ABSTRACT The adult prevalence of Electronic cigarettes (Ecigs) is ~5%, with young adults having the highest prevalence, and 56% of the young adults were never smokers, which includes women of reproductive age. The novelty and customizability of Ecigs, combined with messaging the Ecigs are ‘safer’ than cigarettes, drives much of the appeal and interest for youth in using Ecigs. Yet, a growing number of studies are showing that Ecig usage has negative vascular actions and that these outcomes are not different than smoking traditional cigarettes. Another area of significant concern relates to maternal vaping during pregnancy. Female smokers are more inclined to experiment with Ecigs compared to males with 5-16% of women using Ecigs during pregnancy. However, emerging pre-clinical data shows that perinatal exposure from vaping dams results in adverse health outcomes in progeny. We have shown that Ecig exposure during this “sensitive” developmental window induces a lasting impact (into adult life) on the vascular health of offspring. Previous studies have shown that environmental exposures in animal models and humans adversely affect cognitive function. This has led the NIH to prioritize studies that examine the basic mechanisms of Ecigs on health outcomes. This proposal leverages our prior work, which establishes a robust and reliable pre-clinical phenotype, to better understand the dose and potential molecular mechanisms underpinning vascular dysfunction with direct and in utero Ecig exposures. Xanthine oxidoreductase (XOR) is a significant source of oxidants (hydrogen peroxide, superoxide) that are implicated in the pathogenesis of vascular diseases. We have evidence to support that XOR is a key mediator of this vascular dysfunction with both direct Ecig exposure (F0) and in utero Ecig exposure (the F1 offspring). Our central hypothesis is that (direct and/or and in-utero) Ecig exposure elevates hepatic XOR, which is released into the circulation causing cerebrovascular and aortic dysfunction via the direct actions of XOR-oxidants on the endothelium. As such, Ecig exposure accelerates vascular-associated diseases and cognitive decline (i.e., VCID). We have a unique exposure system that measures real-time (puff-by-puff) Ecig dose exposure in a controlled environment, allowing us to examine high-fidelity dose-related exposure-induced effects on our animal models. Aim 1a will establish a dose-related Ecig exposure in the development of Ecig-mediated vascular dysfunction and XOR activity. In Aim 1b, we use our liver (hepatocyte)-and endothelial-specific XOR conditional KO mouse to manipulate the XOR pathway during direct Ecig exposure (F0 generation) and to examine vascular and cognitive function. In Aim 2, we will determine the long-term vascular, neurobiological, and behavioral consequences and role of XOR with in-utero (F1 generation) Ecig exposures. Complementary experiments will also examine the interaction of VCID, by manipulating the XOR pathway...