Brain nitric oxide synthase levels increase in response to antenatal ethanol exposure

AIMS: Our previous in vitro data have indicated that ethanol can increase nitric oxide synthase (NOS) expression. Thus, the Aims of this study were to determine whether ethanol produces the same effect in vivo. METHODS: To accomplish this, we utilized the well-established prenatal ethanol (EtOH) exposure model in the guinea pig to examine the effect on brain NOS expression and activity. RESULTS: Brain homogenates isolated from offspring of guinea pigs fed EtOH exhibited an increase in NOS protein expression and NOS activity compared to controls. Increased expression of neuronal NOS was observed only in soluble fractions of brain homogenates (P < 0.05 vs. control). Increased expression of a approximately 60 kDa band was detected in the soluble fraction that was immunoreactive against an antiserum raised against inducible NOS. In addition, an immunoreactive band of the correct predicted molecular weight for iNOS was found in the particulate fraction although the expression was unchanged between control and EtOH-treated animals. Endothelial NOS protein expression could not be detected in either soluble or particulate fractions from control or EtOH-treated animals. CONCLUSIONS: These results suggest that EtOH may exert its toxic effects antenatally via a mechanism of altered nitric oxide availability from NOS.     

Nitric oxide synthase activity in the hippocampus,frontal cerebral cortex,and cerebellum of the guinea pig: Ontogeny and in vitro ethanol exposure

Decreased nitric oxide (NO) formation, resulting from inhibition of NO synthase (NOS), may be important in the pathogenesis of ethanol central nervous system teratogenesis. The objectives of this study were to determine the ontogeny of NOS activity in the hippocampus, frontal cerebral cortex, and cerebellum of the developing guinea pig, and to test the hypothesis that direct exposure to ethanol inhibits NOS activity in these brain regions at selected developmental ages. NOS activity was quantitated by an optimized radiometric assay. The ontogeny study demonstrated that NOS activity in the hippocampus and frontal cortex was not fully developed prenatally, and apparently increased during postnatal life to attain adult level of activity at postnatal day > 60. In the cerebellum, NOS activity increased during prenatal life to an apparent maximum in the mature near-term fetus at gestational day 63 (term, about 68 days), and then apparently declined during postnatal life to attain adult level of activity. In vitro ethanol exposure (25–100 mM) did not affect NOS activity in the hippocampus, frontal cortex, or cerebellum at any developmental age studied. These data indicate that, although the ontogeny of NOS activity varies between brain regions, ethanol does not directly affect NOS activity in the developing guinea pig. The effects of acute and chronic in utero ethanol exposure on NOS activity in these brain regions are currently being investigated.     

INACTIVATION OF CEREBELLAR NITRIC OXIDE SYNTHASE BY ETHANOL IN VITRO

The N-methyl-D-aspartate receptor/nitric oxide synthase (NOS)/guanylatecyclase pathway, which plays a crucial role in synaptic plasticityin the brain, is modulated by ethanol. We studied the effectof ethanol in vitro on NOS in rat cerebellum and showed thatethanol (25–200 mM) inactivated NOS in a dose-dependentmanner. This inactivation was prevented by the biopterin cofactortetrahydrobiopterin (BH⁴) as well as by L-arginine, a NOS substrate,but not by NADPH. These results suggest that ethanol reducesNOS activity by modulating the conformation of the enzyme andthereby its stability, probably by interacting with the bindingsites of BH⁴ and/or of L-arginine. Our data also suggest thatinactivation of NOS may contribute to the decrease in the cGMPlevel, and thus may play a role in the pharmacological actionsof ethanol in vivo.     

Ethanol increases tumor necrosis factor-alpha receptor-1 (TNF-R1) levels in hepatic, intestinal, and cardiac cells.

