The effect of glutamine-supplemented total parenteral nutrition on nutrition and intestinal absorptive function in a rat model

Influence of Growth Hormone and Glutamine on Intestinal Stem Cells: A Narrative Review

Growth hormone (GH) and glutamine (Gln) stimulate the growth of the intestinal mucosa. GH activates the proliferation of intestinal stem cells (ISCs), enhances the formation of crypt organoids, increases ISC stemness markers in the intestinal organoids, and drives the differentiation of ISCs into Paneth cells and enterocytes. Gln enhances the proliferation of ISCs and increases crypt organoid formation; however, it mainly acts on the post-proliferation activity of ISCs to maintain the stability of crypt organoids and the intestinal mucosa, as well as to stimulate the differentiation of ISCs into goblet cells and possibly Paneth cells and enteroendocrine cells. Since GH and Gln have differential effects on ISCs. Their use in combination may have synergistic effects on ISCs. In this review, we summarize the evidence of the actions of GH and/or Gln on crypt cells and ISCs in the literature. Overall, most studies demonstrated that GH and Gln in combination exerted synergistic effects to activate the proliferation of crypt cells and ISCs and enhance crypt organoid formation and mucosal growth. This treatment influenced the proliferation of ISCs to a similar degree as GH treatment alone and the differentiation of ISCs to a similar degree as Gln treatment alone.

Enteral nutrition combined with glutamine promotes recovery after ileal pouch-anal anastomosis in rats

AIM

To assess the effect of enteral nutrition (EN) supplemented with glutamine on recovery after ileal pouch-anal anastomosis (IPAA) in rats, to provide an experimental basis for nutritional support in patients with ulcerative colitis (UC) after IPAA.

METHODS

Male Sprague-Dawley (SD) rats were randomly divided into three groups (n = 8) after IPAA operation using a microsurgical technique. From the third postoperative day, rats in the control group, EN group, and immune nutrition (IN) group were fed standard rat chow, short peptide EN, and short peptide EN combined with glutamine ad libitum, respectively. The rats’ general condition was observed throughout the study. Serum levels of total protein (TP), albumin (ALB), prealbumin (PA), and transferrin (TF) were detected on the 30th postoperative day, using an automatic biochemical analyzer. The ileal pouch mucosa was stained with hematoxylin and eosin (HE), and occludin protein levels were detected by immunohistochemistry.

RESULTS

The body weight of rats in the EN group (359.20 ± 10.06 g) was significantly higher than that in the control group (344.00 ± 9.66 g) (P < 0.05) and lower than that in the IN group (373.60 ± 9.86 g) (P < 0.05) on the 30th postoperative day. The levels of serum TP, ALB, PA, and TF in the EN group were significantly higher than those in the control group (P < 0.01 for all) and lower than those in the IN group (P < 0.05 for all). Histopathological score (EN: 0.80 ± 0.37; IN: 0.60 ± 0.40; control group: 2.29 ± 0.18) and expression level of occludin protein (EN: 0.182 ± 0.054; IN: 0.188 ± 0.048; control group: 0.127 ± 0.032) were significantly lower in the control group compared with the EN and IN groups (P < 0.05 for all), but there were no significant differences between the latter two groups (P > 0.05 for all).

CONCLUSION

EN combined with glutamine may effectively improve nutritional status after IPAA. Our results suggest a benefit of glutamine supplementation in EN for UC patients undergoing IPAA, although human studies are required to confirm this finding.

Distinct Effects of Growth Hormone and Glutamine on Activation of Intestinal Stem Cells

BACKGROUND

For patients with short bowel syndrome under parenteral nutrition support, growth hormone (GH) and glutamine (GLN) have been found to help the growth of intestinal mucosa. In this research, we studied the effects of GH and GLN on intestinal stem cells (ISCs).

METHODS

The in vitro and in vivo effects of GH and/or GLN on ISCs were evaluated by observing the ability of ISCs to form organoids in a Matrigel culture system. The expression levels of stemness and differentiation markers in ISCs and organoids were assessed using quantitative real-time polymerase chain reaction, immunofluorescence assay, and immunohistochemistry staining.

RESULTS

In vitro administration of GH activated the stemness of ISCs, whereas GLN enhanced the expression of chromogranin A and Muc2, which are differentiation markers in enteroendocrine and goblet cells, respectively. Administration of GH or GLN in mice showed that GH, but not GLN, upregulated the proliferative activity of ISCs with increased formation of crypt organoids. In addition, GH increased the expression of Lgr5 and GLN enhanced expression of Muc2 in the crypt fractions of the intestines in mice.

