Protective effects of Brazilian propolis supplementation on capillary regression in the soleus muscle of hindlimb-unloaded rats

Acute effect of electrical stimulation on muscle protein synthesis and break-down in the soleus muscle of hindlimb unloaded rats

Electrical stimulation (ES) is effective for disuse-induced muscle atrophy. However, the acute effect of ES on muscle protein synthesis (MPS) and muscle protein breakdown (MPB) remains unclear. We investigated the effect of a single-session ES treatment on mTORC1 signaling, MPS, and MPB in the soleus muscle of 2-week hindlimb unloaded rats. Sprague Dawley rats (n = 12 male) were randomly divided into control (CON) and hindlimb unloaded (HU) groups. After 2 weeks, the right soleus muscle was percutaneously stimulated and underwent supramaximal isometric contractions. The left soleus muscle served as an internal control. We collected soleus muscle samples 6 h after ES. Two weeks of HU decreased p70S6K and S6rp activation, downstream factors for mTORC1 signaling, and SUnSET method-assessed MPS, but increased the LC3-II/I ratio, an indicator of autophagy. ES on disused muscle successfully activated mTORC1 signaling but did not affect MPS. Contrary, ES decreased ubiquitinated proteins expression and LC3B-II/I ratio. HU might affect mTORC1 activation and MPS differently in response to acute ES possibly due to excessive ROS production caused by ES. Our findings suggest that ES applied to disused skeletal muscles may suppress MPB, but its effect on MPS appears to be attenuated.

Time course of capillary regression and an expression balance between vascular endothelial growth factor-A and thrombospondin-1 in the soleus muscle of hindlimb unloaded rats

INTRODUCTION/AIMS

Skeletal muscle capillaries regress with disuse; however, information on time-dependent changes in the expression of pro- and anti-angiogenic factors in disused muscle is limited. This study aimed to clarify time-dependent changes in skeletal muscle capillarization, pro-angiogenic vascular endothelial growth factor-A (VEGF-A), and anti-angiogenic thrombospondin-1 (TSP-1) in the soleus muscle of hindlimb unloaded rat.

METHODS

Eight-week-old male Sprague Dawley rats were randomly divided into four groups corresponding to different hindlimb unloading (HU) duration at 0, 1, 2, and 3 weeks.

RESULTS

Muscle atrophy and capillary regression worsened in the soleus muscle with longer periods of HU. The VEGF-A protein expression level was lower at week 1 than at week 0. In addition, the value at week 3 was also lower than those at weeks 0, 1, and 2. The TSP-1 protein expression level was higher at week 1 than that at week 0 but was similar at weeks 2 and 3. Moreover, reactive oxygen species, assessed by dihydroethidium fluorescence intensity on cryosection, were higher at weeks 2 and 3 than that at week 0.

DISCUSSION

Depending on the HU period, VEGF-A and TSP-1 showed different expression patterns. In the early HU phase, TSP-1 may play an important role in capillary regression. However, when HU extends for a longer period, decreased VEGF-A, and/or increased oxidative stress may be more involved in capillary regression. This article is protected by copyright. All rights reserved.

Antioxidant activity and protective effect of propolis against carbon tetrachloride-induced liver and kidney injury by modulation of oxidative parameters

Background and Aim:

Propolis has a protective effect against cellular damage caused by toxic agents such as drugs, metals, xenobiotics, and chemicals. The aim of this study was to investigate the antioxidant activity and the effect of ethanolic extract of propolis on carbon tetrachloride (CCl4)-induced oxidative stress on kidney and liver injury in rat.

Materials and Methods:

The study quantified phenol, flavone, and flavonol in propolis and assessed antioxidant activity using 2, 2-diphenyl-1-picrylhydrazyl, ferric reducing antioxidant power, and molybdate. The investigators used four groups of rats to study the effect of propolis on CCl₄-induced toxicity. Propolis extract was given orally (500 mg/kg) for 12 days, and CCl_{4 (}1 mL/kg) was administered intraperitoneally on day 5 of the experiment. Blood and tissue samples of the liver and kidney were collected on day 13 to measure biochemical and oxidative parameters. The parameters included malondialdehyde (MDA), protein carbonyl formation (PCO), advanced oxidation protein products (AOPP), catalase (CAT), glutathione peroxidase (GPx), reduced glutathione (GSH), and ascorbic acid (AA). Biochemical parameters included liver enzymes, blood urea (BU), creatinine, and uric acid (UA).

