Changes in Skeletal Muscle Protein Metabolism Signaling Induced by Glutamine Supplementation and Exercise.

AIM: To evaluate the effects of resistance exercise training (RET) and/or glutamine supplementation (GS) on signaling protein synthesis in adult rat skeletal muscles. METHODS: The following groups were studied: (1) control, no exercise (C); (2) exercise, hypertrophy resistance exercise training protocol (T); (3) no exercise, supplemented with glutamine (G); and (4) exercise and supplemented with glutamine (GT). The rats performed hypertrophic training, climbing a vertical ladder with a height of 1.1 m at an 80° incline relative to the horizontal with extra weights tied to their tails. The RET was performed three days a week for five weeks. Each training session consisted of six ladder climbs. The extra weight load was progressively increased for each animal during each training session. The G groups received daily L-glutamine by gavage (one g per kilogram of body weight per day) for five weeks. The C group received the same volume of water during the same period. The rats were euthanized, and the extensor digitorum longus (EDL) muscles from both hind limbs were removed and immediately weighed. Glutamine and glutamate concentrations were measured, and histological, signaling protein contents, and mRNA expression analyses were performed. RESULTS: Supplementation with free L-glutamine increased the glutamine concentration in the EDL muscle in the C group. The glutamate concentration was augmented in the EDL muscles from T rats. The EDL muscle mass did not change, but a significant rise was reported in the cross-sectional area (CSA) of the fibers in the three experimental groups. The levels of the phosphorylated proteins (pAkt/Akt, pp70S6K/p70S6K, p4E-BP1/4E-BP1, and pS6/S6 ratios) were significantly increased in EDL muscles of G rats, and the activation of p4E-BP1 was present in T rats. The fiber CSAs of the EDL muscles in T, G, and GT rats were increased compared to the C group. These changes were accompanied by a reduction in the 26 proteasome activity of EDL muscles from T rats. CONCLUSION: Five weeks of GS and/or RET induced muscle hypertrophy, as indicated by the increased CSAs of the EDL muscle fibers. The increase in CSA was mediated via the upregulated phosphorylation of Akt, 4E-BP1, p70S6k, and S6 in G animals and 4E-BP1 in T animals. In the EDL muscles from T animals, a decrease in proteasome activity, favoring a further increase in the CSA of the muscle fibers, was reported.

Fish Oil Supplementation Improves the Repeated-Bout Effect and Redox Balance in 20-30-Year-Old Men Submitted to Strength Training.

Herein, we investigated the effect of fish oil supplementation combined with a strength-training protocol, for 6 weeks, on muscle damage induced by a single bout of strength exercise in untrained young men. Sixteen men were divided into two groups, supplemented or not with fish oil, and they were evaluated at the pre-training period and post-training period. We investigated changes before and 0, 24, and 48 h after a single hypertrophic exercise session. Creatine kinase (CK) and lactate dehydrogenase (LDH) activities, plasma interleukin-6 (IL-6) and C-reactive protein (CRP) levels, and the redox imbalance were increased in response to the single-bout session of hypertrophic exercises at baseline (pre-training period) and decreased during the post-training period in the control group due to the repeated-bout effect (RBE). The fish oil supplementation exacerbated this reduction and improved the redox state. In summary, our findings demonstrate that, in untrained young men submitted to a strength-training protocol, fish oil supplementation is ideal for alleviating the muscle injury, inflammation, and redox imbalance induced by a single session of intense strength exercises, highlighting this supplementation as a beneficial strategy for young men that intend to engage in strength-training programs.

