EFFECTS OF DIFFERENT DIETS IN A MOUSE MODEL OF NEURODEGENERATIVE DISEASE

Effects of different diets in a mouse model of neurodegeneration Abstract Tauopathies are neurodegenerative disorders characterized by the accumulation of abnormal Tau protein leading to cognitive and/or motor dysfunction; several studies suggest that dietary manipulations are increasingly viewed as possible approaches to treating neurodegenerative diseases. The mouse model chosen for this study was P301L; mice expressing P301L mutant Tau mimics features of human tauopathies and provides a model for investigating the neuropathogenesis of diseases. In this study we investigate at 7 and 15 months of age the effects of different diets (high fat-protein diet and low fat-protein diet) on P301L TG and CTR mice valuating metabolic, behavioral and cognitive activities; for the metabolic activities we analyzed survival rate, body weight gain and food and water consumption of animals. For behavioral activities we valuated mnemonic, locomotor and exploratory performances of animals; for cognitive activities we investigated the cognitive impairment (identifying agglomerates of hyperphosphorylated tau, neuronal loss, astrogliosis and oxidative damage) using immunohistochemical analysis and neuronal counts. We characterized P301L TG mouse model (trial 1-3) that replicated the impairments found in patients affected by tauophaty in a way age-gender-dependent showing in female TG mice a strong cognitive impairment strictly correlated with an increase in P-Tau, in both cerebral cortex and hippocampus, as well as astrogliosis and oxidative damage. We found an improvement of pathological conditions in TG mice administrating a low fat-protein diet in a way age-gender-dependent (trial 2-3), occurred with an increased lifespan, a reduction of food and water consumption, a reduction of aggregates of P-Tau, neuronal loss, astrogliosis and oxidative damage. We found an interaction between tauophaty and consumption of high fat-protein expressed on peripheral organs as hepatic insulin resistance and fatty accumulation in the liver, which induced nonalcoholic fatty liver disease in TG mice (trial 4). The correlation between P-Tau, insulin/IGF resistance and high fat-protein diet consumption was expressed by a condition of hepatomegaly characterized by the presence of lobular inflammatory infiltrate and deposits of collagen in liver and spleen, an increase of weight and size of liver and spleen, the highest increase of median levels of triglycerides, AST and ALT in P301L TG mice fed with high-fat protein diet in a way age-gender-dependent. In summary, we demonstrated the importance of interaction between nutrition and neurodegeneration and the role that different diets can have on the onset and development of tauophaty, obtaining an improvement of pathological conditions administrating a low fat-protein diet. Results obtained in this study suggest that P301L-Tau model could represent a valuable tool to study the role and the mechanisms through hyperphosphorylation and Tau aggregation leading to cognitive and memory impairment. Using the influence of nutrition for preventing or reducing the accumulation of hyperphosphorylated tau in this model could finally lead to the development of preventive potential treatments for tauopathies

Taurine administration recovers motor and learning deficits in an angelman syndrome mouse model

Angelman syndrome (AS, MIM 105830) is a rare neurodevelopmental disorder affecting 1:10\ue2\u80\u9320,000 children. Patients show moderate to severe intellectual disability, ataxia and absence of speech. Studies on both post-mortem AS human brains and mouse models revealed dysfunctions in the extra synaptic gamma-aminobutyric acid (GABA) receptors implicated in the pathogenesis. Taurine is a free intracellular sulfur-containing amino acid, abundant in brain, considered an inhibiting neurotransmitter with neuroprotective properties. As taurine acts as an agonist of GABA-A receptors, we aimed at investigating whether it might ameliorate AS symptoms. Since mice weaning, we orally administered 1 g/kg/day taurine in water to Ube3a-deficient mice. To test the improvement of motor and cognitive skills, Rotarod, Novel Object Recognition and Open Field tests were assayed at 7, 14, 21 and 30 weeks, while biochemical tests and amino acid dosages were carried out, respectively, by Western-blot and high-performance liquid chromatography (HPLC) on frozen whole brains. Treatment of Ube3am\ue2\u80\u93/p+mice with taurine significantly improved motor and learning skills and restored the levels of the post-synaptic PSD-95 and pERK1/2-ERK1/2 ratio to wild type values. No side effects of taurine were observed. Our study indicates taurine administration as a potential therapy to ameliorate motor deficits and learning difficulties in AS

The c-jun N-terminal kinase plays a key role in ocular degenerative changes in a mouse model of Alzheimer disease suggesting a correlation between ocular and brain pathologies

