Role of Nutritional Supplements on Gut-Muscle Axis Across Age: a Mini-Review.

Sarcopenia is a progressive skeletal muscle disorder associated with aging, resulting in loss of muscle mass and function. It has been linked to inflammation, oxidative stress, insulin resistance, hormonal changes (i.e. alterations in the levels or activity of hormones which can occur due to a variety of factors, including aging, stress, disease, medication, and environmental factors), and impaired muscle satellite cell activation. The gut microbiome is also essential for muscle health, and supplements such as probiotics, prebiotics, protein, creatine, and betaalanine can support muscle growth and function while also promoting gut health. Chronic low-grade inflammation is a leading cause of sarcopenia, which can activate signaling pathways that lead to muscle wasting and reduce muscle protein synthesis. Insulin resistance, hormonal changes, and impaired muscle satellite cell activation contribute to sarcopenia, and high levels of fat mass also play a role in the pathogenesis of sarcopenia. Resistance exercise and dietary supplementation have been shown to be effective treatments for sarcopenia. In addition, a combination of resistance exercise and supplementation has been shown to have a more significant beneficial effect on anthropometric and muscle function parameters, leading to a decrease in sarcopenic state. Thus, understanding the relationship between the gut microbiome and muscle metabolism is crucial for developing new treatments for sarcopenia across age groups.

Evaluation of the Diaphragm Muscle Remodeling, Inflammation, Oxidative Stress and Vascularization in Smokers: An Autopsy Study.

BACKGROUND/AIMS: Cigarette smoking is a key factor in systemic inflammation and oxidative stress, and it has also been associated with the loss of muscle strength and an elevated risk of pulmonary diseases. Thus, this study aimed to analyze the effects of cigarette smoking on the diaphragm muscle structure of postmortem samples. METHODS: Immunohistochemical techniques were used for muscle remodeling (metalloproteinases 2 and 9), inflammation (cyclooxygenase-2), oxidative stress (8-hydroxy-2'-deoxyguanosine), and vascularization (vascular endothelial growth factor). Hematoxylin and eosin stain was used for histopathological analysis and Picrosirius stain was used to highlight the collagen fibers. RESULTS: Cigarette smokers had an increase of diaphragm muscle remodeling, oxidative stress, inflammation, and vascularization compared to non-smokers. CONCLUSION: Diaphragm muscle structure may be negatively affected by cigarette smoking.

Cigarette Smoking Impairs the Diaphragm Muscle Structure of Patients without Respiratory Pathologies: An Autopsy Study.

BACKGROUND/AIMS: Smoking is a major risk factor for several cardiovascular and pulmonary diseases, and it has also been associated with the loss of skeletal muscle mass and strength leading to sarcopenia. The aim of this is study is to analyze the effects of cigarette smoking on the diaphragm muscle histopathology of postmortem samples from patients without respiratory diseases. METHODS: Diaphragm samples were stained with hematoxylin and eosin for histopathological analysis. Picrosirius stain was used to highlight the collagen fibers. RESULTS: Cigarette smokers had an increase of histopathological alterations as abnormal cytoplasm, abnormal fiber size and shape, and central nucleus. Additionally, smokers had an increase of collagen fibers on diaphragm muscle. CONCLUSION: Smoking may influence in a negatively fashion the diaphragm musculature.

Effects of resistance training on liver structure and function of aged rats.

The aging process may cause negative physiological changes. However, exercises as resistance training (RT) have been considered an important intervention to attenuate these changes. Additionally, liver plays an important role in blood glucose homeostasis in exercise. AIM: This study aimed to analyze the effects of RT on the liver components of aged animals. METHODS: Male Wistar rats were divided into two groups: 24 months' group (CONTROL); and group submitted to a progressive RT protocol for 16 weeks (EXERCISE). Both groups were sacrificed at 24 months. RESULTS: We observed a decrease in blood flow due to the practice of resistance exercises. Besides, our results showed that hepatic tissue plays an important role in glycemic homeostasis during RT. In addition, RT increased mitogen capacity of hepatocytes. CONCLUSIONS: Our study showed many implications for the knowledge about the effects of strength training on old animals' liver.

Effects of testosterone administration on liver structure and function in aging rats.

