Overexpression of human copper/zinc superoxide dismutase in transgenic mice attenuates oxidative stress caused by methylenedioxymethamphetamine (Ecstasy).

Administration of 3,4-methylenedioxymethamphetamine (4 x 20 mg/kg) to non-transgenic CD-1 mice caused marked depletion in dopamine, 3,4-dihydroxyphenylacetic acid and 5-hydroxytryptamine in the caudate-putamen. There were no significant changes in serotonergic markers in the hippocampus and frontal cortex. Homozygous and heterozygous copper/zinc superoxide dismutase transgenic mice show partial protection against the toxic effects of 3,4-methylenedioxymethamphetamine on striatal dopaminergic markers. In addition, 3,4-methylenedioxymethamphetamine injections caused marked decreases in copper/zinc superoxide dismutase activity in the frontal cortex, caudate-putamen and hippocampus of wild-type mice. Moreover, there were concomitant 3,4-methylenedioxymethamphetamine-induced decreases in catalase activity in the caudate-putamen and hippocampus, decreases in glutathione peroxidase activity in the frontal cortex as well as increases in lipid peroxidation in the frontal cortex, caudate-putamen, and hippocampus of wild-type mice. In contrast, administration of 3,4-methylenedioxymethamphetamine to homozygous superoxide dismutase transgenic mice caused no significant changes in antioxidant enzyme activities nor in lipid peroxidation. These results provide further substantiation of a role for oxygen-based radicals in 3,4-methylenedioxymethamphetamine-induced neurotoxicity. The present data also suggest that free radicals generated during 3,4-methylenedioxymethamphetamine administration may perturb antioxidant enzymes. Consequently, there might be further overproduction of free radicals with associated peroxidative damage to cell membranes and associated terminal degeneration.     

AlphaMUPA mice: a transgenic model for increased life span

AlphaMUPA is a line of transgenic mice that, compared with their wild type (WT) counterparts, spontaneously eat less (approximately 20%) and live longer (average approximately 20%), thus resembling dietary-restricted (DR) mice. Here, we show that body temperature was significantly reduced in alphaMUPA compared with WT throughout a wide range of ages. Plasma corticosterone was significantly higher in young alphaMUPA compared to young WT; however, it significantly declined in aged alphaMUPA, but not in aged WT. In addition, age-associated thymus involution occurred in alphaMUPA as it did in WT. Thus alphaMUPA mice appear to largely resemble, but also to somewhat differ from diet-restricted animals. We also report on four new transgenic lines that, like alphaMUPA, produced in the brain the mRNA that encodes the extracellular protease urokinase (uPA); however, transgenic uPA expression was most extensive and widespread in the alphaMUPA brain, where it also occurred in the hypothalamus. AlphaMUPA was also the only line that ate less, but also showed another characteristic, high frequency leg muscle tremor seen only at unstable body states. We hypothesize that transgenic uPA in the brain could have caused the alphaMUPA phenotypic alterations. Thus alphaMUPA offers a unique transgenic model of inherently reduced eating to investigate the homeostatic state of delayed aging at the systemic and single-cell levels.     

Thioredoxin is related to life span regulation and oxidative stress response in Caenorhabditis elegans

Thioredoxin, an oxidoreductase, is a multifunction protein. The thioredoxin system is composed of NADPH, thioredoxin reductase and thioredoxin. This enzyme is highly conserved from bacteria to humans. We have characterized TRX-1, a thioredoxin homolog in C. elegans, which has about 36% identity in amino acid sequence with human thioredoxin. By gfp reporter system, trx-1 has been shown to be restrictedly expressed in ASI and ASJ neurons and in intestine. Immunostaining confirmed the intestinal expression. Full-length cDNA of trx-1 has been isolated by cDNA library PCR and subsequently cloned and sequenced. We have shown that the encoded protein functions as a reductase in the insulin reducing assay. Moreover, we have isolated a deletion mutant by PCR-based TMP-UV mutagenesis method. Mutant animals have reduced life span and are sensitive to oxidative stress. Reintroduction of trx-1 into mutant worms fully restored the wild-type phenotype. Our results suggest that trx-1 has important functions in life span regulation and oxidative stress response in C. elegans.     