Recently a range of ocular manifestations such as retinal and lens amyloid-beta accumulation and retinal nerve fiber layer loss have been proposed as potential biomarkers in Alzheimer disease (AD). The TgCRND8 mouse model of AD exhibits age-dependent amyloid \u3b2 (A\u3b2) oligomers accumulation and cognitive defects, amyloid plaques and hyperphosphorylated Tau deposition and inflammation. We proved the correlation between ocular pathologies and AD, observing increased levels of p-APP and p-Tau, accumulation of A\u3b2 oligomers in the retina, eye, and optic nerve. The accumulation of amyloid markers was significantly stronger in the retinal ganglion cell (RGC) layer, suggesting that RGC might be more susceptible to degeneration. We detected a thinning of the RGC layer as well as RGC death in the retina of TgCRND8 mice, by using a combination of Optical Coherence Tomography (OCT), immunofluorescence, immunohistochemistry and Western blotting techniques. We proved for the first time the key role of C-Jun N-terminal Kinase (JNK) in the ocular degeneration. In support of this, the administration of the JNK inhibitor, D-JNKI1, was able to counteract the A\u3b2 and p-Tau accumulation in the retina of TgCRND8 mice, and consequently reduce RGCs loss. These results confirm that degenerative changes in the retina/eye of AD mouse model mirrors the events observed in the brain parenchyma. Ocular changes can be detected by non-invasive imaging techniques, such as OCT, to study and test different therapeutic strategies against degenerative events associated to AD

The effect of two different Individually Ventilated Cage systems on anxiety-related behaviour and welfare in two strains of laboratory mouse

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Infrared thermography (IRT): a new noninvasive tool for the evaluation of Lab Animal Welfare

It is widely recognized that the welfare of the animals submitted in biomedical experiments is crucial for the consistency of the results achieved. The \u201cwelfare\u201d of laboratory animals is related not only to the experimental paradigm but also to the housing conditions. Animals born and maintained in different cages may, in fact, behave in a slightly (but significant) different way, giving rise to experimental variability. The presence into the home cage of environmental enrichment can modify the behavioural and immune response of the animals to different stimuli. In these complex situations it is important to determine animal welfare through easy and non-invasive methods that can be applied to wide range of different situations (i.e. different cage types). Infrared thermography (IRT) is an innovative method to measure the skin temperature in order to identify stressful situations which could lead to a decrease in this parameter due to peripheral vasoconstriction in mammals. A recent study used IRT, to assess the effects of management systems and farming on the physiology and behavior of rabbits and another study, in nude mice, used IRT to detect the effects of anesthesia by assessing whether the skin temperature of the animals undergoing anesthesia quickly returned to a baseline level or could cause some type of stress to the animals. Since variations in surface temperature and alteration in blood flow are some of the most interesting indicators to evaluate a response to the presence of stress (peripheral vasoconstriction), this technique is a potential, non-invasive and objective method for the evaluation of welfare in laboratory animals. During the presentation will be shown data to support the argumentations

Gender-genotype interaction lead to an increase of cognitive impairment, locomotor dysfunctions and neurola damage in young and aged female TAU P301L mice model of tauopathy

P301L transgenic (TG) mice well mimic features of human tauopathies and provide a good model for investigating Tau role in neurodegenerative events. We analysed the possible interaction among P-Tau, spine injury, neuronal death and sex differences in P301L transgenic mice at 15 months of age. Comparing CTR versus P301L transgenic mice, TG mice present a lower body weight, a less survival rate, hyperphosphorylated Tau, spine injury and neuronal loss in both cerebral cortex and hippocampus at the time point analysed. Importantly, pathological features described are more pronounced in female than male TG mice. Recent reports underlined that Tau may be localized within both pre- and post-synaptic compartments, suggesting that it may possibly induce or contribute to synaptic dysfunction. Therefore, we focus our attention on Tau localization at the dendritic spine level. We detected a huge level of both Tau and P-Tau in dendritic spine of P301L transgenic mice. In addition, P-Tau correlated with a significant reduction of post-synaptic markers: NR2a, NR2b, Glur1, Glur2, Debrin and PSD-95 levels in P301L Tg. The P-Tau levels are higher in female than in male mice, and the increased P-Tau was consistent with a proportional decrease in the post-synaptic marker levels analysed. The P301L tg females presented a more severe synaptopathy compared to males. Future investigations on P-Tau postsynaptic role will be necessary for understanding its toxic effects and providing insights into new therapeutic targets for maintaining spine integrity, highlighting the importance of Tau toxicity as well as the impact of sex on tau-pathology

The Stress c-Jun N-terminal Kinase Signaling Pathway Activation Correlates with Synaptic Pathology and Presents A Sex Bias in P301L Mouse Model of Tauopathy

