Abstract 15835: Inhibition of Soluble Epoxide Hydrolase Reduces Cognitive Impairment and Improves Cerebral Hemodynamics in AD/ADRD

Abstract

Alzheimer's Disease and Alzheimer's Disease-Related Dementias (AD/ADRD) is an emerging global healthcare crisis. However, underlying mechanisms have not been understood well enough to translate into precision medicine. Recent human genetic evidence indicated that soluble hydrolase (sEH) is linked to AD/ADRD. Inhibition of sEH has been reported to improve cognition in AD mice due to its anti-inflammatory and neuronal protective effects. Here, we examined whether inhibition of sEH with TPPU could reduce cognitive impairments by improving cerebral hemodynamics in 18-month-old diabetes (DM)-related ADRD rats and 6 months of TgF344-AD rats. The myogenic responses of the middle cerebral artery (MCA) were impaired in both AD and ADRD rats and were normalized with TPPU. The inner diameters of MCA increased by 49.16 ± 17.02 % in DM rats but decreased by 16.06 ± 2.46% and 11.24 ± 0.05% in age-matched control and TPPU-treated DM rats when pressure was elevated from 40 to 180 mmHg. Similarly, TPPU-treated AD rats significantly enhanced the MCA constriction by 25%. Forced dilatation occurred at pressures > 140 mmHg in MCAs in both rats and was rescued with TPPU treatment. Endothelial denuded MCAs from TPPU-treated DM rats constricted to 75.15 ± 4.25 % at a perfusion pressure of 140 mmHg and further constricted to 74.66 ± 4.01 % at 180 mmHg, compared to dilation of 155.48 ± 17.35 % and 172.78 ± 13.36 % in DM rats at the same pressures. The percentage of time spent with the novel object was 43.32 ± 8.04% and 83.23 ± 8.70% in DM and TPPU-treated DM rats, versus 75.68 ± 3.33% in non-DM rats. Impaired learning and short and long-term memory function examined with an 8-arm water maze in both DM and AD rats were rescued with TPPU treatment. These results provide the first evidence demonstrating that inhibition of sEH reverses cerebrovascular dysfunction and cognitive impairments in AD/ADRD.