Project description:Astrocytes are key cells in brain aging, helping neurons to undertake healthy aging or otherwise letting them enter into a spiral of neurodegeneration. We aimed to characterize astrocytes cultured from senescence-accelerated prone 8 (SAMP8) mice, a mouse model of brain pathological aging, along with the effects of caloric restriction, the most effective rejuvenating treatment known so far. Analysis of the transcriptomic profiles of SAMP8 astrocytes cultured in control conditions and treated with caloric restriction serum was performed using mRNA microarrays. A decrease in mitochondrial and ribosome mRNA, which was restored by caloric restriction, confirmed the age-related profile of SAMP8 astrocytes and the benefits of caloric restriction. An amelioration of antioxidant and neurodegeneration-related path- ways confirmed the brain benefits of caloric restriction. Studies of oxidative stress and mitochondrial function demonstrated a reduction of oxidative damage and partial improvement of mito- chondria after caloric restriction. In summary, caloric restriction showed a significant tendency to normalize pathologically aged astrocytes through the activation of pathways that are protective against the age-related deterioration of brain physiology. Key words: astrocytes; caloric restriction; mitochondria; oxidative stress; RNA microarrays; SAMP8. Primary cultures enriched in astrocytes were obtained from cerebral cortical tissue from 2-day-old SAMP8 and SAMR1 mice. Astrocyte cultures were established and experiments were routinely carried out after 21 days in culture. Established astrocyte cultures of both SAMR1 and SAMP8 consisted of 85-90% astrocytes, 10-15% microglia and 0.1-1% oligodendroglia. Sera from rats subjected to ad libitum (AL) diet and to CR were obtained as described for the establishment of the CR in vitro model (de Cabo et al., 2003). Serum was heat inactivated at 56°C prior to use in astrocyte culture experiments. Treatment in vitro was performed by adding 10% volume CR or AL serum onto the astrocyte culture medium for 48 h, the cells were harvested and RNA was extracted for the microarray studies. Three biological replicates for each condition were done and RNA was extracted for the microarray studies. Please note that SAM models were developed from AKR/J by Kyoto University. Five litters with severe senescence were selected to further propagate and examine these characteristics. Litters that showed normal aging were selected as a senescence-resistant series (R-series). The genetic background of the SAM mice became suspect after the pathological findings were different from the AKR/J mouse. Each SAM model is genetically different. Each SAM colony was acquired by Harlan by Takeda Chemical Ltd. in 2002. And here is the link to the company site. http://www.harlan.com/products_and_services/research_models_and_services/research_models/sam_inbred_mice/samp8tahsd.hl

Project description:Abstract Background: The prevalence of sarcopenia is increasing and effective interventions are required to prevent or reverse age-related muscle loss. However it is often challenging expensive and time-consuming to develop and test the effectiveness of such interventions. Furthermore translational animal models that adequately mimic underlying physiological pathways are scarce. Strong predictors for the incidence of sarcopenia include a sedentary life-style and malnutrition. Therefore our objective was to investigate the translational value of three potential mouse models for sarcopenia namely partial immobilized caloric restricted (CR) and a combination (immobilized & CR) model. Methods: C57BL/6J mice were calorically restricted (-40%) and/or one hindleg was immobilized for two weeks to induce loss of muscle mass and function. Muscle mass function and diameter and distribution of slow (type 1) and fast ( type 2) myofibers were compared to those of young control (4 months) and old reference mice (21 months). Transcriptome analysis of quadriceps muscle was performed to identify underlying pathways and were compared with those being expressed in aged human vastus lateralis muscle-biopsies using a meta-analysis of five different human studies. Results: Caloric restriction induced overall loss of lean body mass (-15% p<0.001) whereas immobilization decreased muscle strength (-28% p<0.001) and muscle mass of hindleg muscles specifically (on average -25% p<0.001). The proportion of slow myofibers increased with aging in mice (+5% p<0.05) and this was not recapitulated by the CR and/or immobilization models. The diameter of fast myofibers decreased with aging (-7% p<0.05) and this was mimicked by all models. Transcriptome analysis revealed that the combination of CR and immobilization recapitulated more pathways characteristic for human muscle-aging (73%) than naturally aged (21 months old) mice (45%). These pathways included critical pathways relevant for protein synthesis/ breakdown (mitochondrial) metabolism neurology and the vascular system. Conclusions: The combination model exhibits loss of both muscle mass (due to CR) and function (due to immobilization) and has a remarkable similarity with pathways underlying human sarcopenia. Our results demonstrate that naturally aging up to 21 months in mice only partially recapitulates the human pathology with fewer overlapping pathways than the combination model. These findings underline that external factors such as sedentary behavior and malnutrition are key elements of a translational mouse model and favor the combination model as a rapid model for testing the treatments against sarcopenia.

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Saccharomyces cerevisiae

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