Platelet monoamine oxidase activity in alcoholism subtypes: relationship to personality traits and executive functions

- AIMS: The purpose of the present study was to compare alcoholic subtypes (type 1 versus type 2) with regard to platelet monoamine oxidase (MAO) activity. A possible relationship between enzyme activity, personality traits and executive functions was also investigated. METHODS: Seventeen type 1 and 16 type 2 in-patient male chronic alcoholic patients and 17 healthy male volunteers were included in the study. The personality traits were investigated by the Minnesota Multiphasic Personality Inventory-2 (MMPI-2). Executive functions were assessed by the Wisconsin Card Sorting Test (WCST). RESULTS: When compared to the healthy subjects, platelet MAO activity was reduced in both alcoholic groups. The enzyme activity of the type 2 group was significantly lower than that of type 1 patients. Both groups of alcoholic patients also displayed impairment in executive functions. The comparison of the MMPI-2 scores of the study groups revealed that type 2 alcoholics had more severe psychopathology. CONCLUSIONS: The results support previous evidence suggesting that platelet MAO activity is a useful biochemical measure for the subtyping of alcoholics.     

Platelet monoamine oxidase B activity in workers exposed to styrene

A cross-sectional study was conducted to evaluate monoamine oxidase type B (MAO-B) activity in platelets as a biomarker of effect of styrene and perchloroethylene exposures. MAO-B is an enzyme system involved in dopamine catabolism, the impairment of which has been postulated as a mechanism of styrene-induced neurotoxicity. We previously observed an inverse association between blood styrene and MAO-B among reinforced plastics manufacturing workers. The present study included 59 male boat plant workers exposed to styrene (exposure range < 1–144 ppm, 8-h TWA). Two comparison groups comprised six male dry cleaning workers exposed to perchloroethylene (PCE; exposure range < 2-37 ppm) and 14 male laundry workers not exposed to either agent. Respiratory protection was not used by any of the styrene- or PCE-exposed workers; thus, air concentrations were regarded as valid exposure indicators. MAO-B activity (pmol/10⁸ cells/h) was measured in peripheral blood platelets, using phenylethylamine as substrate. Only small overall mean differences in MAO-B were observed among the three groups; mean values were 4.21, 4.51, and 4.12 for the styrene-exposed, PCE-exposed, and laundry workers, respectively. Despite the absence of gross differences among the groups, styrene exposure was inversely related to MAO-B. Mean values for four increasing exposure group quartiles were: 5.60, 4.13, 3.69, and 3.44. The Spearman rank correlation coefficient for styrene with MAO-B was –0.41. Adjustment for age, medication use, smoking, and alcohol consumption had only a minimal effect on this trend. Duration of exposure to styrene bore a weak positive relation to MAO-B (Spearman r = + 0.29), which was nearly entirely explained by collinearity with age. The results from this study are in close quantitative agreement with previous findings of an inverse association between styrene exposure and MAO-B. More agents need to be evaluated to establish specificity, and longitudinal analyses of styrene-exposed workers will be required before confident conclusions can be reached about the predictive value of MAO-B as a biomarker of styrene-related neurotoxicity.     

Platelet monoamine oxidase B in family history positive and family history negative type 1 alcohol-dependent subjects

- AIMS AND METHODS: In the present study platelet monoamine oxidase B (MAO-B) activity was investigated in 76 male type 1 alcohol-dependent subjects with and without a family history of alcoholism. RESULTS: Platelet MAO-B activity did not differ between family history positive (FHP) and family history negative alcohol-dependent subjects. The smoking status of the subjects was registered and there was still no difference between the groups when possible effects of smoking were taken into account. It should, however, be noted that platelet MAO-B activity was lower in alcohol-dependent subjects with three or four alcohol-dependent first-degree relatives. CONCLUSIONS: Although this latter finding should be interpreted with caution due to the small number of subjects, it cannot be excluded that FHP alcohol-dependent subjects with a large number of alcohol-dependent first-degree relatives may have lower platelet MAO-B activity.     

Platelet monoamine oxidase-B activity in type 1 alcohol-dependent subjects in sustained full remission

AIMS: The present study investigated platelet monoamine oxidase-B (MAO-B) activity in male alcohol-dependent subjects in sustained full remission (minimum 1 year), to exclude possible transient changes in platelet MAO-B activity, which occur up to several months after the end of alcohol intake. METHODS: MAO-B activity was examined in 16 alcohol-dependent subjects, characterized as type 1 alcoholics, with an abstinence period of 6 +/- 7 years (mean +/- SD) and in 12 healthy controls. RESULTS: The long-term abstinent alcohol-dependent subjects did not differ from controls in platelet MAO-B activity. CONCLUSIONS: Type 1 male alcohol-dependent subjects appear to have normal platelet MAO-B activity. The possibility, however, cannot be excluded that type 2 long-term abstinent alcoholics may have lower platelet MAO-B activity.     

