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.

Characterization of muscle mass, strength and mobility of critically ill patients with SARS-CoV-2 pneumonia: Distribution by sex, age, days on mechanical ventilation, and muscle weakness.

Objective: Quantify and categorize by sex, age, and time spent on mechanical ventilation (MV), the decline in skeletal muscle mass, strength and mobility in critically ill patients infected with SARS-CoV-2 and requiring mechanical ventilation while at intensive care unit (ICU). Design: Prospective observational study including participants recruited between June 2020 and February 2021 at Hospital Clínico Herminda Martin (HCHM), Chillán, Chile. The thickness of the quadriceps muscle was evaluated by ultrasonography (US) at intensive care unit admission and awakening. Muscle strength and mobility were assessed, respectively, through the Medical Research Council Sum Score (MRC-SS) and the Functional Status Score for the Intensive Care Unit Scale (FSS-ICU) both at awakening and at ICU discharge. Results were categorized by sex (female or male), age (<60 years old or ≥60 years old) and time spent on MV (≤10 days or >10 days). Setting: Intensive care unit in a public hospital. Participants: 132 participants aged 18 years old or above (women n = 49, 60 ± 13 years; men n = 85, 59 ± 12 years) admitted to intensive care unit with a confirmed diagnosis of severe SARS-CoV-2 and requiring MV for more than 48 h were included in the study. Patients with previous physical and or cognitive disorders were excluded. Interventions: Not applicable. Results: Muscle thickness have significantly decreased during intensive care unit stay, vastus intermedius (-11%; p = 0.025), rectus femoris (-20%; p < 0.001) and total quadriceps (-16%; p < 0.001). Muscle strength and mobility were improved at intensive care unit discharge when compared with measurements at awakening in intensive care unit (time effect, p < 0.001). Patients ≥60 years old or on MV for >10 days presented greater muscle loss, alongside with lower muscle strength and mobility. Conclusion: Critically ill patients infected with SARS-CoV-2 and requiring MV presented decreased muscle mass, strength, and mobility during their intensive care unit stay. Factors associated with muscle mass, such as age >60 years and >10 days of MV, exacerbated the critical condition and impaired recovery.

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.

Molecular and cellular mechanisms involved in tissue-specific metabolic modulation by SARS-CoV-2.

Coronavirus disease 2019 (COVID-19) is triggered by the SARS-CoV-2, which is able to infect and cause dysfunction not only in lungs, but also in multiple organs, including central nervous system, skeletal muscle, kidneys, heart, liver, and intestine. Several metabolic disturbances are associated with cell damage or tissue injury, but the mechanisms involved are not yet fully elucidated. Some potential mechanisms involved in the COVID-19-induced tissue dysfunction are proposed, such as: (a) High expression and levels of proinflammatory cytokines, including TNF-α IL-6, IL-1ß, INF-α and INF-ß, increasing the systemic and tissue inflammatory state; (b) Induction of oxidative stress due to redox imbalance, resulting in cell injury or death induced by elevated production of reactive oxygen species; and (c) Deregulation of the renin-angiotensin-aldosterone system, exacerbating the inflammatory and oxidative stress responses. In this review, we discuss the main metabolic disturbances observed in different target tissues of SARS-CoV-2 and the potential mechanisms involved in these changes associated with the tissue dysfunction.

Maternal low-protein diet reduces skeletal muscle protein synthesis and mass via Akt-mTOR pathway in adult rats.

Several studies have demonstrated that a maternal low-protein diet induces long-term metabolic disorders, but the involved mechanisms are unclear. This study investigated the molecular effects of a low-protein diet during pregnancy and lactation on glucose and protein metabolism in soleus muscle isolated from adult male rats. Female rats were fed either a normal protein diet or low-protein diet during gestation and lactation. After weaning, all pups were fed a normal protein diet until the 210th day postpartum. In the 7th month of life, mass, contractile function, protein and glucose metabolism, and the Akt-mTOR pathway were measured in the soleus muscles of male pups. Dry weight and contractile function of soleus muscle in the low-protein diet group rats were found to be lower compared to the control group. Lipid synthesis was evaluated by measuring palmitate incorporation in white adipose tissue. Palmitate incorporation was higher in the white adipose tissue of the low-protein diet group. When incubated soleus muscles were stimulated with insulin, protein synthesis, total amino acid incorporation and free amino acid content, glucose incorporation and uptake, and glycogen synthesis were found to be reduced in low-protein diet group rats. Fasting glycemia was higher in the low-protein diet group. These metabolic changes were associated with a decrease in Akt and GSK-3ß signaling responses to insulin and a reduction in RPS6 in the absence of the hormone. There was also notably lower expression of Akt in the isolated soleus muscle of low-protein diet group rats. This study is the first to demonstrate how maternal diet restriction can reduce skeletal muscle protein and mass by downregulating the Akt-mTOR pathway in adulthood.

