Angiotensin converting enzyme insertion/deletion genotype is associated with leukoaraiosis in lacunar syndromes

OBJECTIVES: Pathological and clinical data suggest that patients presenting with ischaemic lacunar syndromes may be a heterogenous group. Those with isolated lacunar infarction are thought to have localised atherosclerosis whereas in those with coexisting leukoaraiois a distinct diffuse small vessel vasculopathy may be the predominant underlying pathology. The ACE insertion/deletion (I/D) polymorphism is an important candidate gene in ischaemic cerebrovascular disease but, where lacunar stroke specifically has been examined, there have been discrepant reports concerning a possible association. It was hypothesised that the influence of the ACE gene may be different among the two subgroups of ischaemic lacunar stroke reflecting the heterogeneity of the small vessel disease phenotype. METHODS: Eighty four consecutive patients presenting with classic lacunar syndromes were studied. All had acute cranial CT to exclude primary intracerebral haemorrhage and these were subsequently assessed for the presence and extent of leukoaraiosis. All patients were genotyped for the ACE insertion/deletion polymorphism. RESULTS: There was a significant difference in the distribution of ACE genotype with the DD genotype occurring more often in patients with leukoaraiosis and the II and ID genotypes occurring more often among those in whom this was absent (chi(2)=9.06, p=0.01). In a logistic regression model the ACE DD genotype remained as an independent predictor for the presence of leukoaraiosis (p=0.02) in patients presenting with classic lacunar syndromes. CONCLUSION: This study supports the hypothesis that there may be different types of small vessel disease in patients with classic lacunar syndromes and that the influence of the ACE DD genotype may be relevant in mediating the diffuse form of vessel injury.     

血管紧张素转换酶基因多态性与脑出血的关系

目的高血压是脑出血最主要的危险因素，与血压水平或高血压相关的基因可能通过血压和其它途径在脑出血的发生、发展中起重要作用。本文通过大样本病例一对照研究，拟探讨血管紧张素转换酶(ACE)基因I／D多态性与脑出血的相关性。方法多中心病例对照研究，从7个研究中心收集475例脑出血病例，匹配475例对照．病例和对照均接受心脑血管病标准问卷调查、血生化检查。PCR检测ACE基因I／D多态性。结果脑出血组和对照组ACE基因I／D多态性基因型频数分布符合Hardy—Weinberg平衡。两组ACE基因I／D多态性基因型和等位基因频率分布差异无明显统计学意义(基因型：x^2=0．172，P=0．918；等位基因：x^2=0．08，P=0．773)。多因素分析调整传统危险因素后，ACE基因ORDI／Ⅱ=1．09(95％ CI 0．68～1．78)，ORDD／Ⅱ=1．10(95％ CI 0．69～1．77)，表明ACE基因I／D多态性和脑出血无关。结论ACE基因I／D多态性和脑出血不存在关联关系，ACE基因I／D多态性可能不是中国人脑出血的遗传影响因素。     

血管紧张素转换酶基因DD基因型与脑出血的相关性研究

目的探讨血管紧张素转换酶(ACE)基因多态性分布与高血压脑出血发病的关系。方法应用聚合酶链反应方法检测200名健康人(NT)及80例高血压合并脑出血患者ACE I/D基因多态性。结果脑出血患者的DD基因型及D等位基因频率和正常对照组比较差异有显著意义(P＜0．05)。结论ACE基因DD基因型和D等位基因携带者可能是高血压合并脑出血的易感因素。     

Genetic variants of angiotensin converting enzyme and methylenetetrahydrofolate reductase may act in combination to increase migraine susceptibility