Platelet monoamine oxidase B activity as a state marker for alcoholism: trend over time during withdrawal and influence of smoking and gender

- AIMS AND METHODS: The present study evaluated time-related changes in platelet monoamine oxidase B (MAO-B) activity in an Italian cohort of alcohol-dependent subjects (n = 98) during early abstinence, and the effect of potential confounding factors, such as gender and smoking status, on the temporal trend of the enzyme activity. RESULTS: While still under the influence of ethanol (time point T1), the mean value of platelet MAO-B activity in alcoholics was 6.4 +/- 3.1 nmol/mg of protein/h. This increased by >40% (to 9.3 +/- 4.4 nmol/mg of protein/h) after 8 days of withdrawal (T2), and remained stable thereafter (T3 and T4: 15 and 22 days of abstinence, respectively). In a cohort of 138 healthy subjects, MAO activity levels averaged 9.9 +/- 0.9 nmol/mg of protein/h. In the group of alcoholic patients, alcohol intake cessation was confirmed by the progressive decrease of serum % carbohydrate-deficient transferrin (CDT), which was pathologically above the reference limits (6%) at T1 (7.8 +/- 3.3%), declined to 6.6 +/- 2.1% at T2 and reached physiological values at T3 and T4. In a subgroup of cirrhotic alcoholics, %CDT did not decrease over time, while MAO activity rose after the first week of abstinence, without further change at T3 and T4. During early withdrawal, neither gender nor tobacco smoking affected the temporal pattern of MAO activity. CONCLUSIONS: MAO-B can be regarded as a state marker of alcohol consumption. The temporal pattern of platelet MAO-B activity may be used for the diagnostic assessment of alcoholism and early abstinence, regardless of gender and smoking status.     

Possible linkage of alcoholism, monoamine oxidase activity and P300 amplitude to markers on chromosome 12q24

Multipoint linkage analysis was used to screen for evidence of linkage between alcoholism and five alcoholism-related quantitative traits. The results suggest that a susceptibility locus that influences monoamine oxidase activity and P300 amplitude at the Pz lead, and increases the risk of alcohol dependence may be linked to markers in the 12q24 region. Furthermore, the susceptibility for alcoholism may be associated with allele 3 (allele size 144) of D12S392.     

Aldehyde dehydrogenase and monoamine oxidase in rat liver mitochondria

Monoamine oxidase (EC 1.4.3.4) and aldehyde dehydrogenase (EC 1.2.1.3) activities were compared in the liver mitochondria of male and female rats. Monoamine oxidase activity using benzylamine as a substrate was significantly higher in males as compared with females: 1.45 versus 0.74 mumols/mg mitochondrial protein/hr, respectively. Monoamine oxidase activity using tyramine as a substrate and aldehyde dehydrogenase activity were the same in males and females. Monoamine oxidase-tyramine and aldehyde dehydrogenase activities did not vary with the different phases of the estrous cycle in the female but the activity of monoamine oxidase-benzylamine did; rats in the proestrous phase had the highest activity and those in the estrous phase had the lowest.     

Synthesis, human monoamine oxidase inhibitory activity and molecular docking studies of 3-heteroarylcoumarin derivatives

Monoamine oxidase (MAO) is an important drug target for the treatment of neurological disorders. Series of 3-indolyl and 3-thiophenylcoumarins were synthesized and evaluated as inhibitors of the two human MAO isoforms, hMAO-A and hMAO-B. In general, the derivatives were found to be selective hMAO-B inhibitors with IC₅₀ values in the nanoMolar (nM) to microMolar (μM) range. Docking experiments were carried out in order to compare the theoretical and experimental affinity of these compounds to the hMAO-B protein. According to our results, docking experiments could be an interesting approach to try to predict the activity of this class of coumarins against MAO-B receptors.     

