Abstract Body: We have shown that 17β-estradiol (E2)-cytochrome P450 (CYP) 1B1 and catechol-ο-methyltrasnferase-generated metabolite 2-methoxyestradiol (2-ME) in the paraventricular nucleus (PVN) protects against angiotensin (Ang) II-induced hypertension and neuroinflammation. This study was conducted to determine the relationship between CYP4A10 that is expressed in the PVN and metabolizes arachidonic acid (AA) into prohypertensive eicosanoid, 20-hydroxyeicosatetraenoic acid (20-HETE), and CYP1B1 in Ang II-induced hypertension, neuroinflammation, and reactive oxygen species (ROS) production in female mice. Systemic Ang II infusion (700 ng/kg/min, s.c., two weeks) and transduction in the PVN with adenovirus (Ad)-GFP scrambled (Scr)-short hairpin (sh) RNA (200 nL bilaterally, 6.4×10¹¹ pfu/mL, single injection) produced a significant increase in systolic blood pressure (SBP, tail-cuff) at Day 12 compared to Day 0 (mmHg, 114±3 vs 151±3 respectively, P<0.05, n=6/group) in wild-type (WT) and a much larger increase in CYP1B1 knockout (KO) female mice having E2 but not 2-ME (119±4 vs 173±6 respectively, P<0.05, n=5/group). Ad-GFP-CYP4A10 shRNA (200 nL bilaterally, 1.0×10¹² pfu/mL, single injection) but not Ad-GFP Scr-shRNA transduced in the PVN diminished Ang II-induced increase in SBP at Day 12 in WT mice (mmHg, 119±2 vs 122±3 respectively, P<0.05, n=5/group), and CYP1B1KO mice (mmHg, 115±1 vs 133±2 respectively, P<0.05, n=5/group). Similar results were obtained with Ad-GFP-CYP4A10 shRNA compared to Ad-GFP Scr-shRNA transduced in the PVN on mean arterial pressure (MAP) measured by radiotelemetry (Day 12: mmHg, 121±4 vs 152±4 respectively, P<0.05, n=4/group) in CYP1B1 KO mice. The number of TMEM119⁺ microglia and GFAP⁺ astrocytes, markers of neuroinflammation determined by immunofluorescence, and ROS production by dihydroethidium staining followed the changes in blood pressure produced by Ang II in the above groups. To determine the contribution of central AA-CYP4A10-generated 20-HETE to Ang II-induced hypertension, the effect of 20-HETE receptor GPR75 siRNA administered intracerebroventricularly (Dharmacon, SMARTpool: 0.4 nmol 2 μl, single injection) was examined in CYP1B1KO mice. GPR75 siRNA but not its non-target siRNA minimized Ang II-induced increase in SBP (Day 12: mmHg, 132±4 vs 171±3, P<0.05, n=6/group). These data suggest that the 20-HETE receptor antagonist could be useful in treating hypertension and associated neuroinflammation in females with ovarian dysfunction.