Effects of Conjugated Linoleic Acid Associated With Endurance Exercise on Muscle Fibres and Peroxisome Proliferator-Activated Receptor γ Coactivator 1 α Isoforms

Fat infiltration in skeletal muscle: Influential triggers and regulatory mechanism

Fat infiltration in skeletal muscle (also known as myosteatosis) is now recognized as a distinct disease from sarcopenia and is directly related to declining muscle capacity. Hence, understanding the origins and regulatory mechanisms of fat infiltration is vital for maintaining skeletal muscle development and improving human health. In this article, we summarized the triggering factors such as aging, metabolic diseases and metabolic syndromes, nonmetabolic diseases, and muscle injury that all induce fat infiltration in skeletal muscle. We discussed recent advances on the cellular origins of fat infiltration and found several cell types including myogenic cells and non-myogenic cells that contribute to myosteatosis. Furthermore, we reviewed the molecular regulatory mechanism, detection methods, and intervention strategies of fat infiltration in skeletal muscle. Based on the current findings, our review will provide new insight into regulating function and lipid metabolism of skeletal muscle and treating muscle-related diseases.

Effect of resveratrol on skeletal slow-twitch muscle fiber expression via AMPK/PGC-1α signaling pathway in bovine myotubes

The purpose of this study was to evaluate the impact of resveratrol on slow-twitch muscle fiber expression in bovine myotubes. The results revealed that resveratrol enhanced slow myosin heavy chain (MyHC) and suppressed fast MyHC protein expression, accompanied by increased MyHC I/IIa and decreased MyHC IIx/IIb mRNA levels in bovine myotubes (P < 0.05). Resveratrol also enhanced the activities of succinic dehydrogenase (SDH), malate dehydrogenase (MDH) and the mitochondrial DNA (mtDNA) content, but reduced lactate dehydrogenase (LDH) activity (P < 0.05). Meanwhile, the protein and gene expression of AMPK, SIRT1 and PGC-1α were upregulated by resveratrol (P < 0.05). Furthermore, PGC-1α inhibitor SR-18292 could attenuate resveratrol-induced muscle fiber conversion from fast-twitch to slow-twitch. These results suggest that resveratrol might promote muscle fiber type transition from fast-twitch to slow-twitch through the AMPK/PGC-1α signaling pathway and mitochondrial biogenesis in bovine myotubes.

Conjugated linoleic acid (CLA) as a functional food: Is it beneficial or not?

Conjugated linoleic acid (CLA) has attracted great attention in recent years as a popular class of functional food that is broadly used. It refers to a group of geometric and positional isomers of linoleic acid (LA) with a conjugated double bond. The main natural sources of CLA are dairy products, beef and lamb, whereas only trace amounts occur naturally in plant lipids. CLA has been shown to improve various health issues, having effects on obesity, inflammatory, anti-carcinogenicity, atherogenicity, immunomodulation, and osteosynthesis. Also, compared to studies on humans, many animal researches reveal more positive benefits on health. CLA represents a nutritional avenue to improve lifestyle diseases and metabolic syndrome. Most of these effects are attributed to the two major CLA isomers [conjugated linoleic acid cis-9,trans-11 isomer (c9,t11), and conjugated linoleic acid trans-10,cis-12 isomer (t10,c12)], and their mixture (CLA mix). In contrast, adverse effects of CLA have been also reported, such as glucose homeostasis, insulin resistance, hepatic steatosis and induction of colon carcinogenesis in humans, as well as milk fat inhibition in ruminants, lowering chicken productivity, influencing egg quality and altering growth performance in fish. This review article aims to discuss the health benefits of CLA as a nutraceutical supplement and highlight the possible mechanisms of action that may contribute to its outcome. It also outlines the feasible adverse effects of CLA besides summarizing the recent peer-reviewed publications on CLA to ensure its efficacy and safety for proper application in humans.

The effect of conjugated linoleic acids on inflammation, oxidative stress, body composition and physical performance: a comprehensive review of putative molecular mechanisms

Conjugated linoleic acids (CLAs) are polyunsaturated fatty acids primarily found in dairy products and ruminant animal products such as beef, lamb, and butter. Supplementation of CLAs has recently become popular among athletes due to the variety of health-promoting effects, including improvements in physical performance. Preclinical and some clinical studies have shown that CLAs can reduce inflammation and oxidative stress and favorably modulate body composition and physical performance; however, the results of previously published clinical trials are mixed. Here, we performed a comprehensive review of previously published clinical trials that assessed the role of CLAs in modulating inflammation, oxidative stress, body composition, and select indices of physical performance, emphasizing the molecular mechanisms governing these changes. The findings of our review demonstrate that the effect of supplementation with CLAs on inflammation and oxidative stress is controversial, but this supplement can decrease body fat mass and increase physical performance. Future well-designed randomized clinical trials are warranted to determine the effectiveness of (1) specific doses of CLAs; (2) different dosing durations of CLAs; (3) various CLA isomers, and the exact molecular mechanisms by which CLAs positively influence oxidative stress, inflammation, body composition, and physical performance.