Migraine, with and without aura (MA and MO), is a prevalent and complex neurovascular disorder that is likely to be influenced by multiple genes some of which may be capable of causing vascular changes leading to disease onset. This study was conducted to determine whether the ACE I/D gene variant is involved in migraine risk and whether this variant might act in combination with the previously implicated MTHFR C677T genetic variant in 270 migraine cases and 270 matched controls. Statistical analysis of the ACE I/D variant indicated no significant difference in allele or genotype frequencies (P > 0.05). However, grouping of genotypes showed a modest, yet significant, over-representation of the DD/ID genotype in the migraine group (88%) compared to controls (81%) (OR of 1.64, 95% CI: 1.00-2.69, P = 0.048). Multivariate analysis, including genotype data for the MTHFR C677T, provided evidence that the MTHFR (TT) and ACE (ID/DD) genotypes act in combination to increase migraine susceptibility (OR = 2.18, 95% CI: 1.15-4.16, P = 0.018). This effect was greatest for the MA subtype where the genotype combination corresponded to an OR of 2.89 (95% CI:1.47-5.72, P = 0.002). In Caucasians, the ACE D allele confers a weak independent risk to migraine susceptibility and also appears to act in combination with the C677T variant in the MTHFR gene to confer a stronger influence on the disease.     

Expression of angiotensin converting enzyme mRNA in rat brain.

Using molecular genetic approaches, two forms of angiotensin-converting enzyme (ACE) have so far been identified; a pulmonary form and a testicular form. This study utilized both northern blot analysis and in-situ hybridization to examine the expression of ACE mRNA in the rat brain. Northern blot analysis using oligonucleotide probes specific to the testicular or pulmonary forms of ACE demonstrated expression of a 4-5kb mRNA doublet in the rat brain, identical in size to pulmonary ACE mRNA. No expression of the testicular form of ACE mRNA was detected in the brain. In situ hybridization demonstrated that ACE mRNA was expressed in the choroid plexus, caudate putamen and cerebellum. A weak signal was also observed in the hippocampus. This distribution correlated well with the expression of ACE mapped by radioligand binding and autoradiography.     

Postnatal activity of angiotensin converting enzyme in rat brain.

The specific activity of angiotensin converting enzyme (ACE) was studied in eight brain regions in rats 2--65 days of age. At 65 days of age the activities in various regions relative to the cortex were: neostriatum, 1,200%; hippocampus/amygdala, 430%; hypothalamus, 190%; cerebellum, 140%; and midbrain, thalamus and pons/medulla, 110%. Significant linear increases were found in the neostriatum, hippocampus/amygdala and cortex at 2--65 days of age, in the pons/medulla and thalamus at 2--42 days of age and in the midbrain at 2--21 days of age. The increase with age was greatest in the neostriatum and the data are consistent with the occurrence of ACE in neurons in this area.     

脑卒中患者血管紧张素转换酶基因多态性分析

目的：研究血管紧张素转换酶（ＡＣＥ）基因多态性和脑卒中的发病关系。方法：应用ＰＣＲ方法检测１０５例脑卒中患者、１０６例原发性高血压（ＥＨＴ）患者及６４例正常人的 ＡＣＥ基因的缺失／插人（Ｄ／Ｉ）多态性。结果：脑卒中组ＡＣＥ基因型及等位基因频率与ＥＨＴ组及正常对照组比较差异无显著意义,脑卒中组中脑梗死组和脑出血组分别与正常对照组比较ＡＣＥ基因型均无显著差异。脑卒中伴ＥＨＴ组与无伴ＥＨＴ组比较,Ⅱ基因型频率明显升高,而ＤＤ基因型频率则明显降低;脑卒中伴 ＥＨＴ组Ⅱ基因型频率明显高于 ＥＨＴ组,而 ＤＤ基因型频率远低于 ＥＨＴ组和正常对照组,同时脑卒中伴ＥＨＴ组的平均年龄较其它组明显高。结论：原发性高血压患者中Ⅱ基因型携带者可能具有卒中易感性,ＤＤ基因型携带者有随年龄增加而减少的趋势。     

