The P2X7 receptor, a member of the ionotropic purinergic P2X family of extracellular ATP-gated receptors, exerts strong trophic effects when tonically activated in cells, in addition to cytotoxic effects after a sustained activation. Because of its widespread distribution, P2X7 regulates several cell- and tissue-specific physiological functions, and is involved in a number of disease conditions. A novel role has recently emerged for P2X7 in the regulation of glucose and energy metabolism. In previous work, we have demonstrated that genetic depletion, and to a lesser extent also pharmacological inhibition of P2X7, elicits a significant decrease of the whole body energy expenditure and an increase of the respiratory exchange ratio. In the present work, we have investigated the effects of P2X7 stimulation in vivo on the whole body energy metabolism. Adult mice were daily injected with the specific P2X7 agonist 2'(3')-O-(4-Benzoylbenzoyl)adenosine 5'-triphosphate for 1 week and subjected to indirect calorimetric analysis for 48 h. We report that 2'(3')-O-(4-Benzoylbenzoyl)adenosine 5'-triphosphate increases metabolic rate and O2 consumption, concomitantly decreasing respiratory rate and upregulating NADPH oxidase 2 in gastrocnemius and tibialis anterior muscles. Our results indicate a major impact on energy homeostasis and muscle metabolism by activation of P2X7.
Keywords: BzATP; P2X7 receptor; energy expenditure; fatty acid oxidation; oxygen consumption.