Abstract P384: Cytochrome P450 1B1-Testosterone Metabolite 6β-Hydroxytestosterone Promotes Ang II-induced Hypertension And Neuroinflammation Via Group IV Cytosolic Phospholipase A 2 α In Paraventricular Nucleus Of Male Mice

Abstract

We reported previously that Ang (angiotensin) II-induced hypertension depends on the activation of group IV cPLA 2 α (cytosolic phospholipase A 2 α). Moreover, we showed that testosterone (T) metabolite 6β-hydroxytestosterone (6β-OHT) generated by CYP1B1 (cytochrome P450 1B1) in the paraventricular nucleus (PVN) promotes Ang II-induced hypertension and neuroinflammation in male mice. This study determined the relationship of cPLA 2 α and CYP1B1-T derived 6β-OHT in the PVN to Ang II-induced hypertension and neuroinflammation in male mice. cPLA 2 α knockdown in the PVN by transduction with adenovirus (Ad)-cPLA 2 α-short hairpin (sh)RNA (200 nL, bilaterally, 5.4X10 11 pfu/mL) but not its control Ad-scrambled (Scr)-shRNA (2.5X10 11 pfu/mL) in wild-type (WT) male mice, inhibited Ang II (700 ng/kg/min, s.c., two weeks)-induced increase in systolic blood pressure (Day 12- SBP mmHg, tail-cuff) (126±4 vs 167±4, respectively, P<0.05, n=4/group). Moreover, reconstitution of cPLA 2 α in the PVN by Ad-cPLA 2 α-DNA (5.5X10 9 pfu/mL), but not its control Ad-GFP-DNA (1.0X10 11 pfu/mL) in cPLA 2 α -/- mice restored the increase in SBP (153±6 vs 117±4, respectively, P<0.05, n=4/group). Ang II-induced increase in mean arterial blood pressure (MAP mmHg, radiotelemetry) that was minimized in WT-orchidectomized (ORX) or intact Cyp1b1 -/- mice were restored by ICV injections of 6β-OHT (1.5 μg/2 μL/alternate day), but it was attenuated by ICV (2 μL, single injection) Ad-cPLA 2 α-shRNA, but not its control Ad-Scr-shRNA (114±4 vs 150±7, and 121±2 vs 154±9, respectively, P<0.05, n=4-6/group). Ang II-induced increase in MAP was restored by 6β-OHT, but not its vehicle (2-hydroxypropyl-β-cyclodextrin in CSF, 2 μL/alternate day) in Ad-cPLA 2 α-DNA transduced ORX- cPLA 2 α -/- mice (165±6 vs 121±2, respectively, P<0.05, n=4/group). The number of TMEM119 + microglia and GFAP + astrocytes in PVN, markers of neuroinflammation, followed the changes in BP in the above groups produced by Ang II. In conclusion, T-CYP1B1 metabolite 6β-OHT promotes Ang II-induced hypertension and neuroinflammation by a mechanism dependent on cPLA 2 α in the PVN. Therefore, agents that reduce CYP1B1 or cPLA 2 α activity could be useful for treating Ang II/T-dependent hypertension and neuroinflammation in males.