Highlights in Pathophysiology of the Musculoskeletal System

The intention of the present Special Issue is to focus on the latest research in the musculoskeletal system, with an emphasis on the molecular mechanisms underlying its pathophysiology, as well as innovative diagnostic tools and therapeutic perspectives [...]

Effects of conjugated linoleic acid and exercise on body composition and obesity: a systematic review and meta-analysis

CONTEXT

Conjugated linoleic acid (CLA) has been reported to have anti-obesity and antidiabetic effects. However, the benefits of CLA combined with exercise remain unclear, and studies report conflicting results.

OBJECTIVE

A systematic review and meta-analysis were performed to investigate the synergistic effect of CLA and exercise on body composition, exercise-related indices, insulin resistance, and lipid profiles; and of the safety of CLA supplements.

DATA SOURCES

In October 2021, the PubMed, Embase, and Cochrane Library databases were searched for reports on clinical trials of the combined intervention of CLA and exercise.

DATA EXTRACTION

A total of 18 randomized controlled trials and 2 crossover trials were included. The methodological quality assessment was performed using the revised Cochrane risk-of-bias tool. Pooled effect sizes were reported as standardized mean difference (SMD) for continuous data and risk ratio for dichotomous data with their corresponding 95% confidence intervals (CIs). Heterogeneity was tested using the I2 statistic.

DATA ANALYSIS

The combination of CLA and exercise resulted in significantly decreased body fat (SMD, -0.42 [95%CI, -0.70, -0.14]; P = 0.003; I2 = 65) and insulin resistance (SMD, -0.25 [95%CI, -0.44, -0.06]; P = 0.01; I2 = 0) than did exercise alone. In subgroup analysis, the following factors were associated with significant outcomes: (1) body mass index ≥25 kg/m2; (2) female sex; (3) follow-up time >4 weeks; and (4) intervention duration >4 weeks. Nevertheless, supplementation with CLA during exercise programs was not effective for body-weight control, exercise performance enhancement, or lipid-profile improvement. CLA in combination with exercise did not result in a higher risk of adverse events (risk ratio, 1.32 [95%CI, 0.94-1.84]; P > 0.05; I2 = 0).

CONCLUSION

CLA combined with exercise is generally safe and can lower body fat and insulin resistance but does not reduce body weight, enhance exercise performance, or improve lipid profiles.

PPARγ Gene as a Possible Link between Acquired and Congenital Lipodystrophy and its Modulation by Dietary Fatty Acids

Lipodystrophy syndromes are rare diseases that could be of genetic or acquired origin. The main complication of lipodystrophy is the dysfunction of adipose tissue, which leads to an ectopic accumulation of triglycerides in tissues such as the liver, pancreas and skeletal muscle. This abnormal fat distribution is associated with hypertriglyceridemia, insulin resistance, liver steatosis, cardiomyopathies and chronic inflammation. Although the origin of acquired lipodystrophies remains unclear, patients show alterations in genes related to genetic lipodystrophy, suggesting that this disease could be improved or aggravated by orchestrating gene activity, for example by diet. Nowadays, the main reason for adipose tissue dysfunction is an imbalance in metabolism, caused in other pathologies associated with adipose tissue dysfunction by high-fat diets. However, not all dietary fats have the same health implications. Therefore, this article aims to summarize the main genes involved in the pathophysiology of lipodystrophy, identify connections between them and provide a systematic review of studies published between January 2017 and January 2022 of the dietary fats that can modulate the development of lipodystrophy through transcriptional regulation or the regulation of protein expression in adipocytes.