Attenuation of retinal photooxidative damage in thioredoxin transgenic mice

Thioredoxin (TRX) is an endogenous redox (reduction/oxidation) regulator that has cytoprotective effects against various types of oxidative stresses. Exposure to excessive levels of white light induces retinal photoreceptor damage. To test the cytoprotective effect of overexpressed TRX against retinal photooxidative damage, both TRX transgenic (trx-tg) mice and C57BL/6 (wild type) mice were exposed to intense white fluorescent light. The amounts of oxidized and tyrosine-phosphorylated proteins decreased in the neural retinas of the trx-tg mice compared to the wild type mice after light exposure. The electroretinographic amplitudes were higher and the formation of oxidized DNA was lower in trx-tg mice compared to wild type mice after light exposure. These results suggest that overexpression of TRX suppresses retinal photooxidative damage. TRX intensification may be a useful therapeutic strategy to prevent retinal photic injury.     

Enhanced oxidative stress and impaired thioredoxin expression in spontaneously hypertensive rats

As oxidative stress plays a crucial role in the development and pathogenesis of hypertension, we analyzed the redox (reduction/oxidation) status in tissues from Wistar-Kyoto rats (WKY), spontaneously hypertensive rats (SHR), and stroke-prone SHR (SHRSP). Expressions of 8-hydroxy-2'-deoxyguanosine, a marker for oxidative stress-induced DNA damage, and protein carbonylation, a marker for oxidation status of proteins, were enhanced in aorta, heart, and kidney from SHR and SHRSP compared with WKY. The expression of redox regulating protein, thioredoxin (TRX), estimated by immunohistochemistry and western blot, and expression of TRX gene estimated by real-time RT-PCR were markedly suppressed in those tissues from SHR and SHRSP compared with WKY. Induction of TRX was impaired after angiotension II treatment in peripheral blood mononuclear cells isolated from SHR and SHRSP compared with those isolated from WKY. Although previous reports have shown that TRX is induced by a variety of oxidative stress in tissues, the present study shows the impaired induction of TRX in tissues from genetically hypertensive rats despite the relative increment of oxidative stress. Redox imbalance in essential organs may play a crucial role in the development and pathogenesis of hypertension.     

Pituitary removal in adult mice increases life span

Dwarf mutations reduce levels of pituitary hormones and increase life span in mice. But because these dwarf mutations confer life-long hormone deficits that alter development and dramatically reduce fecundity, the relevance of these models to normal aging has been questioned. We examined effects of pituitary hormone withdrawal at different ages using hypophysectomy (surgical removal of the pituitary). Hypophysectomy at 1 month of age extended life span significantly (15%), but hypophysectomy at 9 months of age extended life span to the greatest magnitude (21%) of any age we tested. These results demonstrate pituitary hormone withdrawal can extend life span even if these hormones are removed relatively late in life.     

Overexpression of agouti protein and stress responsiveness in mice

Ectopic overexpression of agouti protein, an endogenous antagonist of melanocortin receptors' linked to the beta-actin promoter (BAPa) in mice, produces a phenotype of yellow coat color, Type II diabetes, obesity and increased somatic growth. Spontaneous overexpression of agouti increases stress-induced weight loss. In these experiments, other aspects of stress responsiveness were tested in 12-week-old male wild-type mice and BAPa mice. Two hours of restraint on three consecutive days produced greater increases in corticosterone and post-stress weight loss in BAPa than wild-type mice. In Experiment 2, anxiety-type behavior was measured immediately after 12 min of restraint. This mild stress did not produce many changes indicative of anxiety, but BAPa mice spent more time in the dark side of a light-dark box and less time in the open arms of an elevated plus maze than restrained wild-type mice. In a defensive withdrawal test, grooming was increased by restraint in all mice, but the duration of each event was substantially shorter in BAPa mice, possibly due to direct antagonism of the MC4-R by agouti protein. Thus, BAPa mice showed exaggerated endocrine and energetic responses to restraint stress with small differences in anxiety-type behavior compared with wild-type mice. These results are consistent with observations in other transgenic mice in which the melanocortin system is disrupted, but contrast with reports that acute blockade of central melanocortin receptors inhibits stress-induced hypophagia. Thus, the increased stress responsiveness in BAPa mice may be a developmental compensation for chronic inhibition of melanocortin receptors.     

The evolution of menopause and human life span

Noteworthy data is emerging to support the existence of longevity-enabling genes. Our observations of the relationship between reproductive fitness and longevity among centenarians support theories that posit strong selective forces in the determination of how fast humans age and their susceptibility to diseases associated with ageing. Current data support the idea that there is no selective advantage for humans to have a lifespan of approximately 100 years. Rather, getting to such a very old age may be a by-product of longevity-enabling genes that maximize the length of time during which women can bear children, and during which they can increase the survival probabilities of their children and grandchildren. We thus review the literature pertaining to the relationship between reproductive fitness and longevity.     

