Long-term intermittent glutamine supplementation repairs intestinal damage (structure and functional mass) with advanced age: assessment with plasma citrulline in a rodent model.

Objective: Glutamine is the preferred fuel for the rat small intestine and promotes the growth of intestinal mucosa, especially in the event of gut injury. Quantitatively, glutamine is one important precursor for intestinal citrulline release. The aim of this study was to determine whether the effect of glutamine on the increase in intestinal villus height is correlated with an increase in both gut mass and citrulline plasma level in very old rats.

Effect of intermittent glutamine supplementation on skeletal muscle is not long-lasting in very old rats.

Background And Objective: Muscle is the major site for glutamine synthesis via glutamine synthetase (GS). This enzyme is increased 1.5-2 fold in 25-27-mo rats and may be a consequence of aging-induced stress.

Coordinate expression of the 19S regulatory complex and evidence for ubiquitin-dependent telethonin degradation in the unloaded soleus muscle.

Catabolic stimuli induce a coordinate expression of the 20S proteasome subunits in skeletal muscles. However, contradictory data have been obtained for the 19S regulatory complex (RC) subunits, which could reflect differential regulation at the transcriptional and/or translational level. To address this point we used a well-established model of muscle atrophy (hindlimb suspension) and determined the mRNA levels for 19S subunits belonging to both the base (non-ATPase S1, ATPases S7 and S8) and the lid (S14) of the 19S RC.

Insulin-dependent glycogen synthesis is delayed in onset in the skeletal muscle of food-deprived aged rats.

Insulin resistance with aging may be responsible for impaired glycogen synthesis in the skeletal muscle of aged rats and contribute to the well-known decreased ability to respond to stress with aging. For this reason, to assess the ability of the skeletal muscle to utilize glucose for glycogen synthesis during aging, the time course of glycogen synthesis was continuously monitored by 13C nuclear magnetic resonance for 2 h in isolated [13C] glucose-perfused gastrocnemius-plantaris muscles of 5-day food-deprived adult (6-8 months; n=10) or 5-day food-deprived aged (22 months; n=8) rats. [13C] glucose (10 mmol/L) perfusion was carried out in the presence or absence of an excess of insulin (1 micromol/L).