Maria José Pedreira Ramalho

Evaluation of Laser Phototherapy in the Inflammatory Process of the Rat's TMJ Induced by Carrageenan

AIM The aim of this study was to evaluate, by light microscopy, the effects of laser phototherapy (LPT) at 780 nm or a combination of 660 and 790 nm, on the inflammatory process of the rat temporomandibular joint (TMJ) induced by carrageen. BACKGROUND Temporomandibular disorders (TMDs) are frequent in the population and generally present an inflammatory component. Previous studies have evidenced positive effects of laser phototherapy on TMDs. However, its mechanism of action on the inflammation of the TMJ is not known yet. MATERIALS AND METHODS Eighty-five Wistar rats were divided into 9 groups: G1, Saline; G2, Saline + LPT IR; G3, Saline + LPT IR + R; G4, Carrageenan; G5, Carrageenan + LPT IR; G6, Carrageenan + LPT IR + R; G7, previous LPT + Carrageenan; G8, previous LPT + carrageenan + LPT IR; and G9, previous LPT + carrageenan + LPT IR + R, and then subdivided in subgroups of 3 and 7 days. After animal death, specimens were taken, routinely cut and stained with HE, Sirius Red, and Toluidine Blue. Descriptive analysis of components of the TMJ was done. The synovial cell layers were counted. RESULTS Injection of saline did not produced inflammatory reaction and the irradiated groups did not present differences compared to nonirradiated ones. After carrageenan injection, intense inflammatory infiltration and synovial cell layers proliferation were observed. The infrared irradiated group presented less inflammation and less synovial cell layers number compared to other groups. Previous laser irradiation did not improve the results. CONCLUSION It was concluded that the LPT presented positive effects on inflammatory infiltration reduction and accelerated the inflammation process, mainly with IR laser irradiation. The number of synovial cell layers was reduced on irradiated group.

Assessment of laser photobiomodulation and polarized light on the healing of cutaneous wounds on euthyroid and hypothyroid induced rats

The aim of this study was to assess the influence of low-level laser therapy (LLLT) or polarized light (PL) in cutaneous wound healing of hypothyroid rats at dosages of 20 or 40J/cm2. Bioestimulatory effects of Laser radiation and Polarized light are recognized alternative therapies to improve healing on systemic disease patients, but their usefulness in the improvement of hypothyroidism healing impairment is uncertain till date. Forty Wistar rats were used in this study. Hypothyroidism was propylthiouracil- induced. Standard excisional cutaneous wounds were created without suturing and LLLT (λ660nm, 30mW, φ 3mm) or PL (λ 400-2000nm, 40mW, φ 10mm) was applied every 48 hours up to seven days on experimental groups. The rats were killed on the eighth day when wound contraction was assessed. The healing features were evaluated by light microscopy (H/E and Sirius Red). The cutaneous wounds of hypothyroid rats showed delayed healing process characterized by reduced thickness of epithelial layers, incipient formation of disorganized collagen fibers and wound contraction to a lesser extent (FISHER, p=0.0276), when compared to the euthyroid group. The use of both the Laser and Polarized Light on hypothyroid rats increased the amount of fibroblasts and the thickness of collagen fibers, especially on the L 20J/cm2 group. Euthyroid rats have still demonstrated more regular collagen fibers pattern than hypothyroid rats. It was therefore concluded that hypothyroidism delays wound healing and both Laser photobiomodulation and Polarized Light at 20j/cm2 dosages had improved the healing process in hypothyroid rats.

Assessment of the effects of laser or LED photobiomodulation on hypothyroid rats of cutaneous wound healing: A morphometric study.

Hypothyroid has been associated to a disruption of the bodys metabolism, including the healing process. Laser and LED have been shown to be effective on improving healing in many situations, but their benefit in the improvement of healing on hypothyroidism remains unknown. The aim of this study was to assess, morphometrically, the influence of Laser (λ660nm, 24 J/cm2, 40mW, CW, spot output= 4mm2;) and LED (λ630nm ± 20, 24 J/cm2, 150mW, CW, spot output= 0.5 cm2) on the wound healing of rats with Hypothyroid. Under general anesthesia, a standard surgical wound (1cm2) was created on the dorsum of 72 male Wistar rats divided into 6 groups of 12 animals each: G1: Euthyroid; G2: Euthyroid + Laser; G3: Euthyroid + LED; G4: Hypothyroid; G5: Hypothyroid + Laser and G6: Hypothyroid + LED. Hypothyroidism was induced in rats with propylthiouracil (0.05g/100mL) administered orally for 4 weeks and maintained until the end of the experiment. Rats were irradiated after surgery each 48h then killed after 7 and 14 days. S...