The Chaperone System in Salivary Glands: Hsp90 Prospects for Differential Diagnosis and Treatment of Malignant Tumors

Salivary gland tumors represent a serious medical problem and new tools for differential diagnosis and patient monitoring are needed. Here, we present data and discuss the potential of molecular chaperones as biomarkers and therapeutic targets, focusing on Hsp10 and Hsp90. The salivary glands are key physiological elements but, unfortunately, the information and the means available for the management of their pathologies, including cancer, are scarce. Progress in the study of carcinogenesis has occurred on various fronts lately, one of which has been the identification of the chaperone system (CS) as a physiological system with presence in all cells and tissues (including the salivary glands) that plays a role in tumor-cell biology. The chief components of the CS are the molecular chaperones, some of which belong to families of evolutionarily related molecules named heat shock protein (Hsp). We are quantifying and mapping these molecular chaperones in salivary glands to determine their possible role in the carcinogenetic mechanisms in these glands and to assess their potential as diagnostic biomarkers and therapeutic targets. Here, we report recent findings on Hsp10 and Hsp90 and show that the quantitative and topographic patterns of tissue Hsp90 are distinctive of malignant tumors and differentiate benign from malignant lesions. The Hsp90 results show a correlation between quantity of chaperone and tumor progression, which in turn calls for negative chaperonotherapy, namely, elimination/inhibition of the chaperone to stop the tumor. We found that in vitro, the Hsp90 inhibitor Ganetespib is cytotoxic for the salivary gland UM-HACC-2A cell line. The drug, by interfering with the pro-survival NF-κB pathway, hampers cellular proliferation and migration, and favors apoptosis, and can, therefore, be considered a suitable candidate for future experimentation to develop a treatment for salivary gland tumors.

Low-Volume Squat Jump Training Improves Functional Performance Independent of Myofibre Changes in Inactive Young Male Individuals

An investigation into the histological changes in skeletal muscle fibres and jump performance indicators after 8 weeks of plyometric squat jump training was conducted. Healthy inactive participants (n = 13; age: 21.5 ± 1.7 year.; height: 173.6 ± 10.7 cm; weight: 68.5 ± 18.4 kg; BMI 22.4 ± 3.8 kg/m²) were recruited, where eight participants completed plyometric squat jump training and five control participants refrained from performing any jumping activities. Blood samples, vastus lateralis muscle biopsies and functional testing (peak and average power, peak and average velocity, maximal jump height) were collected/recorded 10 days prior to and 3 days after the training/rest period. Participants completed 1644 squat jumps over an 8-week training period of 24 sessions with a progressive increase in the number of squat jumps. The trained group significantly increased their jumping average and peak power (mean increases in average power: 16.7 ± 1.2% and peak power: 8.2% ± 0.1) and velocity (mean increases in average velocity: 13.7 ± 0.1% and peak velocity: 5.2% ± 0.03), resulting in a 25% improvement in vertical jump height. No muscle morphological changes in terms of the cross-sectional area (CSA) or muscle-fibre-type transition were observed after the plyometric training. Improvements in the functional performance indicators following training may more likely be explained by sarcomere ultrastructural adaptation, which did not directly affect myosin heavy chain or CSA.

Cancer-Related Cachexia: The Vicious Circle between Inflammatory Cytokines, Skeletal Muscle, Lipid Metabolism and the Possible Role of Physical Training

Cachexia is a multifactorial and multi-organ syndrome that is a major cause of morbidity and mortality in late-stage chronic diseases. The main clinical features of cancer-related cachexia are chronic inflammation, wasting of skeletal muscle and adipose tissue, insulin resistance, anorexia, and impaired myogenesis. A multimodal treatment has been suggested to approach the multifactorial genesis of cachexia. In this context, physical exercise has been found to have a general effect on maintaining homeostasis in a healthy life, involving multiple organs and their metabolism. The purpose of this review is to present the evidence for the relationship between inflammatory cytokines, skeletal muscle, and fat metabolism and the potential role of exercise training in breaking the vicious circle of this impaired tissue cross-talk. Due to the wide-ranging effects of exercise training, from the body to the behavior and cognition of the individual, it seems to be able to improve the quality of life in this syndrome. Therefore, studying the molecular effects of physical exercise could provide important information about the interactions between organs and the systemic mediators involved in the overall homeostasis of the body.

Ellagic acid enhances muscle endurance by affecting the muscle fiber type, mitochondrial biogenesis and function

Ellagic acid (EA) is a natural polyphenolic compound, which shows various effects, such as anti-inflammatory and antioxidant effects and inhibition of platelet aggregation. In this study, we investigated the effect of EA on muscle endurance and explored its possible underlying mechanism. Our data showed that EA significantly improved muscle endurance in mice. EA increased the protein level of slow myosin heavy chain (MyHC) I and decreased the protein level of fast MyHC. We also found that the AMP-activated protein kinase (AMPK) signaling pathway was activated by EA. Finally, our data indicated that EA could increase mitochondrial biogenesis and function by increasing the content of mitochondrial DNA (mtDNA), the concentration of ATP, the activities of succinodehydrogenase (SDH) and malate dehydrogenase (MDH), and the mRNA levels of ATP synthase (ATP5G), mtDNA transcription factor A (TFAM), mitochondrial transcription factor b1 (Tfb1m) and citrate synthase (Cs) in mice and C2C12 myotubes. These results proved that EA could enhance muscle endurance via transforming the muscle fiber type and improving mitochondrial biogenesis and function.

