Effects Of Low-level Light Therapy Research Articles

Local and systemic effects of low-level light therapy with light-emitting diodes to improve erythema after fractional ablative skin resurfacing: a controlled study.

Therapy with light-emitting diodes (LED) has been associated with the reduction of erythema and accelerated wound healing. LED phototherapy has been used in various clinical practices including post-laser wound healing enhancement. Fractional laser resurfacing is one of the popular dermatological procedures; however, the duration and degree of downtime may limit daily life activity and studies on the effect of LED low-level light therapy (LED-LLLT) on post-ablative laser wound care are still limited. To evaluate local and systemic effects of LED-LLLT on post-ablative laser erythema and wound healing acceleration after fractional ablative laser resurfacing. The study was divided into two arms. First, a prospective split-face randomized controlled and single-blinded study involved 17 patients (split-face group) to determine the local and systemic effect of LED-LLLT. Patients with acne scars or rhytides were treated with a single session of fractional CO2 laser followed by 830/590nm LED-LLLT on one side of their faces. The duration of post-laser erythema, the erythema index, and transepidermal water loss were collected at baseline, and compared with 7-daily follow-up visits posttreatment for the non LED- and LED-treated sides. The second controlled arm of the study was performed on an additional 19 subjects (CO2 group). The patients received a single fractional CO2 laser treatment without any LED-LLLT with the same follow-up protocol. All measurements were compared with the results from the patients from the split-face group. In the split-face group, the duration of erythema post laser was equal (7.4 ± 2.8days). No significant reduction in the erythema index and transepidermal water loss was seen in the LED-treated vs the non-treated side (p values = 0.99 and 0.78 respectively). For the second part of the study that compared the results between the split-face group and the control CO2 only group, the duration of the post-laser erythema was comparable (p value = 0.32). However, the percentage difference of the erythema index from baseline in the split-face group was significantly lower than the CO2 group on days 1, 4, 5, and 7 post-laser treatment (p value = 0.03 on days 1, 4, 5, and 0.04 on day 7) and the LED-treated side provided the lowest percentage difference of the erythema index followed by the non LED-treated side compared with the control CO2 only group. 830/590nm LED-LLLT may provide both local and systemic effects on the degree of post-ablative laser erythema in human skin, however, appropriate protocol settings should be considered to achieve a significant clinical outcome.

Slow oscillations of cerebral hemodynamics changes during low-level light therapy in the elderly with and without mild cognitive impairment: An fNIRS study

Low-level light therapy (LLLT) is used to stimulate cell function or reduce pain by applying light emitting diodes (LED) to the skin. LLLT is known to contribute to the neuronal recovery during the reconstruction of brain tissue for the treatment of degenerative disorders. This research aims to confirm the slow oscillations of cerebral hemodynamics changes when LLLT is applied to the elderly and patients with mild cognitive impairment (MCI). Eight patients with MCI and 7 healthy elderly participated in this study. They were randomly divided into four groups; carotid artery stimulation, vertebral artery stimulation, simultaneous carotid and vertebral artery stimulation, or sham stimulation. The subjects received LLLT using Color DNA ® (Color Seven Co.) with a LED light source for 30 minutes a day during 20 days. The hemodynamic responses were recorded by an fNIRS system (NIRScout ® ) with 74 channels at the first and the 20th intervention days, before, during, and after the LLLT. The spectral power density over the very low-frequency oscillations (VLFO) of cerebral hemodynamics was calculated using Welch technique. In both healthy and MCI patients, VLFO increased in the whole cerebral area during LLLT compared to the resting state, and these changes are more contrasting in the condition with simultaneous carotid and vertebral artery stimulation condition. These characteristics were observed in both the first and 20th intervention days however, VLFO in the 20th intervention day were more increased than the first day. Increase of very low frequency oscillations demonstrated increasing spontaneous activity of cerebrovascular tone and neuronal activation. These findings may suggest a possibility of modulating effect of LLLT on neuronal activity and blood vessel reconstruction.