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.

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.

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.

Effectiveness of short-term physical agents treatment on macroscopic morphology in patients with plaque psoriasis / Efectividad del tratamiento a corto plazo de los agentes físicos en la morfología macroscópica de las placas de psoriasis

Psoriasis is a chronic inflammatory disease that presents skin rashes which can arise through plaques. The aim of this work was to compare the effectiveness of short-term physical agents treatment on macroscopic morphology (area and erythema) in patients with plaque psoriasis. This prospective randomized experimental study included fourteen subjects, medically diagnosed with psoriasis, with more than one plaque in the skin and voluntarily without topical treatment. All subjects completed the study that consisted of 12 treatment sessions divided in control (C), artificial balneotherapy (AB), phototherapy (PT) or balneophototherapy (BPT) groups. After session 12, there was a significant reduction of the plaque area by all treatments when compared to C group and BPT was the most effective one. However, only AB and PT presented a reduction of erythema. Regarding severity, 9 patients changed to a lower category on the PASI test, and 5 of them maintained a mild psoriasis, but lowered their score. Finally, 13 of 14 subjects improved their quality of life. The physical agents used reduced the severity of psoriasis and improved quality of life of patients after 12 sessions of treatment during a onemonth period. The BPT was the more effective in controlling psoriasis by diminishing its area and PT by attenuating the erythema.

La Psoriasis es una enfermedad inflamatoria crónica que presenta irritación cutánea que puede derivar a placas. El objetivo de este trabajo fue comparar la efectividad del tratamiento a corto plazo con agentes físicos en la morfología macroscópica (área y eritema) en pacientes con placas de psoriasis. Estudio experimental, prospectivo, randomizado. Catorce sujetos participaron con diagnóstico médico de psoriasis, con más de una placa en la piel y sin tener tratamiento tópico de forma voluntaria. Todos los sujetos completaron el estudio, el cual consistió de 12 sesiones de tratamiento dividido en grupo control (C), BA, FT y BFA. Posterior a la sesión 12, se observó una reducción significativa en toda el área de las placas que recibieron tratamiento al compararlas al grupo C y el grupo BFA fue el más efectivo. Sin embargo, solo los grupos BA y FT presentaron una reducción del eritema. Respecto a la severidad, 9 pacientes cambiaron de la baja categoría en el test de PASI y 5 de ellos se mantuvieron en el nivel medio, pero disminuyeron su puntaje. Finalmente, 13 de 14 sujetos mejoraron su calidad de vida. Los agentes físicos usados redujeron la severidad de la psoriasis y mejoraron la calidad de vida de los pacientes después de 12 sesiones de tratamiento durante el período de un mes. La BFA fue la más efectiva en controlar la psoriasis por la disminución en el área y la FT por la atenuación del eritema.

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.

Experimental Model of HindLimb Suspension-Induced Skeletal Muscle Atrophy in Rodents.

Due to the difficulty of performing research protocols that reproduce human skeletal muscle disuse conditions, an experimental animal model of "hindlimb suspension" (or hindlimb unloading) was developed. This method was created in the 1970s and utilizes rats and mice to mimic space flight and bed rest in humans. It provides an alternative to investigate mechanisms associated with skeletal muscle mass loss and interventions designed to attenuate atrophy induced by hindlimb unloading. The mentioned protocol also allows investigating quality of bones and changes in several physiological parameters such as blood pressure, heart rate, plasma or tissue lipid composition, and glycemia.

Sarcomere structure: the importance of desmin protein in muscle atrophy / Estructura de sarcómera: la importancia de proteína desmina en atrofia muscular

Knowing the ultrastructure of skeletal muscle is critical to understand how it works under normal situation and the disorders caused by extreme or pathological conditions. Sarcomere is the basic structural unit of striated muscle tissue. An important element of sarcomere architecture are the intermediate filaments, including the desmin protein. Desmin protein contributes to maintenance of cell integrity, efficient transmission of force and mechanochemical signaling within the myocyte. Because of this, desmin protein has constantly been a focus of research that investigates its alterations associated to damage and muscle atrophy under different conditions. The purpose of the following literature review is to describe the basic concepts of muscle ultrastructure, emphasizing the desmin protein role under conditions of muscle disuse atrophy and aging.