Chronic ethanol consumption leads to cell injury in virtually every tissue. Tumor necrosis factor-alpha (TNF-alpha) constitutes a major factor in the development of alcohol-induced liver injury. In alcohol-dependent subjects, elevated levels of plasma TNF-alpha are strongly predictive of mortality. Binding of TNF-alpha to TNF-alpha receptor-1 (TNF-R1) activates death domain pathways, leading to necrosis and apoptosis in most tissues, and it also increases the expression of intercellular adhesion molecules (i.e., ICAM-1), which promote inflammation. We determined whether ethanol exposure leads to increases in cellular TNF-R1. We incubated HepG2 human hepatoma cells and H4-II-E-C3 rat hepatoma cells with 25, 50, and 100 mM ethanol for various intervals of time up to 48 h. Human colonic adenocarcinoma cells (Caco-2 cells) and neonatal rat primary cardiomyocytes were also incubated with different concentrations of ethanol. Levels of TNF-R1 were measured either by a sandwich enzyme-linked immunosorbent assay (ELISA) method or by determining the extracellular transmembrane domain of TNF-R1 by an intact-cell ELISA method. Ethanol exposure for 48 h increased TNF-R1 levels in human hepatoma cells in a dose-dependent manner. Levels increased significantly by 164% at 50 mM and by 240% at 100 mM ethanol. Effects were time dependent and did not reach a plateau at 48 h. Similar increases in TNF-R1 were also observed in rat hepatoma cells (90% at 50 mM and 230% at 100 mM ethanol). Under similar conditions, Caco-2 cells showed a significant 80% increase in TNF-R1 levels at 200 mM ethanol, a concentration found in intestine. Neonatal rat primary cardiomyocytes showed TNF-R1 increases of 36% at 50 mM and 44% at 100 mM ethanol. These results indicate that exposure of different cell types to pharmacologic concentrations of ethanol increases TNF-R1 levels and may augment TNF-alpha-mediated cell injury in different tissues.     

染矽尘大鼠肺组织一氧化氮合酶的表达

目的　研究染矽尘大鼠早期炎性肺损伤过程中一氧化氮合酶 (NOS)的表达规律 ,为矽肺纤维化机制提供理论依据。方法　气管暴露法建立矽肺动物模型。测定支气管肺泡灌洗液 (BALF)中诱导型NOS(iNOS)的表达和总NOS的活力。在组织芯片上使用SP法检测大鼠肺组织iNOS的表达 ,并用Image ProPlus图像分析法对iNOS的表达进行定量测定。结果　iNOS主要表达在巨噬细胞和中性粒细胞胞浆内。与对照组相比 ,染矽尘大鼠肺组织中iNOS积分光密度于染尘后 3、7d时分别增加了1.47× 10 5 、2 .73× 10 5 ,2 8d时降低了 1.11× 10 5 ,差异均有显著性 (P <0 .0 5或P <0 .0 1)。大鼠BALF中iNOS活力在染尘后 3、7、14d时分别增加了 0 .86、1.89、0 .92U/ml ,差异均有显著性 (P <0 .0 5或P <0 .0 1)。BALF总NOS活力在染尘后 1、3、7、14d时分别增加了 1.43、2 .0 5、2 .61、2 .19U/ml,差异均有显著性 (P <0 .0 5或P <0 .0 1)。结论　在矽尘诱导下 ,大鼠肺组织中表达iNOS的细胞主要是肺泡巨噬细胞和中性粒细胞 ,其肺组织中iNOS的表达从染尘后 1d至 2 8d有一抛物线型的过程     

Steroid hormones augment nitric oxide synthase activity and expression in rat uterus

