Monoamine metabolism and behavioral responses to ethanol in mitochondrial aldehyde dehydrogenase knockout mice

BACKGROUND: It is widely accepted that, in addition to removing acetaldehyde produced during the metabolism of ethanol, mitochondrial aldehyde dehydrogenase (ALDH2) functions in the pathway by which aldehyde metabolites of the monoamines dopamine (DA) and serotonin (5-HT) are converted to their acidic metabolites. Moreover, studies of ALDH2 inhibitors used for treating alcoholism suggest that their antidipsotropic effects may be related to inhibition of monoamine metabolism. Therefore, we examined the hypothesis that altered brain monoamine metabolism is related to the influence of ALDH2 on behavioral responses to ethanol. METHODS: Mice were generated with a gene-trap mutation of the ALDH2 gene. ALDH2 mRNA was absent in ALDH2-/- mice. Western blot analysis of liver mitochondria confirmed the absence of ALDH2 protein in the ALDH2-/- mice. Wild-type and ALDH2-deficient mice were tested for the effects of different doses of ethanol on locomotor activity, ataxia, and a 2-bottle ethanol-water preference test. RESULTS: Wild-type and ALDH2+/- mice preferred ethanol to water. However, ALDH2-/- mice drank significantly less ethanol than wild-type or ALDH2+/- mice. Locomotor activity and ataxia were significantly more affected by ethanol in ALDH2-/- mice than in wild-type or ALDH2+/- mice. There was no effect of genotype on levels of 5-HT, DA, or their precursors or metabolites in several brain regions, as measured by HPLCec. CONCLUSIONS: The results indicate that: (1) the effect of the mutant genotype on behavioral responses to ethanol is unrelated to altered brain monoamine metabolism and (2) ALDH2 is not required for the metabolism of brain monoamines in vivo.     

Effects of biogenic aldehydes and aldehyde dehydrogenase inhibitors on rat brain tryptophan hydroxylase activity in vitro

The effect of indole-3-acetaldehyde, 5-hydroxyindole-3-acetaldehyde, disulfiram, diethyldithiocarbamate, coprine, and 1-amino-cyclopropanol on tryptophan hydroxylase activity was studied in vitro using high performance liquid chromatography with electro-chemical detection. With the analytical method developed, 5-hydroxytryptophan, serotonin, and 5-hydroxyindole-3-acetic acid could be measured simultaneously. Indole-3-acetaldehyde (12-1200 microM) was found to cause a 6-33% inhibition of the enzyme. Dependent upon the nature of the sulfhydryl- or reducing-agent (dithiotreitol, glutathione, or ascorbate) present in the incubates, the degree of inhibition by disulfiram varied, probably due to the formation of various mixed disulfides. Also the presence of diethyldithiocarbamate (160-1600 microM) was found to inhibit tryptophan hydroxylase (28-91%), while 5-hydroxyindole-3-acetaldehyde, coprine, or 1-aminocyclopropanol appeared to have no effect on the enzyme activity.     

乙醇和乙醛脱氢酶基因多态与食道癌易感性

目的 研究乙醇脱氢酶2(ADH2)和乙醛脱氧酶2(ALDH2)基因多态与食道癌易感性.方法 对江苏省泰兴市221例食道癌新发病例和191名对照的饮酒习惯等因素进行调查,采用PCR和变性高效液相色谱法(DHPLC)检测ADH2和ALDH2基因型.结果 (1)与携带ALDH2 G/G基因型者相比,携带ALDH2A/A(OR=5.69,95%CI:2.51～12.18)和ALDH2 G/A(OR=1.70,95%CI:1.08～2.68)基因型者患食道癌危险性明显增加,以携带ALDH2A/A的饮酒者最为显著(OR=8.63,95%CI:2.07～35.95).(2)无论是否饮酒,携带不同ADH2基因型者之间患食道癌的风险差异均无统计学意义.(3)携带ALDH2 A/A或G/A基因型者,不论同时携带何种ADH2基因型患食道癌的风险均显著增加,且作用效应为ALDH2 A/A≥G/A.(4)与同时携带ALDH2 G/G和ADH2 A/A的不饮酒者相比,同时携带ALDH2 G/A或A/A和ADH2 G/A或G/G的饮酒者,患食道癌危险性OR值高达8.36(95%CI:2.98～23.46).结论 饮酒及醇醛脱氢酶基因多态与食道癌的联系主要与ALDH2有关;携带ALDH2A/A和G/A者减少酒精消耗量,有助于降低患食道癌危险性.     

酒精代谢酶基因多态性与酒精性肝病关系

目的：研究酒精代谢酶基因多态性与酒精性肝病的关系。方法：检索PubMe暾据库及参考互联网文献．并进行分析综述。结果：酒精性肝病的形成和发展与酒精代谢关键酶（包括乙醇脱氢酶、乙醛脱氢酶和细胞色素4502E1）的基因多态性密切关联。结论：酒精性肝病与酒精代谢酶基因多态性有密切关系。