Results:

CCl₄ decreased antioxidant agents, including CAT, GPx, GSH, and AA in the liver and kidney tissues. The oxidative agents’ levels, including MDA, PCO, and AOPP, increased by CCl₄ compared to the control group. CCl₄ increased liver enzymes, UA, BU, and creatinine in the blood samples. Propolis significantly alleviated liver and kidney function, improved antioxidant parameters, and decreased levels of oxidative agents.

Conclusion:

The data showed for the 1^st time that Moroccan propolis has a protective effect against CCl₄-induced kidney and liver toxicity by maintaining the activity of the antioxidant defense system, which was most likely due to its antioxidant activity.

Nucleoprotein-enriched diet enhances protein synthesis pathway and satellite cell activation via ERK1/2 phosphorylation in unloaded rat muscles

NEW FINDINGS

What is the central question of this study? The purpose of this study was to determine whether the nucleotides in a nucleoprotein-enriched diet could ameliorate the unloading-associated decrease in soleus muscle mass and fibre size. What is the main finding and its importance? The results indicate that the nucleotides in the nucleoprotein-enriched diet could ameliorate the unloading-associated decrease in type I fibre size and muscle mass, most probably owing to the activation of protein synthesis pathways and satellite cell proliferation and differentiation via ERK1/2 phosphorylation. Thus, nucleotide supplementation appears to be an effective countermeasure for muscle atrophy.

ABSTRACT

Hindlimb unloading decreases both the protein synthesis pathway and satellite cell activation and results in muscle atrophy. Nucleotides are included in nucleoprotein and provide the benefits of increasing extracellular signal-regulated kinase (ERK) 1/2 phosphorylation. ERK1/2 phosphorylation is also important in the activation of satellite cells, especially for myoblast proliferation and stimulating protein synthesis pathways. Therefore, we hypothesized that nucleotides in the nucleoproteins would ameliorate muscle atrophy by increasing the protein synthesis pathways and satellite cell activation during hindlimb unloading in rat soleus muscle. Twenty-four female Wistar rats were divided into four groups: control rats fed a basal diet without nucleoprotein (CON), control rats fed a nucleoprotein-enriched diet (CON+NP), hindlimb-unloaded rats fed a basal diet (HU) or hindlimb-unloaded rats fed a nucleoprotein-enriched diet (HU+NP). HU for 2 weeks resulted in reductions in phosphorylation of p70S6K and rpS6, the numbers of myoblast determination protein (MyoD)- and myogenin- positive nuclei, type I muscle fibre size and muscle mass. Both CON+NP and HU+NP rats showed an increase in ERK1/2, phosphorylation of p70S6K and rpS6, and the numbers of MyoD- and myogenin-positive nuclei compared with their basal diet groups. The NP diet also ameliorated the unloading-associated decrease in type I muscle fibre size and muscle mass. The results indicate that the nucleotides in the nucleoprotein-enriched diet could ameliorate the unloading-associated decrease in type I fibre size and muscle mass, most probably owing to the activation of protein synthesis pathways and satellite cell proliferation and differentiation via ERK1/2 phosphorylation. Thus, nucleotide supplementation appears to be an effective countermeasure for muscle atrophy.

Green propolis extract attenuates acute kidney injury and lung injury in a rat model of sepsis

Sepsis is the leading cause of acute kidney injury (AKI) and lung injury worldwide. Despite therapeutic advances, sepsis continues to be associated with high mortality. Because Brazilian green propolis (GP) has promising anti-inflammatory, antioxidant, and immunomodulatory properties, we hypothesized that it would protect kidneys and lungs in rats induced to sepsis by cecal ligation and puncture (CLP). Male Wistar rats were divided into groups-control (sham-operated); CLP (CLP only); and CLP + GP (CLP and treatment with GP at 6 h thereafter)-all receiving volume expansion and antibiotic therapy at 6 h after the procedures. By 24 h after the procedures, treatment with GP improved survival, attenuated sepsis-induced AKI, and restored renal tubular function. Whole-blood levels of reduced glutathione were higher in the CLP + GP group. Sepsis upregulated the Toll-like receptor 4/nuclear factor-kappa B axis in lung and renal tissues, as well as increasing inflammatory cytokine levels and macrophage infiltration; all of those effects were attenuated by GP. Treatment with GP decreased the numbers of terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling-positive cells in renal and lung tissue, as well as protecting the morphology of the renal mitochondria. Our data open the prospect for clinical trials of the use of GP in sepsis.

