Abstract P60: Xanthine Oxidase Mediates Cerebrovascular Dysfunction in Chronically Stressed Female Mice

Abstract

Chronic stress is a risk factor for many cerebrovascular diseases including stroke and vascular dementia. Our lab has preciously shown that chronic stress in male mice and rats reduces cerebrovascular function, mediated by an increase in oxidative stress, potentially via the xanthine oxidase pathway. However, the role of xanthine oxidase on cerebrovascular function in female mice has yet to be explored. Here, we examined the effect of chronic stress on middle cerebral artery function and xanthine oxidase expression in female mice. At 18 weeks of age, mice underwent the unpredictable chronic mild stress (UCMS; 5days/week for 7hrs/day) paradigm to elicit a chronic stress phenotype. On week 26, mice were euthanized and the middle cerebral arteries (MCA) were removed and positioned in a pressurized myobath. To test for vessel health, the MCA was exposed to increasing concentrations of acetylcholine (Ach; 10-9M to 10-4M) in the presence or absence of febuxostat (10uM), a xanthine oxidase inhibitor as well as increasing doses of phenylephrine (PE; 10-9M to 10-4M) and sodium nitroprusside (SNP; 10-9M to 10-4M). Coronal sections of brain tissue were then stained for the xanthine oxidase enzyme, imaged using a Nikon Eclipse 800 and fluorescence intensity was analyzed via ImageJ. MCA dilation to Ach was impaired in female mice that underwent UCMS compared to control mice (9.5±1um vs 20±1um; p<0.05). Incubating the MCA with febuxostat had no effect on control mice but improved MCA dilation in the UCMS mice (9.5±1um to 17±0.5um; p<0.05). No differences were found between control vs UCMS groups in response to PE or SNP. To support this, preliminary data (n=3-4/group) shows a trend of increased fluorescence intensity of xanthine oxidase expression within the somatosensory cortex of the mice exposed to UCMS compared to controls (41,666±2,923AU vs 31,091±3,759AU, respectively; p=0.059). Together, these data suggest increased xanthine oxidase activity plays a role in cerebrovascular dysfunction in female mice.