Conocer la ultraestructura del músculo esquelético es crítico para entender cómo trabaja bajo situaciones normales y en desórdenes causados por condiciones extremas o patológicas. La sarcómera es la unidad de estructura básica del tejido muscular estriado. Elementos importantes en la arquitectura de la sarcómera son los filamentos intermedios, incluyendo la proteína desmina. La proteína desmina contribuye en mantener la integridad celular, la transmisión eficiente de fuerza y la señalización mecanoquímica dentro del miocito. Debido a lo anterior, la proteína desmina ha sido constante foco de investigación en trabajos que estudian sus alteraciones asociadas a daño y atrofia muscular bajo diferentes condiciones. El propósito de la siguiente revisión de la literatura es describir los conceptos básicos de la ultraestructura muscular, enfatizando en el rol de la proteína desmina bajo condiciones de atrofia muscular por desuso y envejecimiento.

Balanced Diet-Fed Fat-1 Transgenic Mice Exhibit Lower Hindlimb Suspension-Induced Soleus Muscle Atrophy.

The consequences of two-week hindlimb suspension (HS) on skeletal muscle atrophy were investigated in balanced diet-fed Fat-1 transgenic and C57BL/6 wild-type mice. Body composition and gastrocnemius fatty acid composition were measured. Skeletal muscle force, cross-sectional area (CSA), and signaling pathways associated with protein synthesis (protein kinase B, Akt; ribosomal protein S6, S6, eukaryotic translation initiation factor 4E-binding protein 1, 4EBP1; glycogen synthase kinase3-beta, GSK3-beta; and extracellular-signal-regulated kinases 1/2, ERK 1/2) and protein degradation (atrophy gene-1/muscle atrophy F-box, atrogin-1/MAFbx and muscle RING finger 1, MuRF1) were evaluated in the soleus muscle. HS decreased soleus muscle wet and dry weights (by 43% and 26%, respectively), muscle isotonic and tetanic force (by 29% and 18%, respectively), CSA of the soleus muscle (by 36%), and soleus muscle fibers (by 45%). Fat-1 transgenic mice had a decrease in the ω-6/ω-3 polyunsaturated fatty acids (PUFAs) ratio as compared with C57BL/6 wild-type mice (56%, p < 0.001). Fat-1 mice had lower soleus muscle dry mass loss (by 10%) and preserved absolute isotonic force (by 17%) and CSA of the soleus muscle (by 28%) after HS as compared with C57BL/6 wild-type mice. p-GSK3B/GSK3B ratio was increased (by 70%) and MuRF-1 content decreased (by 50%) in the soleus muscle of Fat-1 mice after HS. Balanced diet-fed Fat-1 mice are able to preserve in part the soleus muscle mass, absolute isotonic force and CSA of the soleus muscle in a disuse condition.

Iodine excess exposure during pregnancy and lactation impairs maternal thyroid function in rats.

Adequate maternal iodine consumption during pregnancy and lactation guarantees normal thyroid hormones (TH) production, which is crucial to the development of the fetus. Indeed, iodine deficiency is clearly related to maternal hypothyroidism and deleterious effects in the fetal development. Conversely, the effects of iodine excess (IE) consumption on maternal thyroid function are still controversial. Therefore, this study aimed to investigate the impact of IE exposure during pregnancy and lactation periods on maternal hypothalamus-pituitary-thyroid axis. IE-exposed dams presented reduced serum TH concentration and increased serum thyrotropin (TSH) levels. Moreover, maternal IE exposure increased the hypothalamic expression of Trh and the pituitary expression of Trhr, Dio2, Tsha and Tshb mRNA, while reduced the Gh mRNA content. Additionally, IE-exposed dams presented thyroid morphological alterations, increased thyroid oxidative stress and decreased expression of thyroid genes/proteins involved in TH synthesis, secretion and metabolism. Furthermore, Dio1 mRNA expression and D1 activity were reduced in the liver and the kidney of IE-treated animals. Finally, the mRNA expression of Slc5a5 and Slc26a4 were reduced in the mammary gland of IE-exposed rats. The latter results are in accordance with the reduction of prolactin expression and serum levels in IE-treated dams. In summary, our study indicates that the exposure to IE during pregnancy and lactation induces primary hypothyroidism in rat dams and impairs iodide transfer to the milk.

