Low-level laser therapy alleviates periodontal age-related inflammation in diabetic mice via the GLUT1/mTOR pathway.

Diabetes mellitus (DM) is a chronic age-related disease that was recently found as a secondary aging pattern regulated by the senescence associated secretory phenotype (SASP). The purpose of this study is to detect the potential efficacy and the specific mechanisms of low-level laser therapy (LLLT) healing of age-related inflammation (known as inflammaging) in diabetic periodontitis. Diabetic periodontitis (DP) mice were established by intraperitoneal streptozotocin (STZ) injection and oral P. gingivalis inoculation. Low-level laser irradiation (810 nm, 0.1 W, 398 mW/cm2, 4 J/cm2, 10 s) was applied locally around the periodontal lesions every 3 days for 2 consecutive weeks. Micro-CT and hematoxylin-eosin (HE) stain was analyzed for periodontal soft tissue and alveolar bone. Western blots, immunohistochemistry, and immunofluorescence staining were used to evaluate the protein expression changes on SASP and GLUT1/mTOR pathway. The expression of aging-related factors and SASP including tumor necrosis factor-α, interleukin (IL)-1ß, and IL-6 were reduced in periodontal tissue of diabetic mice. The inhibitory effect of LLLT on GLUT1/mTOR pathway was observed by detecting the related factors mTOR, p-mTOR, GLUT1, and PKM2. COX, an intracytoplasmic photoreceptor, is a key component of the anti-inflammatory effects of LLLT. After LLLT treatment a significant increase in COX was observed in macrophages in the periodontal lesion. Our findings suggest that LLLT may regulate chronic low-grade inflammation by modulating the GLUT1/mTOR senescence-related pathway, thereby offering a potential treatment for diabetic periodontal diseases.

Effects of photobiomodulation on oxidative stress in rats with type 2 diabetes mellitus.

The present study aimed to evaluate photobiomodulation effects on oxidative stress in type 2 diabetes mellitus (DM2). Thirty-one male Wistar rats were used and divided into 4 groups: group 1 - animals without diabetes mellitus 2 without laser 21 J/cm2 (C-SHAM), group 2 - animals with diabetes mellitus 2 without laser 21 J/cm2 (C-DM2), group 3 - animals without diabetes mellitus 2 with laser 21 J/cm2 (L-SHAM), group 4 - animals with diabetes mellitus 2 with laser 21 J/cm2 (L-DM2). The protocol was performed 5 days/week, for 6 weeks. The animals that received photobiomodulation had one dose irradiated at two spots in the right gastrocnemius muscle. Twenty-four hours after the last intervention, the animals were euthanized. Heart, diaphragm, liver, right gastrocnemius, plasma, kidneys, weighed, and stored for further analysis. In rats with DM2, photobiomodulation promoted a decrease in thiobarbituric acid reactive substance assay (TBARS) in plasma levels. On the other hand, photobiomodulation demonstrated an increase in non-protein thiol levels (NPSH) in the heart, diaphragm and gastrocnemius. Moreover, photobiomodulation produced in the heart, diaphragm and plasma levels led to an increase in superoxide dismutase (SOD). Interestingly, photobiomodulation was able to increase superoxide dismutase in rats without DM2 in the heart, diaphragm, gastrocnemius and kidneys. These findings suggested that 6 weeks of photobiomodulation in rats with DM2 promoted beneficial adaptations in oxidative stress, with a decrease in parameters of oxidant activity and an increase in antioxidant activity.

Photobiomodulation isolated or associated with adipose-derived stem cells allograft improves inflammatory and oxidative parameters in the delayed-healing wound in streptozotocin-induced diabetic rats.

