Suppressed vascular Rho-kinase activation is a protective cardiovascular mechanism in obese female mice
BackgroundObesity is the number one cardiovascular risk factor for both men and women and is a complex condition. Although a sex dimorphism on vascular function has already been noted, the underlying processes remain unclear. The Rho-kinase pathway has a unique role in controlling vascular tone, and in obese male mice, hyperactivation of this system results in worsened vascular constriction. We investigated whether female mice exhibit decreased Rho-kinase activation as a protective mechanism in obesity. MethodsWe exposed male and female mice to a high-fat diet (HFD) for 12 weeks. At the end, energy expenditure, glucose tolerance, adipose tissue inflammation, and vascular function were investigated. ResultsMale mice were more sensitive to HFD-induced body weight gain, glucose tolerance, and inflammation than female mice. After establishing obesity, female mice demonstrated increase in energy expenditure, characterized by an increase in heat, whereas male mice did not. Interestingly, obese female mice, but not male, displayed attenuated vascular contractility to different agonists, such difference was blunted by inhibition of Rho-kinase. Finally, aortae from obese female mice, but not male, responded prematurely to Rho-kinase inhibitor, which was accompanied by a suppressed Rho-kinase activation, measured by western blot. ConclusionIn obesity, female mice demonstrate a vascular protective mechanism - suppression of vascular Rho-kinase - to minimize the cardiovascular risk associated with obesity, whereas male mice do not generate any adaptive response. Future investigations can help to understand how Rho-kinase becomes suppressed in female during obesity.