Photobiomodulation therapy reduces acute pain and inflammation in mice

Involvement of Opioid System and TRPM8/TRPA1 Channels in the Antinociceptive Effect of Spirulina platensis

Spirulina platensis is a "super-food" and has attracted researchers' attention due to its anti-inflammatory, antioxidant, and analgesic properties. Herein, we investigated the antinociceptive effects of Spirulina in different rodent behavior models of inflammatory pain. Male Swiss mice were treated with Spirulina (3-300 mg/kg, p.o.), indomethacin (10 mg/kg, p.o.), or vehicle (0.9% NaCl 10 mL/kg). Behavioral tests were performed with administration of acetic acid (0.6%, i.p.), formalin 2.7% (formaldehyde 1%, i.pl.), menthol (1.2 µmol/paw, i.pl.), cinnamaldehyde (10 nmol/paw, i.pl.), capsaicin (1.6 µg/paw, i.pl.), glutamate (20 µmol/paw, i.pl.), or naloxone (1 mg/kg, i.p.). The animals were also exposed to the rotarod and open field test to determine possible effects of Spirulina on locomotion and motor coordination. The quantitative phytochemical assays exhibited that Spirulina contains significant concentrations of total phenols and flavonoid contents, as well as it showed a powerful antioxidant effect with the highest scavenging activity. Oral administration of Spirulina completely inhibited the abdominal contortions induced by acetic acid (ED₅₀ = 20.51 mg/kg). Spirulina treatment showed significant inhibition of formalin-induced nociceptive behavior during the inflammatory phase, and the opioid-selective antagonist markedly blocked this effect. Furthermore, our data indicate that the mechanisms underlying Spirulina analgesia appear to be related to its ability to modulate TRMP8 and TRPA1, but not by TRPV1 or glutamatergic system. Spirulina represents an orally active and safe natural analgesic that exhibits great therapeutic potential for managing inflammatory pain disorders.

Analgesia for Sheep in Commercial Production: Where to Next?

Simple Summary

Increasing societal and customer pressure to provide animals with ‘a life worth living’ continues to apply pressure on industry to alleviate pain associated with husbandry practices, injury and illness. Although a number of analgesic solutions are now available for sheep, providing some amelioration of the acute pain responses, this review has highlighted a number of potential areas for further research.

Abstract

Increasing societal and customer pressure to provide animals with ‘a life worth living’ continues to apply pressure on livestock production industries to alleviate pain associated with husbandry practices, injury and illness. Over the past 15–20 years, there has been considerable research effort to understand and develop mitigation strategies for painful husbandry procedures in sheep, leading to the successful launch of analgesic approaches specific to sheep in a number of countries. However, even with multi-modal approaches to analgesia, using both local anaesthetic and non-steroidal anti-inflammatory drugs (NSAID), pain is not obliterated, and the challenge of pain mitigation and phasing out of painful husbandry practices remains. It is timely to review and reflect on progress to date in order to strategically focus on the most important challenges, and the avenues which offer the greatest potential to be incorporated into industry practice in a process of continuous improvement. A structured, systematic literature search was carried out, incorporating peer-reviewed scientific literature in the period 2000–2019. An enormous volume of research is underway, testament to the fact that we have not solved the pain and analgesia challenge for any species, including our own. This review has highlighted a number of potential areas for further research.

Photobiomodulation exerts anti-inflammatory effects on the vascular and cellular phases of experimental inflammatory models

