Inhibition of phosphodiesterase type 9 reduces obesity and cardiometabolic syndrome in mice.

Central obesity with cardiometabolic syndrome (CMS) is a major global contributor to human disease, and effective therapies are needed. Here, we show inhibiting cyclic-GMP selective phosphodiesterase-9A (PDE9-I) in both ovariectomized female or male mice suppresses pre-established severe diet-induced obesity/CMS with or without superimposed mild cardiac pressure-load. PDE9-I reduces total body, inguinal, hepatic, and myocardial fat, stimulating mitochondrial activity in brown and white fat, and improving CMS, without significantly altering activity or food intake. PDE9 localized at mitochondria, and its inhibition in vitro stimulated lipolysis and mitochondrial respiration in adipocytes and myocytes coupled to PPARα-dependent gene regulation. PPARα upregulation was required to achieve the lipolytic, anti-obesity, and metabolic effects of PDE9-I. All these PDE9-I induced changes were not observed in obese/CMS non-ovariectomized females, indicating a strong sexual dimorphism. We found that PPARα chromatin binding was re-oriented away from fat-metabolism regulating genes when stimulated in the presence of co-activated estrogen receptor-alpha, and this may underly the dimorphism. These findings have translational relevance given that PDE9-I is already being studied in humans for indications including heart failure, and efficacy against obesity/CMS would enhance its therapeutic utility.