[4136.7] Chronic Parenteral Nutrition Reduces Lean Tissue Growth and Induces Insulin Resistance in Neonatal Piglets
David A. Horst, Mareah Sedenquist, Barbara Stoll, Ken Ellis, Douglas Burrin. Pediatrics, Baylor College of Medicine, Houston, TX.
BACKGROUND: Most very low birthweight infants receive their nutrition parenterally prior to achieving full enteral feedings. Recent studies indicate that infants born less than 32 weeks' gestation showed evidence of insulin resistance at 4 to 10 years. However, there is little information regarding the effect of parenteral nutrition on body composition and glucose tolerance in premature infants.
OBJECTIVE: Our aim was to test the hypothesis that parenteral nutrition will decrease lean and increase fat mass accretion compared to enteral nutrition containing equal distribution of macronutrients and total calories.
DESIGN/METHODS: Three-day old piglets were implanted with jugular venous and carotid arterial catheters and randomized to receive either enteral formula (n=9) or a total parenteral nutrition (TPN) mixture (n=8) providing 25 g•kg-1•d-1 of carbohydrate, 13 g•kg-1•d-1 of protein and 5 g•kg-1•d-1 of fat in an equal fluid volume (240 ml•kg-1•d-1) for 17 days. Baseline and 17-day dual-energy X-ray absorptiometry (DXA) scans were performed. On day 14, after an eight-hour fast, pigs received an intravenous glucose tolerance test (IVGTT)(0.5 g glucose/kg body wt) with arterial blood glucose and insulin sampled at 0, 10, 20, 60, and 90 min. Liver, spleen and pancreas were weighed at 17 days.
RESULTS: Enterally fed piglets gained significantly (P < .001) more weight (48.2 vs. 36.2 g•kg-1•d-1,), lean mass (44.9 vs. 32.8 g•kg-1•d-1) and bone mass (0.736 vs. 0.473 g•kg-1•d-1). There was no difference in fat mass accretion (2.64 vs 2.92 g•kg-1•d-1, P = 0.648). There was no difference in pancreas weight, but liver (4.27 vs. 2.47 g/kg) and spleen (0.756 vs 0.379 g/kg) weights were higher (P < 0.01) in TPN-fed piglets. IVGTT results showed that TPN-fed piglets had significant insulin resistance at 14 days compared to enterally-fed controls (AUC insulin:AUC glucose 2.05 vs. 1.04, P < 0.05).
CONCLUSIONS: In term piglets, TPN reduced lean mass accretion and induced relative insulin resistance when compared to enterally fed piglets after two weeks. Further studies are warranted to establish the mechanism of TPN-induced insulin resistance and whether there are long-term metabolic consequences of this life-saving and universal form of artificial nutrition in premature neonates.