Effect of angiotensin converting enzyme inhibitor on chronic ischemic patients

Most of patients with cerebrovascular diseases are associated with hyper-tension. Hypertension induces progressive atheromatous changes in cerebral arteries, and often causes steno-occlusive lesions of cerebral arteries. Angiotensin converting enzyme (ACE) inhibitor cilazapril is one of the antihypertensive drugs. It was reported that cilazapril improved resting cerebral blood flow (CBF) and cerebrovascular reserve capacity (CRC) in experimental studies. In this clinical study, the authors investigated whether long-term treatment with cilazapril could improve CBF and CRC in patients with steno-occlusive lesions of the major cerebral arterial trunk, measured by stable xenon computerized tomography (Xe-CT) with acetazolamide challenge. On the other hand, CBF and CRC in the calcium blocker-treated patients were measured in the same way. CBF did not change after long-term treatment with both cilazapril and calcium blocker. In the cilazapril-treated group, CRC was increased significantly (p < 0.05). However, CRC did not change in the calcium blocker-treated group. It was recognized that long-term treatment with cilazapril did not decrease CBF and improved CRC in patients with occlusive lesions of the major cerebral arterial trunk.     

Inhibition of angiotensin converting enzyme by N-terminal fragments of substance P

A range of N-terminal fragments of substance P (SP) were evaluated for inhibitory activity against angiotensin converting enzyme (ACE) from rat lung and brain (striatum). SP inhibited the enzyme from both sources in a concentration dependent manner (IC50 30 microM). The N-terminal fragments SP[1-7], SP[1-6], SP[1-4] and SP[3-4] were equipotent with SP for both sources of the enzyme. However, SP[1-3] showed a difference in its activity, being more active than SP (IC50 10 microM) in inhibiting the brain enzyme, but inactive against lung ACE. These results suggest that the inhibitory action of SP on ACE resides in the N-terminus of the peptide. The difference in reactivity towards SP[1-3] lends support to the idea that lung and brain ACE are different isozymes.     

Circadian rhythm and neural regulation of rat pineal angiotensin converting enzyme

Systemic administration of capsaicin and dihydrocapsaicin to adult rats of two different strains and of capsaicin to neonatal rats, depleted substance P levels in dorsal roots plus ganglia and in dorsal spinal cord. In no case was this depletion accompanied by substantially altered tail-flick latencies. The results are not consistent with a role of the neuropeptide in nociceptive thermal sensitivity in the rat.     

Reversal of experimental acute cerebral vasospasm by angiotensin converting enzyme inhibition

We tested the hypothesis that cerebral arteriospasm developing after rupture of a subarachnoid aneurysm may be due to the vasoconstrictor effect of locally generated angiotensin II. Ten dogs had subarachnoid hemorrhage simulated by intracisternal introduction of 2 ml autologous blood, and were followed by cineangiography. Thirty minutes later, when acute arteriospasm was established, seven dogs received injection of the angiotensin converting enzyme inhibitor teprotide and 3 control dogs received normal saline. Repeat angiography at 30 and 90 minutes after injection, showed total or partial release of spasm in the experimental dogs and no change or further intensification of spasm in the control animals. We concluded that angiotensin converting enzyme inhibition may be a potentially useful approach for the reversal or prevention of cerebral arteriospasm after subarachnoid hemorrhage.     

Central angiotensin converting enzyme facilitates memory impairment in intracerebroventricular streptozotocin treated rats

Preclinical and clinical studies indicated involvement of renin angiotensin system (RAS) in memory functions. However, exact role of RAS in cognition is still ambiguous. Our aim was to explore how angiotensin converting enzyme (ACE) modulates memory in experimental model of memory impairment. Memory deficit was induced by intracerebroventricular administration of streptozotocin (STZ, 3 mg/kg) in rats. Perindopril, an ACE inhibitor, was given for 21 days and memory function was evaluated by Morris water maze test. Cerebral blood flow (CBF) was measured by laser doppler flowmetry. The biochemical and expression studies were done in cortex and hippocampus of rat brain after the completion of behavioral studies. STZ caused impairment in memory along with significant reduction in CBF, ATP level and elevated oxidative and nitrosative stress. The activity and mRNA expression of acetylcholinesterase (AChE) and ACE were also increased in rat brain regions following STZ administration. However, serum ACE activity remained unaffected. Treatment with perindopril dose dependently improved memory by increasing energy metabolism and CBF. Perindopril also decreased oxidative and nitrosative stress, activity and mRNA expression of AChE and ACE in STZ treated rat. Further, ACE inhibition mitigated STZ induced neurodegeneration as observed in histopathological studies. Moreover, perindopril per se improved memory and CBF, decreased oxidative stress with no effect on AChE activity and expression. However, perindopril per se significantly reduced ACE activity but increased mRNA expression of ACE in rat brain. These results suggest that ACE occupies a pivotal role in STZ induced memory deficit thus implicating central RAS in cognition.     

