BACKGROUND: The main components of GH/insulin-like growth factor (IGF)-1 axis and Sirtuin 4 (Sirt4), highly expressed in liver and skeletal muscle mitochondria, serve as active regulators of mitochondrial oxidative capacity with opposite functions. In obesity both GH/IGF-1 status and serum Sirt4 levels, likely mirroring its reduced mitochondrial expression, might be altered. OBJECTIVE: To evaluate the association between circulating levels of Sirt4, body composition, metabolic parameters and cardio-metabolic risk profile in obese patients according to their different GH/IGF-1 status. DESIGN: Cross-sectional study with measurement of serum Sirt4, GH after GH releasing hormone (GHRH)+Arginine test, IGF-1 and assessment of body composition, glucose and lipid metabolism in 50 class II-III obese subjects (BMI 35.6 to 62.1kg/m(2)) and 15 normal weight subjects. Low GH secretion and IGF-1 were defined using pre-determined cutoff-points. The Homeostatic Metabolic Assessment of insulin resistance index and Visceral adiposity index were also calculated. The association of Sirt4 with peak stimulated GH and IGF-1, body composition, metabolic parameters and cardio-metabolic risk profile was assessed. RESULTS: Serum Sirt4 was inversely related to anthropometric and metabolic parameters and positively related to peak GH and IGF-1. After adjusting for peak GH and IGF-1, the relationships between Sirt4 and BMI became not significant. At multiple regression analysis IGF-1 (p<0.001) was the independent predictor for Sirt4. CONCLUSION: There was a close relationship between low IGF-1 and low serum Sirt4. This observation suggested that in obese patients, low GH/IGF-1 status was likely associated with a major compensatory decrease in circulating levels of Sirt4 to oppose to its negative regulator effect on mitochondrial oxidative capacity.

Preliminary data on the relationship between circulating levels of Sirtuin 4, anthropometric and metabolic parameters in obese subjects according to growth hormone/insulin-like growth factor-1 status.

ORIO, Francesco
2015

Abstract

BACKGROUND: The main components of GH/insulin-like growth factor (IGF)-1 axis and Sirtuin 4 (Sirt4), highly expressed in liver and skeletal muscle mitochondria, serve as active regulators of mitochondrial oxidative capacity with opposite functions. In obesity both GH/IGF-1 status and serum Sirt4 levels, likely mirroring its reduced mitochondrial expression, might be altered. OBJECTIVE: To evaluate the association between circulating levels of Sirt4, body composition, metabolic parameters and cardio-metabolic risk profile in obese patients according to their different GH/IGF-1 status. DESIGN: Cross-sectional study with measurement of serum Sirt4, GH after GH releasing hormone (GHRH)+Arginine test, IGF-1 and assessment of body composition, glucose and lipid metabolism in 50 class II-III obese subjects (BMI 35.6 to 62.1kg/m(2)) and 15 normal weight subjects. Low GH secretion and IGF-1 were defined using pre-determined cutoff-points. The Homeostatic Metabolic Assessment of insulin resistance index and Visceral adiposity index were also calculated. The association of Sirt4 with peak stimulated GH and IGF-1, body composition, metabolic parameters and cardio-metabolic risk profile was assessed. RESULTS: Serum Sirt4 was inversely related to anthropometric and metabolic parameters and positively related to peak GH and IGF-1. After adjusting for peak GH and IGF-1, the relationships between Sirt4 and BMI became not significant. At multiple regression analysis IGF-1 (p<0.001) was the independent predictor for Sirt4. CONCLUSION: There was a close relationship between low IGF-1 and low serum Sirt4. This observation suggested that in obese patients, low GH/IGF-1 status was likely associated with a major compensatory decrease in circulating levels of Sirt4 to oppose to its negative regulator effect on mitochondrial oxidative capacity.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11367/31999
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