The single and associated impressions of photobiomodulation (PBM) and adipose-derived stem cells (ADS) on stereological parameters (SP), and gene expression (GE) of some antioxidant and oxidative stressors of repairing injured skin at inflammation and proliferation steps (days 4 and 8) of a delayed healing, ischemic, and infected wound model (DHIIWM) were examined in type one diabetic (DM1) rats. DM1 was induced by administration of streptozotocin (40 mg/kg) in 48 rats. The DHIIWM was infected by methicillin-resistant Staphylococcus aureus (MRSA). The study comprised 4 groups (each, n = 6): Group 1 was the control group (CG). Group 2 received allograft human (h) ADSs transplanted into the wound. In group 3, PBM (890 nm, 80 Hz, 0.2 J/cm2) was emitted, and in group 4, a combination of PBM+ADS was used. At both studied time points, PBM+ADS, PBM, and ADS significantly decreased inflammatory cell count (p < 0.05) and increased granulation tissue formation compared to CG (p < 0.05). Similarly, there were lower inflammatory cells, as well as higher granulation tissue in the PBM+ADS compared to those of alone PBM and ADS (all, p < 0.001). At both studied time points, the GE of catalase (CAT) and superoxide dismutase (SOD) was remarkably higher in all treatment groups than in CG (p < 0.05). Concomitantly, the outcomes of the PBM+ADS group were higher than the single effects of PBM and ADS (p < 0.05). On day 8, the GE of NADPH oxidase (NOX) 1 and NOX4 was substantially less in the PBM+ADS than in the other groups (p < 0.05). PBM+ADS, PBM, and ADS treatments significantly accelerated the inflammatory and proliferative stages of wound healing in a DIIWHM with MRSA in DM1 rats by decreasing the inflammatory response, and NOX1 and 4 as well; and also increasing granulation tissue formation and SOD and CAT. The associated treatment of PBM+ADS was more effective than the individual impacts of alone PBM and ADS because of the additive anti-inflammatory and proliferative effects of PBM plus ADS treatments.

Photobiomodulation treatments drive osteogenic versus adipocytic fate of bone marrow mesenchymal stem cells reversing the effects of hyperglycemia in diabetes.

Diabetes mellitus (DM) is a chronic metabolic disease that affects bone metabolism, which can be related to a reduced osteogenic potential of bone marrow mesenchymal stem cells (BM-MSCs). MSCs from diabetic rats (dBM-MSC) have shown a tendency to differentiate towards adipocytes (AD) instead of osteoblasts (OB). Since photobiomodulation (PBM) therapy is a non-invasive treatment capable of recovering the osteogenic potential of dBM-MSCs, we aimed to evaluate whether PBM can modulate MSC's differentiation under hyperglycemic conditions. BM-MSCs of healthy and diabetic rats were isolated and differentiated into osteoblasts (OB and dOB) and adipocytes (AD and dAD). dOB and dAD were treated with PBM every 3 days (660 nm; 5 J/cm2; 0.14 J; 20 mW; 0.714 W/cm2) for 17 days. Cell morphology and viability were evaluated, and cell differentiation was confirmed by gene expression (RT-PCR) of bone (Runx2, Alp, and Opn) and adipocyte markers (Pparγ, C/Ebpα, and C/Ebpß), production of extracellular mineralized matrix (Alizarin Red), and lipid accumulation (Oil Red). Despite no differences on cell morphology, the effect of DM on cells was confirmed by a decreased gene expression of bone markers and matrix production of dOB, and an increased expression of adipocyte and lipid accumulation of dAD, compared to heatlhy cells. On the other hand, PBM reversed the effects of dOB and dAD. The negative effect of DM on cells was confirmed, and PBM improved OB differentiation while decreasing AD differentiation, driving the fate of dBM-MSCs. These results may contribute to optimizing bone regeneration in diabetic patients.

Early effect of laser irradiation in signaling pathways of diabetic rat submandibular salivary glands.