Nitric oxide (NO) is synthesized in a variety of tissues, including rat uterus, from L-arginine by NO synthase (NOS), of which there are three isoforms, namely neuronal, endothelial and inducible NOS (nNOS, eNOS and iNOS, respectively). Nitric oxide is an important regulator of the biology and physiology of the organs of the reproductive system, including the uterus. Some studies have shown increased variation in NO production and NOS expression during the oestrous cycle. However, the factors that regulate NO production in the uterus remain unclear. Therefore, in the present study, we investigated the effect of sex steroids on NOS expression and activity in the ovariectomized rat uterus. Ovariectomized rats received progesterone (4 mg per rat) or 17beta-oestradiol (1 microg per rat). All rats were killed 18 h after treatment. Both progesterone and oestradiol were able to augment NOS activity. The effect of oestradiol was abolished by pre-incubation with 500 micro M aminoguanidine, an iNOS inhibitor, or by coadministration of oestradiol with 3 mg kg(-1) dexamethasone, but the effect of progesterone was not affected by these treatments. Uterine nNOS, eNOS and iNOS protein levels were assessed using Western blots. Ovariectomized rat uteri expressed iNOS and eNOS. Progesterone increased the expression of eNOS and iNOS, whereas oestradiol increased iNOS expression only. These results suggest that oestradiol and progesterone are involved in the regulation of NOS expression and activity during pregnancy and implantation in the rat.     

Acute ethanol exposure inhibits renal folate transport, but repeated exposure upregulates folate transport proteins in rats and human cells

Deficiency of folate in heavy-drinking alcoholic populations can occur partly because of an increased urinary folate excretion. Ethanol directly reduces the reabsorption of folate in the renal proximal tubule (PT) by acting on either of 2 folate transport proteins, the reduced folate carrier (RFC) and the folate receptor (FR). This study was designed to determine the effects of ethanol on the transport of folate by PT cells and to examine the effects of ethanol on RFC and the FR protein expression. Normal human PT (HPT) cells were cultured on membrane inserts to study intracellular transport of 5-methyltetrahydrofolate from the apical or basolateral direction in the presence of ethanol [11-109 mmol/L (50-500 mg/dL)]. The long-term effect of ethanol on the renal folate transport protein content was determined by western blot in treated HPT cells and in vivo in rats pair-fed control diets or ethanol-containing liquid diets. A 1-h treatment of HPT cells with ethanol (> or = 65 mmol/L) reduced the apically directed transport of folate by 20-25% without affecting the basolateral transport. A 5-d exposure of HPT cells to ethanol dose-dependently increased the content of both the FR and RFC proteins, with a greater effect on the RFC. Similarly, a 14-d exposure of rats to ethanol increased the in vivo expression of both the RFC and FR. These studies demonstrate that ethanol decreases the reabsorptive transport of folate by renal PT cells, which would increase urinary folate excretion. In contrast, subchronic exposure of PT cells, both in vivo and in vitro, to folate-depleting concentrations of ethanol leads to an upregulation of the 2 folate transport proteins. The increase in folate transporters partly counteracts the inhibitory effects of ethanol on folate transport activity, which explains the lower magnitude of ethanol's effect on transport with subchronic exposure compared with that with acute exposure.     

人胃癌组织中一氧化氮合酶的表达及其与血管形成机制的探讨

目的　研究诱导型一氧化氮合酶 (iNOS)在人胃癌组织中的表达及其与胃癌微血管形成的关系。方法　采用免疫组化SP法检测 5 0例原发性胃癌中iNOS的表达 ,同时检测微血管密度 (MVD) ,以CD3 4 标记。结果　iNOS阳性表达率为 70 %,在iNOS阴性表达组MVD均值为 (11 8± 5 9) ,在iNOS阳性表达组中MVD均值分别为 (18 7± 6 3) ,(2 4 5± 5 6 ) ,(30 1± 9 4 ) ,iNOS阴性组和阳性组MVD均值差异有显著统计学意义 (P <0 0 1)。结论　iNOS在胃癌组织中有高表达 (70 %) ,与肿瘤微血管形成有关。     

