A New Translational Rat Model for Evaluating Anti-Aging Interventions

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We propose to develop as sustainable aging research infrastructure, a new and unique genetically heterogeneous laboratory rat model that can be used to evaluate putative life- and health-extending interventions. The rat has numerous advantages over the mouse for interventional aging research including more human-like physiology and pathophysiology, more cognitive sophistication, and greater genetic diversity compared with standard mouse strains. Inspired by the UM-HET3 mice used by the Interventions testing program, our rat model (OKC-HETb/w) will also be populations of genetically heterogeneous F2 descendants of 4 divergent, inbred strains. A significant difference from the UM-HET3 mice, our breeding scheme takes advantage of the rat’s substantial mitochondrial genomic diversity compared with the mouse to create a population half of which carries the BN strain mitochondria (OKC-HETb), the other half carries the WKY strain mitochondria (OKC- HETw). These mitochondrial genomes mimic great human mitochondrial diversity in that they differ at 95 nucleotides involving 11 of 13 mitochondrial protein-coding genes, 5 tRNA’s and both ribosomal subunits. Our preliminary data show that the OKC-HETb and OKC-HETw rats respond differently to exercise endurance, grip strength, and responsiveness to 17α-estradiol. As a proof of principle, we will evaluate in the OKC-HETb/w rat an anti-aging intervention (17α-estradiol) that was previously found to enhance the longevity of male mice only. An intriguing outcome of our project will be to verify whether or not, this sex-specificity is also seen in our rat model. In the R21 phase of this project we will produce the OKC-HETb/w rats and (1) characterize energetics-based health assays at whole animal and cellular levels under standard and stressed (HFD) conditions in both sexes in both mitochondrial genotypes, (2) determine the dose of 17α-estradiol that will yield blood levels comparable to those found at effective life-extending doses in the ITP study and the short-term effects of 17α-estradiol on metabolic parameters in diet-induced obese mice of both sexes, and (3) provide investigators with tissues as well as young and old OKC-HETb/w. In the R33 phase, we will use the information gained in the R21 phase to: (1) determine the effect of 17α-estradiol on the longevity and age-related pathology in both sexes and both mitochondrial genotypes and (2) determine the long-term effects of 17α-estradiol on age-related changes in metabolic and health parameters, again, in both sexes and both mitochondrial genotypes.