Enkephalinase and angiotensin converting enzyme activities in human venous and arterial plasma

Circulating opioids, particularly enkephalins, can act on specific receptors located on the neurovascular sympathetic junction. These peptides are quickly metabolized by enkephalinase and angiotensin converting enzyme (ACE). According to the parallel distribution of enkephalinase with opioid receptors in the rat brain, and its location in the vascular bed, putative differences of enkephalinase and ACE activity between arterial and venous plasma of the same subjects was researched. Venous enkephalinase activity was found to be greater than arterial activity. No arterovenous differences were present in ACE activity. The activities of both enzymes presented a positive correlation between venous and arterial plasma in the same subjects. The arterovenous difference in enkephalinase activity supports a release of the enzyme from microvessels.     

Localization and characterization of angiotensin II receptor binding and angiotensin converting enzyme in the human medulla oblongata

Angiotensin II receptor and angiotensin converting enzyme distributions in the human medulla oblongata were localised by quantitative in vitro autoradiography. Angiotensin II receptors were labelled with the antagonist analogue 125I-[Sar1, Ile8] AII while angiotensin converting enzyme was labelled with 125I-351A, a derivative of the specific converting enzyme inhibitor, lisinopril. Angiotensin II receptor binding and angiotensin converting enzyme are present in high concentrations in the nucleus of the solitary tract, the dorsal motor nucleus of vagus, the rostral and caudal ventrolateral reticular nucleus, and in a band connecting the dorsal and ventral regions. In the rostral and caudal ventrolateral reticular nucleus, angiotensin II receptors are distributed in a punctate pattern that registers with neuronal cell bodies. The distribution and density of these cell bodies closely resemble those of catecholamine-containing neurones mapped by others. In view of the known interactions of angiotensin II with both central and peripheral catecholamine-containing neurons of laboratory animals, the current anatomical findings suggest similar interactions between these neuroactive compounds in the human central nervous system. The presence of angiotensin II receptors and angiotensin converting enzyme in the nucleus of the solitary tract, dorsal motor nucleus of vagus, and rostral and caudal ventrolateral reticular nucleus demonstrates sites for central angiotensin II to exert its known actions on vasopressin release and autonomic functions including blood pressure control. These data also suggest a possible interaction between angiotensin II and central catecholeminergic systems.     

Effects of long-term angiotensin converting enzyme inhibition on cardiovascular variability in aging rats

We studied the effects of chronic (4 weeks) angiotensin converting enzyme inhibition with captopril on arterial pressure (AP) and heart rate (HR) variability, as well as on cardiac baroreflex sensitivity (BRS), in aged (20 months) rats. Series of basal RR interval (RRi) and systolic AP (SAP) were studied by autoregressive spectral analysis with oscillations quantified in low (LF: 0.2-0.8 Hz) and high frequency (HF: 0.8-2.5 Hz). BRS was measured by linear regression between HR and MAP changes. Captopril did not affect the spectra of RRi or SAP in young rats. Aged rats presented a reduction in variance (time domain) and in LF and HF oscillations of RRi and SAP. Captopril induced, in aged rats, a decrease in absolute and normalized LF oscillations and in LF/HF ratio of RRi. Captopril also reduced the variance, without changing its LF or HF components of SAP. Reflex tachycardia was reduced in aged as compared to young rats (-1.1+/-0.2 versus -3.4+/-0.5 bpm/mm Hg) and captopril did not affect it. Reflex bradycardia was also reduced in aged rats (-0.7+/-0.5 versus -2.0+/-0.4 bpm/mm Hg), but captopril prevented this attenuation in aged rats (-2.3+/-0.3 versus -0.7+/-0.5 bpm/mm Hg). These data indicate that there is a reduction in HR and SAP variability during aging, suggesting impairment of cardiovascular autonomic control. Captopril was able to change the power of oscillatory components of RRi, suggesting a shift in cardiac sympatho/vagal balance toward parasympathetic predominance. In addition, blockage of ACE improved the reflex bradycardia, but not the reflex tachycardia in aged rats.     