Changes in skeletal muscle protein metabolism signaling induced by glutamine supplementation and esxercise

Aim: To evaluate the effects of resistance exercise training (RET) and/or glutamine supplementation (GS) on signaling protein synthesis in adult rat skeletal muscles. Methods: The following groups were studied: (1) control, no exercise (C); (2) exercise, hypertrophy resistance exercise training protocol (T); (3) no exercise, supplemented with glutamine (G); and (4) exercise and supplemented with glutamine (GT). The rats performed hypertrophic training, climbing a vertical ladder with a height of 1.1 m at an 80° incline relative to the horizontal with extra weights tied to their tails. The RET was performed three days a week for five weeks. Each training session consisted of six ladder climbs. The extra weight load was progressively increased for each animal during each training session. The G groups received daily L-glutamine by gavage (one g per kilogram of body weight per day) for five weeks. The C group received the same volume of water during the same period. The rats were euthanized, and the extensor digitorum longus (EDL) muscles from both hind limbs were removed and immediately weighed. Glutamine and glutamate concentrations were measured, and histological, signaling protein contents, and mRNA expression analyses were performed. Results: Supplementation with free L-glutamine increased the glutamine concentration in the EDL muscle in the C group. The glutamate concentration was augmented in the EDL muscles from T rats. The EDL muscle mass did not change, but a significant rise was reported in the cross-sectional area (CSA) of the fibers in the three experimental groups. The levels of the phosphorylated proteins (pAkt/Akt, pp70S6K/p70S6K, p4E-BP1/4E-BP1, and pS6/S6 ratios) were significantly increased in EDL muscles of G rats, and the activation of p4E-BP1 was present in T rats. The fiber CSAs of the EDL muscles in T, G, and GT rats were increased compared to the C group. These changes were accompanied by a reduction in the 26 proteasome activity of EDL muscles from T rats. Conclusion: Five weeks of GS and/or RET induced muscle hypertrophy, as indicated by the increased CSAs of the EDL muscle fibers. The increase in CSA was mediated via the upregulated phosphorylation of Akt, 4E-BP1, p70S6k, and S6 in G animals and 4E-BP1 in T animals. In the EDL muscles from T animals, a decrease in proteasome activity, favoring a further increase in the CSA of the muscle fibers, was reported.

Linseed Oil Attenuates Liver Inflammation, Fatty Acid Accumulation, and Lipid Distribution in Periportal and Perivenous Hepatocytes Induced by a High-Carbohydrate Diet in Mice.

We evaluated whether linseed oil (LO) modulates the effects of a high-carbohydrate diet (HCD) on liver inflammation, fatty acid (FA) accumulation, and lipid distribution in periportal and perivenous hepatocytes. The control group (control high-carbohydrate diet [HCD-C]) received an HCD with lard and soybean oil as the lipid source. The L10 and L100 groups received the HCD with 10% and 100% of LO as the lipid source, respectively. The animals were killed by decapitation before (day 0) and after receiving the diets. Liver FA composition, inflammation, and fibrogenesis gene expression were evaluated. Also, the percentage of lipid-occupied area in periportal end perivenous hepatocytes were measured. The L100 group exhibited a higher (P < .05) liver amount of omega-3 polyunsaturated FA (n-3 PUFA) and lower (P < .05) amounts of saturated FA (SFA), monounsaturated FA (MUFA), and omega-6 polyunsaturated FA (n-6 PUFA) compared with L10 or HCD-C mice. On day 56, interleukin 10 and type IV collagen gene expression were significantly upregulated and downregulated, respectively in L100. Also, the L100 group showed lower (P < .05) FA accumulation (i.e., total FA, SFA, MUFA, and n-6 PUFA). Also, L10 and L100 presented lower (P < .05) percentage of high lipid-containing portion in periportal and perivenous hepatocytes. We concluded that LO attenuation of liver inflammation promoted by an HCD is associated with increased liver n-3 PUFA levels, so modulating FA composition, deposition, and distribution in periportal and perivenous hepatocytes.

Evidence for a neuromuscular circuit involving hypothalamic interleukin-6 in the control of skeletal muscle metabolism.

