Effects of Power Densities, Continuous and Pulse Frequencies, and Number of Sessions of Low-Level Laser Therapy on Intact Rat Brain

Ilić, Sanja; Leichliter, S. G.; Streeter, Jackson; Oron, Amir; Taboada, Luis De; Oron, Uri

doi:10.1089/pho.2006.24.458

Cited by 120 publications

(72 citation statements)

References 13 publications

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“…In each case, any tissue damage appeared mechanical, caused by the optical fiber itself. When relating our results to those of Ilic and colleagues, 15 we may have needed to increase the power output at the optical fiber even more-perhaps by another factor of 10, which was well over the level needed for our positive neuroprotective result-to cause any neuronal damage and/or behavioral deficits.…”

Section: Toxicity Of Nir: Evidence Of Tissue Necrosis At the Implant mentioning

confidence: 68%

“…Previous authors using external applications of NIr (for example, WARP-LED) at power intensities ranging from 7.5 to 75 mW/cm 2 have reported no adverse effect on brain tissue; 8,15,24,35,40 it is only at exceptionally high power intensities (750 mW/cm 2 ) that some neuronal damage and negative behavioral outcomes have been noted. 15 Notwithstanding this exceptionally high dose, the impact of NIr on all body tissues examined thus far has been overwhelmingly positive.…”

Section: Toxicity Of Nir: Evidence Of Tissue Necrosis At the Implant mentioning

confidence: 97%

“…15 Notwithstanding this exceptionally high dose, the impact of NIr on all body tissues examined thus far has been overwhelmingly positive. [8][9][10]13,19,24,34,35,40 In keeping with these previous reports, our histological results revealed little evidence of tissue necrosis caused by NIr irradiation when it was delivered intracranially and in direct contact with brain tissue, whether the radiation was low power (0.16 mW), pulsed (360-second exposure) or continuous for 6 days, or higher power (67 mW, 2.5-hour exposure).…”

Section: Toxicity Of Nir: Evidence Of Tissue Necrosis At the Implant mentioning

confidence: 99%

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Photobiomodulation inside the brain: a novel method of applying near-infrared light intracranially and its impact on dopaminergic cell survival in MPTP-treated mice

Moro

Massri²,

Torres

et al. 2014

JNS

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Object Previous experimental studies have documented the neuroprotection of damaged or diseased cells after applying, from outside the brain, near-infrared light (NIr) to the brain by using external light-emitting diodes (LEDs) or laser devices. In the present study, the authors describe an effective and reliable surgical method of applying to the brain, from inside the brain, NIr to the brain. They developed a novel internal surgical device that delivers the NIr to brain regions very close to target damaged or diseased cells. They suggest that this device will be useful in applying NIr within the large human brain, particularly if the target cells have a very deep location. Methods An optical fiber linked to an LED or laser device was surgically implanted into the lateral ventricle of BALB/c mice or Sprague-Dawley rats. The authors explored the feasibility of the internal device, measured the NIr signal through living tissue, looked for evidence of toxicity at doses higher than those required for neuroprotection, and confirmed the neuroprotective effect of NIr on dopaminergic cells in the substantia nigra pars compacta (SNc) in an acute 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) model of Parkinson disease in mice. Results The device was stable in freely moving animals, and the NIr filled the cranial cavity. Measurements showed that the NIr intensity declined as distance from the source increased across the brain (65% per mm) but was detectable up to 10 mm away. At neuroprotective (0.16 mW) and much higher (67 mW) intensities, the NIr caused no observable behavioral deficits, nor was there evidence of tissue necrosis at the fiber tip, where radiation was most intense. Finally, the intracranially delivered NIr protected SNc cells against MPTP insult; there were consistently more dopaminergic cells in MPTP-treated mice irradiated with NIr than in those that were not irradiated. Conclusions In summary, the authors showed that NIr can be applied intracranially, does not have toxic side effects, and is neuroprotective.

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Section: Toxicity Of Nir: Evidence Of Tissue Necrosis At the Implant mentioning

confidence: 68%

Section: Toxicity Of Nir: Evidence Of Tissue Necrosis At the Implant mentioning

confidence: 97%

Section: Toxicity Of Nir: Evidence Of Tissue Necrosis At the Implant mentioning

confidence: 99%

See 1 more Smart Citation

Photobiomodulation inside the brain: a novel method of applying near-infrared light intracranially and its impact on dopaminergic cell survival in MPTP-treated mice

Moro

Massri²,

Torres

et al. 2014

JNS

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“…Adverse behavioral effects can be induced with massive energy densities 100 times higher than those observed to induce beneficial effects, but even the adverse effects of high doses can be attenuated if the total energy is delivered using intermittent energy pulses. 85 …”

