Effect of catechol oestrogens on extraneuronal metabolism of noradrenaline by rabbit uterine endometrium and myometrium

Summary The effects of 2-hydroxy and 2-methoxy oestrogens on the extraneuronal O-methylation of ³H-(–)noradrenaline were examined in progesterone-dominated, monoamine oxidase (MAO)-inhibited, rabbit uterine tissues in vitro. Both the corticosteroid- sensitive system in myometrium and the cocaine-sensitive system in endometrium were examined.In myometrial slices preincubated with nialamide to inhibit MAO and incubated with cocaine to inhibit neuronal uptake, ³H-normetanephrine (³H-NMN) formation was inhibited in the order of potency 2-hydroxy oestrone 2-hydroxy oestradiol = 2-methoxy oestradiol 2-methoxy oestrone. In myometrial slices not exposed to cocaine and nialamide, inhibition of ³H-NMN formation by both 2-hydroxy and 2-methoxy oestradiol did not affect the formation of deaminated metabolites of ³H-(–)-noradrenaline by the alternative metabolising pathway. In endometrial slices preincubated with nialamide to inhibit MAO, only 2-hydroxy oestrogens inhibited ³H-NMN formation, but they were one to two orders of magnitude less potent in this regard than in the myometrium. The uptake of ³H-(–)-noradrenaline by MAO- and COMT-inhibited myometrial slices was inhibited by 2-hydroxy and 2-methoxy oestrogens in the order of potency 2-methoxy oestradiol 2-methoxy oestrone 2-hydroxy oestrone > 2-hydroxy oestradiol. Uptake of ³H-(–)-noradrenaline by endometrial slices was not affected by either 2-hydroxy or 2-methoxy oestrogens.It is concluded that the O-methylatiog system for noradrenaline in myometrial tissue is more sensitive than that in endometrial tissue to the inhibitory actions of 2-hydroxy and 2-methoxy oestrogens. 2-Hydroxy oestrogens inhibit ³H-NMN formation by competing for COMT rather than noradrenaline uptake sites, since (1) they inhibited O-methylation but not uptake of ³H-noradrenaline in endometrium and (2) 2-hydroxy oestrogens were two orders of magnitude more potent against ³H-NMN formation than ³H-(–)-noradrenaline uptake in myometrium. In contrast, the ability of 2-methoxy oestrogens to inhibit myometrial but not endometrial ³H-NMN formation reflects the selective inhibitory effect of 2-methoxy oestrogens on the corticosteroid-sensitive uptake system for noradrenaline which predominates in myometrium but is minimal in endometrium. These interactions may be important in pregnancy when the local concentrations of catechol and methoxy oestrogens rise.     

Putative cortical dopamine levels affect cortical recruitment during planning

Planning, the decomposition of an ultimate goal into a number of sub-goals is critically dependent upon fronto-striatal dopamine (DA) levels. Here, we examined the extent to which the val158met polymorphism in the catechol O-methyltransferase (COMT) gene, which is thought to primarily alter cortical DA levels, affects performance and fronto-parietal activity during a planning task (Tower of London). COMT genotype was found to modulate activity in the left superior posterior parietal cortex (SPC) during planning, relative to subtracting, trials. Specifically, left SPC blood oxygenation level-dependent (BOLD) response was reduced in groups with putatively low or high cortical DA levels (COMT homozygotes) relative to those with intermediate cortical DA levels (COMT heterozygotes). These set of results are argued to occur either due to differences in neuronal processing in planning (and perhaps subtracting) caused by the COMT genotype and/or the cognitively heterogeneous nature of the TOL, which allows different cognitive strategies to be used whilst producing indistinguishable behavioural performance in healthy adults. The implications of this result for our understanding of COMT′s effect on cognition in health and disease are discussed.     