Hypothalamic interleukin-6 (IL6) exerts a broad metabolic control. Here, we demonstrated that IL6 activates the ERK1/2 pathway in the ventromedial hypothalamus (VMH), stimulating AMPK/ACC signaling and fatty acid oxidation in mouse skeletal muscle. Bioinformatics analysis revealed that the hypothalamic IL6/ERK1/2 axis is closely associated with fatty acid oxidation- and mitochondrial-related genes in the skeletal muscle of isogenic BXD mouse strains and humans. We showed that the hypothalamic IL6/ERK1/2 pathway requires the α2-adrenergic pathway to modify fatty acid skeletal muscle metabolism. To address the physiological relevance of these findings, we demonstrated that this neuromuscular circuit is required to underpin AMPK/ACC signaling activation and fatty acid oxidation after exercise. Last, the selective down-regulation of IL6 receptor in VMH abolished the effects of exercise to sustain AMPK and ACC phosphorylation and fatty acid oxidation in the muscle after exercise. Together, these data demonstrated that the IL6/ERK axis in VMH controls fatty acid metabolism in the skeletal muscle.

Prefrontal Cortex and Hippocampus Inflammation in Mice Fed High-Carbohydrate or High-Fat Diets.

We previously reported that a high-carbohydrate diet (HCD) induced systemic inflammation and higher gene expression of proinflammatory mediators in the liver, skeletal muscle, and brain than a high-fat diet (HFD). However, the differences between the groups were less pronounced in the brain. In this study, we extended the evaluation of inflammation to specific areas of the brain. In this study, we evaluated the gene expression of caspase 2, caspase 3, caspase 9, cyclooxygenase-2 (Cox 2), inducible nitric oxide synthase (iNOS), interleukin (IL), IL-6, IL-1ß, IL-10, IL-4, tumor necrosis factor-alpha (TNF-α), integrin subunit alpha m (Itgam), S100 protein (S100), allograft inflammatory factor 1 (Aif1), and glial fibrillary acidic protein (Gfap) in the prefrontal cortex and hippocampus of male Swiss mice that were fed with HCD or HFD for 8 weeks. The HCD group exhibited higher IL-1ß expression, whereas the HFD group showed higher TNF-α expression in the prefrontal cortex. In the hippocampus, TNF-α expression was higher in the HFD group. IL-1ß and TNF-α are proinflammatory cytokines that have been associated with impaired brain function and numerous brain disorders. Our results indicate that both HCD and HFD promote prefrontal cortex inflammation; however, the hippocampus seems more sensitive to a HFD than HCD.

The Myristic Acid:Docosahexaenoic Acid Ratio Versus the n-6 Polyunsaturated Fatty Acid:n-3 Polyunsaturated Fatty Acid Ratio as Nonalcoholic Fatty Liver Disease Biomarkers.

It is well established that diets containing an increased omega-6 polyunsaturated fatty acid (n-6 PUFA) to omega-3 polyunsaturated fatty acid (n-3 PUFA) ratios are linked to inflammation and chronic diseases such as nonalcoholic fatty liver disease (NAFLD). However, the influence of an elevated n-6 PUFA:n-3 PUFA ratio in the tissues requires clarification. Herein, we identified primary experimental and clinical studies where it is possible to compare the performance of the myristic acid (Myr):docosahexaenoic acid (DHA) and n-6 PUFA:n-3 PUFA ratios in the liver and/or serum as potential NAFLD biomarkers. Articles were included if quantitative values of n-6 PUFA, n-3 PUFA, Myr, DHA, and information about liver inflammation or liver disease progression parameters were provided. Overall, most experimental (91.6%) and clinical studies (87.5%) reported higher Myr:DHA ratios associated with inflammation and/or NAFLD progression than the n-6 PUFA:n-3 PUFA ratio. We conclude that the Myr:DHA ratio represents a better biomarker of NAFLD than the n-6 PUFA:n-3 PUFA ratio. Future studies are necessary for verifying this observation.

Hydrolyzed whey protein enriched with glutamine dipeptide attenuates skeletal muscle damage and improves physical exhaustion test performance in triathletes.

