谷氨酰胺对模拟失重大鼠心脏氧化应激的影响

王馨佩; 张佳欣; 邢长洋; 李昀初; 杨红燕; 张鹏飞; 张星; 高峰; 李嘉

doi:10.12125/j.chj.202002027

摘要:

目的探讨谷氨酰胺（Gln）对模拟失重大鼠心脏氧化应激的影响。

方法利用尾部悬吊方法建立大鼠模拟失重模型，将18只成年雄性Sprague-Dawley大鼠随机分为3组：对照（Control）组、尾部悬吊（HU）组和尾部悬吊+Gln干预（HU + Gln）组。尾吊4周后，超声检测大鼠心脏功能，免疫荧光法检测心肌组织内二氢乙锭（DHE）标记的超氧阴离子含量，试剂盒测定心肌组织中丙二醛（MDA）、谷胱甘肽（GSH）和过氧化氢（H₂O₂）的含量。分离原代乳鼠心肌细胞和成年大鼠心肌细胞，均分为以下4组：对照（Control）组，Gln干预（Gln）组，H₂O₂处理（H₂O₂）组和H₂O₂处理+Gln干预（H₂O₂ + Gln）组。采用流式细胞术检测乳鼠心肌细胞的凋亡。检测成年大鼠心肌细胞中MDA和GSH含量，并通过对心肌细胞内Ca²⁺进行fluo-4染色，在共聚焦显微镜下对心肌细胞的收缩功能进行测量。

结果与Control组相比，HU组心肌组织中DHE染色荧光强度、MDA和H₂O₂含量显著增加（P均<0.01），GSH含量显著降低（P <0.01），提示HU可导致心肌组织氧化应激增强；而Gln干预可降低HU大鼠心肌组织中DHE染色荧光强度、MDA和H₂O₂含量（P均<0.05），并增加GSH含量（P <0.05）。HU组大鼠的左室射血分数（EF）、缩短分数（FS）和心排出量（CO）均显著低于Control组（P均<0.05），而Gln干预可使HU大鼠心脏EF、FS和CO显著增加（P 均<0.05）。对于原代培养的乳鼠心肌细胞，给予Gln可显著抑制H₂O₂所致的心肌细胞凋亡（P <0.01）。对于成年大鼠心肌细胞，给予Gln可减轻H₂O₂处理所致的心肌细胞氧化应激（P <0.05），并且增强H₂O₂处理降低的心肌细胞缩短幅值（P <0.01）和Ca²⁺瞬变幅度（P <0.05）。

结论 Gln通过减轻模拟失重大鼠心脏的氧化应激损伤改善心脏功能，其机制可能与促进心肌细胞GSH合成有关。

Abstract:

AIM To investigate the effects of glutamine (Gln) on simulated microgravity induced oxidative stress in the heart.

METHODS Microgravity was simulated by tail suspension. Eighteen male Sprague-Dawley rats were randomly assigned into a control group (Control), a tail suspension group (HU) and a Gln-treated tail suspension group (HU + Gln). After 4 weeks of tail suspension, cardiac functions and contents of dihydroethidium (DHE) labeled superoxide anion, malondialdehyde (MDA), glutathione (GSH) and hydrogen peroxide (H₂O₂) in myocardial tissues were detected. Neonatal rat cardiomyocytes and adult rat cardiomyocytes were isolated and divided into 4 groups: a control group (Control), a Gln-treated group (Gln), a H₂O₂ group (H₂O₂) and a Gln-treated H₂O₂ group (H₂O₂ + Gln). Flow cytometry was used to detect myocardial apoptosis in different groups. The contents of MDA and GSH in adult rat cardiomyocytes were detected. Intracellular Ca²⁺ were stained with fluo-4, and then myocardial contraction amplitude and Ca²⁺ transient amplitude were detected by laser confocal microscope.

RESULTS Compared with those in the control group, the DHE fluorescence intensity, MDA content and H₂O₂ content were increased (all P < 0.01), and GSH content was decreased in the HU group (P < 0.01), indicating an increased oxidative stress level. Gln treatment decreased the DHE fluorescence intensity, MDA content and H₂O₂ content (P < 0.05), but increased GSH content (P < 0.05). Gln also restored the impaired cardiac functions induced by HU, as manifested by increased left ventricular ejection fraction, fractional shortening and cardiac output (all P < 0.05). In neonatal rat cardiomyocytes, Gln significantly reduced the increased apoptosis induced by H₂O₂ treatment (P < 0.01). In adult rat ventricular cardiomyocytes, Gln treatment significantly alleviated the increased oxidative stress level (P < 0.05) and enhanced the decreased myocardial contraction amplitude (P < 0.01) and Ca²⁺ transient amplitude (P < 0.05) induced by H₂O₂ treatment.

CONCLUSION Gln treatment significantly alleviates cardiac oxidative stress and improves the impaired cardiac functions induced by simulated microgravity probably through promoting GSH synthesis in cardiomyocytes.

谷氨酰胺对模拟失重大鼠心脏氧化应激的影响

Effects of glutamine on simulated microgravity induced cardiac oxidative stress