Low-power laser irradiation (LPLI) is clinically used to modulate inflammation, proliferation and apoptosis. However, its molecular mechanisms are still not fully understood. This study aimed to describe the effects of LPLI upon inflammatory, apoptotic and proliferation markers in submandibular salivary glands (SMGs) in an experimental model of chronic disorder, 24h after one time irradiation. Diabetes was induced in rats by the injection of streptozotocin. After 29 days, these animals were treated with LPLI in the SMG area, and euthanized 24h after this irradiation. Treatment with LPLI significantly decreased diabetes-induced high mobility group box 1 (HMGB1) and tumor necrosis factor alpha (TNF-α) expression, while enhancing the activation of the transcriptional factor cAMP response element binding (CREB) protein. LPLI also reduced the expression of bax, a mitochondrial apoptotic marker, favoring the cell survival. These findings suggest that LPLI can hamper the state of chronic inflammation and favor homeostasis in diabetic rats SMGs.

Far-infrared radiation prevents decline in ß-cell mass and function in diabetic mice via the mitochondria-mediated Sirtuin1 pathway.

Insulin deficiency in type 2 diabetes mellitus (DM) involves a decline in both pancreatic ß-cell mass and function. Enhancing ß-cell preservation represents an important therapeutic strategy to treat type 2 DM. Far-infrared (FIR) radiation has been found to induce promyelocytic leukemia zinc finger protein (PLZF) activation to protect the vascular endothelium in diabetic mice. The influence of FIR on ß-cell preservation is unknown. Our previous study reveals that the biologically effective wavelength of FIR is 8-10 µm. In the present study, we investigated the biological effects of FIR (8-10 µm) on both survival and insulin secretion function of ß-cells. FIR reduced pancreatic islets loss and increased insulin secretion in nicotinamide-streptozotocin-induced DM mice, but only promoted insulin secretion in DM PLZF-/- mice. FIR-upregulated PLZF to induce an anti-apoptotic effect in a ß cell line RIN-m5f. FIR also upregulated mitochondrial function and the ratio of NAD+/NADH, and then induced Sirtuin1 (Sirt1) expression. The mitochondria Complex I inhibitor rotenone blocked FIR-induced PLZF and Sirt1. The Sirt1 inhibitor EX527 and Sirt1 siRNA inhibited FIR-induced PLZF and insulin respectively. Sirt1 upregulation also increased CaV1.2 expression and calcium influx that promotes insulin secretion in ß-cells. In summary, FIR-enhanced mitochondrial function prevents ß-cell apoptosis and enhances insulin secretion in DM mice through the Sirt1 pathway.

Stereological and gene expression examinations on the combined effects of photobiomodulation and curcumin on wound healing in type one diabetic rats.

We examined the effects of photobiomodulation (PBM) independently and combined with curcumin on stereological parameters and basic fibroblast growth factor (bFGF), hypoxia-inducible factor-1α (HIF-1α), and stromal cell-derived factor-1α (SDF-1α) gene expressions in an excisional wound model of rats with type one diabetes mellitus (T1DM). T1DM was induced by an injection of streptozotocin (STZ) in each of the 90 male Wistar rats. One round excision was generated in the skin on the back of each of the 108 rats. The rats were divided into six groups (n = 18 per group): control (diabetic), untreated group; vehicle (diabetic) group, which received sesame oil; PBM (diabetic) group; curcumin (diabetic) group; PBM + curcumin (diabetic) group; and a healthy control group. On days 4, 7, and 15, we conducted both stereological and quantitative real-time PCR (qRT-PCR) analyses. The PBM and PBM + curcumin groups had significantly better inflammatory response modulation in terms of macrophages (P < .01), neutrophils (P < .001), and increased fibroblast values compared with the other groups at day 4 (P < .001), day 7 (P < .01), and day 15 (P < .001). PBM treatment resulted in increased bFGF gene expression on days 4 (P < .001) and 7 (P < .001), and SDF-1α gene expression on day 4 (P < .001). The curcumin group had increased bFGF (P < .001) expression on day 4. Both the PBM and PBM + curcumin groups significantly increased wound healing by modulation of the inflammatory response, and increased fibroblast values and angiogenesis. The PBM group increased bFGF and SDF-1α according to stereological and gene expression analyses compared with the other groups. The PBM and PBM + curcumin groups significantly increased the skin injury repair process to more rapidly reach the proliferation phase of the wound healing in T1DM rats.

