Increased mitochondrial ROS generation mediates the loss of the anti-contractile effects of perivascular adipose tissue in high-fat diet obese mice.

Background And Purpose: Obesity is associated with structural and functional changes in perivascular adipose tissue (PVAT), favouring release of reactive oxygen species (ROS), vasoconstrictor and proinflammatory factors. The cytokine TNF-α induces vascular dysfunction and is produced by PVAT. We tested the hypothesis that obesity-associated PVAT dysfunction was mediated by augmented mitochondrial ROS (mROS) generation due to increased TNF-α production in this tissue.

Experimental Approach: C57Bl/6J and TNF-α receptor-deficient mice received control or high fat diet (HFD) for 18 weeks. We used pharmacological tools to determine the participation of mROS in PVAT dysfunction. Superoxide anion (O ) and H O were assayed in PVAT and aortic rings were used to assess vascular function.

Key Results: Aortae from HFD-fed obese mice displayed increased contractions to phenylephrine and loss of PVAT anti-contractile effect. Inactivation of O , dismutation of mitochondria-derived H O , uncoupling of oxidative phosphorylation and Rho kinase inhibition, decreased phenylephrine-induced contractions in aortae with PVAT from HFD-fed mice. O and H O were increased in PVAT from HFD-fed mice. Mitochondrial respiration analysis revealed decreased O consumption rates in PVAT from HFD-fed mice. TNF-α inhibition reduced H O levels in PVAT from HFD-fed mice. PVAT dysfunction, i.e. increased contraction to phenylephrine in PVAT-intact aortae, was not observed in HFD-obese mice lacking TNF-α receptors. Generation of H O was prevented in PVAT from TNF-α receptor deficient obese mice.

Conclusion And Implications: TNF-α-induced mitochondrial oxidative stress is a key and novel mechanism involved in obesity-associated PVAT dysfunction. These findings elucidate molecular mechanisms whereby oxidative stress in PVAT could affect vascular function.

Linked Articles: This article is part of a themed section on Molecular Mechanisms Regulating Perivascular Adipose Tissue - Potential Pharmacological Targets? To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.20/issuetoc.