The effect of low-level laser therapy on oxidative stress and functional fitness in aged rats subjected to swimming: an aerobic exercise

Photobiomodulation therapy reverses spermatogenesis arrest in hyperthermia-induced azoospermia mouse model

Testicular heat stress leads to impairment of spermatogenesis in mammals. Involved mechanism in this vulnerability to heat-induced injury remains unclear, and research is being conducted to find an approach to reverse spermatogenesis arrest caused by hyperthermia. Recently, different studies have utilized photobiomodulation therapy (PBMT) therapy for the improvement of sperm criteria and fertility. This study aimed at evaluating the effect of PBMT on the improvement of spermatogenesis in mouse models of hyperthermia-induced azoospermia. A total of 32 male NMRI mice were equally divided into four groups consisting of control, hyperthermia, hyperthermia + Laser 0.03 J/cm2, and hyperthermia + Laser 0.2 J/cm2. To induce scrotal hyperthermia, mice were anesthetized and placed in a hot water bath at 43 °C for 20 min for 5 weeks. Then, PBMT was operated for 21 days using 0.03 J/cm2 and 0.2 J/cm2 laser energy densities in the Laser 0.03 and Laser 0.2 groups, respectively. Results revealed that PBMT with lower intensity (0.03 J/cm2) increased succinate dehydrogenase (SDH) activity and glutathione (GSH)/oxidized glutathione (GSSG) ratio in hyperthermia-induced azoospermia mice. At the same time, low-level PBMT reduced reactive oxygen species (ROS), mitochondrial membrane potential, and lipid peroxidation levels in the azoospermia model. These alterations accompanied the restoration of spermatogenesis manifested by the elevated number of testicular cells, increased volume and length of seminiferous tubules, and production of mature spermatozoa. After conducting experiments and analyzing the results, it has been revealed that the use of PBMT at a dosage of 0.03 J/cm2 has shown remarkable healing effects in the heat-induced azoospermia mouse model.

Photobiomodulation in 3D tissue engineering

SIGNIFICANCE

The method of photobiomodulation (PBM) has been used in medicine for a long time to promote anti-inflammation and pain-resolving processes in different organs and tissues. PBM triggers numerous cellular pathways including stimulation of the mitochondrial respiratory chain, alteration of the cytoskeleton, cell death prevention, increasing proliferative activity, and directing cell differentiation. The most effective wavelengths for PBM are found within the optical window (750 to 1100 nm), in which light can permeate tissues and other water-containing structures to depths of up to a few cm. PBM already finds its applications in the developing fields of tissue engineering and regenerative medicine. However, the diversity of three-dimensional (3D) systems, irradiation sources, and protocols intricate the PBM applications.

AIM

We aim to discuss the PBM and 3D tissue engineered constructs to define the fields of interest for PBM applications in tissue engineering.

APPROACH

First, we provide a brief overview of PBM and the timeline of its development. Then, we discuss the optical properties of 3D cultivation systems and important points of light dosimetry. Finally, we analyze the cellular pathways induced by PBM and outcomes observed in various 3D tissue-engineered constructs: hydrogels, scaffolds, spheroids, cell sheets, bioprinted structures, and organoids.

RESULTS

Our summarized results demonstrate the great potential of PBM in the stimulation of the cell survival and viability in 3D conditions. The strategies to achieve different cell physiology states with particular PBM parameters are outlined.

CONCLUSIONS

PBM has already proved itself as a convenient and effective tool to prevent drastic cellular events in the stress conditions. Because of the poor viability of cells in scaffolds and the convenience of PBM devices, 3D tissue engineering is a perspective field for PBM applications.

Photobiomodulation intervention improves oxidative, inflammatory, and morphological parameters of skeletal muscle in cirrhotic Wistar rats

