ROLE OF VARIANT OF ALDH2--TRANSGENIC MICE CARRYING ASIAN VARIANT ALLELE ALDH2-2

线粒体乙醛脱氢酶（ALDH 2）是主要的ALDH 参与乙醛代谢的同工酶。 已充分证实 单核苷酸取代（G至A），导致氨基酸 Glu 487 Lys的改变导致ALDH 2活性的显性失活。 这种遗传多态性是引起潮红反应的原因 在许多亚洲人饮酒后。 虽然ALDH 2 -2 等位基因已被证明对酒精中毒具有保护作用， 这种酶的生理作用尚不清楚。 进一步探讨在 ALDH 2可能的生理作用，我们生产了转基因小鼠 携带人ALDH 2变体（Haldh 2 -2）。 目前已经 建立了两个独立的Haldh 2转基因小鼠品系。 这些小鼠 用于研究Haldh 2对酒精偏好的影响， 内源性和外源性底物的代谢、行为和组织 长期饮酒后的危害。 人ALDH 2蛋白是 在检测的所有组织中表达，并且人ALDH 2 -2的表达 在转基因小鼠中抑制小鼠ALDH 2酶活性。 小鼠 腹腔注射20%乙醇2周以上。 我们观察到， 背景品系小鼠表现出恐惧、回避和逃避行为， 乙醇处理，但这些行为的变化并不明显， 暴露于乙醇的转基因小鼠（p<0.001）。 将明显的 行为变化与神经递质水平，并研究其作用 ALDH 2在内源性代谢中的水平，各种单胺 HPLC法测定神经递质含量。 在大脑中，多巴胺及其 代谢产物3.4-二羟基苯乙酸（DOPAC）， 在用乙醇处理的FVB/N小鼠中升高。 相比之下， 在转基因小鼠中不存在。 脑血清素水平也升高 通过乙醇处理，但程度低于多巴胺水平。 大脑 去甲肾上腺素在任何菌株中均未发生变化。 这些结果 表明转基因动物的行为差异是由于 通过引入Haldh 2 -2改变单胺代谢。 我们 初步数据还表明，雌性转基因小鼠消耗40%的 在两瓶中，酒精比FVB/N背景小鼠少（p<0.0001） 选择范式 男性无显著性差异 转基因小鼠 这些数据表明，转基因小鼠携带 Haldh 2 -2可以作为研究ALDH在行为中作用的有价值的模型， 神经递质代谢和饮酒偏好。

The mitochondrial aldehyde dehydrogenase (ALDH2) is the major ALDH isozyme involved in acetaldehyde metabolism. It is well established that a single nucleotide substitution (G to A) which results in the amino acid change (Glu487Lys) leads to dominant inactivation of ALDH2 activity. This genetic polymorphism is the cause of the flushing response observed in many Asian people following alcohol intake. Although the ALDH2-2 allele has been shown to have a protective role against alcoholism, the physiological role of this enzyme is still unclear. To further examine the possible physiological role of ALDH2, we produced transgenic mice carrying the human ALDH2 variant (Haldh2-2). Currently, we have established two independent lines of Haldh2 transgenic mice. These mice were used to study the effects of Haldh2 on alcohol preference, metabolism of endogenous and exogenous substrates, behavior and tissue damage after long-term alcohol consumption. Human ALDH2 protein was expressed in all tissues examined and expression of human ALDH2-2 inhibited mouse ALDH2 enzyme activity in transgenic mice. Mice were injected with 20% ethanol ip for over two weeks. We observed that fubin background strain mice showed fear, avoidance and escape behavior after ethanol-treatment but these changes in behavior were not evident in the transgenic mice exposed to ethanol (p<0.001). To correlate the apparent behavioral change with levels of neurotransmitters and to study the role of ALDH2 in endobiotic metabolism, the levels of various monoamine neurotransmitters were determined by HPLC. In brain, dopamine and its metabolite, 3.4-dihydroxyphenyl acetic acid (DOPAC), were significantly elevated in FVB/N mice treated with ethanol. In contrast, this elevation was absent in transgenic mice. Brain serotonin level was also elevated by ethanol treatment but to a lesser extent than dopamine level. Brain norepinephrine was unchanged in any of the strains. These results suggest that behavioral differences in the transgenics are due to alteration in monoamine metabolism by the introduction of Haldh2-2. Our preliminary data also indicate that female transgenic mice consume 40% less alcohol (p<0.0001) than do FVB/N background mice in a two-bottle choice paradigm. No significant difference was observed in male transgenic mice. These data indicate that transgenic mice carrying the Haldh2-2 can be a valuable model to study the role of ALDH in behavior, neurotransmitter metabolism and drinking preference.