Abstract 085: Role of Suppressor of Cytokines Signaling 3 (Socs3) in Modulating Chronic Metabolic and Cardiovascular Effects of Leptin

Abstract

Suppressor of cytokine signaling 3 (SOCS3) is a negative regulator of leptin signaling. Hypothalamic SOCS3 is upregulated in obese animals fed a high-fat diet and has been suggested to contribute to development of resistance to leptin’s anorexic effects. In this study we determined whether deletion of SOCS3 in the entire central nervous system (CNS) amplifies the chronic anorexic and blood pressure (BP) effects of physiological increases in plasma leptin in mice fed a normal diet. SOCS3 flox/flox -Nestin-cre mice were generated by breeding SOCS3 flox/flox with Nestin-cre mice. BP and heart rate (HR) were recorded by telemetry, and oxygen consumption (VO 2 ) was monitored by indirect calorimetry in 22-week-old SOCS3 flox/flox -Nestin-cre (n=4) and control mice (SOCS3 flox/flox , n=4). Compared to controls SOCS3 flox/flox -Nestin-cre mice were lighter (30±1 vs 33±1 g) and normoglycemic (124±7 vs 146±10 mg/dl), consumed less food (3.0±0.4 vs 3.6±0.2 g/day) and had similar VO 2 (77±6 vs 73±3 ml/kg/min). SOCS3 flox/flox -Nestin-cre mice had similar MAP (103±3 vs 107±3 mmHg) but higher HR (666±15 vs 602±17 bpm) compared to control mice. Chronic leptin infusion greatly reduced food in SOCS3 flox/flox -Nestin-cre (46±3 vs 35±4%) and increased MAP (15±3 vs 7±2 mmHg) and VO2 (18±3 vs 14±2%) compared to control mice. No significant changes were observed in HR in either group. Leptin infusion significantly reduced blood glucose levels in both groups (124±7 to 97±7 vs 146±10 to 105±7 mg/dl). These results indicate that SOCS3 deletion in the entire CNS reduces body weight and food intake, and amplifies leptin’s effect on appetite and blood pressure and also suggest the SOCS3 signaling attenuates the chronic actions of leptin on blood pressure as well as appetite regulation even in non-obese mice fed a normal diet. (NHLBI-PO1HL51971, NIGMS P20GM104357 and AHA SDG5680016)