Oral administration of antioxidants improves skin wound healing in diabetic mice.

Oxidative stress aggravates several long-term complications in diabetes mellitus. We evaluated the effectiveness of the oral administration of antioxidants (vitamins E and C, 40 and 100 mg/kg b.w., respectively) on skin wound healing acceleration in alloxan-induced diabetic mice. Mice were wounded 30 days after the induction of diabetes. Antioxidants were effective in preventing oxidative stress, as assessed by TBARS. The enzymes catalase, glutathione reductase, glutathione peroxidase, and superoxide dismutase were increased in diabetics on the 3rd day post-wounding; catalase and glutathione peroxidase remained still augmented in diabetics after 14th day postwounding, and the treatment with vitamins restored their activities to control. After 3 days, diabetic mice showed lower infiltration of inflammatory cells (including CD11b+ and Ly6G+ cells) and reduced levels of KC, TNF-α, IL-1ß, and IL-12 p40 when compared with control mice. The treatment restored cytokine levels. After 14 days, diabetic mice showed late wound closure, persistent inflammation and delayed reepithelialization, accompanied by an increase in MIG+ /CD206- macrophages whereas CD206+ /MIG- macrophages were decreased. Cytokines IL-12p40, TNF-α, IL-1ß, and KC were increased and normal levels were restored after treatment with antioxidants. These results suggest that oxidative stress plays a major role in diabetic wound healing impairment and the oral administration of antioxidants improves healing by modulating inflammation and the antioxidant system with no effect on glycemia.

Effects of high EPA and high DHA fish oils on changes in signaling associated with protein metabolism induced by hindlimb suspension in rats.

The effects of either eicosapentaenoic (EPA)- or docosahexaenoic (DHA)-rich fish oils on hindlimb suspension (HS)-induced muscle disuse atrophy were compared. Daily oral supplementations (0.3 mL/100 g b.w.) with mineral oil (MO) or high EPA or high DHA fish oils were performed in adult rats. After 2 weeks, the animals were subjected to HS for further 2 weeks. The treatments were maintained alongside HS At the end of 4 weeks, we evaluated: body weight gain, muscle mass and fat depots, composition of fatty acids, cross-sectional areas (CSA) of the soleus muscle and soleus muscle fibers, activities of cathepsin L and 26S proteasome, and content of carbonylated proteins in the soleus muscle. Signaling pathway activities associated with protein synthesis (Akt, p70S6K, S6, 4EBP1, and GSK3-beta) and protein degradation (atrogin-1/MAFbx, and MuRF1) were evaluated. HS decreased muscle mass, CSA of soleus muscle and soleus muscle fibers, and altered signaling associated with protein synthesis (decreased) and protein degradation (increased). The treatment with either fish oil decreased the ratio of omega-6/omega-3 fatty acids and changed protein synthesis-associated signaling. EPA-rich fish oil attenuated the changes induced by HS on 26S proteasome activity, CSA of soleus muscle fibers, and levels of p-Akt, total p70S6K, p-p70S6K/total p70S6K, p-4EBP1, p-GSK3-beta, p-ERK2, and total ERK 1/2 proteins. DHA-rich fish oil attenuated the changes induced by HS on p-4EBP1 and total ERK1 levels. The effects of EPA-rich fish oil on protein synthesis signaling were more pronounced. Both EPA- and DHA-rich fish oils did not impact skeletal muscle mass loss induced by non-inflammatory HS.

Heat transfer by three types of hot pack and its implication on the flexibility of the lower back: a randomized, controlled trial / Transferência de calor por três tipos de compressas quentes e sua implicação na flexibilidade da região lombar: ensaio clínico randomizado e controlado / Transferencia de calor por tres tipos de compresas calientes y su implicación en la flexibilidad en la región lumbar: ensayo clínico aleatorio y controlado