Velocity of orthodontic active space closure with and without photobiomodulation therapy: a single-center, cluster randomized clinical trial

The objective of this two-arm, parallel randomized clinical trial was to assess the effectiveness of low-level light therapy (photobiomodulation) using an intraoral light-emitting diode (LED) device with respect to accelerating premolar extraction space closure during en masse retraction. This trial was conducted between January 2013 and February 2014 at the European Univeristy College Department of Orthodontics. The study included 60 orthodontic patients (age range, 11.3–47.1 years; mean age, 20.4 years) with premolar extractions. Patients (n = 60) were randomized into the photobiomodulation (PBM) group (n = 30) or the control group (n = 30). Eligibility criteria included no active caries, good oral hygiene, and an extraction orthodontic treatment plan. Extraction spaces were closed using NiTi closed springs utilizing 150 g of force. Extraction spaces were measured on study models at the beginning of en masse retraction (T1) and at space closure completion (T2). All measurements were obtained by a single investigator who was blinded to the group allocation of study models. The primary outcome was the velocity of extraction space closure (mm/month) during the period of en masse retraction. Treatment allocation was implemented using randomization with 2 major blocks of 30 patients, by asking each patient to draw a sealed envelope (n = 60) indicating allocation to the PBM or control group. The allocation ratio was 1:1. The PBM group of patients (n = 30) was treated with intraoral infrared LED light therapy for 3 min per arch per day using OrthoPulse™ (Biolux Research®, Vancouver, Canada) producing a continuous 850-nm wavelength and a power density of 33 mW/cm2 per arch per day to achieve a total energy density of approximately 6 J/cm2 at the surface of the device during the en masse retraction phase; patients were required to maintain over 80% compliance with daily device use. Compliance was monitored by the device controller’s onboard computer. Sixty patients were randomized between the two groups. Fifteen patients dropped out during the study period, but were accounted for in the primary analysis as an intention to treat (ITT) analysis through multiple imputations. Mean age for the PBM and control groups were 20.7 and 22 years, respectively. Patients treated with PBM exhibited a statistically significant higher velocity of space closure by 0.22 mm/month (95% confidence interval [CI], 0.09–0.49; p < 0.01). The mean velocity of space closure in the PBM group was 1.08 mm/month (SD 0.54) compared with the control group’s 0.86 mm/month (SD 0.42). A secondary analysis was conducted on the 45 patients that reached the primary outcome and did not deviate from the study protocol (15 dropout patients removed), providing 123 extraction spaces for the analysis—23 patients from the PBM group and 22 patients from the control group. No serious harms due to treatments were encountered during the study period. The results of this study suggest that PBM therapy accelerated the rate of orthodontic space closure during en masse retraction. This trial and its protocol were not registered on a publicly accessible registry.

Low-Level Light Therapy with 410 nm Light Emitting Diode Suppresses Collagen Synthesis in Human Keloid Fibroblasts: AnIn VitroStudy

BackgroundKeloids are characterized by excessive collagen deposition in the dermis, in which transforming growth factor β (TGF-β)/Smad signaling plays an important role. Low-level light therapy (LLLT) is reported as effective in preventing keloids in clinical reports, recently. To date, studies investigating the effect of LLLT on keloid fibroblasts are extremely rare.ObjectiveWe investigated the effect of LLLT with blue (410 nm), red (630 nm), and infrared (830 nm) light on the collagen synthesis in keloid fibroblasts.MethodsKeloid fibroblasts were isolated from keloid-revision surgery samples and irradiated using 410-, 630-, 830-nm light emitting diode twice, with a 24-hour interval at 10 J/cm2. After irradiation, cells were incubated for 24 and 48 hours and real-time quantitative reverse transcription polymerase chain reaction was performed. Western blot analysis was also performed in 48 hours after last irradiation. The genes and proteins of collagen type I, TGF-β1, Smad3, and Smad7 were analyzed.ResultsWe observed no statistically significant change in the viability of keloid fibroblasts after irradiation. Collagen type I was the only gene whose expression significantly decreased after irradiation at 410 nm when compared to the non-irradiated control. Western blot analysis showed that LLLT at 410 nm lowered the protein levels of collagen type I compared to the control.ConclusionLLLT at 410 nm decreased the expression of collagen type I in keloid fibroblasts and might be effective in preventing keloid formation in their initial stage.