Improvement in infected wound healing in type 1 diabetic rat by the synergistic effect of photobiomodulation therapy and conditioned medium.

We investigated the effects of photobiomodulation therapy (PBMT) and conditioned medium (CM) of human bone marrow mesenchymal stem cells (hBM-MSC) individually and/or in combination on the stereological parameters and the expression of basic fibroblast growth factor (bFGF), hypoxia-inducible factor (HIF-1α), and stromal cell-derived factor-1α (SDF-1α) in a wound model infected with methicillin-resistant Staphylococcus aureus (MRSA) in diabetic rats. CM was provided by culturing hBM-MSCs. Type 1 diabetes mellitus (T1DM) was induced in 72 rats, divided into four groups, harboring 18 rats each: group 1 served as a control group, group 2 received PBMT, group 3 received CM, and group 4 received CM + PBMT. On days 4, 7, and 15, six animals from each group were euthanized and the skin samples were separated for stereology examination and gene expression analysis by real-time polymerase chain reaction. In the CM + PBMT, CM, and PBMT groups, significant decreases were induced in the number of neutrophils (1460 ± 93, 1854 ± 138, 1719 ± 248) and macrophages (539 ± 69, 804 ± 63, 912 ± 41), and significant increases in the number of fibroblasts (1073 ± 116, 836 ± 75, 912 ± 41) and angiogenesis (15 230 ± 516, 13 318 ± 1116, 14 041 ± 867), compared with those of the control group (2690 ± 371, 1139 ± 145, 566 ± 90, 12 585 ± 1219). Interestingly, the findings of the stereological examination in the CM + PBMT group were statistically more significant than those in the other groups. In the PBMT group, in most cases, the expression of bFGF, HIF-1α, and SDF-1α, on day 4 (27.7 ± 0.14, 28.8 ± 0.52, 27.5 ± 0.54) and day 7 (26.8 ± 1.4, 29.6 ± 1.4, 28.3 ± 1.2) were more significant than those in the control (day 4, 19.3 ± 0.42, 25.5 ± 0.08, 22.6 ± 0.04; day 7, 22.3 ± 0.22, 28.3 ± 0.59, 24.3 ± 0.19) and other treatment groups. The application of PBMT + CM induced anti-inflammatory and angiogenic activities, and hastened wound healing process in a T1 DM model of MRSA infected wound.

PBMT and topical diclofenac as single and combined treatment on skeletal muscle injury in diabetic rats: effects on biochemical and functional aspects.

Physical exercise generates several benefits in a short time in patients with diabetes mellitus. However, it can increase the chances of muscle damage, a serious problem for diabetic patients. Nonsteroidal anti-inflammatory drugs (NSAIDs) are widely used to treat these injuries, despite the serious adverse effects. In this way, photobiomodulation therapy (PBMT) with low-level laser therapy (LLLT) and/or light emitting diode therapy (LEDT) can be used as an alternative in this case. However, its efficacy in tissue repair of trauma injuries in diabetes mellitus until now is unknown, as well as the combination between PBMT and NSAIDs. The objective of the present study was to evaluate the effects of NSAIDs and PBMT applied alone or combined on functional and biochemical aspects, in an experimental model of muscle injury through controlled trauma in diabetic rats. Muscle injury was induced by means of a single trauma to the animals' anterior tibialis muscle. After 1 h, the rats were treated with PBMT (830 nm; continuous mode, with a power output of 100 mW; 3.57 W/cm2; 3 J; 107.1 J/cm2, 30 s), diclofenac sodium for topical use (1 g), or combination of them. Our results demonstrated that PBMT + diclofenac, and PBMT alone reduced the gene expression of cyclooxygenase-2 (COX-2) at all assessed times as compared to the injury and diclofenac groups (p < 0.05 and p < 0.01 respectively). The diclofenac alone showed reduced levels of COX-2 only in relation to the injury group (p < 0.05). Prostaglandin E2 levels in blood plasma demonstrated similar results to COX2. In addition, we observed that PBMT + diclofenac and PBMT alone showed significant improvement compared with injury and diclofenac groups in functional analysis at all time points. The results indicate that PBMT alone or in combination with diclofenac reduces levels of inflammatory markers and improves gait of diabetic rats in the acute phase of muscle injury.

