Expression of Glutamate Decarboxylase (GAD) mRNA in the Brain of Bile Duct Ligated Rats Serving as a Model of Hepatic Encephalopathy
Expression of Glutamate Decarboxylase (GAD) mRNA in the Brain of Bile Duct Ligated Rats Serving as a Model of Hepatic Encephalopathy
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DOI：
10.1007/s11064-013-1116-y
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发表时间：
2014-03-01
影响因子：
4.4
通讯作者：
Schousboe, Arne
中科院分区：
文献类型：
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作者：
Leke, Renata;Silveira, Themis R.;Schousboe, Arne
肝性脑病（HE）是一种涉及不同病理生理机制的神经系统疾病，包括gaba能神经递质系统紊乱。虽然在HE中未发现神经递质GABA水平的整体增加，但GABA受体和代谢的改变已被描述。此外，据报道，胆管结扎（BDL）大鼠（HE研究的动物模型）表现出GABA生物合成的改变，主要涉及三羧酸（TCA）循环。在这种情况下，应该注意的是，GABA合成酶谷氨酸脱羧酶（GAD）在大脑中以GAD67和GAD65两种亚型表达，GAD65与通过TCA循环发生的GABA合成有关，并与神经递质囊泡池偶联。本研究的目的是探讨GAD67和GAD65 mRNA表达的变化是否与先前观察到的GABA生物合成的改变有关。为此，我们解剖对照组和BDL大鼠的大脑皮层和海马，分离总mRNA，通过逆转录反应合成cDNA。随后以GAPDH为内源对照，采用qPCR多重检测GAD67和GAD65的基因表达。对照组和BDL大鼠的大脑皮层和海马组织中GAD67和GAD65 mRNA的表达均未发生变化，说明HE状态未导致GAD mRNA表达的变化。然而，其他的调节机制可能影响广泛性焦虑症的活性，需要进行更多的研究来澄清这一点。
Hepatic encephalopathy (HE) is a neurologic disorder that involves different pathophysiological mechanisms, including disturbances in the GABAergic neurotransmitter system. Albeit an overall increase in the level of neurotransmitter GABA has not been found in HE, alterations in GABA receptors and metabolism have been described. Moreover, it has been reported that bile duct ligated (BDL) rats, an animal model for the study of HE, exhibited an altered GABA biosynthesis involving preferentially the tricarboxylic (TCA) cycle. In this context it should be noted that the GABA synthesizing enzyme glutamate decarboxylase (GAD) is expressed in the brain in two isoforms GAD67 and GAD65, GAD65 being related to the synthesis of GABA that occurs via the TCA cycle and coupled to the vesicular pool of the neurotransmitter. The aim of the present study was to investigate whether changes in mRNA expression of GAD67 and GAD65 were related to the altered GABA biosynthesis previously observed. To study this, cerebral cortices and hippocampi were dissected from control and BDL rats, total mRNA was isolated and cDNA was synthesized by reverse transcription reaction. Subsequently samples were analyzed for gene expression of GAD67 and GAD65 by qPCR multiplex assay, using GAPDH as endogenous control. No changes in GAD67 and GAD65 mRNA expression between control and BDL rats either in cerebral cortex or in hippocampus were observed indicating that the HE condition did not lead to changes in GAD mRNA expression. However, other regulatory mechanism might be affecting GAD activity and to clarify this additional studies need to be conducted.