ABSTRACT The use of hot pack is a common superficial thermotherapy strategy and one of its benefits is the increase of muscle flexibility. However, there is a lack of information about the effects of the heat pack alone, without being used in association with other therapeutic interventions, in the flexibility of the lumbar region. The aim of this study was to compare the effects generated by the application of three different pack on the flexibility of the lower backs of healthy students. Three sessions of 15 minutes of superficial heat through a hot pack (moist heat pack-MHP, seed pack-SP or gel pack-GP) were applied to the lower back. Pack and lower back temperatures and erythema were registered every 5 minutes. A Schober test was performed before the first session and after the third session. After 15 minutes of treatment, pack temperature was higher in the SP group. At the same time, lumbar temperature was lower in the GP group. The heat treatment also increased erythema in the lower back for all three groups. There was a significant increase in intragroup flexibility as assessed by the Schober Test for all groups. There are significant differences in the effect generated between the three types of pack on the flexibility of the lower back. The MHP was able to transfer more heat to the lumbar area and provided a more pronounced increase in the flexibility of lower back tissues.

RESUMO O uso de compressas quentes é uma estratégia de termoterapia superficial amplamente utilizada e um de seus benefícios é o aumento da flexibilidade muscular. Porém, existem poucas informações sobre os efeitos das compressas quentes, quando não associadas a outras intervenções terapêuticas, na flexibilidade da região lombar. O objetivo do seguinte trabalho foi comparar os efeitos gerados pela aplicação de três tipos diferentes de compressas quentes na flexibilidade da região lombar de estudantes saudáveis. Três sessões de 15 minutos de calor superficial aplicado através de compressas quentes (compressa úmida quente, compressa de sementes e compressa de gel). A temperatura da compressa e da região lombar e a ocorrência de eritema foram registradas a cada 5 minutos. O teste de Schober foi realizado antes da primeira e após a última sessão. Após 15 minutos de tratamento, a compressa de sementes apresentou maior temperatura final. No mesmo período, a menor temperatura lombar foi obtida pela compressa de gel. O tratamento com os três tipos de compressa aumentou a ocorrência de eritema e causou aumento significativo da flexibilidade da região lombar avaliada pelo teste de Schober. Existem diferenças significativas no efeito gerado pelos três tipos de compressas quentes sobre a flexibilidade da região lombar. A compressa úmida quente proporcionou maior transferência de calor para a região lombar e propiciou um aumento mais pronunciado da flexibilidade da região lombar.

RESUMEN El empleo de compresas calientes es muy utilizado por la termoterapia superficial como forma de aumentar la flexibilidad muscular. Pero son pocas las informaciones sobre sus efectos, cuando asociadas a otras intervenciones terapéuticas, en la flexibilidad de la región lumbar. Este estudio tiene el objeto de comparar los efectos de la aplicación de tres tipos distintos de compresas calientas en la flexibilidad de la región lumbar en estudiantes saludables. Fueron tres sesiones de quince minutos de calor superficial aplicadas a través de compresas calientes (compresa húmeda, compresa de semillas y compresa de gel) en la región lumbar de estos participantes. Se registraban cada cinco minutos la temperatura de la compresa y de la región lumbar y la existencia de eritema. Se empleó la prueba de Schober realizada antes de la primera y después de la última sesión. Tras quince minutos de tratamiento, la compresa de semillas presentó una temperatura final mayor. En este mismo periodo, la menor temperatura lumbar la registró la compresa de gel. El tratamiento con tres tipos de compresas aumentó la existencia de eritema y el significativo aumento de la flexibilidad de la región lumbar, evaluado por la prueba de Schober. Diferencias significativas ocurrieron con el empleo de los tres tipos de compresas calientes sobre la flexibilidad de la región lumbar. La compresa húmeda caliente tuvo una transferencia de calor para la región lumbar mayor, por lo que aumentó más la flexibilidad de la región evaluada.

Housekeeping proteins: How useful are they in skeletal muscle diabetes studies and muscle hypertrophy models?

The use of Western blot analysis is of great importance in research, and the measurement of housekeeping proteins is commonly used for loading controls. However, Ponceau S staining has been shown to be an alternative to analysis of housekeeping protein levels as loading controls in some conditions. In the current study, housekeeping protein levels were measured in skeletal muscle hypertrophy and streptozotocin-induced diabetes experimental models. The following housekeeping proteins were investigated: glyceraldehyde-3-phosphate dehydrogenase (GAPDH), ß-actin, α-tubulin, γ-tubulin, and α-actinin. Evidence is presented that Ponceau S is more reliable than housekeeping protein levels for specific protein quantifications in Western blot analysis.