Photobiomodulation therapy (PBMT) is a non-thermal therapeutic procedure widely used in clinical practice. It is considered an effective modality of treatment for the control of various inflammatory conditions with fewer adverse effects as compared to conventional therapy. However, despite the clinical effects, the mechanisms of action and dosimetric parameters of PBMT are not fully understood. This study was performed to describe the effects of two different doses of PBMT on experimental models of inflammation. Male Swiss mice were administered with 0.9% of saline or phlogistic agents (carrageenan, dextran, serotonin, histamine, or bradykinin) by intra-plantar injection and were treated with PBMT at a dose of 1 or 5 J/cm²; right after, the variation of the paw volume was made, and histopathological analysis and myeloperoxidase assay of the carrageenan-induced edematous paw tissues were performed. The action of PBMT on carrageenan-induced vascular permeability was further evaluated. Our results showed that PBMT (1 J/cm²) led to an improvement in paw edema induced by the phlogistic agents and further reduced the histological scores. Inhibition of neutrophil migration was observed following the administration of 1 and 5 J/cm² of PBMT. However, only 1 J/cm² of PBMT showed beneficial effects on carrageenan-induced edema. Laser at a dose of 1 J/cm² showed cellular and vascular effects since it was able to reverse all the inflammatory parameters, and laser at a dose of 5 J/cm² probably has only cellular effects in the presence of acute inflammation.

Levels of Cyclooxygenase 2, Interleukin-6, and Tumour Necrosis Factor-α in Fibroblast Cell Culture Models after Photobiomodulation at 660 nm

Chemicals and signaling molecules released by injured cells at the beginning of wound healing prompt inflammation. In diabetes, prolonged inflammation is one of the probable causes for delayed wound healing. Increased levels of cyclooxygenase-2 (cox-2), interleukin–6 (IL-6), and tumour necrosis factor-alpha (TNF-α) are associated with the inflammatory response and in diabetes, and increased levels of these contribute to chronic wounds that do not heal. Rising levels of cox-2, IL-6, and TNF-α have also been associated with increased oxidative stress. Photobiomodulation (PBM) may impact wound healing processes by affecting the signaling pathways and molecules pertinent to tissue repair. In the present study, the effect of PBM (wavelength: 660 nm; energy density: 5 J/cm²) on levels of cox-2, IL-6, and TNF-α was determined in fibroblast cell culture models. Four WS1 models (normal, normal wounded, diabetic, and diabetic wounded) were irradiated at 660 nm, and the culture media was collected at 0, 24, and 48 h postirradiation. Cells that were not irradiated (0 J/cm²) served as the controls. The following parameters were determined postirradiation: cell morphology using light microscopy, cell viability using the Trypan Blue exclusion assay, and levels of the inflammatory markers cox-2, IL-6, and TNF-α were measured using ELISA. Cell migration increased in the wounded groups over the 48 h interval after PBM; viability improved postirradiation in the diabetic wounded groups at 0 and 24 h (P ≤ 0.05 and P ≤ 0.01, respectively); levels of cox-2 decreased in normal and diabetic wounded groups at 0 h (P ≤ 0.001) and increased in the diabetic and diabetic wounded groups at 48 h postirradiation (P ≤ 0.05 and P ≤ 0.01, respectively), while levels of IL-6 decreased in the normal (P ≤ 0.01), diabetic (P ≤ 0.05), and diabetic wounded (P ≤ 0.001) groups at 24 h and in the diabetic and diabetic wounded groups at 48 h (P ≤ 0.05) postirradiation. TNF-α was decreased in the normal wounded groups (P ≤ 0.05) at 48 h. Through its effect on decreased IL-6 levels in diabetic cell models, PBM at 660 nm may be successful at decreasing oxidative stress; however, the present study also found an increase in cox-2 levels at 48 h postirradiation.

Impact of photobiomodulation using four diode laser wavelengths of on cationic liposome gene transfection into pre-osteoblast cells

