Poster Topical Area: Experimental Animal Nutrition
Location: Hall D
Poster Board Number: 623
Objectives: Our previous data show that glucose concentration is reduced in low (LBWT) compared to normal (NBWT) birthweight pigs, despite similar glucose appearance rates. These data seem to suggest that glucose metabolism may be greater in LBWT pig muscle. The objective of this study was to profile glucose catabolic pathways in skeletal muscle of newborn LBWT and NBWT pigs.
Methods: Eighteen pairs of male and female newborn LBWT and NBWT pigs were euthanized to collect plasma and Longissimus Dorsi (LD) muscle. Plasma glucose and amino acid concentrations were measured by GC-MS. Muscle mRNA expression was measured by real-time PCR.
Results: Relative mRNA expression of GLUT-4 was greater in LBWT compared to NBWT pigs (P<0.05). In contrast, mRNA expression of phosphofructokinase (PFK) and pyruvate kinase (PK2), was reduced in LBWT than in NBWT group (P<0.05). Although mRNA expression of pyruvate dehydrogenase kinase 4 (PDK4) was greater for LBWT than for NBWT pigs, expression of lactate dehydrogenase (LDH), pyruvate dehydrogenase (PDH) and pyruvate carboxylase (PC). Expression of phosphoenolpyruvate carboxykinase 2 (PCK2) was reduced in LBWT compared to NBWT siblings (P<0.01). In addition, while phosphoglycerate dehydrogenase (PHGDH) was not affected by growth status, mRNA expression of phosphoserine aminotransferase 1 (PSAT1) and phosphoserine phosphatase (PSPH) was reduced in LBWT compared to NBWT piglets (P<0.01). However, mRNA expression of glucose-6-phosphate dehydrogenase (G6PD) and phosphoribosyl pyrophosphate synthetase 2 (PRPS2) was greater for LBWT than for NBWT pigs (P<0.01). Plasma glucose concentration was lower in LBWT compared to NBWT pigs (P<0.001). In spite of the reduction in mRNA expression of serine and glycine synthetic enzymes, plasma and skeletal muscle concentrations of free serine and glycine did not differ between LBWT and NBWT pigs.
Conclusions: Despite an increase in mRNA expression of GLUT 4, mRNA expression of glycolytic and serine biosynthetic enzymes were reduced with a concomitant increase in enzymes of pentose phosphate pathway. These changes suggest that glycolytic flux may likely be directed to the pentose phosphate pathway in the skeletal muscle of LBWT pigs.