Pathological Tau (P-Tau) leads to dementia and neurodegeneration in tauopathies, including Alzheimer's disease. The P301L transgenic mice well mimic human tauopathy features; P-Tau localizes also at the dendritic spine level and this correlates with synaptic markers down-regulation. Importantly, tg female present a more severe pathology compared to male mice. We describe JNK activation in P301L-tg mice, characterizing by P-JNK and P-c-Jun, cleaved-Caspase-3, P-PSD95 and P-Tau (direct JNK-targets) increased levels in tg vs control mice. These data indicate that JNK stress pathway is involved in neuronal degenerative mechanisms of this mouse model. In addition, P-JNK level is higher in female compared to male tg mice, underlying a sexual dimorphism in the JNK pathway activation. The behavioral studies highlight that tg female present major cognitive and locomotor defects, strongly correlated with a more severe synaptic injury, in comparison to tg male. Notably, at the dendritic spine level, JNK is powerfully activated and its level reveals a sexual dimorphism that is coherent with behavioral defects and spine pathology. The P301L's synaptic pathology is characterized by a strong increase of P-PSD95/PSD95 and P-JNK/JNK ratios and by an augmented level of cleaved-Caspase-3 and a decrease of Drebrin level in the post-synaptic elements. These results suggest that JNK plays a key role in synaptopathy of P301L mice. Importantly, until now, there are any efficient treatments against synaptic pathology and JNK could represent an interesting target to tackle P-Tau-induced synaptic pathology. It will be important to test specific JNK inhibitors to verify their potential neuroprotective effect

JNK signaling activation in the Ube3a maternal deficient mouse model: Its specific inhibition prevents post-synaptic protein-enriched fraction alterations and cognitive deficits in Angelman Syndrome model

Deficiency of the E3 ubiquitin ligase UBE3A leads to the neurodevelopmental disorder Angelman syndrome (AS), while higher levels are linked to autism spectrum disorder. The mechanisms underlying the downstream effects of UBE3A loss or gain of function in these disorders are still not well understood, and treatments are still lacking. Here, using the Ube3a maternal loss (Ube3am-/p+) mouse model, we report an important JNK signaling activation in the hippocampus, cortex and cerebellum correlating with the onset of behavioral defects and biochemical marker alterations in the post-synaptic element, suggesting important spine pathology. JNK activation occurs at 7 and persists up till 23\u202fweeks in Ube3am-/p+ mice in two different cellular compartments: the nucleus and the post-synaptic protein-enriched fraction. To study JNK's role in Ube3am-/p+ pathology we treated mice with the specific JNK inhibitor peptide, D-JNKI1, from 7 to 23\u202fweeks of age. Preventing JNK action in vivo restores the post-synaptic protein-enriched fraction defects and the cognitive impairment in these mice. Our results imply a critical role of UBE3A-JNK signaling in the pathogenesis of UBE3A-related disorders. In particular, it was clear that JNK is a key player in regulating AS synaptic alterations and the correlated cognitive impairments, in fact, its specific inhibition tackles Ube3am-/p+ pathology. This study sheds new light on the neuronal functions of UBE3A and offers new prospects for understanding the pathogenesis of UBE3A-related disorders

Neuroprotective effects of low fat-protein diet in the P301L mouse model of tauopathy

Tauopathies are a class of neurodegenerative diseases associated with the pathological aggregation of tau protein in the human brain. Although numerous studies in mouse models of Alzheimer disease (AD) have shown a correlation among diet, beta-amyloid and AD onset, little is known about the impact of diet on Tau. We investigated whether a low fat-protein diet (LFPD) may improve lifespan, cognitive and locomotor activity in P301L-tg mouse model of tauopathy. Our data indicate that LFPD has a beneficial effect on these parameters. Tg mice fed with standard diet shown a decrease in body weight, food intake and survival rate if compared to wild type animals. In contrast, LFPD counteracted weight loss, increased mortality and ameliorated cognitive and locomotor performances in tg mice. LFPD also reduced the abnormal accumulation of agglomerates of P-Tau (pathological features of tauopathies) and the expression of apoptotic markers (i.e., TUNEL immunopositive neurons) in the prefrontal cerebral cortex and hippocampus of P301L-tg mice. Interestingly, some of these effects are sex-dependent. For instance, tg females, but not males, fed with LFPD had a significant increase of body weight and a reduction of P-Tau agglomerates compared to tg fed with standard diet. These changes correlated with a more pronounced improvement of cognition and locomotor activity in females than in male tg fed with LFPD. Altogether, these results suggest a sex dependent neuroprotective effect of LFPD in P301L-tg mice, suggesting that lifestyle intervention strategies may be clinically relevant for delaying the onset of cognitive impairment and dementia, especially in females