Long-chain n-3 fatty acids enhance neonatal insulin-regulated protein metabolism in neonate piglets by differentially modifying muscle phospholipid and intramuscular triglyceride composition

Karen Bergeron, Pierre Julien, Teresa A. Davis, Alexandre Myre, and M. Carole Thivierge

Obesity and Metabolic Health Division, Rowett Research Institute, Aberdeen, Scotland AB21 9SB

Corresponding Author: c.thivierge{at}rowett.ac.uk

This study investigated the role of long-chain n-3 polyunsaturated fatty acid (LCn-3PUFA) of muscle phospholipids in the regulation of the neonatal metabolism. Twenty-eight piglets were weaned at 2 d of age and raised on one of two milk formulae that consisted of either a control formulae supplying 0% or a formulae containing 3.5% LCn-3PUFAs until 10 or 28 d of age. There was a developmental decline in the insulin sensitivity of amino acid disposal in control pigs during the first month of life with a slope of –2.24 µmol·kg-1·h-1 (P=0.01) per unit of insulin increment, as assessed using hyperinsulinaemic-euglycaemic-euaminoacidaemic clamps. LCn-3PUFA feeding blunted this developmental decline resulting in differing insulin sensitivities (P<0.001). When protein metabolism was assessed under parenteral feeding-induced hyperinsulinaemia, LCn-3PUFAs reduced by 16% whole-body oxidative losses of amino acids (238 to 231 mmol·kg-1·h-1, P=0.06) allowing 41% more amino acids to accrete into body proteins (90 to 127 mmol·kg-1·h-1, P=0.06). The fractional synthetic rate of muscle mixed proteins remained unaltered by the LCn-3PUFA feeding. However, LCn-3PUFAs retarded a developmental increase in the essential to non-essential amino acid ratio of the muscle intracellular free pool (P=0.05). Overall, alterations in metabolism were concomitant with a preferential incorporation of LCn-3PUFAs into muscle total membrane phospholipids (P<0.001) in contrast to intramuscular triglycerides. These results underscore the potential role of LCn-3PUFAs as regulators of different aspects of protein metabolism in the neonate.

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