Purpose: To investigate the effects of hydrolyzed whey protein enriched with glutamine dipeptide on the percentage of oxygen consumption, second ventilatory threshold, duration and total distance covered, and skeletal muscle damage during an exhaustion test in elite triathletes. Methods: The study was a randomized, double-blinded, placebo-controlled, crossover trial. Nine male triathletes performed a progressive incremental test on a treadmill ergometer (1.4 km h-1·3 min-1) 30 min after ingesting either 50 g of maltodextrin plus four tablets of 700 mg hydrolyzed whey protein enriched with 175 mg of glutamine dipeptide diluted in 250 ml of water (MGln) or four tablets of 700 mg maltodextrin plus 50 g maltodextrin diluted in 250 ml of water (M). Each athlete was submitted to the two dietary treatments and two corresponding exhaustive physical tests with an interval of one week between the interventions. The effects of the two treatments were then compared within the same athlete. Maximal oxygen consumption, percentage of maximal oxygen consumption, second ventilatory threshold, and duration and total distance covered were measured during the exhaustion test. Blood was collected before and immediately after the test for the determination of plasma lactate dehydrogenase (LDH) and creatine kinase (CK) activities and lactate concentration (also measured 6, 10, and 15 min after the test). Plasma cytokines (IL-6, IL-1ß, TNF-α, IL-8, IL-10, and IL-1ra) and C-reactive protein levels were also measured. Results: A single dose of MGln increased the percentage of maximal oxygen consumption, second ventilatory threshold duration, and total distance covered during the exhaustion test and augmented plasma lactate levels 6 and 15 min after the test. MGln also decreased plasma LDH and CK activities indicating muscle damage protection. Plasma cytokine and C-reactive protein levels did not change across the study periods. Conclusion: Conditions including overnight fasting and a single dose of MGln supplementation resulted in exercising at a higher percentage of maximal oxygen consumption, a higher second ventilatory threshold, blood lactate levels, and reductions in plasma markers of muscle damage during an exhaustion test in elite triathletes. These findings support oral glutamine supplementation's efficacy in triathletes, but further studies require.

Prefrontal cortex and hippocampus inflammation in mice fed high-carbohydrate or high-fat diets

We previously reported that a high-carbohydrate diet (HCD) induced systemic inflammation and higher gene expression of proinflammatory mediators in the liver, skeletal muscle, and brain than a high-fat diet (HFD). However, the differences between the groups were less pronounced in the brain. In this study, we extended the evaluation of inflammation to specific areas of the brain. In this study, we evaluated the gene expression of caspase 2, caspase 3, caspase 9, cyclooxygenase-2 (Cox 2), inducible nitric oxide synthase (iNOS), interleukin (IL), IL-6, IL-1β, IL-10, IL-4, tumor necrosis factor-alpha (TNF-α), integrin subunit alpha m (Itgam), S100 protein (S100), allograft inflammatory factor 1 (Aif1), and glial fibrillary acidic protein (Gfap) in the prefrontal cortex and hippocampus of male Swiss mice that were fed with HCD or HFD for 8 weeks. The HCD group exhibited higher IL-1β expression, whereas the HFD group showed higher TNF-α expression in the prefrontal cortex. In the hippocampus, TNF-α expression was higher in the HFD group. IL-1β and TNF-α are proinflammatory cytokines that have been associated with impaired brain function and numerous brain disorders. Our results indicate that both HCD and HFD promote prefrontal cortex inflammation; however, the hippocampus seems more sensitive to a HFD than HCD.

Endoplasmic Reticulum Stress and Autophagy Markers in Soleus Muscle Disuse-Induced Atrophy of Rats Treated with Fish Oil.