精神分裂症与四个候选功能基因多态性的关系

目的 探讨多巴胺D2受体基因启动子(DRD2P)、5-羟色胺2A受体基因(5-m2A)、儿茶酚氧位甲基转移酶基因(C0MT)和单胺氧化酶A(MAO-A)基因相应多态性与汉族精神分裂症的关系及遗传学特征.方法 纳入至少有2名同胞符合国际疾病分类第10版的精神分裂症诊断标准、父母存活的核心家系43个,完成由哈佛大学提供的遗传学研究用诊断性检查和遗传学研究用家属会谈表,同时采集静脉血10ml,提取DNA.用聚合酶链反应(PCR)对候选基因片段进行扩增,酶切后用琼脂糖凝胶电泳检测基因型.统计分析方法 采用x2检验、相关分析及传递不平衡检验(TDT)等.结果 (1)DRD2P、5-HTzA、COMT的基因型和等位基因频率在患病同胞组、非患病同胞组和父母组之间的分布差异无显著性(P>0.05).MAO-A多态性在父母组(86名)的941T/941G和941G/941G基因型频率与患病同胞组(29例)及非患病同胞组(48名)之间的差异有显著性,但非患病同胞组与患病同胞组之间的差异无显著性(P<0.05).(2)在患病同胞中,MAO-A的941G等位基因传递较多[(x2=5.33,P<0.05,比数比(OR)=3.32,95%可信区间(95%CI)=1.58～6.99)];在非患病同胞中,DRD2P的-241A等位基因(x2=6.76,P<0.01,OR=3.17,95% CI=0.57～1.21)和MAO-A的941T等位基因(x2=4.84,P<0.05,OR=6.04,95% CI=2.01～18.69)传递较多.5-HT2A和COMT的等位基因在患病同胞和非患病同胞中均未见有明显的传递不平衡(P>0.05).(3)DRD2P、COMT、MAO-A基因型与精神分裂症的部分临床症状有显著性或非常显著性相关(P<0.05或P<0.01);5-HT2A受体基因型则否.结论 支持精神分裂症的多巴胺假说;上述4个候选功能基因与精神分裂症相关的密切程度有所不同,即MAO-A>DRD2P>COMT>5-HT2A.     

Comparison of the effect of phenol and its derivatives on protein and free radical formation in human erythrocytes (in vitro)

The effect of phenolic compounds: phenol, 2,4-dichlorophenol (2,4-DCP), 2,4-dimethylphenol (2,4-DMP) and catechol on human erythrocytes was studied. The level of fluorescent label - 6-carboxy-2',7'-dichlorodihydrofluorescein diacetate (H(2)DCFDA) oxidation by phenolic compounds in erythrocytes as well as the carbonyl group content and hemoglobin denaturation were monitored. H(2)DCFDA has been utilized extensively as a marker for studies of oxidative stress at the cellular level. We noted that 2,4-DCP, 2,4-DMP and catechol induced an increase in the concentration- and time-dependent H(2)DCFDA oxidation. We also observed an increase in carbonyl group content and the changes in parameter T (denaturation of hemoglobin) in erythrocytes incubated with 2,4-DCP, catechol and 2,4-DMP. The highest level of H(2)DCFDA oxidation was provoked by 2,4-DCP. The biggest changes of proteins in erythrocytes measured as the carbonyl group content were induced by 2,4-DMP, but measured as parameter T they were induced by catechol. It was observed that phenol did not oxidize H(2)DCFDA up to the concentration of 2.5 mM after 3 h of incubation. Phenol did not affect the carbonyl group content but decreased parameter T (induced denaturation of hemoglobin). To sum up, the kind of the substituent in a phenolic ring determines the molecular mechanism of action of the individual compound and the capacity of reactive oxygen species generation and thus damages the specified structures in human erythrocytes.     

咖啡因拮抗噪声引起机体损害作用的研究

噪声和咖啡因联合作用于大鼠后,观察大鼠血清及心肌中Ca~(++)、Mg~(++)含量的变化、心肌儿茶酚胺(CA)和血浆cAMP的变化,并用JEM-1200EX电镜观察了心肌超微结构的改变。结果表明,噪声可导致血清Mg~(++)含量升高,心肌Mg~(++)含量降低,心肌Ca~(++)明显升高。心肌CA和血浆cAMP含量上升。应用咖啡因后心肌Ca~(++)、Mg~(++)及血清Mg~(++)含量接近正常水平,心肌CA降低,血浆cAMP升高。提示咖啡因对可噪声所致的Ca~(++)、Mg~(++)含量异常有一定的拮抗作用,对CA和cAMP有调节作用,对噪声引起的大鼠心肌超微结构的损伤有明显减轻作用。     

Stereoselectivity of the arene epoxide pathway of mephenytoin hydroxylation in man