Gene therapy can be an effective treatment modality for some severe genetic diseases. Despite efforts to improve their performance, non-viral gene delivery methods remain inefficient and costly. As an alternative to viral vectors, cationic liposomes have a good safety profile and low immunogenicity, but relatively low transfection efficiency. They may also be toxic to cells at high concentrations. Given these challenges, the present study explored the impact of photobiomodulation (PBM) on cationic liposome plasmid DNA transfection in terms of its efficiency and toxicity, using Lipofectamine 2000 to carry green fluorescent protein (GFP) encoding plasmid DNA, with the pre-osteoblast MC3T3-E1 cell line as the target. Cultures were irradiated using diode lasers (445, 685, 810, or 970 nm) at 200 mW using pulsed mode (50 Hz), with a power density of 104.64 mW/cm², and irradiance from 6 to 18 joules. To determine transfection efficiency, expression of GFP was assessed using confocal laser scanning microscopy and flow cytometry. Cell viability was evaluated using the MTT assay. PBM using 810 nm and 970 nm lasers significantly enhanced transfection efficiency for GFP, indicating more efficient uptake of plasmid DNA. Conversely, laser irradiation at 445 nm and 685 nm wavelengths reduced the GFP transfection efficiency. Treatment using 685, 810, and 970 nm lasers at 12 J maintained cell viability and prevented toxicity of cationic liposomes. Overall, these findings support the concept that PBM using near infrared laser wavelengths can enhance transfection efficiency and support cell viability when cationic liposomes are used as the vector in gene therapy.

Red and near-infrared light evokes Ca2+ influx, endoplasmic reticulum release and membrane depolarization in neurons and cancer cells

Low level light therapy uses light of specific wavelengths in red and near-infrared spectral range to treat various pathological conditions. This light is able to modulate biochemical cascade reactions in cells that can have important health implications. In this study, the effect of low intensity light at 650, 808 and 1064 nm on neurons and two types of cancer cells (neuroblastoma and HeLa) is reported, with focus on the photoinduced change of intracellular level of Ca²⁺ ions and corresponding signaling pathways. The obtained results show that 650 and 808 nm light promotes intracellular Ca²⁺ elevation regardless of cell type, but with different dynamics due to the specificities of Ca²⁺ regulation in neurons and cancer cells. Two origins responsible for Ca²⁺ elevation are determined to be: influx of exogenous Ca²⁺ ions into cells and Ca²⁺ release from endoplasmic reticulum. Our investigation of the related cellular processes shows that light-induced membrane depolarization is distinctly involved in the mechanism of Ca²⁺ influx. Ca²⁺ release from endoplasmic reticulum activated by reactive oxygen species generation is considered as a possible light-dependent signaling pathway. In contrast to the irradiation with 650 and 808 nm light, no effects are observed under 1064 nm irradiation. We believe that the obtained insights are of high significance and can be useful for the development of drug-free phototherapy.

Effects of photobiomodulation therapy on the local experimental envenoming by Bothrops leucurus snake

Bothrops leucurus is the major causative agent of snakebites in Brazil's Northeast. The systemic effects of its venom are effectively neutralized by antivenom therapy, preventing bitten patients' death. However, antivenom fails in neutralizing local effects that include intense pain, edema, bleeding, and myonecrosis. Such effects can lead to irreversible sequels, representing a clinically relevant issue for which there is no current effective treatment. Herein, the effects of photobiomodulation therapy (PBMT) were tested in the local actions induced by B. leucurus venom (BLV) in mice (n = 123 animals in 20 experimental groups). A continuous emission AlGaAs semiconductor diode laser was used in two wavelengths (660 or 780 nm). Mechanical nociceptive thresholds were assessed with the electronic von Frey apparatus. Local edema was determined by measuring the increase in paw thickness. Hemorrhage was quantified by digital measurement of the bleeding area. Myotoxicity was evaluated by serum creatine kinase (CK) activity and histopathological analysis. PBMT promoted anti-hypernociception in BLV-injected mice; irradiation with the 660 nm laser resulted in faster effect onset than the 780 nm laser. Both laser protocols reduced paw edema formation, whether irradiation was performed immediately or half an hour after venom injection. BLV-induced hemorrhage was not altered by PBMT. Laser irradiation delayed, but did not prevent myotoxicity caused by BLV, as shown by a late increase in CK activity and histopathological alterations. PBMT was effective in the control of some of the major local effects of BLV refractory to antivenom. It is a potential complementary therapy that could be used in bothropic envenoming, minimizing the morbidity of these snakebite accidents.

