Central Interaction of 2-Methoxyestradiol and Lipoxygenase in AngII-Hypertension

Our previous findings that arachidonic acid-12/15-lipoxygenase (LOX)-generated metabolite 12(S)-HETE contributes to angiotensin II (AngII)-induced hypertension and 17β-estradiol protects from AngII-induced hypertension via its cytochrome P450 (CYP)1B1-generated metabolite 2-methoxyestradiol in the paraventricular nucleus (PVN) in female mice led us to test the hypothesis that 2-methoxyestradiol acts by inhibiting the LOX/12(S)-HETE in the PVN.

AngII was infused subcutaneously by osmotic pumps for 2 weeks in wild-type, LOX-knockout (LOXKO), and CYP1B1KO female mice. The blood pressure was measured by tail-cuff/radiotelemetry. Adenovirus (Ad)-GFP (green fluorescence protein)-LOX-short hairpin RNA, Ad-GFP-LOX-DNA, 12(S)-HETE, and 2-methoxyestradiol were injected selectively in PVN or intracerebroventricularly. Histological, immunohistochemical, and biochemical techniques were used to determine pathophysiological changes caused by various interventions.

AngII-induced hypertension that was exaggerated in CYP1B1KO compared with wild-type mice was minimized by PVN-LOX knockdown with Ad-LOX-short hairpin RNA and restored by PVN-LOX reconstitution with Ad-LOX-DNA in intact-LOXKO mice and exacerbated in ovariectomized-LOXKO mice. Furthermore, intracerebroventricular-12(S)-HETE restored AngII-induced increases in blood pressure, autonomic impairment, neuroinflammation, and renal pathogenesis in intact-LOXKO mice, which were exacerbated in ovariectomized-LOXKO mice. Intracerebroventricular-2-methoxyestradiol that reduced the LOX expression and 12(S)-HETE content in PVN minimized AngII effects mentioned above in ovariectomized-LOXKO mice transduced with intracerebroventricular-Ad-LOX-DNA.

These data suggest that 2-methoxyestradiol protects against AngII-induced hypertension and associated pathogenesis, most likely by inhibiting LOX/12(S)-HETE actions in the PVN of female mice. Therefore, the selective LOX inhibitors or 12(S)-HETE receptor antagonists could be useful in treating hypertension and its pathogenesis in postmenopausal, hypoestrogenic women or females with ovarian failure.