The Effectiveness of Low-Level Light Therapy in Attenuating Vocal Fatigue

Low-level light therapy (LLLT) is effective in reducing inflammation, promoting wound healing, and preventing tissue damage, but has not yet been studied in the treatment of voice disorders. The objective of this study was to investigate the possible effectiveness of LLLT in attenuating symptoms of vocal fatigue created by a vocal loading task as measured by acoustic, aerodynamic, and self-reported vocal effort. In a randomized, prospective study, 16 vocally healthy adults divided into four groups underwent a 1-hour vocal loading procedure, followed by infrared wavelength LLLT (828 nm), red wavelength LLLT (628 nm), heat, or no heat-light (control) treatment targeting the laryngeal region of the ventral neck surface. Phonation threshold pressure (PTP), relative fundamental frequency (RFF), and the inability to produce soft voice (IPSV) self-perceptual rating scale were recorded (1) at baseline, (2) immediately after vocal loading, (3) after treatment, and (4) 1 hour after treatment. Vocal loading significantly increased PTP and IPSV and decreased onset and offset RFFs, consistent with a shift toward vocal dysfunction. Red light significantly normalized the combination of PTP, IPSV, and RFF measures compared to other conditions. RFF is sensitive to a vocal loading task in conjunction with PTP and IPSV, and red LLLT may have a normalizing effect on objective and subjective measures of vocal fatigue. The results of this study lay the groundwork and rationale for future research to optimize LLLT wavelength combinations and overall dose.

Decrowding of lower anterior segment with and without photobiomodulation: a single center, randomized clinical trial.

The aim of this study was to evaluate the effect of low-level light therapy using light-emitting diodes (LEDs) on the speed of tooth movements that were required for the leveling and aligning of the lower anterior segment during non-extraction orthodontic treatment. The sample was comprised of patients (n = 40) with lower anterior crowding who were treated with self-ligating orthodontic brackets and a standardized wire sequence. A test group of patients (n = 20) who were treated with extraoral infrared light therapy for 20min daily with at least 80% compliance was compared to a control group (n = 20). The date of the first arch wire placement was recorded as T1, and the date of the completion of the lower anterior segment decrowding was recorded as T2. A final impression was also taken at T2. The time between T1 and T2 was significantly reduced by 22% in the test group compared to the control group (68.3 vs. 87.8days, respectively, p < 0.043). The use of photobiomodulation for 20min daily at a wavelength of 850nm might reduce the time required to resolve lower anterior crowding. This trial and its protocol were not registered on a publicly accessible registry.

The use of low-level light therapy in supportive care for patients with breast cancer: review of the literature.

Breast cancer is the most common cancer in women worldwide, with an incidence of 1.7 million in 2012. Breast cancer and its treatments can bring along serious side effects such as fatigue, skin toxicity, lymphedema, pain, nausea, etc. These can substantially affect the patients' quality of life. Therefore, supportive care for breast cancer patients is an essential mainstay in the treatment. Low-level light therapy (LLLT) also named photobiomodulation therapy (PBMT) has proven its efficiency in general medicine for already more than 40years. It is a noninvasive treatment option used to stimulate wound healing and reduce inflammation, edema, and pain. LLLT is used in different medical settings ranging from dermatology, physiotherapy, and neurology to dentistry. Since the last twenty years, LLLT is becoming a new treatment modality in supportive care for breast cancer. For this review, all existing literature concerning the use of LLLT for breast cancer was used to provide evidence in the following domains: oral mucositis (OM), radiodermatitis (RD), lymphedema, chemotherapy-induced peripheral neuropathy (CIPN), and osteonecrosis of the jaw (ONJ). The findings of this review suggest that LLLT is a promising option for the management of breast cancer treatment-related side effects. However, it still remains important to define appropriate treatment and irradiation parameters for each condition in order to ensure the effectiveness of LLLT.