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.

The influence of low-intensity He-Ne laser on the wound healing in diabetic rats.

The low-level laser irradiation at certain wavelengths is reported to facilitate the healing process of diabetic wounds. Thus, this study carried out to look for the suitable laser parameters that could speed up the healing process. Fourteen healthy male and female rats were used in which a circular wound with a diameter of 2.5 ± 0.2 cm was created on the dorsum in each rat after injected them with alloxan to induced diabetic. They have been divided into two groups: control group (N = 7) and study group (N = 7) to conduct the study. He-Ne laser with a wavelength of 632.8 nm at power density of 4.0 mW/cm2 was used to irradiate the study group for five times a week until the wound healed (closed) completely, while the control group was kept untreated. The results showed that the laser-treated group healed (wounds were totally closed) faster compared to the control group. In numbers, the laser-treated group healed on average at the 21st day (0.0 ± 0.0 cm) (P ≤ 0.005), whereas the control group healed after 40 days or even 60 days in some cases (sample no. 2). This confirms that laser promotes the tissue repair process of diabetic wounds and reduces the healing period to the half.

Photobiomodulation laser and pulsed electrical field increase the viability of the musculocutaneous flap in diabetic rats.

The purpose of this study is to investigate the effect of pulsed electrical field (PEF) and photobiomodulation laser (PBM) on the viability of the TRAM flap in diabetic rats. Fifty Wistar rats were divided into five homogeneous groups: Group 1-control; Group 2-diabetics; Group 3-diabetics + PEF; Group 4-diabetic + laser 660 nm, 10 J/cm2, 0.27 J; Group 5-diabetic + laser 660 nm, 140 J/cm2, 3.9 J. The percentage of necrotic area was evaluated using software Image J®. The peripheral circulation of the flap was evaluated by infrared thermography FLIR T450sc (FLIR® Systems-Oregon USA). The thickness of the epidermis (haematoxylin-eosin), mast cell (toluidine blue), leukocytes, vascular endothelial growth factor, fibroblast and newly formed blood vessels were evaluated. For the statistical analysis, the Kruskal-Wallis test was applied followed by Dunn and ANOVA test followed by Tukey with critical level of 5% (p < 0.05). The PEF reduced the area of necrosis, decreased the leukocytes, increased the mast cells, increased the thickness of epidermis and increased newly formed blood vessels when it was compared to the untreated diabetic group of animals. Laser 660 nm, fluence 140 J/cm2 (3.9 J) showed better results than the 10 J/cm2 (0.27 J) related to reduction of the area of necrosis and the number of leukocytes, increased mast cells, increased thickness of the epidermis, increased vascular endothelial growth factor, increased fibroblast growth factor and increase of newly formed blood vessels in diabetic animals. The laser and pulsed electrical field increase the viability of the musculocutaneous flap in diabetic rats.

Low-power laser irradiation in salivary glands reduces glycemia in streptozotocin-induced diabetic female rats.

