Project description:Background: Thiazolidinediones (TZDs) activate peroxisome proliferator-activated receptor gamma (PPARgamma) and are used clinically to help restore peripheral insulin sensitivity in Type 2 diabetes (T2DM). Interestingly, long-term treatment of mouse models of Alzheimer’s disease (AD) with TZDs also has been shown to reduce several well-established brain biomarkers of AD including inflammation, oxidative stress and Abeta accumulation. While some of the TZD actions are becoming clear in AD models and may mediate their reported beneficial impact in AD patients, little is known about the functional consequences of TZDs in animal models of normal aging. Because aging is a common risk factor for both AD and T2DM, we investigated whether the TZD, pioglitazone could alter brain aging under non-pathological conditions. Findings: The TZD pioglitazone (PIO) was incorporated into the diet to yield a final dose of approximately 2.3 mg/kg body weight/day. PIO reduced insulin levels irrespective of age. Interestingly, a significant reduction in the Ca2+-dependent afterhyperpolarization was seen in the aged animals with no significant change in LTP maintenance or learning and memory performance. Finally, a combination of microarray analyses on hippocampal tissue and serum-based multiplex cytokine assays revealed that age-dependent inflammatory changes in brain and periphery were not reversed by PIO. Conclusions: While current research efforts continue to address the underlying processes responsible for the progressive decline in cognitive function seen during aging, available medical treatments are still very limited. Our study, therefore, was aimed at elucidating potentially novel actions of TZDs in the aging brain. Using a clinically-relevant dose and delivery method, PIO had no detectable impact on several indices of brain aging and failed to alter both peripheral and central age-related increases in inflammatory signaling. Keywords: hippocampus, rat, young or aged, control or pioglitazone-treated
Project description:Aging causes a functional decline in tissues throughout the body that may be delayed by caloric restriction (CR). However, the cellular profiles and signatures of aging, as well as those ameliorated by CR, remain unclear. Here, we built comprehensive single-cell and single-nucleus transcriptomic atlases across various rat tissues undergoing aging and CR. CR attenuated aging-related changes in cell type composition, gene expression, and core transcriptional regulatory networks. Immune cells were increased during aging, and CR favorably reversed the aging-disturbed immune ecosystem. Computational prediction revealed that the abnormal cell-cell communication patterns observed during aging, including the excessive proinflammatory ligand-receptor interplay, were reversed by CR. Our work provides multi-tissue single-cell transcriptional landscapes associated with aging and CR in a mammal, enhances our understanding of the robustness of CR as a geroprotective intervention, and uncovers how metabolic intervention can act upon the immune system to modify the process of aging.
Project description:Comparison of the long-term effects of calorie restriction without malnutrition on global gene expression profiles of rat and human skeletal muscle [Rat]