Bactericidal Effects of Low-Irradiance Low Level Light Therapy on Methicillin-Resistant Staphylococcus Aureus in Vitro

Low Level Light Therapy (LLLT) within the visible blue spectrum (400-470 nanometers) is a well-documented therapeutic alternative to combat multidrug resistant organism infections through the generation of reactive oxygen species (ROS). However, one shortcoming of LLLT is that many studies deliver therapy through high powered lasers and lamps. High powered light sources not only require specialized staff to operate, but they also deliver the total light dose (fluence) at an exceptionally high intensity, or irradiance, which could consequently deplete the oxygen supplies required to promote LLLT’s bactericidal properties. To overcome these faults, low-irradiance LLLT, or delivering the same total fluence of LLLT over an extended period of time with decreased irradiance was evaluated in vitro. To further explore this alternative approach, the bactericidal effects of low-irradiance (10.44 mW/cm2) LLLT using wavelengths of 405-nm, 422-nm and 470-nm were studied on methicillin-resistant Staphylococcus aureus (MRSA) cultures. Among these wavelengths, it was determined that 405-nm LLLT provided the most effective reduction of bacterial load at the lowest total fluence (75 J/cm2) (94.50% reduction). The bactericidal effects of 405-nm low-irradiance LLLT were then further studied by treating MRSA cultures to 75 J/cm2 LLLT while using irradiances of 5.22 mW/cm2 and 3.48 mW/cm2. It was concluded that there was a greater reduction of MRSA bacterial load when samples were exposed to irradiances of 5.22 mW/cm2 (95.71% reduction) and 3.48 mW/cm2 (99.63% reduction). This study validates the bactericidal properties of low-irradiance LLLT on MRSA, and subsequent studies should be completed to optimize its full therapeutic potential.

Angiogenic Synergistic Effect of Adipose-Derived Stromal Cell Spheroids with Low-Level Light Therapy in a Model of Acute Skin Flap Ischemia

Human adipose-derived mesenchymal stem cells (hASCs) are an attractive cell source for tissue engineering. However, one obstacle to this approach is that the transplanted hASC population can decline rapidly in the recipient tissue. The aim of this study was to investigate the effects of low-level light therapy (LLLT) on transplanted spheroid hASCs in skin flaps of mice. hASCs were cultured in monolayers or spheroids. LLLT, hASCs, spheroids and spheroids transplanted with LLLT were applied to the skin flaps. Healing of the skin flaps was assessed by gross evaluation and by hematoxylin and eosin staining and elastin van Gieson staining. Compared with the spheroid group, skin flap healing was enhanced in the spheroid + LLLT group, including the neovascularization and regeneration of skin appendages. The survival of hASCs was enhanced by decreased apoptosis of hASCs in the skin flaps of the spheroid + LLLT group. The secretion of growth factors was stimulated in the spheroid + LLLT group compared with the ASC and spheroid groups. These data suggest that LLLT was an effective biostimulator of spheroid hASCs in the skin flaps, enhancing the survival of hASCs and stimulating the secretion of growth factors.

Pre-conditioning with transcranial low-level light therapy reduces neuroinflammation and protects blood-brain barrier after focal cerebral ischemia in mice.

Transcranial low-level light therapy (LLLT) has gained interest as a non-invasive, inexpensive and safe method of modulating neurological and psychological functions in recent years. This study was designed to examine the preventive effects of LLLT via visible light source against cerebral ischemia at the behavioral, structural and neurochemical levels. The mice received LLLT twice a day for 2 days prior to photothrombotic cortical ischemia. LLLT significantly reduced infarct size and edema and improved neurological and motor function 24 h after ischemic injury. In addition, LLLT markedly inhibited Iba-1- and GFAP-positive cells, which was accompanied by a reduction in the expression of inflammatory mediators and inhibition of MAPK activation and NF-κB translocation in the ischemic cortex. Concomitantly, LLLT significantly attenuated leukocyte accumulation and infiltration into the infarct perifocal region. LLLT also prevented BBB disruption after ischemic events, as indicated by a reduction of Evans blue leakage and water content. These findings were corroborated by immunofluorescence staining of the tight junction-related proteins in the ischemic cortex in response to LLLT. Non-invasive intervention of LLLT in ischemic brain injury may provide a significant functional benefit with an underlying mechanism possibly being suppression of neuroinflammation and reduction of BBB disruption.

