Changes in maternal dietary intake during gestation can affect muscle development1 and may be linked to the catabolic actions of hormones, such as glucocorticoids, which inhibits the insulin like growth factor 1 (IGF1) pathway. This study examines the potential effects of glucocorticoids and skeletal muscle adaptations in seven-day-old offspring exposed to suboptimal gestational environments.
Pregnant sows were randomly assigned to a commercial diet (L/H n=8), which increased in energy content during gestation, or an inverse diet (H/L n=8). L/H offspring were ranked according to birth weight as small (SL/H, n=7) or median (CL/H, n=7). Only the H/L median offspring (MH/L, n=8) were selected for this study. Blood samples were taken from week-old piglets before they were euthanased. The biceps femoris was sampled for histological analysis and real-time gene expression of IGF1, 11β-hydroxysteroid dehydrogenase (HSD)-1 and 2, glucocorticoid receptor GR.
Sodium and creatinine plasma concentrations increased in SL/H offspring compared to the controls. The total serum protein rose in both intra-uterine compromised groups in relation to MH/L (SL/H 49.83±3.1*; CL/H31.00±4.8; MH/L 43.04±4; g/l *(P<0.05)). The GR and 11β-HSD-1 genes were upregulated in H/L offspring in relation to the control group, whilst IGF1 expression (SL/H 0.96±0.3; CL/H 1.0±0.1; MH/L 2.2±0.4*; 2-(ΔΔCT)*(P<0.05)) and 11β-HSD-2 was highest in MH/L, compared to the other groups, with more internal nuclei fibres than the SL/H.
Our study suggests that IGF1 and 11β-HSD-2 gene expression in MH/L offspring muscle increase in response to the reduced maternal calorie intake during the second half of gestation. Increased numbers of fibres with central nuclei may indicate glucocorticoid activation. Further investigations will determine whether this promotes a degenerative or regenerative process.
This study was supported by the BBSRC (BB/H002650/1)
Reference: 1. Schakman, O, et al. J Endocrinol 2001 197 (1) 1-10.