Overexpression of human Cripto-1 in transgenic mice delays mammary gland development and differentiation and induces mammary tumorigenesis

Overexpression of Cripto-1 has been reported in several types of human cancers including breast cancer. To investigate the role of human Cripto-1 (CR-1) in mammary gland development and tumorigenesis, we developed transgenic mice that express the human CR-1 transgene under the regulation of the whey acidic protein (WAP) promoter in the FVB/N mouse background. The CR-1 transgene was detected in the mammary gland of 15-week-old virgin WAP-CR-1 female mice that eventually developed hyperplastic lesions. From mid-pregnancy to early lactation, mammary lobulo-alveolar structures in WAP-CR-1 mice were less differentiated and delayed in their development due to decreased cell proliferation as compared to FVB/N mice. Early involution, due to increased apoptosis, was observed in the mammary glands of WAP-CR-1 mice. Higher levels of phosphorylated AKT and MAPK were detected in mammary glands of multiparous WAP-CR-1 mice as compared to multiparous FVB/N mice suggesting increased cell proliferation and survival of the transgenic mammary gland. In addition, more than half (15 of 29) of the WAP-CR-1 multiparous female mice developed multifocal mammary tumors of mixed histological subtypes. These results demonstrate that overexpression of CR-1 during pregnancy and lactation can lead to alterations in mammary gland development and to production of mammary tumors in multiparous mice.     

还脑益聪方组分对APP转基因小鼠脑组织炎症因子和氧化应激的影响

目的: 研究中药复方-还脑益聪方(HNYCF)组分对阿尔茨海默病(AD)动物模型脑组织炎症因子和氧化应激相关指标的影响,探讨其治疗AD的作用机制。方法: 选用3月龄APP695V717I转基因小鼠AD模型,随机分成4组:模型组、盐酸多奈哌齐组、HNYCE组分大剂量组和HNYCF组分小剂量组。另设立正常对照组(相同遗传背景的C57BL/6J小鼠)。各组小鼠按相应处理连续灌胃6个月后进行相关指标检测。采用Morris水迷宫和跳台实验观测小鼠学习记忆能力,采用免疫组织化学法检测脑组织核因子κB(NF-κB) 和过氧化物酶体增殖物激活受体γ(PPARγ)的表达水平,放射免疫法测定脑组织皮层和海马白细胞介素-6 (IL-6)和高敏C-反应蛋白(hs-CRP)的含量,比色法检测血清超氧化物歧化酶(SOD)活性,硫代巴比妥酸法测定血清丙二醛(MDA)含量。结果: HNYCF小鼠在Morris水迷宫中穿越平台次数、第4象限游泳时间和路程均较模型组显著增多(P<0.05或P<0.01);HNYCF大剂量组小鼠在跳台实验中潜伏期较模型组显著延长(P<0.01);HNYCF小鼠脑组织NF-κB表达下调,PPARγ表达上调,IL-6含量减少,与模型组比较有显著差异(P<0.05或P<0.01);HNYCF小鼠血清SOD活性较模型组显著升高(P<0.05或P<0.01)。结论: HNYCF可以改善APP转基因小鼠的学习记忆能力,其作用机制可能与抗炎、抗氧化作用有关。     

The role of thioredoxin in the aging process: involvement of oxidative stress

Reactive oxygen species are produced by various stressors derived from internal and external sources, including endogenous metabolic activities. Glucose metabolism is one of the most primitive sources for energy production for most cells; however, it may at the same time yield hazardous oxidative stress via simultaneous oxidant production. The protective mechanism against oxidative stress is thus an indispensable biological function. Recently, genetic mutation loci affecting life span were isolated from experimental model organisms, and several locus products were found to be closely linked with machinery either producing or defending oxidative stress. Thioredoxin (TRX) is a small protein having strong antioxiradical quenching capabilities and other multiple functions depending on the cellular redox state. In this review, we focus on the role of TRX in the aging process (senescence) as a redox-regulating molecule against oxidative stress. We also discuss the possibility of the TRX system serving as an index marker for cellular proliferation and senescence.     