Low-power laser irradiation (LPLI) has been extensively employed to modulate inflammation in vitro and in vivo. Previous reports from our group indicated that LPLI might regulate glycemia in diabetic animals. Diabetes results in chronic hyperglycemia and therefore chronic inflammation by upregulation of inflammatory markers such as the high mobility group box 1 (HMGB1) protein. Thus this study aimed to analyze the LPLI effects upon blood glucose levels, plasma insulin and HMGB1 concentrations in a diabetes experimental rat model. Streptozotocin-induced diabetic rats were irradiated in the salivary glands area with a diode laser applied at 660 nm, 70 mW, 20 J/cm2 , 22.4 J, with a spot area of 0.028 cm2 and its effects were evaluated. LPLI significantly reduced diabetic rat hyperglycemia, without changing insulin or HMGB1 plasma levels, but possibly by ameliorating the insulin resistance in these animals. These findings suggest that LPLI might have a systemic effect, but more studies are necessary to better understand its mechanisms. Fasting blood glucose measured by peroxidase-glucose oxidase (PGO) method (A), showing a reduction of diabetic animals glycemia after LPLI. LPLI probably reduced the hyperglycemia in diabetes by improving the insulin resistance in these animals (B). C n = 10, CL n = 10, D n = 7 and DL n = 8. Data are expressed as mean ± SD; * P < 0.05 vs. respective control group; # P < 0.05 vs. D group.

Effect of photobiomodulation on ischemia/reperfusion-induced renal damage in diabetic rats.

This study was designed to investigate the possible effect of photobiomodulation (PBM) on renal damage induced by ischemia reperfusion (IR) in diabetic rats. Twenty streptozotocin-induced diabetic rats were randomly distributed into two groups, containing ten rats each: IR group (G1) and IR + PBM group (G2). After the right nephrectomy, the ischemia was produced in the left kidney for 30 min, followed by the reperfusion for 24 h. Then, a 685-nm laser diode with an output power of 15 mW (spot size = 0.28 cm2 and energy density = 3.2 J/cm2) was employed. PBM was carried out by irradiating the rats over six points on the skin over the left kidney region three times, i.e., immediately after skin suturing and 1 and 2 h after initiating reperfusion for 6 min. At the end of reperfusion period, the rats were anesthetized, and blood samples were collected and used for the estimation of renal function (blood urea nitrogen (BUN) and creatinine). Then, the left kidney was harvested for histological and biochemical examination. The serum levels of BUN and creatinine were significantly higher in G1 compared to G2 (P < 0.05). G1 had higher renal malondialdehyde (MDA) levels compared to G2 (P < 0.05). Renal IR in diabetic rats (G1) resulted in a significant decrease in renal tissue glutathione (GSH) (P < 0.05) when compared to laser-treated rats (G2). A significant restoration was observed in the levels of superoxide dismutase (SOD) (P < 0.05) and catalase (CAT) (P < 0.05) in G2 as compared to G1. The levels of nitric oxide (NO) were increased in G1 in comparison to G2 (P < 0.05). The myeloperoxidase (MPO) activity was significantly higher in the renal tissue of G1 than that of G2 (P < 0.05). In addition, specimens from the G1 had a significantly greater histological injury than those from the G2 (P < 0.05). The results of present investigation revealed that PBM attenuated kidney damage induced by renal IR in diabetic rats.

Investigation of the Comparative Effects of Red and Infrared Laser Therapy on Skeletal Muscle Repair in Diabetic Rats.

OBJECTIVE: The aim of this study was to evaluate the in vivo response of 2 different laser wavelengths (red and infrared) on skeletal muscle repair process in diabetic rats. DESIGN: Forty Wistar rats were randomly divided into 4 experimental groups: basal control-nondiabetic and muscle-injured animals without treatment (BC); diabetic muscle-injured without treatment (DC); diabetic muscle-injured, treated with red laser (DCR) and infrared laser (DCIR). The injured region was irradiated daily for 7 consecutive days, starting immediately after the injury using a red (660 nm) and an infrared (808 nm) laser. RESULTS: The histological results demonstrated in both treated groups (red and infrared wavelengths) a modulation of the inflammatory process and a better tissue organization located in the site of the injury. However, only infrared light significantly reduced the injured area and increased MyoD and myogenin protein expression. Moreover, both red and infrared light increased the expression of the proangiogenic vascular endothelial growth factor and reduced the cyclooxygenase 2 protein expression. CONCLUSION: These results suggest that low-level laser therapy was efficient in promoting skeletal muscle repair in diabetic rats. However, the effect of infrared wavelength was more pronounced by reducing the area of the injury and modulating the expression proteins related to the repair.