Aging males have a decrease in testosterone levels, by which the testosterone treatment may influence in a negatively fashion the liver. AIM: This study aimed to analyze the effects of aging with or without testosterone administration on the liver components of animals. METHODS: Wistar rats were divided into three groups: 20 months' group (G20), 24 months' group (G24), group treated with testosterone for 16 weeks (GT). All groups were sacrificed at 24 months except for G20 that was sacrificed at 20 months. RESULTS: Aging and testosterone treatment alters the body weight (BW), liver weight (LW) and relative liver weight. Besides, testosterone increased the mitogen capacity of hepatocytes. Nonetheless, we reinforce the negative effects of testosterone on old animals' liver as chronic hepatic congestion and/or cholestasis. In addition, we observed that testosterone plays an important role on hepatic glycogen stores. CONCLUSIONS: Our study showed many implications for the knowledge about the effects of aging with or without testosterone administration on old animals' liver.

Smoking Intensity Increases Diaphragm Muscle Injury: A Clinicopathologic Study.

BACKGROUND: Studying the effects of smoking intensity is important to evaluate the risk of tobacco use on a range of illnesses, such as as sarcopenia among the elderly. Thus, this study aimed to analyze the effects of pack-years of cigarette smoking on the diaphragm muscle (DIAm) histopathology of postmortem samples. METHODS: Subjects were divided into three groups: never-smoker (n = 46); less than 30 pack-years of smoking (n = 12); and more than 30 pack-years of smoking (n = 30). Diaphragm samples were stained with Picrosirius red and hematoxylin and eosin stain for general structure. RESULTS: Participants with more than 30 pack-years of cigarette smoking had a significant increase in adipocytes, blood vessels and collagen deposit, as well as an increase in histopathological alterations. CONCLUSIONS: Pack-years of smoking was associated with DIAm injury. However, further clinicopathological studies are needed to confirm our findings.

Effects of resistance training on kidney morphology of aged ovariectomized rats.

With the advancing age, there is an increase of the incidence of chronic renal diseases. However, it is suggested that exercise, as resistance training, is a key factor in positively modulate the kidney structure and function. Thus, this study aimed to analyze the effects of estrogen deprivation and a moderate resistance protocol on the right kidney structure of rats. A total of 32 animals were randomly divided in four groups (n = 8/per group): control group (CG); resistance trained animals (RT); control ovariectomized animals (OvxC); and trained ovariectomized animals (OvxT). Sections of the right kidney were stained with hematoxylin and eosin for morphometry and blood was collected for biochemical analysis. Our results showed that the group submitted to both ovariectomy and resistance training had significant impact on renal corpuscle components (Bowman's space, renal corpuscle area, and visceral layer), and proximal and distal tubules. Additionally, resistance training, with or without estrogen deprivation, increases creatine phosphokinase and decreases ultrasensitive C-reactive protein. In summary, we suggested that moderate resistance training may be a key factor to maintain the kidney structure and function across age. However, future studies are need to corroborate with our findings.

Remodeling of the soleus muscle of ovariectomized old female rats submitted to resistance training and different diet intake.

Sarcopenia is a common condition that is associated mainly with hormonal factors, nutritional status, physical activity, leading to a lower quality of life. Thus, this study aimed to evaluate the effects of diets with vegetable or animal proteins (AP) associated with resistance training on the structure of the soleus muscle in aged Wistar rats. The histochemical technique was used for the typing of muscle fibers, the cross-sectional area of myocytes, and volume densities of myocytes and interstitium. Picrosirius stain was used to quantify the collagen density. Diet intake, mainly animal protein, associated with resistance training leaded to muscle remodeling, and increased deposit of collagen fibers. We observed hypertrophy in animal groups that consumed animal protein diet, even the sedentary group, although more evident in those trained.

Effects of moderate aerobic exercise on thoracic aortic remodeling of female LDL-receptor knockout ovariectomized mice.