Photobiomodulation (PBM) might be an intervention method to mitigate sarcopenia in cirrhotic patients. Given the lack of research on this issue, the goal of this study was to evaluate possible beneficial effects of PBM on the structural and functional properties of skeletal muscle from cirrhotic rats. Cirrhosis was induced by secondary bile duct ligation (BDL). Wistar rats were randomized into four groups: sham-operated control (Sham), Sham + PBM, BDL, and BDL + PBM. After cirrhosis induction, a dose of PBM (1 J; 100mW; 10 s; 880 nm; 6 × per week) was applied to each quadriceps, from the 15th to the 45th day after surgery. The locomotor ability was performed using an open-field task. The muscle structure was analyzed using histological methods. Cell damage was also evaluated assessing oxidative stress and DNA damage markers, and IL-1β pro-inflammatory interleukin by immunohistochemical analysis. An increase in the number of crossings was observed in the BDL + PBM group in relation to BDL. The BDL group showed muscle atrophy and increased IL-1β in relation to Sham, while in the BDL + PBM group, the fiber muscle was restructured and there was a decrease of IL-1 β. TBARS increased in the liver and muscle tissues in the BDL group and decreased it in the BDL + PBM group. SOD increased while CAT decreased in the BDL + PBM group in relation to the BDL group. No genotoxic or mutagenic effect was observed for PBM treatment. PBM improved the locomotion and the morphology of the muscle fibers, decreasing oxidative stress and inflammation, without causing DNA damage in cirrhotic rats.

Response of Aerobic Capacity to Low-Level Laser Therapy in Burned Patients

BACKGROUND

Severe burns lead to decreased pulmonary function and impaired aerobic capacity for long periods post-injury. Low-level laser therapy is a modality utilized to improve aerobic capacity, enhance exercise performance and increase time until fatigue when utilized before aerobic exercises.

PURPOSE

This work aims to determine the impacts of pre-exercise low-level laser therapy on aerobic capacity in burn cases.

PARTICIPANTS AND METHODS

Sixty adults burned cases of both sexes, aged from 25 to 40 years, with second-degree healed thermal burns, and the total burned body surface area ranged from 20 to 40% participated in this study after complete wound healing. They were randomly categorized into two groups of equal numbers. The study group received low-level laser therapy before aerobic exercises, three sessions/week for 12 weeks, while the control group performed aerobic exercises three times weekly for 12 weeks. All cases received the routine physical treatment program. Aerobic capacity was assessed for both groups by measuring maximum oxygen consumption and time to exhaustion at baseline and twelve weeks following interventions.

FINDINGS

There was a statistically significant rise in the mean values of maximum oxygen usage and time to fatigue after 12 weeks of treatment in both groups. However, after comparison, the improvements in the study group were statistically significant than those in the control group with (p < 0.01), (p < 0.05) respectively.

CONCLUSION

Low-level laser therapy has a beneficial therapeutic impact on promoting aerobic capacity, improving maximum oxygen consumption, and increasing treadmill time in burned cases when preceding aerobic exercises.

Oxidative Stress and Abnormal Tendon Sonographic Features in Elite Soccer Players (A Pilot Study)

Objective  Sound experimental data suggest that oxidative stress plays an important role in the pathogenesis of tendinopathies. However, this hypothesis in humans remains speculative given that clinical data are lacking to confirm it. Recently, a new methodology has allowed to quantify the oxidative stress in vivo by measuring the concentration of hydroperoxides of organic compounds, which have been utilized as an oxidative stress-related marker in several pathologic and physiologic conditions. Given the reliability of this test and the lack of information in subjects with tendinopathies, the aim of the present study was to assess the oxidative stress status in elite professional soccer players with and without ultrasonographic features of tendon damage.

Methods  In 73 elite players, blood metabolic parameters were evaluated and oxidative stress was measured by means of a specific test (expressed as U-Carr units). Therefore, an ultrasonographic evaluation of the Achilles and patellar tendons was performed.

Results  No significant relationships were observed between metabolic parameters and oxidative stress biomarkers. The Achilles and patellar tendons showed a normal echographic pattern in 58 athletes, and sonographic abnormalities in 15. The athletes with ultrasonographic alterations, compared to those with normal US picture, showed significantly higher U-Carr levels ( p  = 0.000), body mass index (BMI) values ( p  = 0.03) and were older ( p  = 0.005). The difference in U-Carr values among the subjects remained significant also after adjustment for age and BMI.

Conclusion  The results of the present study support the hypothesis that oxidative substances, also increased at systemic and not only at local level, may favor tendon damage.

Level of Evidence  IV (pilot study).