Mild hyperbaric oxygen exposure attenuates rarefaction of capillary vessels in streptozotocin-induced diabetic soleus muscle in rats

We examined the effects of mild hyperbaric oxygen (mHBO) exposure on capillary rarefaction in skeletal muscles of rats with diabetes. Streptozotocin (100 mg/kg) was administered to male Wistar rats via the tail vein to prepare a diabetic model. These rats were divided into 2 groups: the group with mHBO exposure (1.25 atmospheres absolute (ATA) with 36% oxygen; 3 h/day) and the group without mHBO exposure. Age-matched rats were used as the control group. Eight weeks later, the soleus of the rats was removed and then analyzed. With the onset of diabetes mellitus, capillary number, diameter, and volume in the soleus of the rats with diabetes decreased compared with those of the rats in the control group. In addition, increased anti-angiogenic thrombospondin-1 (TSP-1) and decreased pro-angiogenic murine double minute 2 (MDM-2) protein expressions were observed in the rats with diabetes. Alternatively, mHBO exposure attenuated the decrease in capillary diameter and volume in skeletal muscles of rats with diabetes, suppressed the overexpression of TSP-1, and restored the MDM-2 expression. These results indicate the exposure of mHBO partially attenuates capillary rarefaction in diabetic soleus muscle.

Effects of reloading after chronic neuromuscular inactivity on the three-dimensional capillary architecture in rat soleus muscle

The purpose of the study was to investigate the effects of ambulatory reloading following hindlimb unloading on the three-dimensional (3D) capillary architecture of rat soleus muscle. In this study, 15 male Sprague-Dawley rats were used. The rats were randomly assigned to the following 3 groups: a normal weight bearing control group (CON), 14 days of hindlimb unloading group (HU), and 14 days of hindlimb unloading followed by 7 days of ambulatory reloading group (HU-RL). The capillary diameter and volume were measured using confocal laser microscopy, and capillary number was determined by two-dimensional (2D) capillary staining in the soleus muscle of each group. The capillary diameter and volume as well as the capillary number were significantly lower in the HU group than in the CON group and significantly higher in the HU-RL group than in the HU group. These results provided novel information about the effectiveness of reloading following unloading on not only the 2D increase in capillary number but also the 3D capillary remodeling in the diameter and volume within the unloaded soleus muscle.

Apitherapy for Age-Related Skeletal Muscle Dysfunction (Sarcopenia): A Review on the Effects of Royal Jelly, Propolis, and Bee Pollen

The global pandemic of sarcopenia, skeletal muscle loss and weakness, which prevails in up to 50% of older adults is increasing worldwide due to the expansion of aging populations. It is now striking young and midlife adults as well because of sedentary lifestyle and increased intake of unhealthy food (e.g., western diet). The lockdown measures and economic turndown associated with the current outbreak of Coronavirus Disease 2019 (COVID-19) are likely to increase the prevalence of sarcopenia by promoting sedentarism and unhealthy patterns of eating. Sarcopenia has multiple detrimental effects including falls, hospitalization, disability, and institutionalization. Although a few pharmacological agents (e.g., bimagrumab, sarconeos, and exercise mimetics) are being explored in different stages of trials, not a single drug has been approved for sarcopenia treatment. Hence, research has focused on testing the effect of nutraceuticals, such as bee products, as safe treatments to prevent and/or treat sarcopenia. Royal jelly, propolis, and bee pollen are common bee products that are rich in highly potent antioxidants such as flavonoids, phenols, and amino acids. These products, in order, stimulate larval development into queen bees, promote defenses of the bee hive against microbial and environmental threats, and increase royal jelly production by nurse bees. Thanks to their versatile pharmacological activities (e.g., anti-aging, anti-inflammatory, anticarcinogenic, antimicrobial, etc.), these products have been used to treat multiple chronic conditions that predispose to muscle wasting such as hypertension, diabetes mellitus, cardiovascular disorder, and cancer, to name a few. They were also used in some evolving studies to treat sarcopenia in laboratory animals and, to a limited degree, in humans. However, a collective understanding of the effect and mechanism of action of these products in skeletal muscle is not well-developed. Therefore, this review examines the literature for possible effects of royal jelly, bee pollen, and propolis on skeletal muscle in aged experimental models, muscle cell cultures, and humans. Collectively, data from reviewed studies denote varying levels of positive effects of bee products on muscle mass, strength, and function. The likely underlying mechanisms include amelioration of inflammation and oxidative damages, promotion of metabolic regulation, enhancement of satellite stem cell responsiveness, improvement of muscular blood supply, inhibition of catabolic genes, and promotion of peripheral neuronal regeneration. This review offers suggestions for other mechanisms to be explored and provides guidance for future trials investigating the effects of bee products among people with sarcopenia.