Prolactin secretion in hypothyroid endotoxemic rats: involvement of L-arginine and nitric oxide synthase.

The identification of nitric oxide (NO) within the hypothalamus and pituitary gland has suggested its role as modulator of the activity on hypothalamic-pituitary axis. Hypothalamic NO synthase (NOS) is known to be regulated by thyroid hormones. We investigated the effects of previous injection of Nϖ-nitro-L-arginine methyl ester (L-NAME), a NOS inhibitor, and L-arginine (L-Arg), the substrate for NO synthesis, on prolactin (PRL) secretion, through the lipopolysaccharide (LPS)-induced inflammatory response in thyroidectomized (TX) rats. TX or sham-operated (N) rats were intraperitoneally (i.p.) injected with L-NAME (10 mg kg-1) or L-Arg (200 mg kg-1) or the same volume of vehicle (saline solution) 30 min before endotoxemia-induction with LPS at 250 μg (100 g body weight)-1, i.p.. In N rats, NO increased PRL release in response to endotoxemia, whereas in hypothyroid rats, NO appeared to have the opposite effect. Our data support the hypothesis that NO exerts a modulatory influence on PRL secretion after LPS-induced inflammatory response.

Effect of LED phototherapy (λ630 ± 20nm) on mast cells during wound healing in hypothyroid

Hypothyroidism has been associated with the disruption of the bodys metabolism, including the healing process. LED phototherapy has been studied using several healing models, but their effects on mast cells proliferation associated to hypothyroidism remains unknown. The aim of this study was to assess the effect LED (λ630±20nm) phototherapy on mast cells proliferation during tissue repair in hypothyroid rats. Under general anesthesia, a standard surgical wound (1cm2) was created on the dorsum of 24 male Wistar rats divided into 4 groups of 6 animals each: EC-Control Euthyroid; ED-Euthyroid+LED; HC-Control Hypothyroid and HD-Hypothyroid+LED. The irradiation started immediately after surgery and was repeated every other day for 7 days, when animals death occurred. Hypothyroidism was induced in rats with propylthiouracil (0.05g/100mL) administered orally for 4 weeks and maintained until the end of the experiment. The specimens removed were processed to wax and stained with toluidine blue for mast cell identification. The mast cell proliferation was significantly higher in HC group than in EC group (Mann Whitney, p<0.05), but when ED group was compared to HD group, no significant difference was found. Our results showed that there was increase of mast cells in the presence of hypothyroidism, prolonging the inflammatory phase of repair, and the LED light has a biomodulative effect on mast cell population, even when hipothyroidism was present.

Evaluation of LED photobiomodulation on wound healing in hypothyroid and euthyroid rats

Thyroid hormone deficiency has been associated to disruption of the bodys metabolism, including healing process. LED phototherapy has been shown to be effective in improving healing in many situations, but their usefulness in the improvement of hypothyroidism wound healing remains unknown. The aim of this study was to assess histologically the effect of LED (λ630 ± 20nm, 150mW, CW, φ=0.5 cm2, 24J/cm2 per session) on wounds healing in hypothyroid and euthyroid Wistar rats. Standard cutaneous wound (1cm2) was created on the dorsum of 24 animals divided into four groups of 6 animals each: G1: Euthyroid; G2: Euthyroid + LED; G3: Hypothyroid; G4: Hypothyroid + LED. Hypothyroidism was induced in rats with propylthiouracil (0.05g/100mL) administered orally for 4 weeks and maintained until the end of the experiment. The irradiation started immediately after surgery and was repeated every other day for 7 days. Animals were killed 8 days after surgery. The specimens were removed, routinely processed and stained wi...