Post-resistance exercise photobiomodulation therapy has a more effective antioxidant effect than pre-application on muscle oxidative stress

This study evaluated the effect of photobiomodulation therapy (PBMt) before or after a high-intensity resistance exercise (RE) session on muscle oxidative stress. Female Wistar rats were assigned to one of the following groups: Sham (non-exercised, undergoing placebo-PBMt); NLRE (exercised, undergoing placebo-PBMt); PBMt + RE (pre-exercise PBMt); RE + PBMt (post-exercise PBMt). The RE comprised four climbs bearing the maximum load with a 2 min rest between each climb. An 830-nm aluminum gallium arsenide diode laser (100 mW; 0.028 cm²; 3.57 mW/cm²; 142.8 J/cm²; 4 J; Photon Laser III, DMC, São Paulo, Brazil) was applied 60 s before or after RE in gastrocnemius muscles. Analyses were performed at 24 h after RE: lipoperoxidation using malondialdehyde (MDA) and protein oxidation (OP) on Western blot. Superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) activity were spectrophotometrically assessed. Nitric oxide (NO) level was determined by the Griess reaction. The MDA and OP levels were significantly higher in the NLRE group. Increased OP was prevented in all PBMt groups; however, increased MDA was prevented only in the RE + PBMT group. The RE + PBMt group had higher SOD activity compared to all other groups. A higher GPx activity was observed only in the PBMT + RE compared to Sham group, and CAT activity was reduced by RE, without PBMt effect. NO levels were unchanged with RE or PBMt. Therefore, PBMt application after a RE section has a more potent antioxidant effect than previous PBMt. Rats submitted to post-RE PBMt illustrated prevention of increased lipoperoxidation and protein oxidation as well as increased SOD activity. The photobiomodulation can attenuate oxidative stress induced by resistance exercise. A more evident benefit shows to be obtained with the application after exercise, in which it has increased the activity of superoxide dismustase.

Effect of Photobiomodulation on Critical Swimming Velocity: A Randomized, Crossover, Double-Blind, and Placebo-Controlled Study

PURPOSE

To analyze the acute effect of photobiomodulation (PBM) on swimming critical velocity (CV).

METHODS

A total of 15 male federated swimmers (20.9 [2.4] y old) participated in this study. Three sets of front crawl were performed at distances of 100, 200, and 400 m to determine the CV under 3 experimental conditions: PBM (420 J), placebo (PLA), and control (C) in this randomized, crossover, double-blind, and placebo-controlled study. One-way analysis of variance for repeated measurements was used for statistical analyses.

RESULTS

The results showed that the prior application of PBM did not have ergogenic effects on CV and front crawl swimming performance: CV (PBM = 1.15 [0.15]; PLA = 1.20 [0.25]; C = 1.15 [0.14] m·s-1), swim time (ST) 100 m (PBM = 65.5 [6.3]; PLA = 65.2 [5.6]; C = 66.0 [5.9] s), ST 200 m (PBM = 148.5 [17.9]; PLA = 149.4 [16.4]; C = 150.1 [17.9] s), and ST 400 m (PBM = 327.7 [38.2]; PLA = 321.6 [47.7]; C = 329.5 [41.2] s).

CONCLUSIONS

A PBM application prior to front crawl swimming test did not significantly modify the CV, ST, physiological factors of metabolic fatigue, perceptual, and front crawl stroke efficiency parameters in competition swimmers covering distances of 100, 200, and 400 m.

Photobiomodulation: A review of the molecular evidence for low level light therapy

Light energy is harnessed for therapeutic use in a number of ways, most recently by way of photobiomodulation (PBM). This phenomenon is a cascade of physiological events induced by the nonthermal exposure of tissue to light at the near infrared end of the visible spectrum. Therapeutic PBM has become a highly commercialized interest, marketed for everything from facial rejuvenation to fat loss, and diode-based devices are popular in both the clinic setting and for use at home. The lack of regulatory standards makes it difficult to draw clear conclusions about efficacy and safety but it is crucial that we understand the theoretical basis for PBM, so that we can engage in an honest dialogue with our patients and design better clinical studies to put claims of efficacy to the test. This article presents a summary of the science of PBM and examines the differences between laser light, on which much of the preclinical evidence is based and light from diodes, which are typically used in a clinical setting.