Both inorganic and organic selenium supplements can decrease brain monoamine oxidase B enzyme activity in adult rats

It has been observed that the levels of brain monoamine oxidase B (MAO-B) increase during ageing. MAO catalyses the oxidative deamination of neurotransmitters, in which the by-product H2O2 is subsequently generated. Se exists naturally in inorganic and organic forms and is considered to play a key role in antioxidation functioning. The objective of the present study was to investigate two chemical forms of Se compounds for their inhibition effect on rat brain MAO-B. The total antioxidant capacity and lipid peroxidation of rats were also examined. The rats (age 7 weeks) were divided into four groups: the control group, tocopherol group (T group, positive control), selenite group (SE group, representing the inorganic Se group) and seleno-yeast group (SY group, representing the organic Se group). The rats were fed for 11 weeks with normal diets and 12 weeks with test diets. The serum total antioxidant capacity of the SE and SY groups was significantly higher than that in the control and T groups. In rat brains and livers, the lipid peroxidation levels were significantly decreased in the T, SE and SY groups. MAO-B activity showed a significant decrease in the T, SE and SY groups in rat brains but no significant change could be noted in the rat livers. In conclusion, the present study indicates that inorganic or organic Se supplementation can decrease the brain MAO-B enzyme activity in adult rats and can be accomplished by the effect of the Se antioxidation capability.     

Inhibition of monoamine oxidase activity after combined action of chlordimeform with the antidepressant nialamide

The 40-day oral administration of 5, 10, and 50 mg/kg chlordimeform to male rats moderately decreased monoamine oxidase activity (MAO) in the brain, liver, and serum, determined with the substrates kynuramine, tyramine, tryptamine, serotonin, dopamine, and benzylamine. The enzyme was inhibited predominantly in the liver. The study of MAO inhibition after 10 days application of 2, 6, 10, 15, and 20 mg/kg nialamide revealed that 2 mg/kg had a threshold effect. A dose of 6 mg/kg resulted in a pronounced decrease in the enzyme activity. Experiments with a 30-day application of 5, 10, and 50 mg/kg chlordimeform were made, followed by treatment with 6 mg/kg nialamide in combination for another 10 days. The statistical evaluation by the Student's t-test demonstrated increased MAO inhibitory action. Dose-effect relationship was established with kynuramine in liver, brain, and serum, and with benzylamine in liver.     

血清单胺氧化酶与儿童青少年肥胖之间的关系研究

目的 探究血清单胺氧化酶水平与儿童青少年肥胖程度及其与心血管代谢指标之间的关系,为肥胖及其相关并发症的预防和治疗提供理论依据.方法 于2018年4-11月对沈阳市1 007名中学生进行体检,包括身体测量和血清生化指标检测,并根据不同肥胖等级分组进行分析.结果 研究对象中肥胖率为14.40％,男性高于女性(16.33％v...     

Transient increase in platelet monoamine oxidase b activity during early abstinence in alcoholics: implications for research

Some earlier studies have suggested that platelet monoamine oxidase (MAO)-B activity should be determined at time points other than early in the abstinence phase. However, the optimal times for blood sampling have not been precisely defined. We therefore assessed platelet MAO-B activity repeatedly in 13 male alcohol-dependent patients over the 2 months after the end of a period of heavy alcohol intake. Twelve healthy men were used as controls. In the alcohol-dependent patients, platelet MAO-B activity was transiently increased from 2 to 6 weeks after the end of alcohol intake and the values during this time period were not different from those of controls. Platelet MAO-B activity was, however, significantly lower in the alcohol-dependent patients at 1 week and at 2 months after the end of alcohol intake, in comparison to controls. It is concluded that the transient increase in platelet MAO-B activity after the end of alcohol intake in alcohol-dependent patients may conceal a difference from a control group. Therefore, it is suggested that when platelet MAO-B activity is determined, the preferential time point for obtaining those values in alcohol-dependent patients is after 2 months of abstinence.     

苯乙烯对大鼠不同脑区多巴胺递质含量及单胺氧化酶活性的影响

目的观察苯乙烯在不同染毒期限和染毒剂量下对大鼠神经系统多巴胺递质含量及单胺氧化酶活性的影响。方法大鼠随机分为5组,每组12只动物,雌雄各半。苯乙烯急性染毒剂量为600mg/kg,亚急性染毒剂量为150~600mg/kg,恢复组在苯乙烯染毒后正常饲养3周,L-dopa组在苯乙烯染毒同时腹腔注射600mg/kgbw的L-dopa。方法监测动物尿中苯乙烯代谢物苯乙醇酸(MA)和苯乙醛酸(PGA)的含量作为苯乙烯染毒的内剂量,测定苯乙烯染毒大鼠不同脑区多巴胺(DA)含量及参与多巴胺代谢的单胺氧化酶(MAO)活性的变化。结果尿中的PGA和MA含量与染毒剂量均呈正相关,由于存在一定的环境本底,MA比PGA在作为苯乙烯染毒内剂量的指标上更有代表性。视网膜、垂体和纹状体中的DA含量在苯乙烯染毒下显著降低,垂体中的MAO活性增加,而纹状体和视网膜中的MAO活性减小。结论苯乙烯可以通过多巴胺通路产生对机体的神经损伤。