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

• Published in: Journal of biophotonics 2018-04, Vol.11 (4), p.e201700179-n/a
• Main Authors: de Castro, Juliana R., de Souza, Eugen M. N., Park, Yun‐Jong, de Campos, Luana, Cha, Seunghee, Arana‐Chavez, Victor E., Nicolau, José, Simões, Alyne
• Format: Article
• Language: English
• Subjects: Accumulation; Animals; Calcium; Calcium (intracellular); Calcium-binding protein; Calmodulin; Cytoplasm; Diabetes; Diabetes mellitus; Exocrine glands; Glands; Intracellular; Irradiation; Lasers; lipid droplets; Lipids; low‐power laser; Micrography; Parotid gland; Photomicrographs; Rats; Rodents; Salivary gland; salivary glands; Transmission electron microscopy; Western blotting
• ISSN: 1864-063X; 1864-0648
• DOI: 10.1002/jbio.201700179

Lipid droplet accumulation has been related to salivary gland hypofunction in diabetes. In this study, the effect of laser irradiation on the parotid glands (PGs) of diabetic rats was analyzed with regard to its effect on lipid droplet accumulation, intracellular calcium concentration and calmodulin expression. The animals were distributed into 6 groups: D0, D5, D20 and C0, C5, C20, for diabetic (D) and control animals (C), respectively. Twenty‐nine days following diabetes induction, PGs of groups D5 and C5; D20 and C20 were irradiated with 5 and 20 J/cm2 of a red diode laser at 100 mW, respectively. After 24 hours, PGs were removed for histological, biochemical, and western blotting analysis. The diabetic animals showed lipid droplet accumulation, which was decreased after irradiation. Ultrastructurally, the droplets were nonmembrane bound and appeared irregularly located in the cytoplasm. Moreover, diabetic animals showed an increased intracellular calcium concentration. In contrast, after laser irradiation a progressive decrease in the concentration of this ion was observed, which would be in agreement with the results found in the increased expression of calmodulin in D20. These data are promising for using laser to decrease lipid droplet accumulation in PGs, however, more studies are necessary to better understand its mechanisms. Micrographs showing decreased lipid accumulation after laser irradiation in light micrographs (LM), and morphology of lipid droplet in transmission electron microscopic (TEM). LM: (A) PGs from nondiabetic rats that did not receive Laser irradiation (LI), (B) PGs from nondiabetic rats that received a dose of 20 J/cm2, (C) lipid accumulation (arrows) in the secretory cells from diabetic rats that did not receive irradiation, (D) reduction of lipid accumulation in the secretory cells from diabetic rats that received a dose of 20 J/cm2 and TEM: (E) scale bar = 5 μm, (F) scale bar = 1 μm, and (G) scale bar = 0.5 μm. Lipid droplet accumulation observed in secretory cells of salivary glands has been related to salivary gland hypofunction and, consequently, to a reduction in patient's quality of life. In this study, it was observed a reduction in lipid droplet accumulation of parotid glands of streptozotocin‐induced diabetic animals, after irradiation with a low‐power laser. In addition, it was observed a decrease in intracellular calcium concentration and an increased expression of calmodulin.