The Effect of Low-Level Light Therapy on Capsaicin-Induced Peripheral and Central Sensitization in Healthy Volunteers: A Double-Blinded, Randomized, Sham-Controlled Trial

Introduction

Several clinical trials have demonstrated that low-level light therapy (LLLT), a method of photobiomodulation, is an effective analgetic treatment. However, the mechanism of action has not yet been finally clarified. In particular, unanswered questions include whether it only affects peripheral or whether it also affects the spinal or supraspinal level. This study aimed to evaluate the effect of low-level light therapy on primary and secondary hyperalgesia in a human pain model.

Methods

This study was planned as a randomized, sham-controlled, and double-blinded trial with repeated measures within subject design. Capsaicin was applied on both forearms of ten healthy volunteers to induce peripheral and central sensitization. One forearm was treated with low-level light therapy; the other served as sham control.

Results

Low-level light therapy significantly increased the mechanical pain threshold, heat pain threshold, and decreased pain intensity.

Conclusions

Our data indicate that low-level light therapy is effective at reducing the heat and mechanical pain threshold in a human pain model, pointing to a significant modulating effect on peripheral and central sensitization. These effects—especially in the absence of reported side effects—make low-level light therapy a promising tool in pain management. The application of low-level light therapy to treat chronic pain should be considered for further clinical trials.

Laser-photobiomodulation on experimental cancer pain model in Walker Tumor-256

CONTEXT

Cancer Pain is considered a common and significant clinical problem in malignant neoplasms, comprising 20% to 50% of all patients with tumor progression. Laser photobiomodulation (L-PBM) has been used in a multitude of pain events, ranging from acute trauma to chronic articular. However, L-PBM has never been tested in cancer pain.

OBJECTIVES

Evaluate hyperalgesia, edema, COX-1, COX-2, IL-10, and Bdkrb1 mRNA in low-level laser irradiated Walker-256 tumor-bearing rats.

METHODS

Rat hind paw injected with Walker Tumor-256 (W-256) and divided into six groups of 6 rats: G1 (control) - W-256 injected, G2- W-256 + Nimesulide, G3- W-256 + 1 J, G4- W-256 + 3 Jand G5- W256 + 6 J. Laser parameters: λ = 660 nm, 3.57 W/cm², Ø = 0.028 cm². Mechanical hyperalgesia was evaluated by Randall-Selitto test. Plethysmography measured edema; mRNA levels of COX-1, COX-2, IL-10, and Bdkrb1were analyzed.

RESULTS

It was found that the W-256 + 1 J group showed a decrease in paw edema, a significant reduction in pain threshold. Higher levels of IL-10 and lower levels of COX-2 and Bdkrb1 were observed.

CONCLUSION

Results suggest that 1 J L-PBM reduced the expression of COX-2 and Bdkrb1 and increasing IL-10 gene expression, promoting analgesia to close levels to nimesulide.

Chemical structure, anti-inflammatory and antinociceptive activities of a sulfated polysaccharide from Gracilaria intermedia algae

The present work aimed at carrying out the isolation and biochemical characterization of a sulfated polysaccharide fraction (PLS) from the marine algae Gracilaria intermedia and investigating its anti-inflammatory and antinociceptive potential. PLS was obtained through enzymatic digestion with papain and analyzed by means of gel permeation chromatography and Nuclear Magnetic Resonance to ¹H and ¹³C. In order to evaluate the potential of anti-inflammatory action of PLS, we performed paw edema induced by carrageenan, dextran, compound 48/80, histamine and serotonin. In addition, we also measured the concentration of myeloperoxidase, cytokines, the count of inflammatory cells and performed tests of the nociception. The PLS isolated was of high purity and free of contaminants such as proteins, and had molecular weight of 410 kDa. The same macromolecule was able to decrease the paw edema induced by all inflammatory agents (P < 0.05), myeloperoxidase (MPO) activity, neutrophil migration and IL-1β levels. It also decreased acetic acid-induced writhing (P < 0.05) and formalin-induced paw licking time (P < 0.05), but no in hot plate test. In summary, the PLS decreased the inflammatory response by reducing neutrophil migration and modulating IL-1β production and antinociceptive effects by a peripheral mechanism dependent on the down-modulation of the inflammatory mediators.