铅对大鼠脑细胞一氧化氮合酶表达的影响

目的观察实验性铅中毒对大鼠脑细胞一氧化氮合酶(NOS)表达的影响,为进一步揭示铅的神经毒作用机制提供科学依据。方法取健康成年雄性SD大鼠24只,随机分为4组,每组6只,经腹腔注射醋酸铅连续染毒5d,剂量分别为25、50、100mg/kg体重,分别取海马、皮层部位脑组织,用免疫组化方法分别测定海马、皮层组织中神经元型一氧化氮合酶(nNOS)和依赖型一氧化氮合酶(iNOS)的蛋白含量。结果各剂量染铅组皮层、海马组织中iNOS表达与对照组相比,明显升高(P均<0.05),并有良好的剂量-反应关系(r=-0.727,P<0.05)。各剂量染毒组海马nNOS表达明显升高(P均<0.05),并有良好的线性关系(r=0.847,P<0.05),皮层组织nNOS表达无明显变化(P均>0.05)。结论铅所引起的神经细胞毒性可能通过铅诱导NOS的高表达,使得NO生成过多进而造成神经损害。     

The effects of ethanol on glucose 6-phosphate dehydrogenase enzyme activity from human erythrocytes in vitro and rat erythrocytes in vivo

AIMS: The effects of ethanol on erythrocyte glucose 6-phosphate dehydrogenase (G6PD) activity were investigated under in vitro and in vivo conditions. METHODS: For in vitro studies, glucose 6-phosphate dehydrogenase was purified from human erythrocyte and rats were used for in vivo studies. Enzyme activity was determined spectrophotometrically by the Beutler method. RESULTS: The in vitro study showed that the I(50) value was 17 mM for ethanol. In the case of the in vivo study, a 2 ml/kg dose of ethanol significantly inhibited the G6PD activity. The inhibition rate after ethanol administration was 59%, 40% and 6% at 1, 3 and 6 h after, respectively. CONCLUSIONS: The results of this study suggest that ethanol has a significant inhibitory effect on the G6PD activity both in vivo and in vitro.     

EPA、DHA对人单核细胞NO的产生、iNOSmRNA表达及NFκB活性的影响

目的探讨n-3多不饱和脂肪酸(Eicosapentaenoic acid EPA,Docosahexenoic acid DHA)对人单核细胞炎症因子——一氧化氮(NO)的分泌和诱导型NO合酶(iNOS mRNA)表达的影响,以及EPA、DHA对核转录因子(NFκB)与DNA结合活性的影响。方法硝酸还原酶法测定NO的含量,RT-PCR技术分析iNOS mRNA表达水平,凝胶电泳迁移实验检测NFκB与DNA的结合活性。结果EPA、DHA在10~20μg/ml浓度范围内能够降低体外培养的人外周血单核细胞NO的分泌和iNOS mRNA的表达并降低NFκB的DNA结合活性。结论EPA,DHA能够抑制单核细胞炎症因子NO的产生,减少iNOS mRNA的表达,并通过抑制信号转导途径中NFκB与DNA的结合活性这一通路来抑制炎症因子分泌,产生抑制炎症作用。     

Effects of acute ethanol exposure on glutamate release in the hippocampus of the fetal and adult guinea pig

The effects of in vitro and/or acute in vivo ethanol exposure on l-glutamate (GLU) release were determined in transverse hippocampal slices of the adult guinea pig and the immature and mature fetal guinea pig. In vitro ethanol (34–110 mM) exposure produced age-dependent and narrow concentration range-dependent depressant effects on K⁺-stimulated and basal GLU release, in which the fetal hippocampus was more sensitive than the adult. For acute in vivo ethanol exposure, the hippocampal slices were prepared 1 h after oral intubation of 4 g ethanol/kg body weight. In vivo ethanol exposure produced a persistent depressant effect on stimulated GLU release in the fetus and no effect in the adult. After acute in vivo ethanol treatment, in vitro ethanol (48 mM) exposure also decreased stimulated GLU release in the hippocampus of the immature and mature fetus and decreased basal GLU release only in the immature fetus. Furthermore, this acute in vivo/in vitro ethanol regimen did not affect stimulated or basal GLU release in the adult, which is indicative of tolerance development. Overall, the data indicate that ethanol depresses GLU release in the hippocampus of the guinea pig and that the fetal hippocampus is more susceptible to these depressant effects.     