Hsp27 and Hsp60 in human submandibular salivary gland: Quantitative patterns in healthy and cancerous tissues with potential implications for differential diagnosis and carcinogenesis

Tumors of the submandibular salivary gland (SMG) are uncommon but sufficiently frequent for the physician to consider them in routine examinations and for the pathologist to be prepared to differentiate them from other tissue abnormalities. However, scarcity of specimens makes training difficult, a situation compounded by the lack of accepted universal diagnostic guidelines. Furthermore, there is little information on the chaperone system (CS) of the gland, despite the increasing evidence of its participation in carcinogenesis as a biomarker for diagnosis and patient follow up, and in the mechanisms by which the tumor cells thrive. We are investigating this aspect of various tumors, and here we describe standardized methods for assessing the tissue levels of two chaperones, Hsp27 and Hsp60, in normal SMG and its tumors. We present illustrative results obtained with immunohistochemistry (IHC) and immunofluorescence-confocal microscopy (IF-CM), which we propose as a platform onto which a data base could be built by adding new information and which would provide material for developing guidelines for tumor identification and monitoring. The initial findings are encouraging in as much as the tumors surveyed showed quantitative patterns of Hsp27 and Hsp60 that distinguished tumoral from normal tissue and certain tumors from the others, and the results from IHC were confirmed by IF-CM.

JNK pathway and heat shock response mediate the survival of C26 colon carcinoma bearing mice fed with the mushroom Pleurotus eryngii var. eryngii without affecting tumor growth or cachexia

In the last few years, there has been emerging interest in developing treatments against human diseases using natural bioactive content. Here, the powder of the edible mushroom Pleurotus eryngii var. eryngii was mixed with the normal diet of mice bearing C26 colon carcinoma. Interestingly, it was evidenced by a significant increase in the survival rate of C26 tumor-bearing mice accompanied by a significant increase in Hsp90 and Hsp27 protein levels in the tumors. These data were paralleled by a decrease in Hsp60 levels. The mushroom introduced in the diet induced the inhibition of the transcription of the pro-inflammatory cytokines IL-6 and IL-1 exerting an anti-inflammatory action. The effects of the mushroom were mediated by the activation of c-Jun NH₂-terminal kinases as a result of metabolic stress induced by the micronutrients introduced in the diet. In the tumors of C26 bearing mice fed with Pleurotus eryngii there was also a decreased expression of the mitotic regulator survivin and the anti-apoptotic factor Bcl-xL as well as an increase in the expression levels of Atg7, a protein that drives autophagy. In our hypothesis the interplay of these molecules favored the survival of the mice fed with the mushroom. These data are promising for the introduction of Pleurotus eryngii as a dietary supplement or as an adjuvant in anti-cancer therapy.

Function and Fiber-Type Specific Distribution of Hsp60 and αB-Crystallin in Skeletal Muscles: Role of Physical Exercise

Simple Summary

Skeletal muscle represents about 40% of the body mass in humans and it is a copious and plastic tissue, rich in proteins that are subject to continuous rearrangements. Physical exercise is considered a physiological stressor for different organs, in particular for skeletal muscle, and it is a factor able to stimulate the cellular remodeling processes related to the phenomenon of adaptation. All cells respond to various stress conditions by up-regulating the expression and/or activation of a group of proteins called heat shock proteins (HSPs). Although their expression is induced by several stimuli, they are commonly recognized as HSPs due to the first experiments showing their increased transcription after application of heat shock. These proteins are molecular chaperones mainly involved in assisting protein transport and folding, assembling multimolecular complexes, and triggering protein degradation by proteasome. Among the HSPs, a special attention needs to be devoted to Hsp60 and αB-crystallin, proteins constitutively expressed in the skeletal muscle, where they are known to be important in muscle physiopathology. Therefore, here we provide a critical update on their role in skeletal muscle fibers after physical exercise, highlighting the control of their expression, their biological function, and their specific distribution within skeletal muscle fiber-types.