Adipose-derived stromal cell cluster with light therapy enhance angiogenesis and skin wound healing in mice

Human adipose-derived mesenchymal stem cells (hASCs) are attractive cell source for skin tissue engineering. The aim of this study was to investigate the effects of low-level light therapy (LLLT) on transplanted cluster hASC in a skin wound animal model. The hASCs were cultured in monolayer or clusters. The LLLT, hASCs, hASC clusters, and hASC clusters transplantation with LLLT (cluster + LLLT) were applied to the wound bed in athymic mice. Wound healing was assessed by gross evaluation and by hematoxylin and eosin staining, and elastin van gieson histochemistry. The survival, differentiation, and secretion of vascular endothelial growth factor (VEGF), basic fibroblast growth factor (FGF), and hepatocyte growth factor (HGF) of the cluster ASC were evaluated by immunohistochemistry and Western blotting. The cluster + LLLT group enhanced the wound healing, including neovascularization and regeneration of skin appendages, compared with the cluster group. The secretion of growth factors was stimulated in the cluster + LLLT group compared with the ASCs and cluster group. These data suggest that LLLT is an effective biostimulator of cluster hASCs in wound healing that enhances the survival of hASCs and stimulates the secretion of growth factors in the wound bed.

Prevention of skin flap necrosis by use of adipose-derived stromal cells with light-emitting diode phototherapy

Background aimsThe aim of this study was to investigate the effects of low-level light therapy (LLLT) on transplanted human adipose-derived mesenchymal stromal cells (ASCs) in the skin flap of mice. MethodsLLLT, ASC transplantation and ASC transplantation with LLLT (ASC + LLLT) were applied to the skin flap. Immunostaining and Western blot analysis were performed to evaluate cell survival and differentiation and secretion of vascular endothelial growth factor and basic fibroblast growth factor by the ASCs. Vascular regeneration was assessed by means of immunostaining in addition to hematoxylin and eosin staining. In the ASC + LLLT group, the survival of ASCs was increased as the result of the decreased apoptosis of ASCs. ResultsThe secretion of growth factors was higher in this group as compared with ASCs alone. ASCs contributed to tissue regeneration through vascular cell differentiation and secretion of angiogenic growth factors. The ASC + LLLT group displayed improved treatment efficacy including neovascularization and tissue regeneration compared with ASCs alone. Transplanting ASCs to ischemic skin flaps improved therapeutic efficacy for ischemia treatment as the result of enhanced cell survival and paracrine effects. ConclusionsThese data suggest that LLLT is an effective biostimulator of ASCs in vascular regeneration, which enhances the survival of ASCs and stimulates the secretion of growth factors in skin flaps.

Low level light therapy modulates inflammatory mediators secreted by human annulus fibrosus cells during intervertebral disc degeneration in vitro.

Intervertebral disc degeneration (IVD) is one of the important causes of low back pain and is associated with inflammation induced by interaction between macrophages and the human annulus fibrosus (AF) cells. Low-level light therapy (LLLT) has been widely known to regulate inflammatory reaction. However, the effect of LLLT on macrophage-mediated inflammation in the AF cells has not been studied till date. The aim of this study is to mimic the inflammatory microenvironment and to investigate the anti-inflammatory effect of LLLT at a range of wavelengths (405, 532 and 650nm) on the AF treated with macrophage-like THP-1 cells conditioned medium (MCM) containing proinflammatory cytokines and chemokines (interleukin-1beta, tumor necrosis factor-alpha, interleukin-6 and 8). We observed that AF cells exposed to MCM secrete significantly higher concentrations of IL-6, IL-8, IL-1β and TNF-α. LLLT markedly inhibited secretion of IL-6 at 405nm in a time-dependent manner. Level of IL-8 was significantly decreased at all wavelengths in a time-dependent manner. We showed that MCM can induce the inflammatory microenvironment in AF cells and LLLT selectively suppressed IL-6 and 8 levels. The results indicate that LLLT is a potential method of IVD treatment and provide insights into further investigation of its anti-inflammation effect on IVD.

Low-level light therapy induces mucosal healing in a murine model of dextran-sodium-sulfate induced colitis.