Flow cytometric and fluorescence microscopic analysis of ethanol-induced G2+M block: ethanol dose-dependently delays the progression of the M phase.

We found previously that short-term (3 and 6 h) exposure to ethanol (100 and 200 mM) induced the transient arrest of L929 cells at the G2+M phase. To identify the exact site blocked during the G2+M phase, we carried out flow cytometry and microscopic analysis with asynchronous L929 cells exposed to ethanol (12.5-330 mM) for 3, 6 or 24 h. Flow cytometry (the simultaneous analysis of cellular DNA and cyclin B1 content) revealed that the percentage of 4c (tetraploid) cells with a high level of cyclin B1 increased after continuous 6 h exposure to ethanol (> or =82.5 mM) and decreased after 24 h exposure, which supports the idea of a transient M-phase block. To determine the sub-M phase of 4c cells with high levels of cyclin B1 based on spindle microtubules and their karyotype, we viewed immunofluorescent images by double staining with Hoechst 33258 (bis-benzimide trihydrochloride) for DNA and with fluorescein isothiocyanate-labelled antibody for cyclin B1 or beta-tubulin. A 6 h exposure to intermediate concentrations (50-100 mM) of ethanol increased the number of early-anaphase cells, compared with the control, suggesting an inhibition of the elongation of polar microtubules. Both 6 and 24 h exposure to higher concentrations (100-200 mM) of ethanol increased metaphase cells, indicating an arrest at the spindle assembly checkpoint and suggesting an inhibition of the shortening of kinetochore microtubules and/or the degradation of cyclin B . Moreover, 6 h exposure to 330 mM ethanol increased round, probably early-prophase, cells, suggesting inhibition of the formation of spindle microtubules. Thus, it is likely that higher concentrations of ethanol affect the elongation, contraction, and formation of the spindle microtubules of L929 cells dose-dependently and also disrupt the correlation between microtubule organization and the synthesis and degradation of cyclin B1, thereby delaying the progress of karyokinesis, which may lead to an ethanol-induced G2+M block.     

NO、NOS与宫缩乏力性产后出血关系的研究

目的:探讨血清NO及NOS在预测宫缩乏力性产后出血发生发展中的作用。方法:选择剖宫产终止妊娠的孕妇180例,因臀位、社会因素、骨盆狭窄、胎儿宫内窘迫等行剖宫产术,按产后24 h内出血量≥500 m l分为产后出血组(n=47)及非产后出血组(n=133)。所有孕妇于剖宫产术麻醉前30 m in及术后2 h测血清NO及NOS,术中娩出胎儿后于子宫切缘上缘及胎盘母体面中央无钙化区分别取子宫肌组织及胎盘组织各一,切片作免疫组织化学分析iNOS的表达,准确收集剖宫产术中出血量及产后24 h出血量。结果:产后出血组术前、术后血清NO及NOS含量较非产后出血组明显增高,差异有显著性意义(P<0.05);血清NOS预测产后出血的灵敏度、特异度、阳性预测值、阴性预测值均高于血清NO值;从SABC免疫组化结果可见在子宫肌及胎盘均有iNOS表达,产后出血组子宫肌和胎盘的iNOS阳性表达率均显著高于非产后出血组,P<0.05;经等级相关检验,子宫肌、胎盘组织iNOS的表达强度随术前血清NO、NOS水平的升高而增加,均呈正相关。结论:血清NO、NOS水平可以正确反映子宫、胎盘NOS的活性,可作为预测宫缩乏力性产后出血的1项有效的指标。     

Opposing effects of ethanol and nicotine on hippocampal calbindin-D28k expression.