Endoplasmic reticulum stress (ERS) and autophagy pathways are implicated in disuse muscle atrophy. The effects of high eicosapentaenoic (EPA) or high docosahexaenoic (DHA) fish oils on soleus muscle ERS and autophagy markers were investigated in a rat hindlimb suspension (HS) atrophy model. Adult Wistar male rats received daily by gavage supplementation (0.3 mL per 100 g b.w.) of mineral oil or high EPA or high DHA fish oils (FOs) for two weeks. Afterward, the rats were subjected to HS and the respective treatments concomitantly for an additional two-week period. After four weeks, we evaluated ERS and autophagy markers in the soleus muscle. Results were analyzed using two-way analysis of variance (ANOVA) and Bonferroni post hoc test. Gastrocnemius muscle ω-6/ω-3 fatty acids (FAs) ratio was decreased by both FOs indicating the tissue incorporation of omega-3 fatty acids. HS altered (p < 0.05) the protein content (decreasing total p38 and BiP and increasing p-JNK2/total JNK2 ratio, and caspase 3) and gene expressions (decreasing BiP and increasing IRE1 and PERK) of ERS and autophagy (decreasing Beclin and increasing LC3 and ATG14) markers in soleus. Both FOs attenuated (p < 0.05) the increase in PERK and ATG14 expressions induced by HS. Thus, both FOs could potentially attenuate ERS and autophagy in skeletal muscles undergoing atrophy.

Macrophage inflammatory state in Type 1 diabetes: triggered by NLRP3/iNOS pathway and attenuated by docosahexaenoic acid.

Type 1 diabetes mellitus (T1D) is a chronic autoimmune disease characterized by insulin-producing pancreatic ß-cell destruction and hyperglycemia. While monocytes and NOD-like receptor family-pyrin domain containing 3 (NLRP3) are associated with T1D onset and development, the specific receptors and factors involved in NLRP3 inflammasome activation remain unknown. Herein, we evaluated the inflammatory state of resident peritoneal macrophages (PMs) from genetically modified non-obese diabetic (NOD), NLRP3-KO, wild-type (WT) mice and in peripheral blood mononuclear cells (PBMCs) from human T1D patients. We also assessed the effect of docosahexaenoic acid (DHA) on the inflammatory status. Macrophages from STZ-induced T1D mice exhibited increased inflammatory cytokine/chemokine levels, nitric oxide (NO) secretion, NLRP3 and iNOS protein levels, and augmented glycolytic activity compared to control animals. In PMs from NOD and STZ-induced T1D mice, DHA reduced NO production and attenuated the inflammatory state. Furthermore, iNOS and IL-1ß protein expression levels and NO production were lower in the PMs from diabetic NLRP3-KO mice than from WT mice. We also observed increased IL-1ß secretion in PBMCs from T1D patients and immortalized murine macrophages treated with advanced glycation end products and palmitic acid. The present study demonstrated that the resident PMs are in a proinflammatory state characterized by increased NLRP3/iNOS pathway-mediated NO production, up-regulated proinflammatory cytokine/chemokine receptor expression and altered glycolytic activity. Notably, ex vivo treatment with DHA reverted the diabetes-induced changes and attenuated the macrophage inflammatory state. It is plausible that DHA supplementation could be employed as adjuvant therapy for treating individuals with T1D.

Decreased Docosahexaenoic Acid Levels in Serum of HIV Carrier Patients.

The study aimed to measure serum fatty acids (FAs) composition in HIV carrier patients and compare it with non-HIV carrier patients. The FAs composition was measured by gas chromatography as follows: four saturated FAs myristic acid (14:0), palmitic acid (16:0), stearic acid (18:0), and docosanoic acid (22:0); four monounsaturated FAs 7-hexadecenoic acid (16:1 n-9), palmitoleic acid (16:1 n-7), oleic acid (18:1 n-9), and vaccenic acid (18:1 n-7); and three polyunsaturated FAs linoleic acid (18:2 n-6), dihomo-γ-linolenic acid (20:3 n-6), and docosahexaenoic acid (DHA, 22:6 n-3). We reported herein lower (P < .05) DHA concentration (by 40%) in the serum of HIV carrier patients than in non-HIV carrier patients. This FA has a pivotal role as a precursor of anti-inflammatory molecules with beneficial effects on metabolism, cardiovascular system, and immunological system. Even though most clinical studies reported beneficial effects of DHA supplementation in HIV carrier patients, this issue remains under debate. Further investigations then require to fully clarify the role of DHA in preventing or alleviating the comorbidities associated with HIV infection.