Abstract

Skeletal muscle is a plastic and complex tissue, rich in proteins that are subject to continuous rearrangements. Skeletal muscle homeostasis can be affected by different types of stresses, including physical activity, a physiological stressor able to stimulate a robust increase in different heat shock proteins (HSPs). The modulation of these proteins appears to be fundamental in facilitating the cellular remodeling processes related to the phenomenon of training adaptations such as hypertrophy, increased oxidative capacity, and mitochondrial activity. Among the HSPs, a special attention needs to be devoted to Hsp60 and αB-crystallin (CRYAB), proteins constitutively expressed in the skeletal muscle, where their specific features could be highly relevant in understanding the impact of different volumes of training regimes on myofiber types and in explaining the complex picture of exercise-induced mechanical strain and damaging conditions on fiber population. This knowledge could lead to a better personalization of training protocols with an optimal non-harmful workload in populations of individuals with different needs and healthy status. Here, we introduce for the first time to the reader these peculiar HSPs from the perspective of exercise response, highlighting the control of their expression, biological function, and specific distribution within skeletal muscle fiber-types.

Sex-based differences after a single bout of exercise on PGC1α isoforms in skeletal muscle: A pilot study

To date, there are limited and incomplete data on possible sex-based differences in fiber-types of skeletal muscle and their response to physical exercise. Adult healthy male and female mice completed a single bout of endurance exercise to examine the sex-based differences of the peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC1α), heat shock protein 60 (Hsp60), interleukin 6 (IL-6) expression, as well as the Myosin Heavy Chain (MHC) fiber-type distribution in soleus and extensor digitorum longus (EDL) muscles. Our results showed for the first time that in male soleus, a muscle rich of type IIa fibers, endurance exercise activates specifically genes involved in mitochondrial biogenesis such as PGC1 α1 isoform, Hsp60 and IL-6, whereas the expression of PGC1 α2 and α3 was significantly upregulated in EDL muscle, a fast-twitch skeletal muscle, independently from the gender. Moreover, we found that the acute response of different PGC1α isoforms was muscle and gender dependent. These findings add a new piece to the huge puzzle of muscle response to physical exercise. Given the importance of these genes in the physiological response of the muscle to exercise, we strongly believe that our data could support future research studies to personalize a specific and sex-based exercise training protocol.

αB-crystallin response to a pro-oxidant non-cytotoxic environment in murine cardiac cells: An "in vitro" and "in vivo" study

The αB-crystallin (HSPB5) protein is modulated in response to a wide variety of stressors generated by multiple physio-pathological conditions, sustained by reactive oxygen species (ROS) production. In cardiac muscle tissue, this protein regulates various cellular processes, such as protein degradation, apoptosis and the stabilization of cytoskeletal elements. In this work, we studied the role of HSPB5 expression, activation and localization in HL-1 murine cardiomyocytes exposed to pro-oxidant and non-cytotoxic H₂O₂ concentration, as well as in cardiac tissue isolated from mice following an acute, non-damaging endurance exercise. Our results demonstrated that HSPB5 is the most abundant HSP in both cardiac muscle tissue and HL-1 cells when compared to HSPB1 or HSPA1A (≈3-8 fold higher protein concentrations, p < 0.01). The acute exposure of cardiac muscle cells to sustainable level of H₂O₂ "in vitro" or to aerobic non-damaging exercise "in vivo" determined a fast and specific increase of HSPB5 phosphorylation (from 3 up to 25 fold increase, p < 0.01) correlated to an increase in lipid peroxidation (p < 0.05). In both experimental models, p-HSPB5 likely facilitated both the interaction with β-actin, desmin, and α-Filamin 1, the last one identified as new HSPB5 substrate in cardiac cells, as well as the sub-localization of HSPB5 within the same cellular compartment or the re-localization between compartments (i.e., nucleus and cytosol). Taken together, these data point out the role of "oxidative eustress" induced by physiological conditions in activating the molecular machinery devoted to cardiomyocytes' protection and candidate HSPB5 as a putative molecular mediator for the health benefits induced in cardiac tissue by exercise training.

Impacts of exercise interventions on different diseases and organ functions in mice

Background

In recent years, much evidence has emerged to indicate that exercise can benefit people when performed properly. This review summarizes the exercise interventions used in studies involving mice as they are related to special diseases or physiological status. To further understand the effects of exercise interventions in treating or preventing diseases, it is important to establish a template for exercise interventions that can be used in future exercise-related studies.

