Key result
Isoproterenol worsens cardiac function and mortality in pressure-overloaded ovariectomized rats via impaired Akt-eNOS signaling.
The OVX-PO rat model mimics postmenopausal cardiac hypertrophy and demonstrates that impaired Akt-eNOS signaling contributes to cardiac decompensation and increased mortality.
Supports estrogen deficiency worsening cardiac stress response; hypothesis-generating for postmenopausal HF therapies.
OBJECTIVE: The development of animal models of cardiovascular disease are critical to define pathophysiological mechanisms and to advance diagnosis and therapy. The lack of a suitable animal model represents a failure to define the mechanisms responsible for postmenopausal myocardial hypertrophy in hypertension and adverse cardiac remodeling. METHODS: In this review, we presented a rat model of postmenopausal myocardial hypertrophy, with particular focus on the similarities between the animal model and postmenopausal women regarding myocardial function as well as molecular and subcellular mechanisms. To elucidate the molecular mechanism of left ventricular (LV) hypertrophy and remodeling in postmenopausal women, we analyzed myocardial hypertrophy as well as cardiac function and hypertrophy-related protein expression in ovariectomized (OVX) and pressure overloaded (PO) rats. RESULTS: The model is characterized by depletion of serum estrogen and increased heart-to-body weight and lung-to-body weight ratios. Moreover, the OVX-PO rats also show increased mean arterial blood pressure, LV end-diastolic pressure, LV developed pressure, and maximal rates of LV contraction and relaxation compared with the OVX group. Importantly, Akt activity was largely attenuated, and both endothelial nitric oxide synthase expression and activity were markedly reduced in the OVX-PO group. Finally, significant increased mortality was observed in the OVX-PO group after chronic isoproterenol administration. CONCLUSIONS: Our results demonstrate that rats subject to OVX are unable to compensate for hypertrophy partly due to impaired Akt-endothelial nitric oxide synthase signaling along with deteriorated heart function and demonstrated increased mortality. In this review, we discussed the mechanisms of cardiac injury, which could play a critical role in postmenopausal hypertrophy, as well as the characteristics of the OVX-PO female rats as a model to test cardioprotective drugs in postmenopausal women.
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Bhuiyan et al. (2010) conducted a review in Postmenopausal cardiac hypertrophy. Ovariectomy and pressure overload (OVX-PO) vs. Ovariectomized (OVX) group was evaluated on Myocardial hypertrophy, cardiac function, and hypertrophy-related protein expression. Ovariectomized pressure-overloaded rats exhibit increased heart-to-body weight ratios, deteriorated heart function, impaired Akt-eNOS signaling, and increased mortality after chronic isoproterenol.
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