Neurotropin increases in vitro life span of human fibroblasts

Fibroblasts isolated from human fetal tissues (skin, lung and heart) exhibited the following population doubling levels (PDL): about 40 PDL for skin; 60 PDL for lung; 10 PDL for heart. Neurotropin extract from vaccinia-virus infected skin tissues of rabbits increases the growth rate of the fibroblast when added to the old lung cell culture (PDL 40, 70% of the maximum life span) but not when added to the young lung (PDL 5, 8% of the maximum life span). Neurotropin (40 or 80 micrograms/ml) increased the replicative life span of the three lines of fibroblasts (skin, lung and heart) when added to the young cell cultures. The increase of the maximum PDL of skin, lung and heart fibroblasts with the Neurotropin treatment was by 19%, 5% and 17%, respectively. When Neurotropin was added to the old lung cell culture (PDL 44, 73% of the maximum life span), the maximum PDL was increased by 9%. Since the existence of hydrocortisone, known to extend the in vitro life span, was negligible in the fluorimetric test of the medium containing Neurotropin, this agent may belong to the class other than hydrocortisone, for increasing in vitro life span.     

Loss of Caenorhabditis elegans homologue of human MOB4 compromises life span,health life span and thermotolerance

Mob1/phocein family proteins are conserved from yeast to mammals. Human has four MOB genes, MOB1, 2, 3 and 4. Human MOB1 protein, which is a component of the Hippo pathway, is involved in the inhibition of yes-associated protein (YAP1) through large tumor suppressor (LATS) kinases and plays a tumor suppressive role. In contrast, MOB4 activates YAP1. Caernorhabditis elegans (C. elegans) also has four MOB genes. Moreover, C. elegans has homologues of YAP1 (Ce_YAP-1) and LATS kinases (WTS-1). Nevertheless, our previous study revealed that the Hippo pathway is not conserved in C. elegans and that heat shock activates Ce_YAP-1. We also reported that Ce_YAP-1 is involved in the regulation of life span, healthy lifespan and thermotolerance. In this study, we raised a question whether and how C. elegans homologue of MOB4 (Ce_MOB-4) is involved in the regulation of Ce_YAP-1. Ce_MOB-4 is ubiquitously expressed in adult worms. This expression pattern is similar to that of Ce_YAP-1. mob-4 loss-of-function mutants show short life span, short health life span and compromise thermotolerance. However, heat shock activates Ce_YAP-1 in mob-4 mutant. In conclusion, the role of MOB4 in the activation of YAP1 is not conserved in C. elegans.     

Major depression and the stress system: a life span perspective

From a transactional developmental perspective, the authors review findings from studies of animals and humans regarding a proposed relation between stress system abnormalities and major depression. The stress system has evolved to promote successful adaptation across the life span, but disruptions in its functioning may increase the risk of pathological outcomes. Emphasis is placed on the role of prenatal and early postnatal experience in contributing to individual differences in postnatal stress reactivity, which may interact with cognitive and psychosocial vulnerabilities to increase susceptibility to later onset of depression. Findings regarding cognitive, psychosocial, and medical sequelae of depression are also reviewed, with a focus on the possible mediating role of the stress system. The authors highlight the importance of multidisciplinary, longitudinal studies in attempting to gain a deeper understanding of the complex developmental processes involved in the onset and course of depression.     

Mapping cortical change across the human life span

We used magnetic resonance imaging and cortical matching algorithms to map gray matter density (GMD) in 176 normal individuals ranging in age from 7 to 87 years. We found a significant, nonlinear decline in GMD with age, which was most rapid between 7 and about 60 years, over dorsal frontal and parietal association cortices on both the lateral and interhemispheric surfaces. Age effects were inverted in the left posterior temporal region, where GMD gain continued up to age 30 and then rapidly declined. The trajectory of maturational and aging effects varied considerably over the cortex. Visual, auditory and limbic cortices, which are known to myelinate early, showed a more linear pattern of aging than the frontal and parietal neocortices, which continue myelination into adulthood. Our findings also indicate that the posterior temporal cortices, primarily in the left hemisphere, which typically support language functions, have a more protracted course of maturation than any other cortical region.     

Effects of nutrition on disease and life span. I. Immune responses, cardiovascular pathology, and life span in MRL mice.