Menopause is a major factor involved in dyslipidemia increasing the risk of atherosclerosis which may be reversed by a routine of aerobic physical activity. Thus, this study aimed to analyze the effects of aerobic training on the thoracic aorta of female LDL-receptor knockout mice submitted to estrogen deprivation. Fifteen genetically modified female mice, knockout for the low-density lipoprotein receptor (LDL-Knockout group) were used as experimental groups and fifteen wild female mice (C57BL/6 J) were used as control groups. Animals were divided as (n = 5/per group): sedentary control (SC); sedentary control ovariectomized (SCO); trained control ovariectomized (TCO); LDL-Knockout sedentary (KS); LDL-Knockout sedentary ovariectomized (KOS); and LDL-Knockout trained ovariectomized (KOT). Immunohistochemical techniques for TIMP-1 and metalloproteinases 2 and 9 were used to evaluate thoracic aorta remodeling. Picrosirius stain was used to highlight the collagen fibers. Verhoff-Van Gienson was used for the quantitative analyses of elastic lamellae. Our results demonstrate a positive remodeling promoted by physical exercise in ovariectomized and dyslipidemic animals. However, further studies are needed including the evaluation of inflammatory markers present in dyslipidemia.

Diaphragm muscle structure in the elderly: Findings from an autopsy study.

Sarcopenia is characterized as aging-related weakness and atrophy, which decreases the diaphragm force generating capacity leading to a decrease of expulsive non-ventilatory motor behaviors, which are critical for airway clearance. Thus, this study aimed to analyze the histopathology of the diaphragm in postmortem samples. Thirty individuals were included. Diaphragm samples were stained with hematoxylin and eosin for histopathological analysis. Picrosirius stain was used to highlight the collagen fibers. We observed a positive association between advancing age and histopathological findings in the diaphragm structure. We suggest that age is a key factor in increasing diaphragm muscle histopathology. However, further clinicopathological studies are needed to confirm our findings.

Ultrastructural effects of diabetes in the right atrium cardiomyocytes of elderly Wistar rats.

The present study aimed to evaluate the effects of diabetes on quantitative parameters of right atrial cardiomyocytes of elderly rats. Wistar rats (14 months of age) were divided into two groups: streptozotocin-diabetic rats (DG) and control rats (CG). The groups were sacrificed at 16 months. Ultrafine sections of the right atrium were analyzed by electron microscopy. In elderly diabetic animals, histograms of the frequency distribution of natriuretic peptides according to their size showed increased number of small and medium peptides in relation to large peptides, which increased its numerical density leading to a decrease in the mean diameter of both natriuretic peptides. However, elderly diabetic animals remained normotensive. No significant difference was observed between the groups for the volume density of mitochondria, endoplasmic reticulum, and Golgi apparatus. In conclusion, elderly diabetic rats showed increased functional activity of atrial cardiomyocytes with greater production of natriuretic peptides in association with a quantitative maintenance of cytoplasmic components.

Effects of Strength Training and Anabolic Steroid in the Peripheral Nerve and Skeletal Muscle Morphology of Aged Rats.

Thirty male 20-month-old Wistar rats were divided into groups: IC-initial control (n = 6), FC-final control (n = 6), AC-anabolic hormone control (n = 6), ST-strength trained (n = 6) and STA-strength trained with anabolic hormone (n = 6). All groups were submitted to adaptation, familiarization and maximum load carrying test (MLCT). Strength training (6-8×/session with loads of 50%-100% MLCT, 3×/week and pause of 120 s) was performed in ladder climbing (LC) for 15 weeks. The administration of testosterone propionate (TP) was performed 2×/week (10 mg/kg) in animals in the AC and STA groups. After the experimental period, animals were euthanized and the tibial nerve and plantaris muscle removed and prepared for electron transmission and histochemistry. To compare the groups we used one-way ANOVA (post hoc Bonferroni), student's t-tests for pre vs. post (dependent and independent variables) comparisons and significance level set at p ≤ 0.05. The following significant results were found: (a) aging decreased the number of myelinated axon fibers; (b) use of isolated TP increased the diameter of myelinated fibers, along with increased thickness of myelin sheath; (c) ST increased area of myelinated and unmyelinated fibers, together with the myelin sheath. These changes made it possible to increase the area occupied by myelinated fibers keeping their quantity and also reduce the interstitial space; and (d) association of anabolic steroid and ST increased the area of unmyelinated axons and thickness of the myelin sheath. Compared to ST, both strategies have similar results. However, Schwann cells increased significantly only in this strategy.