Effect of Low-Level Laser on Some Metals Related to Redox State and Histological Alterations in the Liver and Kidney of Irradiated Rats

Low-level laser therapy (LLLT) is a type of medicine that uses laser light at low levels to activate the cellular chromophores and the initiation of cellular signaling. This study aimed to evaluate the photomodulation effect of LLL against ionizing radiation (IR)-induced metal disorders related to redox state in the liver and kidney of male rats. Rats were divided into 4 groups (control, LLLT, IR (7Gy), IR+LLLT). The results showed that LLLT 870 nm one time for 3 days post-irradiation revealed redistribution of iron (Fe), copper (Cu), zinc (Zn),calcium (Ca), magnesium (Mg), manganese (Mn), and selenium (Se) in the liver and kidney tissues. Moreover, LLLT attenuated the oxidative stress manifested by a marked reduction of hydrogen peroxide (H₂O₂), 4-hydroxynonenal (4-HNE), total oxidant state (TOS), and oxidative stress index (OSI) associated with a significant increase in total antioxidant status (TAS), glutathione (GSH) content, and glutathione peroxide (GPx), glutathione reductase (GRx), superoxide dismutase(SOD), and catalase (CAT) activities. Moreover, LLLT displayed an increase in glutathione-S-transferase (GSH-T) and ceruloplasmin activities and a decrease in the activity of gamma-glutamyl transferase (γ-GT). Besides, LLLT significantly attenuated the histological changes in the liver and kidney tissues, denoted by a reduction in the necrotic and degenerative changes of hepatocytes and an improvement in the corpuscles and tubules of the kidney. In conclusion, LLLT could be used as an adjuvant treatment post-exposure to radiation, while it is not beneficial to use it on the normal tissue.

Low-Level Laser Effect on Peripheral Sciatic Regeneration Under the Systemic Inflammatory Condition of Periodontal Disease

Introduction: Periodontal disease (PD) is an inflammatory condition, which leads to tooth loss and promotes a systemic inflammatory state that can aggravate the nerve degeneration. As laser therapy may stimulate regeneration, this study aimed to evaluate the effect of the low-level laser (LLL) on peripheral nerve regeneration under the systemic inflammatory condition of PD. Methods: Thirry-two male rats were used, distributed in 4 groups: nerve injury (NIG); periodontal disease with nerve injury (PDNI); nerve injury and treatment (TNIG); periodontal disease with nerve injury and treatment (PDNIT). On the 7th day of the experiment, the animals had ligatures placed around the lower first molars. On the 22nd day, they underwent peripheral nerve damage, and on the 25th day, the LLL treatment was initiated, performed for two weeks. The sciatic functional index (SFI) was evaluated with subsequent euthanasia of all the animals on the 37th day of the experiment. The sciatic nerve was collected for morphological and oxidative stress analysis and the hemi jaws for radiographic analysis. Results: Regarding the SFI, there was no difference among the groups in the first evaluation (EV) pre-injury; as for theEV2, after injury, all the groups presented a decrease in these values, which remained in post-treatment. For the morphology of the PDNI, nerve tissue presented larger diameter fibers, whereas, for NIT and PDNIT, fibers had smaller diameters with endoneurial organization. When it comes to the antioxidant system, there was an increase in protein concentration, higher superoxide activity, and decreased glutathione transferase activity in the treated groups. Catalase and cholinesterase did not differ between the groups, and lipoperoxidation (LPO) increased in the PD groups. For the mandible radiographic analysis, it was possible to verify the induction of PD. Conclusion: As for the used parameters, the low-level laser was not effective in increasing the nociceptive threshold, but it contributed to the regeneration of nerve fibers, although the inflammation was still present in the site. However, the treatment was effective in protecting cells against oxidative damage due to increased SOD and increased protein, although the decrease in GST demonstrates the inhibition of this stage of the antioxidant system.

Role of 904 nm superpulsed laser-mediated photobiomodulation on nitroxidative stress and redox homeostasis in burn wound healing

BACKGROUND

Burn wound healing is delayed due to several critical factors such as sustained inflammation, vascular disorder, neuropathy, enhanced proteolysis, infection, and oxidative stress. Burn wounds have limited oxygen supply owing to compromised blood circulation. Hypoxic burn milieu leads to free radicals overproduction incurring oxidative injury, which impedes repair process causing damage to cell membranes, proteins, lipids, and DNA. Photobiomodulation (PBM) with 904 nm superpulsed laser had shown potent healing efficacy via attenuating inflammation while enhancing proliferation, angiogenesis, collagen accumulation, and bioenergetic activation in burn wounds.