CONCLUSION

These results suggest that GH mainly enhances proliferative activities, whereas GLN promotes the differentiation potential of ISCs.

L-alanyl-L-glutamine ingestion maintains performance during a competitive basketball game

Background

The purpose of this study was to examine the efficacy of L-alanyl-L-glutamine (AG) ingestion on basketball performance, including jump power, reaction time, shooting accuracy and fatigue.

Methods

Ten women (21.2 ± 1.6 years; height: 177.8 ± 8.7 cm; body mass: 73.5 ± 8.0 kg), all scholarship NCAA Division I basketball players, volunteered for this study. Subjects participated in four trials, each consisting of a 40-min basketball game with controlled time-outs for rehydration. During the first trial (DHY) subjects were not allowed to rehydrate, and the total weight lost during the contest was used to determine fluid replenishment during the subsequent three trials. During one trial subjects consumed only water (W), while during the other two trials subjects consumed the AG supplement mixed in water using either a low dose (1 g per 500 ml) (AG1) or high dose (2 g per 500 ml) (AG2) concentration. All data assessed prior to and following each game were converted into a Δ score (Post results - Pre results). All performance data were then analyzed using a one-way repeated measures analysis of variance.

Results

During DHY subjects lost 1.72 ± 0.42 kg (2.3%) of their body mass. No differences in fluid intake (1.55 ± 0.43 L) were seen between rehydration trials. A 12.5% (p = 0.016) difference in basketball shooting performance was noted between DHY and AG1 and an 11.1% (p = 0.029) difference was seen between AG1 and W. Visual reaction time was significantly greater following AG1 (p = 0.014) compared to DHY. Differences (p = 0.045) in fatigue, as determined by player loads, were seen only between AG2 and DHY. No differences were seen in peak or mean vertical jump power during any trial.

Conclusion

Rehydration with AG appears to maintain basketball skill performance and visual reaction time to a greater extent than water only.

Examination of the efficacy of acute L-alanyl-L-glutamine ingestion during hydration stress in endurance exercise

BACKGROUND

The effect of acute L-alanyl-L-glutamine (AG; Sustamine) ingestion on performance changes and markers of fluid regulation, immune, inflammatory, oxidative stress, and recovery was examined in response to exhaustive endurance exercise, during and in the absence of dehydration.

METHODS

Ten physically active males (20.8 +/- 0.6 y; 176.8 +/- 7.2 cm; 77.4 +/- 10.5 kg; 12.3 +/- 4.6% body fat) volunteered to participate in this study. During the first visit (T1) subjects reported to the laboratory in a euhydrated state to provide a baseline (BL) blood draw and perform a maximal exercise test. In the four subsequent randomly ordered trials, subjects dehydrated to -2.5% of their baseline body mass. For T2, subjects achieved their goal weight and were not rehydrated. During T3 - T5, subjects reached their goal weight and then rehydrated to 1.5% of their baseline body mass by drinking either water (T3) or two different doses (T4 and T5) of the AG supplement (0.05 g.kg-1 and 0.2 g.kg-1, respectively). Subjects then exercised at a workload that elicited 75% of their VO2 max on a cycle ergometer. During T2 - T5 blood draws occurred once goal body mass was achieved (DHY), immediately prior to the exercise stress (RHY), and immediately following the exercise protocol (IP). Resting 24 hour (24P) blood samples were also obtained. Blood samples were analyzed for glutamine, potassium, sodium, aldosterone, arginine vasopressin (AVP), C-reactive protein (CRP), interleukin-6 (IL-6), malondialdehyde (MDA), testosterone, cortisol, ACTH, growth hormone and creatine kinase. Statistical evaluation of performance, hormonal and biochemical changes was accomplished using a repeated measures analysis of variance.

RESULTS

Glutamine concentrations for T5 were significantly higher at RHY and IP than T2 - T4. When examining performance changes (difference between T2 - T5 and T1), significantly greater times to exhaustion occurred during T4 (130.2 +/- 340.2 sec) and T5 (157.4 +/- 263.1 sec) compared to T2 (455.6 +/- 245.0 sec). Plasma sodium concentrations were greater (p < 0.05) at RHY and IP for T2 than all other trials. Aldosterone concentrations at RHY and IP were significantly lower than that at BL and DHY. AVP was significantly elevated at DHY, RHY and IP compared to BL measures. No significant differences were observed between trials in CRP, IL-6, MDA, or in any of the other hormonal or biochemical measures.

CONCLUSION

Results demonstrate that AG supplementation provided a significant ergogenic benefit by increasing time to exhaustion during a mild hydration stress. This ergogenic effect was likely mediated by an enhanced fluid and electrolyte uptake.