Long-term ethanol exposure produces multiple neuroadaptations that likely contribute to dysregulation of Ca(2+) balance and neurotoxicity during ethanol withdrawal. Conversely, nicotine exposure may reduce the neurotoxic consequences of Ca(2+) dysregulation, putatively through up-regulation of the Ca(2+)-buffering protein calbindin-D(28k). The current studies were designed to examine the extent to which 10-day ethanol exposure and withdrawal altered calbindin-D(28k) expression in rat hippocampus. Further, in these studies, we examined the ability of nicotine, through action at alpha(7)(*)-bearing nicotinic acetylcholine receptors (nAChRs), to antagonize the effects of ethanol exposure on calbindin-D(28k) expression. Organotypic cultures of rat hippocampus were exposed to ethanol (50-100 mM) for 10 days. Additional cultures were exposed to 500 nM (-)-nicotine with or without the addition of 50 mM ethanol, 100 nM methyllycaconitine (an alpha(7)*-bearing nAChR antagonist), or both. Prolonged exposure to ethanol (>/=50 mM) produced significant reductions of calbindin-D(28k) immunolabeling in all regions of the hippocampal formation, even at nontoxic concentrations of ethanol. Calbindin-D(28k) expression levels returned to near-control levels after 72 h of withdrawal from 10-day ethanol exposure. Extended (-)-nicotine exposure produced significant elevations in calbindin-D(28k) expression levels that were prevented by methyllycaconitine co-exposure. Co-exposure of cultures to (-)-nicotine with ethanol resulted in an attenuation of ethanol-induced reductions in calbindin-D(28k) expression levels. These findings support the suggestion that long-term ethanol exposure reduces the neuronal capacity to buffer accumulated Ca(2+) in a reversible manner, an effect that likely contributes to withdrawal-induced neurotoxicity. Further, long-term exposure to (-)-nicotine enhances calbindin-D(28k) expression in an alpha(7)* nAChR-dependent manner and antagonizes the effects of ethanol on calbindin-D(28k) expression.     

Lipopolysaccharide-stimulated nitric oxide production and inhibition of cell proliferation is antagonized by ethanol in a clonal macrophage cell line.

Both chronic and acute ethanol exposure have been shown to be cytotoxic and also to disrupt normal cell function or responses in a variety of cell types. Macrophage function has specifically been shown to be disrupted by chronic ethanol exposure by mechanisms that have not been elucidated. It is known that exposure of macrophages to lipopolysaccharide (LPS) from gram-negative bacteria will decrease the number of cells. Since increased exposure to endotoxin is often associated with chronic alcoholism, this may be one mechanism to account for loss of macrophages in alcoholic patients. The loss of macrophages, as a consequence of endotoxin treatment, appears to be linked to cell activation and, in particular, LPS-stimulated synthesis of nitric oxide which has been suggested to cause an increase in apoptosis. Ethanol also increases apoptosis in some cell types but, in general, ethanol inhibits activation of macrophages. Thus, the overall effect on cell numbers and cell proliferation elicited by treating macrophages concomitantly with ethanol and LPS depends on the balance between inhibiting LPS-mediated activation and the actions of ethanol. The interaction between ethanol and LPS was investigated in a macrophage cell line (RAW 264.7 cells) by measuring nitric oxide production and cell proliferation. A 24-h exposure to ethanol (100 mM) decreased [3H]-thymidine incorporation significantly. LPS treatment elicited a concentration-dependent decrease in [3H]-thymidine incorporation at LPS concentrations of 0.1 ng/ml to 1000 ng/ml and stimulated nitric oxide production at concentrations above 1 ng/ml. LPS-stimulated nitric oxide production was inhibited by ethanol (20 to 100 mM) and the nitric oxide synthesis inhibitor, N(G)Nitro-L-arginine methyl L-NAME) ester (100 and 500 microM). However, LPS-inhibited [3H]-thymidine incorporation was not be totally reversed by ethanol- or L-NAME-treatment. A direct correlation between nitric oxide production and inhibition of cell proliferation could not be demonstrated. However, it appears that ethanol and LPS do affect some common mechanism(s) in this cell line.     

