Striking changes in anxiety in Huntington's disease transgenic mice

Huntington's disease transgenic mice were tested in the elevated plus-maze test of anxiety at 6, 8, 10 and 12 weeks of age. At all ages, they showed significant and striking increases in the percentages of open arm entries and time spent on the open arms, compared with their normal littermates, indicating reduced anxiety. These increases were not secondary to a non-specific stimulant effect, since the transgenic mice made fewer closed arm entries, significantly so from 10 weeks of age. The mice were also tested in the holeboard, which provides measures of locomotor activity and directed exploration. From 8 weeks of age, the Huntington's mice were significantly less active than their normal littermates and made fewer exploratory head-dips. The increased open arm activity in the elevated plus-maze cannot therefore be secondary to increased exploration in the transgenic mice. In order to determine whether the reduced anxiety was due to differences in benzodiazepine receptor function, the mice were challenged with the benzodiazepine receptor antagonist, flumazenil. The results indicated that some of the reduced anxiety could be attributed to the presence of an endogenous anxiolytic ligand.     

Aggressive behaviour in transgenic mice expressing APP is alleviated by serotonergic drugs

Transgenic mouse strains were generated that overexpress human APP or clinical mutants of APP. All transgenic mouse strains that over-express APP displayed essentially the same phenotype of disturbed behaviour, differential glutamatergic responses, deficits in maintenance of long-term potentiation and premature death, but formation of amyloid plaques was seen in the highest expressing APP/London transgenic mice only. Apart from cognitive deficits, the APP transgenic mice were characterized by aggressive behaviour, which was pharmacologically alleviated with 8-OH-DPAT and buspirone, two serotonergic agonists. The atypical neuroleptic drug risperidone was equally active in this regard. The data establish an important aspect of the transgenic mice as experimental models for behavioural aspects of Alzheimer's disease, in addition to other early and late symptoms.     

Age- and gender-related elastin distribution changes in human vocal folds

To elucidate the mechanism of gut hypertrophy observed in rats artificially reared (AR) on milk formulas, the effects of four refined formulas with different ratios of casein (C) and whey protein (W), CW 2:8, CW 4:6, CW 6:4 and CW 8:2, on the gut growth of AR rats were examined. Four groups of pups were infused with each formula through an intragastric cannula from age 5 to 15 days. Each of the four milk formulas showed a different character in the stomach, such as no curd, very soft curd, soft curd and hard curd, in response to an increasing ratio of C:W. There were no significant differences in body weight gain among the AR groups and mother-reared (MR) controls. The stomach growth, in weight, of AR rats increased in response to the increasing ratios of C:W. In comparison with MR controls, hypertrophy of the stomach of AR rats appeared within the formulas with higher proportions of casein than whey protein (CW 6:4 and CW 8:2), but not those with lower proportions (CW 2:8 and CW 4:6). The growth of the small intestine was also related to the increasing ratio of C:W in the formulas. A similar pattern of hypertrophy in the hindgut was seen in AR rats. There was no association between hypertrophy of the gut in AR rats and plasma triiodothyronine. The present results clearly demonstrated that the gut growth of AR rat pups was directly influenced by the diet but not by AR per se, and that hard casein-curd in the stomach might be one cause of gut hypertrophy.     

Treatment with growth hormone and dexamethasone in mice transgenic for human islet amyloid polypeptide causes islet amyloidosis and beta-cell dysfunction

Islet amyloid derived from islet amyloid polypeptide (IAPP) is a well-recognized feature of type II diabetes. However, the mechanism of islet amyloidogenesis is unknown. In vitro studies suggest that amino acid residues 20-29 in human, but not mouse, IAPP confer amyloidogenicity consistent with the absence of spontaneous islet amyloidosis in mice. Several clinical and in vitro studies suggest that increased synthetic rates of IAPP predispose to IAPP-amyloidosis. In the present study, we sought to test the hypothesis that pharmacological induction of insulin resistance in a mouse transgenic (TG) for human IAPP would induce islet amyloid and beta-cell dysfunction. TG and non-transgenic (N-TG) control mice were treated with both rat growth hormone (12 micrograms/day) and dexamethasone (0.24 mg/day) (dex/GH) or received no treatment for 4 weeks, after which animals were killed to examine islet morphology. Treatment with dex/GH caused hyperglycemia (7.3 +/- 0.4 vs. 5.2 +/- 0.1 mmol/l, TG vs. N-TG, P < 0.001) associated with a decreased plasma insulin concentration (595 +/- 51 vs. 996 +/- 100 pmol/l, TG vs. N-TG, P < 0.05) in TG versus control mice. Islet amyloid was induced in treated TG mice but not in control mice. Islet amyloid was identified in both intra- and extracellular deposits, the former being associated with evidence of beta-cell degeneration. We conclude that dex/GH treatment in mice TG for human IAPP induces IAPP-derived islet amyloid, hyperglycemia, and islet dysfunction. The present model recapitulates the islet morphology and phenotype of type II diabetes.     

