Expression of hexokinase isoforms in the dorsal root ganglion of the adult rat and effect of experimental diabetes
Expression of hexokinase isoforms in the dorsal root ganglion of the adult rat and effect of experimental diabetes
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DOI：
10.1016/j.brainres.2007.08.015
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发表时间：
2007-10-17
期刊：
影响因子：
2.9
通讯作者：
Fernyhough, Paul
中科院分区：
文献类型：
--
作者：
Gardiner, Natalie J.;Wang, Zuocheng;Fernyhough, Paul
研究了链脲佐菌素(STZ)诱导的糖尿病对腰背根神经节(DRG)感觉神经元糖酵解第一步和限速步骤己糖激酶表达和活性的影响。成年大鼠背根神经节和坐骨神经仅表达己糖激酶I亚型。脊髓背根神经节的免疫荧光染色显示，小中型神经元和卫星细胞高表达己糖激酶I。大型神经元，主要是本体感觉神经元，己糖激酶L染色很弱或阴性。对成年大鼠和培养的成年大鼠感觉神经元完整的背根节进行的生化研究表明，己糖激酶I几乎仅见于线粒体室。与年龄匹配的对照组相比，持续6周或12周的STZ糖尿病使腰椎DRG中己糖激酶活性分别降低28%和30%(P<；0.05)。定量Western blotting显示，糖尿病对背根神经节组织匀浆或线粒体中己糖激酶I蛋白的表达没有影响。己糖激酶I免疫荧光染色显示糖尿病大鼠背根神经节中小神经元表达无明显变化，但大神经元表达阳性(P<；0.05)。糖尿病对背根神经节己糖激酶I表达的复杂影响可能是由于葡萄糖驱动的表达上调，或者是大量神经元亚群中轴突运输和核周积聚受损的结果。由于己糖激酶是糖酵解的限速酶，这些结果表明糖尿病患者通过糖酵解途径的代谢流量减少。因此，这一发现质疑了高糖诱导的代谢流作为线粒体产生活性氧物种的关键驱动力所起的作用。(C)2007 Elsevier B.V.保留所有权利。
The effect of streptozotocin (STZ)-induced diabetes on expression and activity of hexokinase, the first enzyme and rate-limiting step in glycolysis, was studied in sensory neurons of lumbar dorsal root ganglia (DRG). The DRG and sciatic nerve of adult rats expressed the hexokinase I isoform only. Immunofluorescent staining of lumbar DRG demonstrated that small-medium neurons and satellite cells exhibited high levels of expression of hexokinase I. Large, mainly proprioceptive neurons, had very low or negative staining for hexokinase L Intracellular localization and biochemical studies on intact DRG from adult rats and cultured adult rat sensory neurons revealed that hexokinase I was almost exclusively found in the mitochondrial compartment. Duration of STZ-diabetes of 6 or 12 weeks diminished hexokinase activity by 28% and 30%, respectively, in lumbar DRG compared with age matched controls (P < 0.05). Quantitative Western blotting showed no effect of diabetes on hexokinase I protein expression in homogenates or mitochondrial preparations from DRG. Immuno fluorescent staining for hexokinase I showed no diabetes-dependent change in small-medium neuron expression in DRG, however, large neurons became positive for hexokinase I (P < 0.05). Such complex effects of diabetes on hexokinase I expression in the DRG may be due to glucose-driven up-regulation of expression or the result of impaired axonal transport and perikaryal accumulation in the large neuron subpopulation. Because hexokinase is the rate-limiting enzyme of glycolysis these results imply that metabolic flux through the glycolytic pathway is reduced in diabetes. This finding, therefore, questions the role of high glucose-induced metabolic flux as a key driving force in reactive oxygen species generation by mitochondria. (C) 2007 Elsevier B.V. All rights reserved.