Endoplasmic reticulum stress and autophagy markers in Soleus muscle disuse-induced atrophy of rats treated with fish oil

Endoplasmic reticulum stress (ERS) and autophagy pathways are implicated in disuse muscle atrophy. The effects of high eicosapentaenoic (EPA) or high docosahexaenoic (DHA) fish oils on soleus muscle ERS and autophagy markers were investigated in a rat hindlimb suspension (HS) atrophy model. Adult Wistar male rats received daily by gavage supplementation (0.3 mL per 100 g b.w.) of mineral oil or high EPA or high DHA fish oils (FOs) for two weeks. Afterward, the rats were subjected to HS and the respective treatments concomitantly for an additional two-week period. After four weeks, we evaluated ERS and autophagy markers in the soleus muscle. Results were analyzed using two-way analysis of variance (ANOVA) and Bonferroni post hoc test. Gastrocnemius muscle ω-6/ω-3 fatty acids (FAs) ratio was decreased by both FOs indicating the tissue incorporation of omega-3 fatty acids. HS altered (p < 0.05) the protein content (decreasing total p38 and BiP and increasing p-JNK2/total JNK2 ratio, and caspase 3) and gene expressions (decreasing BiP and increasing IRE1 and PERK) of ERS and autophagy (decreasing Beclin and increasing LC3 and ATG14) markers in soleus. Both FOs attenuated (p < 0.05) the increase in PERK and ATG14 expressions induced by HS. Thus, both FOs could potentially attenuate ERS and autophagy in skeletal muscles undergoing atrophy.

Macrophage inflammatory state in Type 1 diabetes: triggered by NLRP3/iNOS pathway and attenuated by docosahexaenoic acid

Type 1 diabetes mellitus (T1D) is a chronic autoimmune disease characterized by insulin-producing pancreatic β-cell destruction and hyperglycemia. While monocytes and NOD-like receptor family-pyrin domain containing 3 (NLRP3) are associated with T1D onset and development, the specific receptors and factors involved in NLRP3 inflammasome activation remain unknown. Herein, we evaluated the inflammatory state of resident peritoneal macrophages (PMs) from genetically modified non-obese diabetic (NOD), NLRP3-KO, wild-type (WT) mice and in peripheral blood mononuclear cells (PBMCs) from human T1D patients. We also assessed the effect of docosahexaenoic acid (DHA) on the inflammatory status. Macrophages from STZ-induced T1D mice exhibited increased inflammatory cytokine/chemokine levels, nitric oxide (NO) secretion, NLRP3 and iNOS protein levels, and augmented glycolytic activity compared to control animals. In PMs from NOD and STZ-induced T1D mice, DHA reduced NO production and attenuated the inflammatory state. Furthermore, iNOS and IL-1β protein expression levels and NO production were lower in the PMs from diabetic NLRP3-KO mice than from WT mice. We also observed increased IL-1β secretion in PBMCs from T1D patients and immortalized murine macrophages treated with advanced glycation end products and palmitic acid. The present study demonstrated that the resident PMs are in a proinflammatory state characterized by increased NLRP3/iNOS pathway-mediated NO production, up-regulated proinflammatory cytokine/chemokine receptor expression and altered glycolytic activity. Notably, ex vivo treatment with DHA reverted the diabetes-induced changes and attenuated the macrophage inflammatory state. It is plausible that DHA supplementation could be employed as adjuvant therapy for treating individuals with T1D.

The Dietary Replacement of Soybean Oil by Canola Oil Does Not Prevent Liver Fatty Acid Accumulation and Liver Inflammation in Mice.