Additive protection by LDR and FGF21 treatment against diabetic nephropathy in type 2 diabetes model.

The onset of diabetic nephropathy (DN) is associated with both systemic and renal changes. Fibroblast growth factor (FGF)-21 prevents diabetic complications mainly by improving systemic metabolism. In addition, low-dose radiation (LDR) protects mice from DN directly by preventing renal oxidative stress and inflammation. In the present study, we tried to define whether the combination of FGF21 and LDR could further prevent DN by blocking its systemic and renal pathogeneses. To this end, type 2 diabetes was induced by feeding a high-fat diet for 12 wk followed by a single dose injection of streptozotocin. Diabetic mice were exposed to 50 mGy LDR every other day for 4 wk with and without 1.5 mg/kg FGF21 daily for 8 wk. The changes in systemic parameters, including blood glucose levels, lipid profiles, and insulin resistance, as well as renal pathology, were examined. Diabetic mice exhibited renal dysfunction and pathological abnormalities, all of which were prevented significantly by LDR and/or FGF21; the best effects were observed in the group that received the combination treatment. Our studies revealed that the additive renal protection conferred by the combined treatment against diabetes-induced renal fibrosis, inflammation, and oxidative damage was associated with the systemic improvement of hyperglycemia, hyperlipidemia, and insulin resistance. These results suggest that the combination treatment with LDR and FGF21 prevented DN more efficiently than did either treatment alone. The mechanism behind these protective effects could be attributed to the suppression of both systemic and renal pathways.

Optogenetic control of insulin secretion by pancreatic ß-cells in vitro and in vivo.

The present study assessed the ability of optogenetics techniques to provide a better understanding of the control of insulin secretion, particularly regarding pancreatic ß-cell function in homeostasis and pathological conditions such as diabetes mellitus (DM). We used optogenetics to investigate whether insulin secretion and blood glucose homeostasis could be controlled by regulating intracellular calcium ion concentrations ([Ca(2+)]i) in a mouse pancreatic ß-cell line (MIN6) transfected with the optogenetic protein channelrhodopsin-2 (ChR2). The ChR2-transfected MIN6 (ChR2-MIN6) cells secreted insulin following irradiation with a laser (470 nm). The increase in [Ca(2+)]i was accompanied by elevated levels of messenger RNAs that encode calcium/calmodulin-dependent protein kinase II delta and adenylate cyclase 1. ChR2-MIN6 cells suspended in matrigel were inoculated into streptozotocin-induced diabetic mice that were then subjected to a glucose tolerance test. Laser irradiation of these mice caused a significant decrease in blood glucose, and the irradiated implanted cells expressed insulin. These findings demonstrate the power of optogenetics to precisely and efficiently controlled insulin secretion by pancreatic ß-cells 'on demand', in contrast to techniques using growth factors or chemical inducers. Optogenetic technology shows great promise for understanding the mechanisms of glucose homeostasis and for developing treatments for metabolic diseases such as DM.

Biophotonic effect of diode laser irradiance on tensile strength of diabetic rats.

