Background/aims: [corrected] Skeletal muscle (SM) constitutes more than 40% of the body weight in adulthood. Transports dietary glucose mainly through the insulin-dependent glucose transporter (Glut-4) located in the Transverse tubule membrane system (TT). The TT development ends shortly after birth. The TT membrane hosts the proteins involved in excitation-contraction coupling and glucose uptake. Glycaemic regulation through movement is a key function of fully developed skeletal muscle. In this study, we aimed to characterize the effect of gestational undernourishment (GUN) in rats GLUT-4 expression and on the protein/lipid content of the TT membranes. We also examined the effect of GUN on the mechanical properties of muscles as an indication of the metabolic condition of the SM at birth.
Methods: Isolated TT membrane from SM of GUN rats were used to study lipid/protein content and protein stability by differential scanning calorimetry. The effect of GUN on the SM mechanical properties was determined in isolated Extensor Digitorum Longus (EDL) muscle.
Results: We demonstrate that compared to control, GUN in the new-born produces; i) decreases body weight; ii) diminution in SM mass; iii) decreases the formation of TT membranes; iv) expresses TT membrane proteins with higher thermal stability. The TT membrane expression of GLUT-4 in GUN offspring was twice that of controls. The isolated EDL of GUN offspring was 20% stronger as measured by contractile force and more resistant to fatigue relative to controls.
Conclusion: These results provide the first evidence of adaptive changes of the SM in new-borns exposed to severe gestational food restriction. The effects of GUN on muscle at birth are the first step toward detrimental SM metabolic function, contributing to the physiopathology of metabolic diseases in adulthood.
© 2013 S. Karger AG, Basel