Glucose uptake is increased and glyceroneogenesis is reduced in denervated retroperitoneal adipose tissue from fasted rats

Abstract

It has been know that adipose tissue (WAT) has three sources of glycerol‐3‐phosphate (G3P)generation, but the control of these processes has been little studied. To obtain more information about the control of G3P generation in WAT, we investigate the effects of WAT denervation on the in vivo uptake of glucose by the tissue, and on the acitivities of P‐enol‐pyruvate carboxykinase (PEPCK), a key enzyme of glyceroneogenesis, and of glycerokinase (GyK). Unilateral denervation of retroperitoneal WAT was performed 7 days before the experiments, using contralateral WAT as control. Denervation caused a 68% decrease in WAT norepinephrine content. Rates of glucose uptake (ng.mg tissue−1. min−1) were lower in fasted (0.82±0.068)than in fed (2.60±0.28) rats and increased in denervated tissues: fasted 1.30±0.19 and fed 4.25±0.47. GyK activity (nmol. mg of protein−1. min−1) decreased in fasted rats (0.33±0.01 vs fed 1.13±0.13) and were further reduced by denervation (fasted 0.22±0.01, fed 0.73±0.08). The marked activation of PEPCK (nmol. mg of protein−1. min−1)in fasted rats (13.88±0.98 vs fed 2.32±0.19) was reduced by denervation (fasted 5.50±0.25, fed 1.51±0.16). The data show that sympathetic nervous system control an adequate supply of G3P for triacylglycerol synthesis in WAT in both groups, with reciprocally changes in G3P generation via glycolysis and via glyceroneogenesis. Financial support: CNPq and FAPESP.