Design and synthesis of inhibitors of inducible nitric oxide synthase. Discovery of a new chemical lead with potential for oral bioavailability

A series of 2-iminopiperidines fused to small-membered rings (Tables 1 and 2) were synthesised and biologically evaluated using an in vitro human nitric oxide synthase (NOS) inhibition assay. Fused bicyclic compounds 5-9 exhibited nearly the same potency as compound 1 in the hiNOS inhibition assay. Among these, the 1-methyl analogues 8 and 9 showed better isoform selectivity than their corresponding unsubstituted analogues 7 and 6, respectively. Compounds 5 and 6 were also evaluated by an in vivo NO accumulation assay in a mouse model. The discovery process of new chemical leads for an orally bioavailable inhibitor of human inducible NOS (iNOS) is reported. The structure-activity relationship (SAR) study and chemistry of these compounds are also reported.     

Involvement of inducible nitric oxide synthase in radiation-induced vascular endothelial damage

The use of radiation therapy has been linked to an increased risk of cardiovascular disease. To understand the mechanisms underlying radiation-induced vascular dysfunction, we employed two models. First, we examined the effect of X-ray irradiation on vasodilation in rabbit carotid arteries. Carotid arterial rings were irradiated with 8 or 16 Gy using in vivo and ex vivo methods. We measured the effect of acetylcholine-induced relaxation after phenylephrine-induced contraction on the rings. In irradiated carotid arteries, vasodilation was significantly attenuated by both irradiation methods. The relaxation response was completely blocked by 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one, a potent inhibitor of soluble guanylate cyclase. Residual relaxation persisted after treatment with L-N^ω-nitroarginine (L-NA), a non-specific inhibitor of nitric oxide synthase (NOS), but disappeared following the addition of aminoguanidine (AG), a selective inhibitor of inducible NOS (iNOS). The relaxation response was also affected by tetraethylammonium, an inhibitor of endothelium-derived hyperpolarizing factor activity. In the second model, we investigated the biochemical events of nitrosative stress in human umbilical-vein endothelial cells (HUVECs). We measured iNOS and nitrotyrosine expression in HUVECs exposed to a dose of 4 Gy. The expression of iNOS and nitrotyrosine was greater in irradiated HUVECs than in untreated controls. Pretreatment with AG, L-N⁶-(1-iminoethyl) lysine hydrochloride (a selective inhibitor of iNOS), and L-NA attenuated nitrosative stress. While a selective target of radiation-induced vascular endothelial damage was not definitely determined, these results suggest that NO generated from iNOS could contribute to vasorelaxation. These studies highlight a potential role of iNOS inhibitors in ameliorating radiation-induced vascular endothelial damage.     

Exposure to the Amino Acids Histidine,Lysine, and Threonine Reduces mTOR Activity and Affects Neurodevelopment in a Human Cerebral Organoid Model

Evidence of the impact of nutrition on human brain development is compelling. Previous in vitro and in vivo results show that three specific amino acids, histidine, lysine, and threonine, synergistically inhibit mTOR activity and behavior. Therefore, the prenatal availability of these amino acids could be important for human neurodevelopment. However, methods to study the underlying mechanisms in a human model of neurodevelopment are limited. Here, we pioneer the use of human cerebral organoids to investigate the impact of amino acid supplementation on neurodevelopment. In this study, cerebral organoids were exposed to 10 mM and 50 mM of the amino acids threonine, histidine, and lysine. The impact was determined by measuring mTOR activity using Western blots, general cerebral organoid size, and gene expression by RNA sequencing. Exposure to threonine, histidine, and lysine led to decreased mTOR activity and markedly reduced organoid size, supporting findings in rodent studies. RNA sequencing identified comprehensive changes in gene expression, with enrichment in genes related to specific biological processes (among which are mTOR signaling and immune function) and to specific cell types, including proliferative precursor cells, microglia, and astrocytes. Altogether, cerebral organoids are responsive to nutritional exposure by increasing specific amino acid concentrations and reflect findings from previous rodent studies. Threonine, histidine, and lysine exposure impacts the early development of human cerebral organoids, illustrated by the inhibition of mTOR activity, reduced size, and altered gene expression.