The aim of this study was to demonstrate the effect of low-level light therapy (LLLT) in an acute colitis model in mice. Low-level light therapy (LLLT) has been shown to be an effective treatment for various inflammatory processes such as oral mucositis and diabetic foot ulcers. Colitis was induced by dextran sodium sulfate (DSS) in mice in four blinded controlled studies (validation of model, efficacy study, and two studies for evaluation of optimal dose). LLLT was applied to the colon utilizing a small diameter endoscope with an LED-based light source in several wavelengths (440, 660, and 850 nm at 1 J/cm(2)) and then 850 nm at several doses (1, 0.5, 0.25, and 0.1 J/cm(2)). LLLT was initiated 1 day prior to induction of colitis and went on for the 6 day induction period as well as for the following 3-10 days. Dose was controlled by changing exposure time. Disease activity was scored endoscopically and by histopathological assessment. Statistically significant improvement in disease severity was observed in the treatment groups compared with the control groups. The three wavelengths used demonstrated efficacy, and a clear dose-response curve was observed for one of the wavelengths (850 nm). On day 11, colonoscopic scoring in the sham-treated mice increased from 7.9±1.3 to 12.2±2.2, while activity in all treated groups remained stable. Photobiostimulation with LLLT has a significant positive effect on disease progression in mice with DSS colitis.

Effects of low-level light therapy on facial corticosteroid addiction dermatitis: A retrospective analysis of 170 Asian patients

Effects of low-level light therapy on facial corticosteroid addiction dermatitis: A retrospective analysis of 170 Asian patients

Inhibition of Fibroblast Proliferation In Vitro Using Low-Level Infrared Light-Emitting Diodes

Scars, including hypertrophic and keloidal-type scars, may occur after burns, trauma, or surgery. Despite several treatment options available for scars, few effective, noninvasive modalities exist. Recently, a few small clinical studies revealed the possible benefit of red and infrared (IR) low-level light therapy (LLLT) in scar treatment. One of the important features of scars is proliferation of dermal fibroblasts, but in vitro data regarding the effects of light-emitting diode (LED)-generated IR light on human skin fibroblasts is lacking. To evaluate the effect of IR LLLT generated using LEDs on fibroblast proliferation and viability in vitro. Irradiation of normal human skin fibroblasts using IR LED panels was performed in vitro, and modulation of proliferation and viability was quantified using Trypan blue dye exclusion assay. Fluences of 80, 160 and 320J/cm(2) resulted in statistically significantly less fibroblast proliferation than in controls, without statistically significantly less cellular viability. IR LLLT can effectively inhibit fibroblast proliferation in vitro without altering viability and holds promise for the treatment of scars.

A Preliminary Study of the Safety of Red Light Phototherapy of Tissues Harboring Cancer

Red light phototherapy is known to stimulate cell proliferation in wound healing. This study investigated whether low-level light therapy (LLLT) would promote tumor growth when pre-existing malignancy is present. LLLT has been increasingly used for numerous conditions, but its use in cancer patients, including the treatment of lymphedema or various unrelated comorbidities, has been withheld by practitioners because of the fear that LLLT might result in initiation or promotion of metastatic lesions or new primary tumors. There has been little scientific study of oncologic outcomes after use of LLLT in cancer patients. A standard SKH mouse nonmelanoma UV-induced skin cancer model was used after visible squamous cell carcinomas were present, to study the effects of LLLT on tumor growth. The red light group (n=8) received automated full body 670 nm LLLT delivered twice a day at 5 J/cm(2) using an LED source. The control group (n=8) was handled similarly, but did not receive LLLT. Measurements on 330 tumors were conducted for 37 consecutive days, while the animals received daily LLLT. Daily tumor measurements demonstrated no measurable effect of LLLT on tumor growth. This experiment suggests that LLLT at these parameters may be safe even when malignant lesions are present. Further studies on the effects of photoirradiation on neoplasms are warranted.

Enhancement of Extinction Memory and Prefrontal Cortex Metabolic Capacity Via Low-Level Light Therapy (P07.176)