Low-energy laser irradiance at certain wavelengths is able to stimulate the tissue bio-reaction and enhance the healing process. Collagen deposition is one of the important aspects in healing process because it can increase the strength of the skin. This study was designed to examine the biophotonic effect of irradiance on collagen production of diabetic wound in rat model. The tensile strength of skin was employed as a parameter to describe the wound. Diabetic rat models were induced by streptozotocin via intravenous injection. Skin-breaking strength was measured using an Instron tensile test machine. The experimental animals were treated with 808-nm diode laser at two different powers-0.1 and 0.5 W/cm(2)-and 30, 60, and 120 s for each session. The tensile strength was optimized after treated with high-power diode laser. The photostimulation effect was revealed by accelerated healing process and enhanced tensile strength of wound. Laser photostimulation on tensile strength in diabetic wound suggests that such therapy facilitates collagen production in diabetic wound healing.

Defining a therapeutic window for laser irradiation (810 nm) applied to the inguinal region to ameliorate diabetes in diabetic mice.

OBJECTIVE: The purpose of this study was to determine a therapeutic window of antidiabetic effect by laser irradiating the left inguinal region of diabetic mice (810 nm 20.4 and 40.8 J/cm(2)) for 7 days. BACKGROUND DATA: Irradiation of 810 nm 10.2 J/cm(2) to the left inguinal region of diabetic mice for 7 days significantly decreased blood plasma fructosamine compared with nonirradiated controls. METHODS: Forty-seven diabetic mice were used. Body weight and water intake of the mice were measured daily for 7 days prior to start of treatment (day 0). Mice were irradiated on the left inguinal region with 810 nm laser 20.4 J/cm(2) (n=15) or 40.8 J/cm(2) (n=15) for 7 days, or were not irradiated (control, n=17). Body weight and water intake were measured to day 7. On day 7, mice were fasted for 5 h, anesthetized with sodium pentobarbitone (i.p.), and blood plasma was collected. The blood plasma was assayed for glucose and fructosamine. RESULTS: Water intake was significantly increased on day 7 compared with day 0 for diabetic mice receiving laser treatment. Blood plasma glucose levels on day 7 for diabetic mice irradiated 20.4 and 40.8 J/cm(2) were not significantly different than for nonirradiated controls. The blood plasma fructosamine level of diabetic mice irradiated with 20.4 J/cm(2) was significantly lower than for nonirradiated controls, whereas that for diabetic mice irradiated with 40.8 J/cm(2) was not significantly different than for nonirradiated controls. CONCLUSIONS: Irradiation (810 nm laser 10.2-20.4 J/cm(2)) to the left inguinal region of diabetic mice for 7 days has the potential to ameliorate diabetes, as is shown by decreased blood plasma fructosamine.

Histological analysis of the periodontal ligament and alveolar bone during dental movement in diabetic rats subjected to low-level laser therapy.

OBJECTIVE: The purpose of this research was to evaluate the histological changes of the periodontal ligament and alveolar bone during dental movement in diabetic rats subjected to low level laser therapy (LLLT). METHODS: The movement of the upper molar was performed in 60 male Wistar rats divided into four groups (n=15): CTR (control), DBT (diabetic), CTR/LT (irradiated control) and DBT/LT (irradiated diabetic). Diabetes was induced with alloxan (150 mg/kg, i.p.). LLLT was applied with GaAlAs laser at 780 nm (35 J/cm(2)). After 7, 13 and 19 days, the periodontal ligament and alveolar bone were histologically analyzed. RESULTS: The mean of osteoblasts (p<0.01) and blood vessels (p<0.05) were significantly decreased in DBT compared with CTR at 7 days, whereas the mean of osteoclasts was lower at 7 (p<0.001) and 13 days (p<0.05). In DBT/LT, only the mean of osteoclasts was lower than in CTR (p<0.05) at 7 days, but no difference was observed at 13 and 19 days (p>0.05). The collagenization of the periodontal ligament was impaired in DBT, whereas DBT/LLT showed density/disposition of the collagen fibers similar to those observed in CTR. CONCLUSIONS: LLLT improved the periodontal ligament and alveolar bone remodeling activity in diabetic rats during dental movement.