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confidence: 99%

Low-level light therapy of the eye and brain

Rojas¹,

González-Lima²

2011

117

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Low-level light therapy (LLLT) using red to near-infrared light energy has gained attention in recent years as a new scientific approach with therapeutic applications in ophthalmology, neurology, and psychiatry. The ongoing therapeutic revolution spearheaded by LLLT is largely propelled by progress in the basic science fields of photobiology and bioenergetics. This paper describes the mechanisms of action of LLLT at the molecular, cellular, and nervous tissue levels. Photoneuromodulation of cytochrome oxidase activity is the most important primary mechanism of action of LLLT. Cytochrome oxidase is the primary photoacceptor of light in the red to near-infrared region of the electromagnetic spectrum. It is also a key mitochondrial enzyme for cellular bioenergetics, especially for nerve cells in the retina and the brain. Evidence shows that LLLT can secondarily enhance neural metabolism by regulating mitochondrial function, intraneuronal signaling systems, and redox states. Current knowledge about LLLT dosimetry relevant for its hormetic effects on nervous tissue, including noninvasive in vivo retinal and transcranial effects, is also presented. Recent research is reviewed that supports LLLT potential benefits in retinal disease, stroke, neurotrauma, neurodegeneration, and memory and mood disorders. Since mitochondrial dysfunction plays a key role in neurodegeneration, LLLT has potential significant applications against retinal and brain damage by counteracting the consequences of mitochondrial failure. Upon transcranial delivery in vivo, LLLT induces brain metabolic and antioxidant beneficial effects, as measured by increases in cytochrome oxidase and superoxide dismutase activities. Increases in cerebral blood flow and cognitive functions induced by LLLT have also been observed in humans. Importantly, LLLT given at energy densities that exert beneficial effects does not induce adverse effects. This highlights the value of LLLT as a novel paradigm to treat visual, neurological, and psychological conditions, and supports that neuronal energy metabolism could constitute a major target for neurotherapeutics of the eye and brain.

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“…These have been demonstrated by in vitro 3,4 and in vivo studies 5,6 . Researchers 1,7-11 studying the effect of various lasers on wound healing in diabetic animals have found a higher percentage of wound closure in diabetic and nondiabetic animals.…”

Section: Introductionmentioning

confidence: 85%

Influence of ingaalp laser (660nm) on the healing of skin wounds in diabetic rats

Carvalho

Silva²,

Reis³

et al. 2010

Acta Cir. Bras.

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Purpose:To determine the influence of low-power laser (660 nm) on the collagen percentage and macrophages in skin wounds in diabetic rats. Methods: 30 male Wistar rats were used, distributed in two groups: laser treated diabetic (n= 15); untreated diabetic (n = 15). The diabetes was induced by intravenous injection of alloxan into the dorsal vein of the penis, at a rate of 0.1 ml of solution per 100 g of body weight. A wound was made on the back of all the animals. Groups 2 were treated with Aluminium Gallium Indium Phosphide -InGaAlP type diode laser (Photon Laser III DMC ® ) with a continuous output power of 100 mW and wavelength ( ) of 660 nm (4 J/cm 2 ) for 24 s. five animal from each group was sacrificed on the 3rd, 7th and 14th days after wounding. Samples were taken, embedded in paraffin, stained with hematoxylin-eosin, Masson's trichrome, and immunohistochemical macrophage. morphometrically analyzed using the Image Pro Plus 4.5 software. The percentages of collagen fibers and macrophages were determined from the samples from the euthanasia animals. Results: The data were treated statistically using analysis of variance (ANOVA) and the Post-hocTukey test. The significance level was set at 0.05 or 5%.Conclusion: The low-power laser (660 nm) was shown to be capable of influencing the collagen percentage in skin wounds by increasing the mean quantity of collagen fibers and macrophages. Key words: Laser Therapy, Low-Level. Wound Healing. Collagen. Macrophages. Rats. RESUMOObjetivo: Determinar a influência do diodo laser InGaAlP (660 nm) sobre o percentual de colágeno e macrófagos em feridas cutâneas de ratos diabéticos. Métodos: Para tanto 30 ratos machos Wistar foram distribuídos em dois grupos: diabético tratado com laser (n=15), diabético não tratado (n = 15). O diabetes foi induzido por injeção intravenosa de aloxana na veia dorsal do pênis, a uma taxa de 0,1 ml de solução por 100 g de peso corporal. A lesão foi confeccionada no dorso de todos os animais utilizando um punch de 8mm. 2 grupos foram tratados com o diodo laser arsenieto de gálio e alumínio dopado com, fosforeto de índio -InGaAlP (tipo Photon Laser III DMC ® ) com uma potência contínua de 100 mW e comprimento de onda ( ) de 660 nm (4 J/cm 2 ) por 24 s. cinco animais de cada grupo foi sacrificado no 3, 7 e 14 dias após a lesão. As amostras obtidas foram emblocadas em parafina, coradas com hematoxilina-eosina, tricrômico de Masson, e para a analise dos macrófagos foi realizado um imunohistoquímico. Os resultados foram avaliados morfometricamente pelo programa Image Pro Plus 4.5. Resultados: Os dados foram tratados estatisticamente pela análise de variância (ANOVA) e pós-teste de Tukey. O nível de significância foi fixado em 0,05 ou 5%. Conclusão: O laser de baixa potência (660 nm) mostrou-se capaz de influenciar o percentual de colágeno em feridas cutâneas, aumentando a quantidade média de fibras colágenas e macrófagos. Descritores: Terapia a Laser de Baixa Intensidade. Cicatrização de Feridas. Colágeno. Macrófagos. Ratos.

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Effects of Power Densities, Continuous and Pulse Frequencies, and Number of Sessions of Low-Level Laser Therapy on Intact Rat Brain

Cited by 120 publications

References 13 publications

Photobiomodulation inside the brain: a novel method of applying near-infrared light intracranially and its impact on dopaminergic cell survival in MPTP-treated mice

Photobiomodulation inside the brain: a novel method of applying near-infrared light intracranially and its impact on dopaminergic cell survival in MPTP-treated mice

Low-level light therapy of the eye and brain

Influence of ingaalp laser (660nm) on the healing of skin wounds in diabetic rats

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