The angiotensin I converting enzyme gene as a susceptibility factor for dementia

The frequency of a genetic susceptibility vascular factor, the deletion (D) allele of the angiotensin I converting enzyme gene (ACE), coding for a key enzyme of the renin angiotensin system, was characterized in two independent case--control studies. The results of the current study suggest that bearing at least one ACE D allele is a risk factor to develop dementia for subjects older than 74 years. This observation reinforces the hypothesis of a major implication of vascular risk factors in the occurrence of all types of dementia.     

Genetic polymorphism of the angiotensin converting enzyme and L-dopa-induced adverse effects in Parkinson's disease

There was increasing evidence suggesting that angiotensin I-converting enzyme may play an important role in the pathogenesis of PD. Our former study has shown that angiotensin I-converting enzyme gene (ACE) may confer a susceptibility for the risk of Parkinson's disease (PD). Meanwhile, recent studies have emphasized that genetic factors may involve in the occurrence of the adverse effects of chronic L-dopa therapy in PD patients. This study was designed to assess whether genetic polymorphism of the ACE could be a predictor of L-dopa-induced adverse effects in PD. There were 251 patients included in this study and their mean age at onset of disease was 63.3+/-11.4 years. The duration of disease and the treatment with L-dopa was 6.3+/-5.1 and 5.0+/-4.3 years, respectively. The frequency of the homozygote ACE-II genotype of the ACE in PD patients with L-dopa-induced psychosis was significantly higher than that in PD patients without the adverse effect (63.3% vs 43.0%; chi(2)=6.347, OR=1.435, 95%CI=1.105-1.864, p=0.012). However, the ACE polymorphism was not associated with the risk to develop dyskinesia or motor fluctuation induced by L-dopa. Furthermore, a logistic regression analysis confirmed that the ACE-II genotype was an independent risk factor for L-dopa-induced psychosis in PD patients (OR=2.542, p=0.012). In conclusion, results of the study showed that ACE-II genotype might confer a primary predictor for the occurrence of psychosis in L-dopa-treated PD.     

Cerebrovascular effects of angiotensin converting enzyme inhibition involve large artery dilatation in rats.

BACKGROUND AND PURPOSE: The aim of the study was to selectively examine the effects of converting enzyme inhibition on the large brain arteries by using concomitant inhibition of carbonic anhydrase to cause severe dilatation of mainly parenchymal resistance vessels. METHODS: Cerebral blood flow was measured using the xenon-133 injection technique in three groups of Wistar rats either during carbonic anhydrase inhibition with acetazolamide (treatment A, n = 8), during carbonic anhydrase inhibition followed by converting enzyme inhibition with captopril 40 minutes later (treatment B, n = 10), or during carbonic anhydrase inhibition preceded by converting enzyme inhibition 20 minutes earlier (treatment C, n = 7). RESULTS: After treatment A, cerebral blood flow rose rapidly and stabilized within 20 minutes at an average of 220 ml/100 g.min; flow remained stable until at least 60 minutes. After treatment B, cerebral blood flow increased by a further 17.4%, from an average of 219 ml/100 g.min to an average of 257 ml/100 g.min (p less than 0.01). After treatment C, cerebral blood flow stabilized at an average of 238 ml/100 g.min, with flow from 20 to 60 minutes always being higher (from 5% to 17%) than during carbonic anhydrase inhibition alone (p less than 0.02). Thus the additional inhibition of converting enzyme resulted in higher cerebral blood flow than during inhibition of carbonic anhydrase alone. CONCLUSIONS: These results suggest that converting enzyme inhibition reduced resistance of large brain arteries and support the hypothesis that there is some angiotensin II-induced tone in large cerebral arteries.