METHODS

This study investigated the effects of 904 nm superpulsed laser at 0.4 mW/cm² average power density, 0.2 J/cm² total energy density, 100 Hz frequency, and 200 ns pulse width for 10 min daily for seven days postburn injury on nitroxidative stress, endogenous antioxidants status, and redox homeostasis.

RESULTS

Photobiomodulation treatment significantly decreased reactive oxygen species, nitric oxide, and lipid peroxidation levels as compared to non-irradiated control. Further, protective action of PBM against protein oxidative damage was evidenced by reduced protein carbonylation and advanced oxidation protein product levels along with significantly enhanced endogenous antioxidants levels of SOD, catalase, GPx, GST, reduced glutathione, and thiol (T-SH, Np-SH, P-SH). Biochemical changes aid in reduction of oxidative stress and maintenance of redox homeostasis, which further well corroborated by significantly up-regulated protein expression of Nrf 2, hemeoxygenase (HO-1), and thioredoxin reductase 2 (Txnrd2).

CONCLUSION

Photobiomodulation with 904 nm superpulsed laser led to reduction of nitroxidative stress, induction of endogenous antioxidants, and maintenance of redox homeostasis that could play a vital role in augmentation of burn wound healing.

Potential inhibitory effect of swimming exercise on the Kisspeptin-GnRH signaling pathway in male rats

Aerobic exercises are considered as an effective method of improving several undesirable health outcomes; however, their implications in the male reproductive axis have remained controversial. The present study evaluated the impact of physical exercise on the male reproductive system in rats and investigated the potential central and peripheral mechanisms involved in it. Twenty male Sprague-Dawley rats were randomly divided into control and exercise groups, with 10 rats per group. The rats were subjected to a swimming exercise for 60 min/day for five days a week and the protocol was followed for six constitutive weeks. We found that the swimming exercise significantly decreased the testicular weight and the testicular somatic index. Furthermore, there was a marked reduction in several sperm characteristics, including sperm count, motility, morphology, and viability in the exercised rats. The serum levels of reproductive hormones, i.e., testosterone (T), luteinizing hormone (LH), and follicle stimulating hormone (FSH) were significantly decreased. A histological examination of testes and epididymis revealed defective spermatogenesis. Molecular analysis revealed the downregulation of the expression of mRNAs of the hypothalamic kisspeptin (Kiss1), Kiss1 receptor (Kiss1r), gonadotropin-releasing hormone (GnRH1), GnRH1 receptor (GnRHr), and testicular Kiss1r along with an upregulation in the gene expression of GnRHr in the pituitary. We also observed a significant reduction in the activity and the expression of mRNAs of testicular superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) and a marked elevation in the levelsof malondialdehyde (MDA). These findings implied that chronic swimming exercise suppressed the Kisspeptin-GnRH signaling pathway, consequently reducing the production of male reproductive hormones. A simultaneous increase in the oxidative stress could contribute to exercise-induced inhibition of male reproductive functions. To conclude, an appropriate training program is important to maximize the benefits and minimize the side effects of physical exercises on the male reproductive system.

Effects of Endurance Running Training Associated With Photobiomodulation on 5-Km Performance and Muscle Soreness: A Randomized Placebo-Controlled Trial

This study aimed to investigate the influence of endurance running training associated with PBM on endurance performance variables and muscle soreness in untrained men. Thirty untrained men were distributed randomly into a placebo (PLA) group and photobiomodulation group (PBMG) and they performed 8 weeks of running training. The PBMG had the PBM performed before all training sessions. The PBM was applied using LED equipment with 56 diodes of red light (660 nm) and 48 diodes of infrared light (850 nm). The application was performed in 5 points per leg, with a dose of 60 J at each point and a total energy delivered per leg of 300 J. Peak running velocity, time limit tests and 5-km performance were assessed pre and post-training; muscle soreness was evaluated before all training sessions. The V_peak increased and 5-km running time (t_5–km) decreased (P < 0.001) in both groups. In addition, the magnitude based-inference analysis showed a possibly positive effect on V_peak and t_5–km and for PBMG compared to PLA group. Furthermore, there was a moderate ES of 0.82 on attenuation in muscle soreness in the third week of endurance running training. Therefore, although the magnitude-based inference analysis demonstrated a possibly positive effect on V_peak and t_5–km and for PBMG compared to PLA group and a moderate ES on attenuation in muscle soreness in the last weeks of endurance running training, no significant difference were found between PBMG and PLA interventions.