A high-carbohydrate diet (HCD) is a well-established experimental model of accelerated liver fatty acid (FA) deposition and inflammation. In this study, we evaluated whether canola oil can prevent these physiopathological changes. We evaluated hepatic FA accumulation and inflammation in mice fed with a HCD (72.1% carbohydrates) and either canola oil (C group) or soybean oil (S group) as a lipid source for 0, 7, 14, 28, or 56 days. Liver FA compositions were analyzed by gas chromatography. The mRNA expression of acetyl-CoA carboxylase 1 (ACC1) was measured as an indicator of lipogenesis. The mRNA expression of F4/80, tumor necrosis factor-α (TNF-α), interleukin (IL)-1ß, IL-6, and IL-10, as mediators of liver inflammation, were also measured. The C group stored less n-6 polyunsaturated FAs (n-6 PUFAs) and had more intense lipid deposition of monounsaturated FAs (MUFAs), n-3 PUFAs, and total FAs. The C group also showed higher ACC1 expression. Moreover, on day 56, the C group showed higher expressions of the inflammatory genes F4/80, TNF-α, IL-1ß, and IL-6, as well as the anti-inflammatory IL-10. In conclusion, a diet containing canola oil as a lipid source does not prevent the fatty acid accumulation and inflammation induced by a HCD.

Glutamine depletion disrupts mitochondrial integrity and impairs C2C12 myoblast proliferation, differentiation, and the heat-shock response.

Glutamine and glucose are both oxidized in the mitochondria to supply the majority of usable energy for processes of cellular function. Low levels of plasma and skeletal muscle glutamine are associated with severe illness. We hypothesized that glutamine deficiency would disrupt mitochondrial integrity and impair cell function. C2C12 mouse myoblasts were cultured in control media supplemented with 5.6 mmol/L glucose and 2 mmol/L glutamine, glutamine depletion (Gln-) or glucose depletion (Glc-) media. We compared mitochondrial morphology and function, as well as cell proliferation, myogenic differentiation, and heat-shock response in these cells. Glc- cells exhibited slightly elongated mitochondrial networks and increased mitochondrial mass, with normal membrane potential (ΔΨm). Mitochondria in Gln- cells became hyperfused and swollen, which were accompanied by severe disruption of cristae and decreases in ΔΨm, mitochondrial mass, the inner mitochondrial membrane remodeling protein OPA1, electron transport chain complex IV protein expression, and markers of mitochondrial biogenesis and bioenergetics. In addition, Gln- increased the autophagy marker LC3B-II on the mitochondrial membrane. Notably, basal mitochondrial respiration was increased in Glc- cells as compared to control cells, whereas maximal respiration remained unchanged. In contrast, basal respiration, maximal respiration and reserve capacity were all decreased in Gln- cells. Consistent with the aforementioned mitochondrial deficits, Gln- cells had lower growth rates and myogenic differentiation, as well as a higher rate of cell death under heat stress conditions than Glc- and control cells. We conclude that glutamine is essential for mitochondrial integrity and function; glutamine depletion impairs myoblast proliferation, differentiation, and the heat-shock response.

Effervescent Glutamine Formulation Improves the Beneficial Effects of Antiretroviral Therapies on Immune Function in HIV/AIDS Carrier Patients.

The impact of oral supplementation with an effervescent glutamine formulation on the beneficial effects of antiretroviral therapies was evaluated in people living with HIV/AIDS. For this purpose, 12 HIV/AIDS carrier patients with CD4+ T cell counts <500, and who had received the same antiretroviral therapy for at least 1 year before starting this investigation were selected. The patients were required to dissolve the effervescent glutamine formulation (supplied in sachets) in water immediately before oral ingestion (12.4 g), once a day, after lunch or after dinner during 30 days. CD4+ T cell counts, complete blood cell counts, serum cytokines, and amino acids levels were quantified; biochemical and toxicological measurements were performed. The numbers of CD4+ T cells were increased (P < .05), and the serum C-reactive protein levels decreased (P < .01) after the administration of effervescent glutamine formulation. Serum levels of interferon-gamma inducible protein-10, RANTES, and macrophage inflammatory protein-1ß were decreased after the treatment with effervescent glutamine formulation. No changes were observed in the serum levels of amino acids, hematological, toxicological, and biochemical parameters. In conclusion, the treatment during 30 days with effervescent glutamine formulation was well tolerated, promoted reduction of inflammation, and improved the beneficial effects of antiretroviral therapies in HIV/AIDS carrier patients.