Scrapie infection of transgenic mice leads to network and intrinsic dysfunction of cortical and hippocampal neurones

The human prion encephalopathy Creutzfeldt-Jakob disease often is manifest as rapidly progressing dementia with myoclonus and synchronous, periodic discharges. To investigate the electrophysiology of prion disease we used intra- and extra-cellular recordings from brain slices from Tg(SHaPrP+/+) 81 mice, which express Syrian hamster prion protein and which are susceptible to hamster-passaged scrapie isolates. Forty days after intracerebral inoculation with scrapie isolate Sc237, we recorded prolonged, epileptiform discharges in cortex and hippocampus. Neurological signs were subtle and histopathology was minimal. Central nervous system (CNS) dysfunction progressed; by 57 days the mice were ataxic, had spongiform histopathology and they died in <63 days. During the terminal phase, intrinsic neuronal properties changed dramatically and action potentials broadened from <4 to 20-100 ms in 30% of cortical cells. We conclude that brain dysfunction in experimental scrapie precedes clinical signs and spongiform histopathology, and is preserved in slices maintained in vitro, making it accessible to electrophysiological analysis.     

Formation of neuronal intranuclear inclusions underlies the neurological dysfunction in mice transgenic for the HD mutation

Huntington's disease (HD) is one of an increasing number of human neurodegenerative disorders caused by a CAG/polyglutamine-repeat expansion. The mutation occurs in a gene of unknown function that is expressed in a wide range of tissues. The molecular mechanism responsible for the delayed onset, selective pattern of neuropathology, and cell death observed in HD has not been described. We have observed that mice transgenic for exon 1 of the human HD gene carrying (CAG)115 to (CAG)156 repeat expansions develop pronounced neuronal intranuclear inclusions, containing the proteins huntingtin and ubiquitin, prior to developing a neurological phenotype. The appearance in transgenic mice of these inclusions, followed by characteristic morphological change within neuronal nuclei, is strikingly similar to nuclear abnormalities observed in biopsy material from HD patients.     

Islet regeneration in IFNgamma transgenic mice

The adult pancreas is a developmentally stable organ with limited mitotic activity. This minimal mitotic activity proves critical in insulin-dependent diabetes mellitus (IDDM) since the pathogenesis is characterized by a selective and permanent destruction of islet beta cells. The IFNgamma transgenic mouse model of islet regeneration elucidates the differentiation pathway involved in the regeneration of functional beta cells from ductal precursors and reveals the functional plasticity of the adult pancreas.     

Anxiety-like behavior in transgenic mice with brain expression of neuropeptide Y

In an attempt to understand the relationship between photorepair and dark repair in Neurospora crassa, a new mutant was isolated, which showed defects in both repair processes. The new mutant, mus-38, is moderately sensitive to UV and shows imperfect photoreactivation following UV irradiation. DNA was purified from this mutant and the other UV-sensitive mutants, and analyzed for the removal of cyclobutane pyrimidine dimers (CPDs). UV-specific endonuclease-sensitive sites (ESS) completely disappeared with 1 h of photoreactivation in mus-38 DNA, although the survival recovery with photoreactivation was greatly reduced in this mutant. This suggests that the insufficient survival recovery with photoreactivation in mus-38 does not result from a failure of photo-reversal of CPDs. Removal of ESS during liquid holding (dark repair) was slower in mus-38 compared to wild type. To test the possibility that this mutant was involved in excision repair, the double mutant was made between mus-38 and mus-18, which encodes a UV-damage-specific endonuclease. CPD excision in the mus-18 null mutant was severely affected but not completely inhibited. The double mutant showed a complete loss of the excision activity and was super sensitive to UV. These results indicate that mus-38 participates in an excision pathway that is different from the mus-18 pathway. The mus-38 mutant was sensitive not only to UV but also to some chemical mutagens which make adducts on DNA. Thus, mus-38 is possibly involved in an excision-repair pathway that is related to the Saccharomyces cerevisiae RAD3 pathway.     