Methods

PubMed was used as the data resource for articles. To identify studies related to the effectiveness of exercise interventions for treating various diseases and organ functions in mice, we used the following search language: (exercise [Title] OR training [Title] OR physical activity [Title]) AND (mice [title/abstract] OR mouse [title/abstract] OR mus [title/abstract]). To limit the range of search results, we included 2 filters: one that limited publication dates to "in 10 years" and one that sorted the results as "best match". Then we grouped the commonly used exercise methods according to their similarities and differences. We then evaluated the effectiveness of the exercise interventions for their impact on diseases and organ functions in 8 different systems.

Results

A total of 331 articles were included in the analysis procedure. The articles were then segmented into 8 systems for which the exercise interventions were used in targeting and treating disorders: motor system (60 studies), metabolic system (45 studies), cardio-cerebral vascular system (58 studies), nervous system (74 studies), immune system (32 studies), respiratory system (7 studies), digestive system (1 study), and the system related to the development of cancer (54 studies). The methods of exercise interventions mainly involved the use of treadmills, voluntary wheel-running, forced wheel-running, swimming, and resistance training. It was found that regardless of the specific exercise method used, most of them demonstrated positive effects on various systemic diseases and organ functions. Most diseases were remitted with exercise regardless of the exercise method used, although some diseases showed the best remission effects when a specific method was used.

Conclusion

Our review strongly suggests that exercise intervention is a cornerstone in disease prevention and treatment in mice. Because exercise interventions in humans typically focus on chronic diseases, national fitness, and body weight loss, and typically have low intervention compliance rates, it is important to use mice models to investigate the molecular mechanisms underlying the health benefits from exercise interventions in humans.

Neuropsychiatric and Behavioral Involvement in AAS Abusers. A Literature Review

Background and Objectives: Anabolic androgenic steroids (AASs) are a complex group of molecules that include both steroidal androgens and synthetic compounds, derived from testosterone. AASs are commonly used to support pharmacological therapy in cases of primary or secondary hypogonadism, major burns, and neoplastic cachexia. Their prolonged and supra-physiological consumption can provoke several adverse effects on various organs and systems. Among these, the physiopathological mechanisms that induce neuropsychiatric disorders related to AAS abuse are poorly known. For this reason, the proposed review aims to retrace the pathway of action of testosterone to focus on the effects on the central nervous system and specifically highlight the effects of AASs on neuropsychiatric and behavioral functions, as well as on lifestyle. Materials and Methods: This review was conducted using PubMed and Google Scholar databases. On these database websites, we searched for articles from 1 January 1980 to March 2019 using the key terms: "AAS," "Anabolic Androgenic Steroids," "brain," and "neurology." Results: The use of AASs through self-administration yields circulating androgens levels, inducing neuron apoptosis, which is linked to thinner cortex and, in general, less cortical volume. The same alterations affect the putamen. These differences were more evident when correlated with longer use. From a functional point of view, prolonged AAS consumption seemed to be related to lower connectivity between amygdala and frontal, striatal, limbic, hippocampal and visual cortical areas. On the other hand, AAS use seems to negatively condition the positive effects of the sport exercise, reducing its important anti-apoptotic and pro-proliferative functions on the hippocampus, implicated in anxiolytic control. Conclusion: This review clarifies the major aspects of the side effects related to AAS use/abuse highlighting the complex mechanisms on neuropsychiatric and cognitive pathological alterations and also the emotional and behavioral dysfunctions.

Exercise and Conjugated Linoleic Acid Supplementation Induce Changes in the Composition of Liver Fatty Acids

Exercise and supplementation with conjugated linoleic acid (CLA) are used to reduce body weight and to improve health. Applied together, they may exert a synergistic effect. However, the effects of exercise and CLA supplementation on liver metabolism are poorly understood. The aim of this study was to examine the influence of exercise and CLA supplementation on fatty acids (FA) composition in mouse liver. We analyzed 44 of known FAs of this organ by gas chromatography-mass spectrometry. Our results demonstrated that exercise contributed to a decrease in odd-chain FA and an increase in n-6 polyunsaturated FA contents. In turn, CLA stimulated an increase in branched-chain FAs and n-3 polyunsaturated FAs. Exercise combined with CLA supplementation caused a substantial increase in branched-chain FA content and a slight increase in n-6 polyunsaturated FAs. The elevated liver content of branched-chain FAs after the exercise combined with CLA supplementation, as well as the increase in n-3 polyunsaturated FAs after CLA may be favorable since both these FA groups were previously shown to produce health benefits. However, the expression pattern of enzymes involved in fatty acid synthesis did not match the changes in FA composition. Thus, the mechanism of exercise- and CLA-induced changes in liver FA profile is yet to be established. Also, the consequences of CLA- and/or exercise-induced changes in the composition of liver FAs need to be elucidated.