Mice of the autoimmune, lymphoproliferative strain MRL/lpr and the congenic, nonlymphoproliferative strain MRL/n were fed one of six diets from weaning on-ward. These mice were sacrificed at 3 or 5 months of age. Low fat diets resulted in lower cholesterol and higher triglyceride levels than did cholesterol-containing high-fat diets. Caloric restriction of MRL/lpr mice was associated with an increased plaque-forming cell response to trinitrophenylated polyacrylamide beads, less lymphoproliferation, and less severe glomerulonephritis. Diet did not affect the incidence of autoimmune vasculitis in MRL/lpr mice sacrificed at 5 months. MRL/lpr mice fed a low-fat, calorically restricted diet from 5 months of age to death lived longer than mice which were fed ad libitum a cholesterol-containing, high-fat diet. At death, MRL/lpr mice fed the former diet had the autoimmune vasculitis which had been evident in mice killed at 5 months, whereas mice fed the latter diet, in addition to the vasculitis, had a high incidence of atherosclerotic lesions of intrarenal and aortic branch arteries.     

Against the oxidative damage theory of aging: superoxide dismutases protect against oxidative stress but have little or no effect on life span in Caenorhabditis elegans

The superoxide radical (O₂⁻) has long been considered a major cause of aging. O₂⁻ in cytosolic, extracellular, and mitochondrial pools is detoxified by dedicated superoxide dismutase (SOD) isoforms. We tested the impact of each SOD isoform in Caenorhabditis elegans by manipulating its five sod genes and saw no major effects on life span. sod genes are not required for daf-2 insulin/IGF-1 receptor mutant longevity. However, loss of the extracellular Cu/ZnSOD sod-4 enhances daf-2 longevity and constitutive diapause, suggesting a signaling role for sod-4. Overall, these findings imply that O₂⁻ is not a major determinant of aging in C. elegans.     

Genetic variation for life span, resistance to paraquat, and spontaneous activity in unselected populations of Drosophila melanogaster: implications for transgenic rescue of life span

Genetic variation in adult life span, resistance to paraquat, resistance to DDT, and spontaneous flying activity were measured in 138 recombinant inbred lines of Drosophila melanogaster. We find that the phenotypic correlation between life span and resistance to an exogenous oxidizing agent is positive, though weak, and that there is little correlation between the two traits at the level of quantitative trait loci (QTLs). The sign of the life span-resistance correlation is haplotype-specific, suggesting a high degree of statistical interaction and dependence on genetic background. Because of the genotype-specificity in the relationship between life span and resistance phenotypes, interventions to extend life span by overexpression of antioxidant enzymes are likely to produce strain-specific results. These observations are in general agreement with the "genetic rescue" hypothesis of Sohal et al. [Sohal, R.S., Mockett, R.J., Orr, W.C., 2002. Mechanisms of aging: an appraisal of the oxidative stress hypothesis. Free Radic. Biol. Med. 33, 575-586.], though we emphasize that such statistical interaction is a normal feature of standing genetic variation, and does not imply that some genotypes are pathological. Ad hoc observation of spontaneous flying activity 5 days after emergence proved to be a much better predictor of life span than resistance to an exogenous oxidant in these populations.     

Protection from oxidative stress by thioredoxin and superoxide dismutase of mouse embryos fertilized in vitro.

A low oxygen tension and superoxide dismutase (SOD) have been demonstrated to promote development of embryos in vitro. In this study, we evaluated the effects of thioredoxin (TRX), a powerful protein disulphide reductase, on the development of mouse embryos fertilized in vitro. Moreover, to clarify the difference between the embryo-protecting mechanisms of TRX and SOD, as well as the critical periods of their actions, we carried out experiments in which we transferred embryos among three different media: basic, TRX- and SOD-supplemented. The rates of 4-cell, blastocyst and expanded blastocyst formation in TRX- (53%, 40% and 34% respectively), or SOD- (59%, 29%, 22%) supplemented media were significantly higher than those (28%, 4%, 0%) in the basic medium. The results of the transfer of embryos using basic and TRX-supplemented media indicated an increase in the rate of expanded blastocysts when TRX was applied from 7 to 30 h, and especially from 18 to 24 h after insemination. In contrast, the results of the transfer of embryos using basic and SOD-supplemented media indicated that SOD, which was also most effective when applied from 7 to 30 h after insemination, had some effects after 30 h. These results indicate that TRX and SOD promote the in-vitro development of mouse embryos fertilized in vitro, which suggests that protection of embryos from oxidative stress is a prerequisite for their development in vitro. SOD and TRX provide protection from oxidative stress by different mechanisms.