社交焦虑障碍患者的注意特征及其对症状感知判断的影响

目的:探讨社交焦虑障碍患者以自我为焦点的注意特征及其对其他心理过程的影响,阐明社交焦虑障碍的病理心理学机制.方法:在模拟社交情境下,对社交焦虑障碍患者32例和正常对照组35例进行注意焦点量表及焦虑相关的行为量表及焦虑躯体感受问卷的测评,并进行统计学分析.结果:社交焦虑障碍组患者的以自我为焦点的注意水平和焦虑躯体感受评分均高于正常对照组,差异具有统计学意义(P<0.01).社交焦虑障碍组患者以自我为焦点的注意评分与自我判断偏差、焦虑行为自评分和焦虑躯体感受评分呈正相关关系(r=0.906,P<0.01; r=0.776,P<0.01;r=0.433,P<0.01).结论:社交焦虑障碍患者以自我为焦点的注意特征可能引起更显著的消极焦虑相关行为评价和焦虑症状的感知,导致焦虑相关行为自我判断的偏差.     

Amyloid-beta deposition in Alzheimer transgenic mice is associated with oxidative stress

Increased awareness for a role of oxidative stress in the pathogenesis of Alzheimer's disease has highlighted the issue of whether oxidative damage is a fundamental step in the pathogenesis or instead results from disease-associated pathology. In vitro experiments support both possibilities: Oxidative stress increases amyloid-beta production, and, conversely, amyloid-beta increases oxidative damage. To address the relationship between amyloid-beta and oxidative stress in vivo, we examined, using an array of oxidative markers, transgenic mice that overexpress amyloid-beta precursor protein and, as in Alzheimer's disease, develop characteristic amyloid-beta deposits within the brain parenchyma. Transgenic animals show the same type of oxidative damage that is found in Alzheimer's disease, and it is important that this damage directly correlates with the presence of amyloid-beta deposits. The significance of these studies is twofold. First, they provide evidence that amyloid-beta and oxidative damage are inextricably linked in vivo. Second, they support the use of transgenic animals for the development of antioxidant therapeutic strategies.     

Active signaling by Neu in transgenic mice

Transgenic mice engineered to overexpress the HER-2/neu/erbB-2 protooncogene under the control of a mammary-specific promoter develop mammary tumors and are a model for human breast cancer. Signal transduction by Neu was examined in situ in the tumors of these transgenic mice. This was accomplished using the PN2A monoclonal antibody, which recognizes Neu only in the phosphorylated, and therefore actively signaling, state. Immunohistochemistry using PN2A demonstrated that Neu actively signals in the tumors of Neu transgenic mice. Expression of Neu was always accompanied by co-overexpression of the endogenous epidermal growth factor receptor. Qualitatively similar results were found in mammary tumors from mice bitransgenic for the neu and transforming growth factor-alpha genes (both driven by the mouse mammary tumor virus promoter). Early mammary lesions demonstrated distinctive patterns of Neu activation relative to expression levels. Overexpression and activation were separable both temporally and spatially. These results refine the multi-step model for the role of Neu in mammary neoplasia and establish phosphorylation-state specific antibodies as a powerful tool for investigating tumor progression.     

Primary demyelination in transgenic mice expressing interferon-gamma

Ever since the use of interferon-gamma to treat patients with multiple sclerosis resulted in enhanced disease, the role of IFN-gamma in demyelination has been under question. To address this issue directly, transgenic mice were generated that expressed the cDNA of murine IFN-gamma in the central nervous system by using an oligodendrocyte-specific promoter. Expression of the transgene occurred after 8 weeks of age, at which time the murine immune and central nervous systems are both fully developed. Directly associated with transgene expression, primary demyelination occurred and was accompanied by clinical abnormalities consistent with CNS disorders. Additionally, multiple hallmarks of immune-mediated CNS disease were observed including upregulation of MHC molecules, gliosis and lymphocytic infiltration. These results demonstrate a direct role for IFN-gamma as an inducer of CNS demyelination leading to disease and provide new opportunities for dissecting the mechanism of demyelination.     