Extracellular Vesicles: Delivery Vehicles of Myokines

Movement and regular physical activity are two important factors that help the human body prevent, reduce and treat different chronic diseases such as obesity, type 2 diabetes, heart diseases, hypertension, sarcopenia, cachexia and cancer. During exercise, several tissues release molecules into the blood stream, and are able to mediate beneficial effects throughout the whole body. In particular, contracting skeletal muscle cells have the capacity to communicate with other organs through the release of humoral factors that play an important role in the mechanisms of adaptation to physical exercise. These muscle-derived factors, today recognized as myokines, act as endocrine and paracrine hormones. Moreover, exercise may stimulate the release of small membranous vesicles into circulation, whose composition is influenced by the same exercise. Combining the two hypotheses, these molecules related to exercise, named exer-kines, might be secreted from muscle cells inside small vesicles (nanovesicles). These could act as messengers in tissue cross talk during physical exercise. Thanks to their ability to deliver useful molecules (such as proteins and miRNA) in both physiological and pathological conditions, extracellular vesicles can be thought of as promising candidates for potential therapeutic and diagnostic applications for several diseases.

Conjugated Linoleic Acid Ameliorates High Fructose-Induced Hyperuricemia and Renal Inflammation in Rats via NLRP3 Inflammasome and TLR4 Signaling Pathway

SCOPE

Conjugated linoleic acid (CLA), a bioactive substance predominantly found in ruminant products, improves insulin resistance and exhibits anti-inflammatory activity. The chief objective of the study is to investigate the effects and potential mechanisms of CLA on high fructose-induced hyperuricemia and renal inflammation.

METHODS AND RESULTS

Hyperuricemia and renal inflammation are induced in rats by 10% fructose. Hyperuricemia, insulin resistance, and renal inflammation are evaluated. CLA potently ameliorates fructose-induced hyperuricemia with insulin resistance and significantly reduces the levels of inflammation factors in serum and kidney. It reverses fructose-induced upregulation of glucose transporter 9 (GLUT9) and urate transporter 1 (URAT1) in the kidney. Moreover, CLA dramatically inhibits the activation of the nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome. Additionally, CLA suppresses toll-like receptor 4 (TLR4)/myeloid differentiation factor 88 (MyD88) signaling activation to inhibit nuclear factor-kB (NF-kB) signaling in the kidney of fructose-fed rats.

CONCLUSION

CLA ameliorates hyperuricemia along with insulin resistance and renal inflammatory, which may be associated with the suppression of renal GLUT9 and URAT1 in fructose-fed rats. Its molecular mechanism may be related to the inhibition of NLRP3 inflammasome and TLR4/MyD88 signaling pathway. Therefore, CLA may be a promising candidate for preventing fructose-induced hyperuricemia and renal inflammation.

The early response of αB-crystallin to a single bout of aerobic exercise in mouse skeletal muscles depends upon fiber oxidative features

Besides its substantial role in eye lens, αB-crystallin (HSPB5) retains fundamental function in striated muscle during physiological or pathological modifications. In this study, we aimed to analyse the cellular and molecular factors driving the functional response of HSPB5 protein in different muscles from mice subjected to an acute bout of non-damaging endurance exercise or in C2C12 myocytes upon exposure to pro-oxidant environment, chosen as “in vivo” and “in vitro” models of a physiological stressing conditions, respectively.

To this end, red (GR) and white gastrocnemius (GW), as sources of slow-oxidative and fast-glycolytic/oxidative fibers, as well as the soleus (SOL), mainly composed of slow-oxidative type fibers, were obtained from BALB/c mice, before (CTRL) and at different times (0′, 15′, 30′ 120′) following 1-h of running. Although the total level of HSPB5 protein was not affected by exercise, we found a significantly increase of phosphorylated HSPB5 (p-HSPB5) only in GR and SOL skeletal muscle with a higher amount of type I and IIA/X myofibers. The fiber-specific activation of HSPB5 was correlated to its interaction with the actin filaments, as well as to an increased level of lipid peroxidation and carbonylated proteins. The role of the pro-oxidant environment in HSPB5 response was investigated in terminally differentiated C2C12 myotubes, where most of HSPB5/pHSPB5 pool was present in the cytosolic compartment in standard culture conditions. As a result of exposure to pro-oxidizing, but not cytotoxic, H₂O₂ concentration, the p-38MAPK-mediated phosphorylation of HSPB5 resulted functional to promote its interaction with the myofibrillar components, such as β-actin, desmin and filamin 1.

