Asia Pacific Journal of Clinical Nutrition (2002) 11 (Suppl)S258 Mucosal composition and glutamine metabolism during a 48-hour fast

Glutamine (GLN) is believed to be an essential nutrient for the intestinal mucosa.(1) Interestingly both fasting and nutritional support when given as either enteral or parenteral feeding are associated with glutamine depletion and atrophy of the intestinal mucosa. While there has been intensive research on the intestinal effects of glutamine-supplemented nutritional support (2,3) the intestinal adaptation to fasting with respect to glutamine metabolism has been less studied. The aim of this experiment was to examine the effect of fasting on the activity of glutaminase and glutamine synthetase (the enzymes that regulate GLN metabolism). Male Wistar rats (n = 6 per group) were randomly allocated to be either fed chow ad libitum (CHOW) or fasted (FAST) for 48 hours. At sacrifice, samples were taken to estimate total intestinal mass, mucosal mass, mucosal protein, and mucosal DNA content. Enzyme analyses were used to estimate the activity of glutaminase and glutamine synthetase per unit of mucosal protein. Data were described as mean ± standard deviation and comparisons between the groups were performed using the non-parametric Mann-Whitney Test. The FAST group lost weight while rats in the CHOW group gained weight (–28.5 g ± 7.1 versus +11.5 ± 5.2 g, P = 0.01). The FAST group had a significantly lower intestinal weight (49.1 ± 10.3 versus 71.5 ± 2.4 mg/cm intestine, P = 0.009) and significantly decreased mucosal mass (17.28 ± 5.53 versus 28.10 ± 4.23 mg/cm intestine, P = 0.02). Fasting did not significantly alter mucosal composition as evidenced by mucosal DNA concentration (7.15 ± 2.38 versus 8.36 ± 2.16 ug/mg mucosa, P = 0.35) and mucosal protein concentration (0.076 ± 0.02 versu