Transcriptional response of skeletal muscle to a low protein perinatal diet in rat offspring at different ages: The role of key enzymes of glucose-fatty acid oxidation.

Skeletal muscle is a plastic tissue during development with distinctive acute and chronic response to maternal protein restriction. This study evaluated gene and protein expression of key-enzymes of glycolytic pathway (HK2, PFK, PDK4 and CS), and fatty acid oxidation (CPT1 and β-HAD) of two different types of skeletal muscle [soleus and extensor digitorium longus (EDL)] from offspring rats at 30 and 90 days of age, exposed to maternal isoenergetic low protein diet throughout gestation and lactation. Pups from dams fed 17% protein diet (n=5, normal protein, Np), and low protein pups from dams fed 8% casein diet (low protein, Lp, n=5) were evaluated. Offspring were sacrificed either 30 or 90 days old. Soleus and EDL were analyzed for mRNA and protein expression by quantitative PCR and western blotting, respectively. Soleus was more affected by Lp maternal diet at 90 days by down-regulation of key enzymes of glycolytic pathway, in particular HK2 and PDK4 with a concomitant reduction of β-HAD mRNA. For EDL, the effects of Lp maternal diet were more pronounced at 30 days, as the transcriptional key enzymes of glycolytic pathway were down-regulated. One important finding was that the observed acute (30 days) transcriptional changes did not remain in adult Lp rats (90 days), except for PDK4. The robust PDK4 mRNA down-regulation, observed in both soleus and EDL, and at both ages, and the consequent down-regulation of the PDK4 protein expression can be responsible for a state of reduced metabolic flexibility of skeletal muscle in response to maternal low protein diet.