Effect of Low-Level Laser Irradiation on the Function of Glycated Catalase

Introduction: The aim of this work is to evaluate the effect of low-level laser irradiation (LLLI), by lasers with different wavelengths, on glycated catalase enzyme in vitro experimentally. Methods: This is done by measuring the activity and structure properties of glycated catalase enzyme. The structure properties were evaluated with circular dichroism (CD) and fluoroscopy methods. Three continuous wave (CW) lasers in the visible spectrum (λ =450, 530, 638 nm) and a 100-ns pulsed laser in the infrared spectrum (λ =905 nm) were chosen for comparison. For the infrared laser, same effects have been investigated for different energy doses. The effect of photon energy (hυ) at different wavelengths was measured on activity, CD, and fluoroscopy properties of catalase, and compared with the control group (samples without irradiation). The energy intensity of laser should not exceed 0.1 J/cm² . Experiments were performed on glycated catalase between 2 to 16 weeks after glycation of catalase. The LLLI effect was also investigated on the samples, by comparing the catalase activity, CD and fluoroscopy for different wavelengths. Results: Our results indicated, the decrease in catalase activity as a function of glycation time (weeks) for all samples, and a slight increase on its activity by different laser wavelengths irradiation for any fixed period of glycation time. Finally, the catalase activity has been increased as the laser's photon energy (hυ) intensified. More specifically, the blue laser (λ =450 nm) had the most and the red laser (λ =638 nm) had the least effect, and the green laser (λ =530 nm) had the medium effect on catalase activity as well. Furthermore, pulsed laser had an additional effect by increasing energy dosage. Conclusion: As we expected in all experiments, an increase in the catalase activity was coincident with a decrease in the catalase fluoroscopy and CD parameters.

Effect of photobiomodulation therapy on oxidative stress markers of gastrocnemius muscle of diabetic rats subjected to high-intensity exercise

This study aimed to determine whether photobiomodulation therapy (PBMT) in diabetic rats subjected to high-intensity exercise interferes with the expression of the oxidative stress marker in the gastrocnemius muscle. Twenty-four male Wistar rats were included in this study comprising 16 diabetic and eight control rats. The animals were allocated into three groups-control, diabetic fatigue, and diabetic PBMT fatigue groups. Diabetes was induced via the intraperitoneal administration of streptozotocin (50 mg/kg). We subsequently assessed blood lactate levels and PBMT. The animals of the diabetic fatigue group PBMT were irradiated before the beginning of the exercises, with dose of 4 J and 808 nm, were submitted to treadmill running with speed and gradual slope until exhaustion, as observed by the maximum volume of oxygen and lactate level. The animals were euthanized and muscle tissue was removed for analysis of SOD markers, including catalase (CAT), glutathione peroxidase (GPx), and 2-thiobarbituric acid (TBARS) reactive substances. CAT, SOD, and GPx activities were significantly higher in the diabetic PBMT fatigue group (p < 0.05) than in the diabetic fatigue group. Outcomes for the diabetic PBMT fatigue group were similar to those of the control group (p > 0.05), while their antioxidant enzymes were significantly higher than those of the diabetic fatigue group. PBMT mitigated the TBARS concentration (p > 0.05). PBMT may reduce oxidative stress and be an alternative method of maintaining physical fitness when subjects are unable to perform exercise. However, this finding requires further testing in clinical studies.

Protective effects of photobiomodulation against resistance exercise-induced muscle damage and inflammation in rats

We investigated whether low-level laser therapy (LLLT) prior to or post resistance exercise could attenuate muscle damage and inflammation. Female Wistar rats were assigned to non-LLLT or LLLT groups. An 830-nm DMC Laser Photon III was used to irradiate their hind legs with 2J, 4J, and 8J doses. Irradiations were performed prior to or post (4J) resistance exercise bouts. Resistance exercise consisted of four maximum load climbs. The load work during a resistance exercise bout was similar between Control (non-LLLT, 225 ± 10 g), 2J (215 ± 8 g), 4J (210 ± 9 g), and 8J (226 ± 9 g) groups. Prior LLLT did not induce climbing performance improvement, but exposure to 4J irradiation resulted in lower blood lactate levels post-exercise. The 4J dose decreased creatine kinase and lactic dehydrogenase levels post-exercise regardless of the time of application. Moreover, 4-J irradiation exposure significantly attenuated tumor necrosis factor alpha, interleukin-6, interleukin-1β, cytokine-induced neutrophil chemoattractant-1, and monocyte chemoattractant protein-1. There was minor macrophage muscle infiltration in 4J-exposed rats. These data indicate that LLLT prior to or post resistance exercise can reduce muscle damage and inflammation, resulting in muscle recovery improvement. We attempted to determine an ideal LLLT dose for suitable results, wherein 4J irradiation exposure showed a significant protective role.