Effects of Propolis Extract and Propolis-Derived Compounds on Obesity and Diabetes: Knowledge from Cellular and Animal Models

Propolis is a natural product resulting from the mixing of bee secretions with botanical exudates. Since propolis is rich in flavonoids and cinnamic acid derivatives, the application of propolis extracts has been tried in therapies against cancer, inflammation, and metabolic diseases. As metabolic diseases develop relatively slowly in patients, the therapeutic effects of propolis in humans should be evaluated over long periods of time. Moreover, several factors such as medical history, genetic inheritance, and living environment should be taken into consideration in human studies. Animal models, especially mice and rats, have some advantages, as genetic and microbiological variables can be controlled. On the other hand, cellular models allow the investigation of detailed molecular events evoked by propolis and derivative compounds. Taking advantage of animal and cellular models, accumulating evidence suggests that propolis extracts have therapeutic effects on obesity by controlling adipogenesis, adipokine secretion, food intake, and energy expenditure. Studies in animal and cellular models have also indicated that propolis modulates oxidative stress, the accumulation of advanced glycation end products (AGEs), and adipose tissue inflammation, all of which contribute to insulin resistance or defects in insulin secretion. Consequently, propolis treatment may mitigate diabetic complications such as nephropathy, retinopathy, foot ulcers, and non-alcoholic fatty liver disease. This review describes the beneficial effects of propolis on metabolic disorders.

Effects of astaxanthin supplementation and electrical stimulation on muscle atrophy and decreased oxidative capacity in soleus muscle during hindlimb unloading in rats

The effects of a combination of the antioxidant astaxanthin (AX) and electrical stimulation (ES) on muscle mass and mitochondrial oxidative capacity were investigated in the soleus muscle of hindlimb unloaded rats. Five groups of male Sprague-Dawley rats were used; control, 1-week hindlimb unloading (HU), HU + AX, HU + ES, and HU + AX + ES. Respective rats in the AX groups received 50-mg/kg AX twice daily during HU. Calf muscles of rats in the ES groups were electrically stimulated for 240 s/day during HU. One-week HU decreased muscle mass along with decreased FoxO3a phosphorylation and increased ubiquitinated proteins expressions, decreased oxidative enzymatic activity accompanied with decline in PGC-1α protein expression, and increased reactive oxygen species production. However, the combination treatment could synergistically attenuate/suppress all HU-related changes, suggesting protective effects on muscle atrophy and decreased muscle oxidative capacity due to chronic neuromuscular inactivity.

Application of transcutaneous carbon dioxide improves capillary regression of skeletal muscle in hyperglycemia

The purpose of the present study was to determine the effects of transcutaneous CO2 application on the blood flow and capillary architecture of the soleus muscle in rats with streptozotocin (STZ)-induced hyperglycemia. Wistar rats were randomly divided into four groups: control, control + CO2-treated, STZ-induced hyperglycemia, and STZ-induced hyperglycemia + CO2-treated groups. Blood flow in soleus muscle increased during the transcutaneous CO2 exposure, and continued to increase for 30 min after the treatment. In addition, the transcutaneous CO2 attenuated a decrease in capillary and the expression level of eNOS and VEGF protein, and an increase in the expression level of MDM-2 and TSP-1 protein of soleus muscle due to STZ-induced hyperglycemia. These results indicate that the application of transcutaneous CO2 could improve capillary regression via the change of pro- and anti-angiogenesis factors, which might be induced by an increase in blood flow.