The main focus of this proposal is to discover the physiological mechanisms that underlie the remarkably long reproductive lifespan of female naked mole-rats, which are exceptional for their lack of ageassociated declines in fertility and fecundity into their third decade of life. Naked mole-rats are renowned for being the longest-lived rodent species (>30 years) and for their extraordinary cancer resistance. These characteristics have been attributed to two inter-related pathways: an enhanced cytoprotective signaling pathway (nuclear factor erythroid 2-related factor, NRF2) and an exceptionally high molecular weight (HMW) form of hyaluronan (hyaluronic acid, HA), which is a key component of the extracellular matrix (ECM). Two complementary model systems, naked mole-rats themselves and a transgenic mouse line that expresses the synthase for naked mole-rat HMW-HA (nmrHas2), will be used to determine if nmrHMWHA attenuates the adverse effects of aging on ovarian structure and function via direct means and/or through enhanced signaling of the NRF2 cytoprotective pathway. Aim 1 will interrogate ovaries from nmrHas2 mice to determine if aging-associated inflammation, fibrosis, tissue stiffness, and reduced fertility are attenuated by nmrHMW-HA. Aim 2 will interrogate naked mole-rat ovaries for HA content and localization to specific cell types, and to determine the degree of similarity between them and nmrHas2 mouse ovaries. Aim 3 will interrogate ovaries from nmrHas2 mice and naked mole-rats for NRF2 signaling to test the hypothesis that nmrHMW-HA expression enhances this cytoprotective pathway. And because Nrf2-null mice demonstrated increased sensitivity to the ovarian toxicant 4- vinylcyclohexane diepoxide (VCD), nmrHas2 mice will be evaluated for reduced sensitivity to VCD, which would manifest as a larger ovarian reserve of follicles and better fertility.