基本一致,而CA3区无明显差别。结论:5.9 g/kg TZC能明显增强慢性染铅大鼠海马NOS活性和nNOS蛋白及基因表达。

Objective: To investigate the effect of taurine-zinc compound (TZC) on nitric oxide synthase(NOS) activity, protein and gene expressions of neuron NOS (nNOS) in hippocampus of Pb-exposed rats. Methods: 48 Wistar rats were exposed to lead by drinking 0.2% lead acetate solution (PbAc) for three months, and fed with different dosage of TZC (5.9g or 17.7g/kg) .The changes of NOS activity, nNOS protein and gene expression in rats hippocampus by NADPH-diaphorasel (NADPH-d) histochemistry, ABC immunohistochemistry and the semiquantitative reverse transcription-polymerase chain reaction (RT-PCR) method were studied. Results: Compared with the control group, the number of NOS positive neurons, nNOS positive neurons in CA1 area and the nNOS mRNA content of hippocampus of lead-exposed rats (42.60±6.17, 46.67± 9.04 and 0.071±0.025 respectively) were significantly decreased than the control group(56.80±6.69, 60.67±13.48 and 0.454±0.045, P<0.05 respectively), and those of Pb+5.9g/kg TZC rats were significantly increased than the lead-exposed rats(61.60±7.30 56.87± 6.64 and 0.412± 0.061, P<0.05 respectively). The nNOS mRNA content of hippocampus of Pb+Tau rats and Pb+5.9g/kg TZC rats (0.138±0.026 and 0.137±0.019 respectively) were significantly increased than the lead-exposed rats (P<0.05) .In dentate gyrus, the changes of the number of NOS positive neurons, nNOS positive neurons coincided with the changes in CA1 area, and those changes in CA3 area showed no obvious difference among groups. Conclusion: 5.9 g/kg TZC could enhance NOS activity and nNOS protein gene expression obviously in hippocampus of chronic Pb-exposed rats.