Stereoselective metabolism of mephenytoin has been investigated in four normal subjects by comparing urinary recoveries of hydroxylated metabolites after administration of racemic RS-mephenytoin (1.4 mmol/day) and R-mephenytoin (0.7 mmol/day) on separate occasions. Gas chromatography-mass spectrometry was employed to measure the urinary recovery of 3-methyl-5-(4-hydroxyphenyl)-5-ethylhydantoin (4-OH-M) and mephenytoin catechol, methylcatechol, and dihydrodiol metabolites. Following a single oral dose of racemic mephenytoin, 4-OH-M, mephenytoin catechol, and methylcatechol metabolites were identified in urine mainly as conjugates, whereas the dihydrodiol metabolite was recovered mainly in its unconjugated form. Urinary elimination of each metabolite was similar on days 1 and 10 of chronic racemic mephenytoin administration. Following R-mephenytoin administration, urinary recoveries of hydroxylated metabolites were five to 10 times smaller than after administration of the racemic drug. This implies substrate-stereoselective hydroxylation of the S-enantiomer of mephenytoin. In one subject with a genetic deficiency of aromatic mephenytoin hydroxylation deficiency, the excretion of each hydroxylated mephenytoin metabolite after RS-mephenytoin administration was decreased to 5-15% of the values found in the four extensively hydroxylating study volunteers. The impaired formation of hydroxylated mephenytoin metabolites in genetic hydroxylation deficiency, in conjunction with stereoselective hydroxylation of S-mephenytoin via an extensive NIH shift in normal man, is consistent with the hypothesis that the formation of the S-mephenytoin arene oxide is under genetic control and represents the initial enzymatic reaction of stereoselective aromatic mephenytoin hydroxylation. The formation of this potentially reactive metabolite of S-mephenytoin may have implications in mephenytoin-induced toxicity.     

Entacapone in combination with standard or controlled-release levodopa/carbidopa: a clinical and pharmacokinetic study in patients with Parkinson's disease

We investigated clinical response and pharmacokinetics of levodopa when entacapone, a catechol O-methyltransferase (COMT) inhibitor, was administered concomitantly with either a standard (Std) or a controlled-release (CR) levodopa/carbidopa preparation to 12 patients with Parkinson's disease. An open cross-over study consisted of the initial study day without entacapone followed by two 10-day treatment periods with a study day at the end of each period. The patients who received entacapone (200 mg t.i.d. or q.i.d.) concomitantly with Std levodopa/carbidopa (200/50 mg t.i.d. or q.i.d.) during the first period received subsequently entacapone with CR levodopa/carbidopa (200/50 mg t.i.d. or q.i.d.), and vice versa. On the study days, the patients took the medication at 8 a.m. and the second dose 6 h later. We evaluated the disability before drug administration and then 1-h intervals for 8 h. Repeated blood samples were taken for analysis of plasma levodopa, 3-O-methyldopa (3-OMD), dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), carbidopa, and entacapone. Entacapone decreased significantly the clinical disability with both Std and CR levodopa, slightly more with Std levodopa. The clinical response started earlier with Std levodopa whereas the “on”-time increased by about 1 h, equally with both levodopa preparations. Std levodopa produced 23% higher area under the curve (AUC) of levodopa than the CR preparation, but entacapone increased the AUC approximately equally, 33% with Std and 36% with CR levodopa. Entacapone slightly decreased C_max of levodopa in combination with Std levodopa, whereas it increased that with CR levodopa. The AUC of 3-OMD was about 20% smaller after Std than after CR levodopa. Entacapone decreased the AUC of 3-OMD by 38–40% with both levodopa preparations. Entacapone did not modify the AUC levels of carbidopa although its bioavailability was less from CR levodopa than from Std levodopa. In three patients levodopa dosage was reduced when on Std levodopa because of nausea. Otherwise, the treatments were well tolerated. The study shows that entacapone is an effective COMT inhibitor when combined with either Std levodopa or CR levodopa.     

废水中痕量邻苯二酚的阻抑动力学测定法

目的 研究废水中邻苯二酚的动力学光度分析法.方法 在硫酸介质中,邻苯二酚能灵敏地阻抑铜(Ⅱ)催化过氧化氢氧化偶氮氯膦胂的褪色指示反应,催化反应速度的减慢程度与邻苯二酚的量有关.采用阻抑动力学光度法,测定痕量邻苯二酚并研究了最佳反应条件和动力学参数,探讨了方法的原理.结果 该方法测定邻苯二酚浓度的线性范围为0.2～1.8 mg/L,检出限为0.084 mg/L.对浓度为0.6、1.12、1.6 mg/L的邻苯二酚标准溶液进行11次平行测定,△A值的RSD分别为2.4%,1.2%和1.6%;回收率分别为98.0%和96.0%.结论 该方法用于废水中邻苯二酚含量的测定,结果满意.