Abstract 267: Activation of Non-canonical Estrogen-dependent Pathways to Mitigate Pathological Cardiac Remodeling

Prior to menopause, women are protected against cardiovascular disease (CVD) compared to age-matched men; this protection is gradually lost after menopause. Mechanisms responsible for loss of CVD protection are unknown. We previously demonstrated that menopause and CVD suppress the AMP-activated protein kinase (AMPK) signaling pathway in mice. We also validated the cellular mechanism by which estrogen (E2) potentiates AMPK activity through a direct interaction of estrogen receptors (ER) with members of the AMPK kinase complex. Because AMPK signaling is down in CVD and menopause, we hypothesized that activation of AMPK will prevent pathological cardiac remodeling in menopausal female mice. First, we demonstrated that E2 potentiates AMPK activity in neonatal rat cardiomyocytes (NRCMs) subjected to energy stress. NRCMs, cultured in estrogen-free media, were treated (10-30 minutes at 100nm) with the electron transport chain uncoupler carbonyl cyanide 4-(trifluoromethoxy)phenyphydrazone (FCCP). As expected, AMPK activity determined by phosphorylation of threonine 172 (p-AMPK172) was increased over controls. Adding 1-100nm of E2 potentiated p-AMPK172 over control-treated NRCMs by 5-fold. Next, we used our novel model of menopause with 4-vinylcyclohexene diepoxide (VCD), which induces gradual ovarian failure, preserving the perimenopause transitional period and androgen secreting capacity of residual ovarian tissue. Starting at 2 months, females received daily (i.p.) injections of VCD (160mg/kg, 20 consecutive days) or sesame oil as vehicle. Peri/menopause were confirmed by vaginal cytology. Menopausal females receiving angiotensin II (Ang II, 800 ng/kg/min via alzet s.c. mini-pump, 14 days) demonstrated exacerbation of hypertension and pathological cardiac remodeling compared to pre- and peri-menopausal mice. Female mice treated with Ang II following surgical removal of ovaries (OVX) experienced a similar exacerbation of cardiac remodeling. Daily adminstration of the AMPK activator (A-769662, s.c. 30mg/kg) prevented pathological remodeling in menopausal and OVX female mice subjected to Ang II. We conclude that AMPK represents a non-canonical target for the mitigation of menopausal susceptibly to CVD.