Glutamine supplementation versus functional overload in extensor digitorum longus muscle hypertrophy

Background Glutamine levels directly associate with total protein content in cultured skeletal muscle cells, whereas glutamine supplementation enhances skeletal muscle mass in catabolic experimental conditions. Methods We compared the effect of glutamine administration on Extensor Digitorum Longus muscle (EDL) weight, fiber cross-sectional area (CSA), contractile activity, and protein metabolism signaling with a functional overload-induced skeletal muscle hypertrophy protocol. Results Glutamine supplementation raised the predominance of EDL muscle fibers with CSA between 1001 and 2000 μm2 (49.7 %), the p-4E-BP1/total 4E-BP1 ratio, and the effect of overload on resistance to fatigue. The proportion of the EDL muscle fiber CSA distribution for the combination of both treatments was similar to that induced by overload or glutamine separately; 54.3 % muscle fibers with CSA between 1001 and 2000 μm². Glutamine supplementation did not markedly affect the changes induced by overload on protein synthesis signaling pathways, except for a further increase of the p-4E-BP1/total 4E-BP1 ratio. Conclusions The effect of glutamine on EDL muscle fiber CSA distribution and protein synthesis signaling mimicked the response to overload. The association of glutamine and overload induced EDL muscle hypertrophy further increased the resistance to fatigue.

Decreased Docosahexaenoic acid levels in serum of HIV carrier patients

The study aimed to measure serum fatty acids (FAs) composition in HIV carrier patients and compare it with non-HIV carrier patients. The FAs composition was measured by gas chromatography as follows: four saturated FAs myristic acid (14:0), palmitic acid (16:0), stearic acid (18:0), and docosanoic acid (22:0); four monounsaturated FAs 7-hexadecenoic acid (16:1 n-9), palmitoleic acid (16:1 n-7), oleic acid (18:1 n-9), and vaccenic acid (18:1 n-7); and three polyunsaturated FAs linoleic acid (18:2 n-6), dihomo-γ-linolenic acid (20:3 n-6), and docosahexaenoic acid (DHA, 22:6 n-3). We reported herein lower (P < .05) DHA concentration (by 40%) in the serum of HIV carrier patients than in non-HIV carrier patients. This FA has a pivotal role as a precursor of anti-inflammatory molecules with beneficial effects on metabolism, cardiovascular system, and immunological system. Even though most clinical studies reported beneficial effects of DHA supplementation in HIV carrier patients, this issue remains under debate. Further investigations then require to fully clarify the role of DHA in preventing or alleviating the comorbidities associated with HIV infection.

Oral L-glutamine pretreatment attenuates skeletal muscle atrophy induced by 24-h fasting in mice.

L-Glutamine (L-Gln) supplementation has been pointed out as an anticatabolic intervention, but its effects on protein synthesis and degradation signaling in skeketal muscle are still poorly known. The effects of L-Gln pretreatment (1 g kg-1 day-1 body weight for 10 days) on muscle fiber cross-sectional area (CSA), amino acid composition (measured by LC-MS/MS) and protein synthesis (Akt-mTOR) and degradation (ubiquitin ligases) signaling in soleus and extensor digitorum longus (EDL) muscles in 24-h-fasted mice were investigated. The fiber CSA of EDL muscle was not different between the L-Gln-fasted and L-Gln-fed groups. This finding was associated with reduced contents of L-Leu and L-Iso and activation of protein synthesis signaling (p-RPS6Ser240/244 and Akt-mTOR). The spectrum of soleus muscle fiber CSA distribution was larger in L-Gln-fasted as compared with placebo-fasted mice. This effect of L-Gln pretreatment was associated with changes in red fibers L-Gln metabolism as indicated by increased intracellular L-glutamine/L-glutamate ratio, L-aspartate and GABA levels. L-Gln supplementation reduced fasting-induced mass loss in tibialis anterior and gastrocnemius muscles. Evidence is presented that pretreatment with L-glutamine attenuates skeletal muscle atrophy induced by 24-h fasting through mechanisms that vary with the muscle fiber type.