Swimming Training Improves Myocardial Mechanics, Prevents Fibrosis, and Alters Expression of Ca2+ Handling Proteins in Older Rats

Exercise training effects on the contractility of aged myocardium have been investigated for more than 20 years, but the data are still unclear. This study evaluated the hypothesis that a swimming training (ST) may improve myocardial inotropism in older rats. Male Wistar rats aged 4 (young)-and 21 (old)-months-old were divided into young untrained (YNT), old untrained (ONT), and old trained (OTR; 6 weeks of ST) groups. Echocardiography and hemodynamic were employed to assess left ventricular morphology and function. Myocardial mechanics was evaluated on papillary muscles. Histological and immunoblotting were carried out to evaluate fibrosis and proteins that modulate the myocardial function and calcium handling. We found that older rats did not show cardiac dysfunction, but ONT group showed lower physical performance during a swimming test (YNT: 5 ± 2; ONT: -16 ± 0.4; OTR: 51 ± 3; Δ%, sec). Moreover, ONT group showed worse myocardial inotropism, in which it was reversed by ST (Peak developed tension: YNT: 6.2 ± 0.7; ONT: 3.9 ± 0.3; OTR: 6.9 ± 0.9; g/mm2). The ST was associated with preserved collagen content (YNT: 0.38 ± 0.05; ONT: 0.78 ± 0.12; OTR: 0.34 ± 0.09; %). Exercise partially mitigated the effects of aging on intracellular Ca2+-regulating protein (eg, L-Ca2+ channel and phospholamban) and β-isoform of myosin. Thus, we propose that these molecular alterations together with inhibition of collagen increase contribute to improved myocardial performance in older rats.

Mechanisms and Mitochondrial Redox Signaling in Photobiomodulation

Photobiomodulation (PBM) involves the use of red or near-infrared light at low power densities to produce a beneficial effect on cells or tissues. PBM therapy is used to reduce pain, inflammation, edema, and to regenerate damaged tissues such as wounds, bones, and tendons. The primary site of light absorption in mammalian cells has been identified as the mitochondria and, more specifically, cytochrome c oxidase (CCO). It is hypothesized that inhibitory nitric oxide can be dissociated from CCO, thus restoring electron transport and increasing mitochondrial membrane potential. Another mechanism involves activation of light or heat-gated ion channels. This review will cover the redox signaling that occurs in PBM and examine the difference between healthy and stressed cells, where PBM can have apparently opposite effects. PBM has a marked effect on stem cells, and this is proposed to operate via mitochondrial redox signaling. PBM can act as a preconditioning regimen and can interact with exercise on muscles.

Photobiomodulation Leads to Reduced Oxidative Stress in Rats Submitted to High-Intensity Resistive Exercise

The aim of this study was to determine whether oxidative stress markers are influenced by low-intensity laser therapy (LLLT) in rats subjected to a high-intensity resistive exercise session (RE). Female Wistar rats divided into three experimental groups (Ctr: control, 4J: LLLT, and RE) and subdivided based on the sampling times (instantly or 24 h postexercise) underwent irradiation with LLLT using three-point transcutaneous method on the hind legs, which was applied to the gastrocnemius muscle at the distal, medial, and proximal points. Laser (4J) or placebo (device off) were carried out 60 sec prior to RE that consisted of four climbs bearing the maximum load with a 2 min time interval between each climb. Lipoperoxidation levels and antioxidant capacity were obtained in muscle. Lipoperoxidation levels were increased (4-HNE and CL markers) instantly post-RE. LLLT prior to RE avoided the increase of the lipid peroxidation levels. Similar results were also notified for oxidation protein assays. The GPx and FRAP activities did not reduce instantly or 24 h after RE. SOD increased 24 h after RE, while CAT activity did not change with RE or LLLT. In conclusion, LLLT prior to RE reduced the oxidative stress markers, as well as, avoided reduction, and still increased the antioxidant capacity.