Osteochondrodysplasia occurring in transgenic mice expressing interferon-gamma

Arterial thrombi are primarily composed of platelets. Platelets are bound to injured endothelial cells, sub-endothelial matrices, and other platelets by a range of adhesive proteins. Some of these reactions are governed by shear forces. The role of adhesive proteins in the pathogenesis of arterial thrombosis is not fully understood. The aim of this study was to examine the involvement of von Willebrand factor (vWF), fibrinogen (Fg), and fibronectin (FN) in the formation of microvascular thrombi in vivo using a helium-neon laser-induced thrombosis method. Transmission electron microscopy demonstrated that laser irradiation resulted in platelet-rich thrombosis in arterioles and venules, and revealed that this occurred in the absence of endothelial denudation. The mean wall shear rates in mesenteric arterioles and venules were 641 +/- 40 and 280 +/- 20 s-1, respectively. Shear rates increased approximately fivefold in arterioles and tenfold in venules during the formation of occlusive thrombi. Antibody to vWF inhibited thrombosis in arterioles and venules. Antibodies to Fg and FN inhibited thrombosis in venules but not in arterioles. These results confirm that vWF, Fg and FN were involved in thrombogenesis in vivo and demonstrated that significantly higher shear rates were required for the reactions involving vWF than those involving either Fg or FN.     

Behavioural phenotyping of transgenic mice.

This paper reviews the current work on mouse genetics, brain, and behaviour in my laboratory. It starts with an historical account of our research and shows how certain research themes, such as olfaction, learning, social behaviour, and environmental effects in rodents have led to our current research on behavioural phenotyping of inbred, mutant, knockout, and transgenic mice. We are concerned with finding neural and behavioural sequelae to genetic manipulations in mice and use a battery of tests to detect behaviours that are altered in genetically modified mice. In this way we are working to dissociate neural and behavioural effects of different gene manipulations in mouse models of neurodegenerative diseases. Sensory, motor, cognitive, affective, and social behaviours may all be affected by gene manipulation, thus careful behavioural techniques, with attention to the mice themselves, the apparatus, and procedure, experimenter variables, and environmental effects are necessary in order to determine a reliable and valid mouse behavioural phenotype. As both the genome and the environment have significant effects on the behavioural phenotype, our future research will utilize an epigenetic approach to examine how environmental cues modulate gene expression in the behavioural phenotyping of transgenic mice. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

TGF-beta knockout and dominant-negative receptor transgenic mice

Use of homologous recombination and transgenic technologies have provided mouse models to study the physiological roles of the three mammalian TGF-beta isoforms, and their regulation in the context of the intact animal. Mice harboring null mutations for TGF-beta isoforms demonstrate that each exerts discrete nonoverlapping functions during development. TGF-beta1 null mice reveal a crucial role for this cytokine in modulation of the immune system, with evidence for altered development, activation and function of various immune cell populations. New approaches to tissue- and cell-restricted disruption of TGF-beta signaling pathways in transgenic mice carrying dominant-negative mutant TGF-beta receptors will be discussed.     

Age- and gender-related changes in the hepatic metabolism of 2-methylpropene and relationship to epoxide metabolizing enzymes

The effect of age and gender on the in vitro biotransformation of 2-methylpropene, an alkene metabolized to 2-methyl-1,2-epoxypropane, was studied. The epoxide concentration and the epoxide metabolizing enzymatic activities were investigated in male and female Brown Norway rats of different ages. Liver tissue of senescent rats was exposed to smaller 2-methyl-1,2-epoxypropane concentrations than that of young animals, although changes during ageing were rather modest. With advancing age a feminization of male glutathione S-transferase and cytosolic epoxide hydrolase activities was found, as well as a significant decline of the female microsomal epoxide hydrolase activity and an increase of the cytochrome P-450 content in the oldest female rats.     

Inducible gene expression in mammalian cells and transgenic mice

The discovery of the superantigens (SAgs) offered new insights on the interaction between microorganisms and the host immune system. Associated to Major Histocompatibility Complex (MHC) class II molecules, SAgs bind to the variable domain of the beta chain (V beta) of the TCR alpha beta engaged in the family specificity of lymphocytes. Therefore, these molecules are able to activate a high number of T lymphocytes as well as surface MHC class II bearing cells, leading to an overriding release of cytokines and inflammatory mediators, which have been related to their toxic effects. Endogenous SAgs are encoded by murine tumor proviruses (Mtv) which are integrated in the genome of mice. Bacteria and viruses produce exogenous SAgs and those related to food poisoning have been widely studied. The presence of parasite SAgs is still unclear and further studies are required to establish their existence and effects on the corresponding infections.