Anabolic steroids support postoperative gut/liver amino acid metabolism

Abstract

The effects of an anabolic steroid (nandrolone decanoate, 5 mg/kg) on postoperative splanchnic fuel metabolism were studied in order to gain further understanding of the regulation of the altered gut/liver amino acid metabolism that occurs following catabolic illness. In addition to studying glutamine and alanine, which together transport 60% of whole blood amino acid nitrogen, we determined the fluxes of glutamate and glucose across the gastrointestinal tract and liver in 12 postoperative dogs. Substrate exchange (flux) was calculated by multiplying bloodflow by the arterial-venous concentration difference for each substrate. Arterial glutamine, glutamate, and alanine were significantly increased in dogs receiving the anabolic steroid (AS) compared to control animals (p less than 0.05). Intestinal bloodflow was unchanged, but gut glutamine uptake doubled in dogs receiving steroids (1.4 +/- 0.3 mumol/kg/min in controls vs 2.8 +/- 0.7 in AS, p less than 0.05). Simultaneously, gut alanine release was augmented by 100% in dogs receiving steroids (p less than 0.05). Control dogs demonstrated net glutamate release by the gut, while dogs treated with the anabolic steroid demonstrated glutamate balance (p less than 0.05). Liver bloodflow remained unchanged in AS dogs, but hepatic alanine uptake nearly tripled (p less than 0.01) and hepatic glucose production increased by 60% (p less than 0.05). Anabolic steroids appear to support postoperative splanchnic fuel metabolism by increasing blood amino acid levels, enhancing gut/liver amino acid uptake and processing, and augmenting hepatic gluconeogenesis.