Objective: To determine the ability of low-level light therapy (LLLT) to modulate memory and brain energy metabolism in vivo. Background LLLT enhances the metabolic capacity of neurons in culture through stimulation of the mitochondrial enzyme cytochrome oxidase, but the in vivo effects of LLLT on brain and behavior are poorly characterized. Design/Methods: This study tested the hypothesis that transcranial LLLT facilitates fear extinction memory and prevents the reemergence of extinguished conditioned fear responses via enhancement of brain metabolic capacity in rats. Long-Evans rats were trained in a Pavlovian fear-conditioning paradigm consisting of two sessions of four tone-foot shock presentations. Subsequently, rats underwent extinction training and LLLT was delivered at λ= 660 nm, 5.4 J/cm2, 15 min after each extinction session. Freezing behavior scores were compared to those of control rats (undergoing fear-conditioning training but no LLLT). Effects of LLLT on brain metabolism were determined through measurement of prefrontal cortex oxygen concentration with fluorescent quenching oximetry and brain cytochrome oxidase histochemistry. Results: LLLT-treated rats showed an enhanced rate of extinction, with freezing levels 59 and 70% lower than control, after the 2nd and 3rd extinction sessions. After the 4th extinction session, LLLT-treated rats showed a paradoxical increase in freezing, compared to control. However, LLLT-treated rats showed decreased rates of fear renewal compared to controls. Also, LLLT increased the rate of in situ oxygen consumption in the prefrontal cortex, and induced a hormetic dose-response effect on the metabolic capacity of the prefrontal cortex, with a low dose showing the largest (12%) increase as compared to control. Conclusions: The data demonstrate that in vivo transcranial LLLT can be used to enhance the metabolic capacity of the brain and to facilitate retention of extinction memories, and implicate LLLT as a potential intervention to improve memory in humans. Supported by: NIH grants R01 NS37755 and T32 MH65728 directed by Prof. F. Gonzalez-Lima. Disclosure: Dr. Martinez has nothing to disclose. Dr. Bruchey has nothing to disclose. Dr. Gonzalez-Lima has nothing to disclose.

Low-Level Laser Therapy Activates NF-kB via Generation of Reactive Oxygen Species in Mouse Embryonic Fibroblasts

BackgroundDespite over forty years of investigation on low-level light therapy (LLLT), the fundamental mechanisms underlying photobiomodulation at a cellular level remain unclear.Methodology/Principal FindingsIn this study, we isolated murine embryonic fibroblasts (MEF) from transgenic NF-kB luciferase reporter mice and studied their response to 810 nm laser radiation. Significant activation of NF-kB was observed at fluences higher than 0.003 J/cm2 and was confirmed by Western blot analysis. NF-kB was activated earlier (1 hour) by LLLT compared to conventional lipopolysaccharide treatment. We also observed that LLLT induced intracellular reactive oxygen species (ROS) production similar to mitochondrial inhibitors, such as antimycin A, rotenone and paraquat. Furthermore, we observed similar NF-kB activation with these mitochondrial inhibitors. These results, together with inhibition of laser induced NF-kB activation by antioxidants, suggests that ROS play an important role in the laser induced NF-kB signaling pathways. However, LLLT, unlike mitochondrial inhibitors, induced increased cellular ATP levels, which indicates that LLLT also upregulates mitochondrial respiration.ConclusionWe conclude that LLLT not only enhances mitochondrial respiration, but also activates the redox-sensitive NFkB signaling via generation of ROS. Expression of anti-apoptosis and pro-survival genes responsive to NFkB could explain many clinical effects of LLLT.

Effects of low-level light therapy on streptozotocin-induced diabetic kidney

Hyperglycemia causes oxidative damage in tissues prone to complications in diabetes. Low-level light therapy (LLLT) in the red to near infrared range (630–1000 nm) has been shown to accelerate diabetic wound healing. To test the hypothesis that LLLT would attenuate oxidative renal damage in Type I diabetic rats, male Wistar rats were made diabetic with streptozotocin (50 mg/kg, ip), and then exposed to 670 nm light at a dose of 9 J/cm 2 once per day for 14 weeks. The activity and expression of catalase and the activity of Na K-ATPase increased in kidneys of light-treated diabetic rats, whereas the activity and expression of glutathione peroxidase and the expression of Na K-ATPase were unchanged. LLLT lowered the values of serum BUN, serum creatinine, and BUN/creatinine ratio. In addition, LLLT augmented the activity and expression of cytochrome c oxidase, a primary photoacceptor molecule in the mitochondrial respiratory chain, and reduced the formation of the DNA adduct 8-hydroxy-2′-deoxyguanosine in kidney. LLLT improved renal function and antioxidant defense capabilities in the kidney of Type I diabetic rats. Thus, 670 nm LLLT may be broadly applicable to the amelioration of renal complications induced by diabetes that disrupt antioxidant defense mechanisms.