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

Abstract

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/cm , 22.4 J, with a spot area of 0.028 cm 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.

The Effects of Low-Power Laser Irradiation on Inflammation and Apoptosis in Submandibular Glands of Diabetes-Induced Rats

“…We also found a significantly decrease in animals blood glucose levels, this is consistent with our previous report, that shows that LPLI can improve the insulin sensitivity in diabetic rats, without changing the levels of HMGB1 or insulin in blood serum [26]. We observed the LPLI effect at 24 h, that provided large amounts of favorable data on inflammation and apoptosis in diabetic SMGs, however it must be considered that these findings may not translate to outcome of long-term studies.…”

“…Experimental diabetes-induced rat model was developed as described previously [26]. In brief, female Wistar rats (12-weeks old; n = 30) were purchased from University of Sao Paulo and were housed in isolation cages throughout the experimental period.…”

Low‐power laser irradiation decreases lipid droplet accumulation in the parotid glands of diabetic rats

“…In the present study, a single laser irradiation showed also an effect upon glycemic status, which was previously observed by our group and partially explained by Fukuoka et al study, where a decrease in insulin resistance (HOMA‐IR), an increase in insulin sensitivity (HOMA‐IS) and better β‐cells function (HOMA‐β) were observed in irradiated animals .…”

“…Previously, our studies showed an improvement in the salivary flow rate of normal rats after receiving laser irradiation . In addition, in diabetic animals, we observed a decrease of blood glucose concentration after PBMT, probably by improving the insulin resistance . We also investigated the action mechanism of this therapy upon SG and observed that laser irradiation decreased diabetes‐induced inflammation by reducing the induction of high‐mobility group box‐1 .…”

“…Considering the biochemical changes observed in the SG as a result of diabetes, some therapies have been investigated in an attempt to prevent or treat these alterations . One of these is photobiomodulation therapy (PBMT), which uses red or near infrared laser irradiation, proposed to have analgesic, anti‐inflammatory and/or healing effects .…”