This study provides novel information on the molecular pathway underlying the HSPB5 physiological function in skeletal muscle, confirming the contribution of the pro-oxidant environment in HSPB5 activation and interaction with substrate/client myofibrillar proteins, offering new insights for the study of myofibrillar myopathies and cardiomyopathies.

Hsp60 in Skeletal Muscle Fiber Biogenesis and Homeostasis: From Physical Exercise to Skeletal Muscle Pathology

Hsp60 is a molecular chaperone classically described as a mitochondrial protein with multiple roles in health and disease, participating to the maintenance of protein homeostasis. It is well known that skeletal muscle is a complex tissue, rich in proteins, that is, subjected to continuous rearrangements, and this homeostasis is affected by many different types of stimuli and stresses. The regular exercise induces specific histological and biochemical adaptations in skeletal muscle fibers, such as hypertrophy and an increase of mitochondria activity and oxidative capacity. The current literature is lacking in information regarding Hsp60 involvement in skeletal muscle fiber biogenesis and regeneration during exercise, and in disease conditions. Here, we briefly discuss the functions of Hsp60 in skeletal muscle fibers during exercise, inflammation, and ageing. Moreover, the potential usage of Hsp60 as a marker for disease and the evaluation of novel treatment options is also discussed. However, some questions remain open, and further studies are needed to better understand Hsp60 involvement in skeletal muscle homeostasis during exercise and in pathological condition.

Global transcriptional differences in myokine and inflammatory genes in muscle of mature steer progeny are related to maternal lactation diet and muscle composition

Steer progeny suckled by cows fed a dried distillers grains and solubles (DDGS) diet the first 3 mo of lactation were heavier during feedlot finishing and had significantly lower marbling and larger longissimus muscles than steers suckled by cows fed a control diet (CON). These differences were profound in that progeny were managed and fed identically from weaning until finishing, and findings suggest that the suckling period established the developmental program of muscle composition. Here transcriptomes of longissimus muscle were measured by next-generation sequencing to investigate whether there were any developmental clues to the differences in marbling scores and muscle content between steers suckled by DDGS ( n = 5) vs. control (CON; n = 5) diet-fed cows during lactation. There were 809 genes differentially expressed ( P-adj<0.1) between CON and DDGS muscle. Of these 636 were upregulated and 173 downregulated in DDGS relative to CON. Overall the DDGS vs. CON muscle transcriptomic signature was promyogenic and antiadipogenic. In particular, myokines/satellite cell maintenance factors were found among upregulated (LIF, CNTF, FGFB1, EPHB1) genes. The antiadipogenic signature was typified by the upregulation of anti-inflammatory cytokines and receptors (IL1RAP, IL1RL2, IL13RA2, IL1F10), and downregulation of expression of inflammation/inflammatory cytokines and receptor (TNF, IL6R, CXCL9), which suggests a selection of differentiation pathways away from adipogenic line. The upregulation of TGFB, SPP1, and INHBA supports selection of fibroblast lineage of cells. Thus, the lactation phase of production can effect meat quality by affecting transcriptional signatures that favor myogenesis and depress inflammation.

Muscle type-specific RNA polymerase II recruitment during PGC-1α gene transcription after acute exercise in adult rats

Epigenetic regulation of gene expression differs between fast- and slow-twitch skeletal muscles in adult rats, although the precise mechanisms are still unknown. The present study investigates the differences in responses of RNA polymerase II (Pol II) and histone acetylation during transcriptional activation in the plantaris and soleus muscles of adult rats after acute treadmill running. We targeted the peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) gene to analyze epigenomic changes by chromatin immunoprecipitation. The mRNA expression of the PGC-1α-b isoform was significantly up-regulated in both plantaris and soleus muscles 2 h after acute running, although the magnitude of the up-regulation was more pronounced in the plantaris muscle. The sequences of proximal exons of the PGC-1α locus were expressed more in the plantaris muscle after acute running. Accumulation of Pol II was noted near the alternative exon 1 in both plantaris and soleus muscles in association with the enhanced distribution of acetylated histone 3. Accumulation of Pol II was also observed at the transcription start site, exon 2, and exon 3 in the plantaris muscle, but not the soleus muscle. It was noted that in the soleus muscle, acetylation of histone 3 at lysine 27 was enhanced throughout the PGC-1α locus in response to transcriptional activation, suggesting that elongating Pol II was capable of traveling through to the end of the locus. These results indicate that the mobility of Pol II during PGC-1αtranscription differed between fast- and slow-twitch skeletal muscles, affecting the strength of the transcriptional activity.