Simvastatin prevents large blood pressure variability induced aggravation of cardiac hypertrophy in hypertensive rats by inhibiting RhoA/Ras-ERK pathways

Pronounced variability in blood pressure (BP) is an aggravating factor of hypertensive end-organ damage. However, its pathogenesis remains unknown. Statins have various protective effects on the cardiovascular system. Thus, we determined whether simvastatin would attenuate the aggravation of hypertensive cardiac remodeling in a rat model of hypertension with large BP variability, and also investigated the signaling mechanism involved in its effect. A model of hypertension with large BP variability was created by performing bilateral sinoaortic denervation (SAD) in spontaneously hypertensive rats (SHRs). A SAD or sham operation was performed in 12-week-old rats. Thereafter, simvastatin (0.2 mg kg^-1 per day) or vehicle was intraperitoneally administered every day. After 6 weeks, telemetric recordings revealed that SAD enhanced BP variability without changing the mean BP. SAD increased myocyte hypertrophy, myocardial fibrosis and macrophage infiltration associated with the upregulation of brain natriuretic peptide (BNP), type I procollagen, transforming growth factor (TGF)-Β and monocyte chemoattractant protein (MCP)-1, and activation of RhoA, Ras and ERK1/2. Simvastatin did not change the mean BP or BP variability in SAD-operated SHRs. In SAD-operated SHRs, simvastatin attenuated myocyte hypertrophy and BNP expression, as well as RhoA, Ras and ERK1/2 activities. In contrast, simvastatin did not change myocardial fibrosis, macrophage infiltration, or the expression of procollagen and TGF-Β or MCP-1 in SAD-operated SHRs. Simvastatin did not affect serum lipid levels. In conclusion, simvastatin attenuated the large BP variability-induced aggravation of cardiac hypertrophy, but not myocardial fibrosis, in SHRs. The activation of RhoA/Ras-ERK pathways may contribute to the aggravation of cardiac hypertrophy by a combination of hypertension and large BP variability.