Effect of Glutamine Supplement and Hepatectomy on DNA and Protein Synthesis in the Remnant Liver

Abstract

One of the physiological roles of glutamine is as a precursor for DNA synthesis. The aims of this study were to determine (1) whether glutamine-supplemented total parenteral nutrition (TPN) enhanced DNA and protein synthesis in the liver and (2) whether glutamine uptake was increased following partial hepatectomy in rats. Male Donryu rats ( n = 59; body weight, 250-275 g) were randomized into four groups: (1) sham operation + standard TPN solution (C-STPN); (2) C + glutamine-supplemented TPN (C-GTPN); (3) 70% partial hepatectomy + STPN (H-STPN); (4) partial hepatectomy + GTPN (H-GTPN). On Day 0, rats underwent either a sham operation or 70% partial hepatectomy and concomitantly were catheterized in the jugular vein. TPN was begun immediately after the surgery. GTPN was isocaloric and isonitrogenous with STPN and 25% of total nitrogen was given as glutamine. On Day 2, the animals were sacrificed after either a continuous infusion of 1- 14C-leucine or a bolus iv injection of bromodeoxyuridine. The rate of hepatic regeneration was enhanced with glutamine supplementation (H-STPN, 60.8 ± 1.6% vs H-GTPN, 66.3 ± 2.0, P < 0.05) due to an increase in protein synthesis in the liver (H-STPN, 134.0 ± 10.3%/day vs H-GTPN, 160.9 ± 6.9, P < 0.05) and DNA synthesis in hepatocytes (H-STPN, 23.1 ± 2.5% vs H-GTPN, 31.4 ± 2.9, P < 0.05). The uptake of glutamine by the liver was increased following hepatectomy with GTPN supplementation. In conclusion, glutamine supplement and partial hepatectomy stimulated glutamine uptake in the liver and this results in an enhancement of protein and DNA synthesis in the remnant liver.