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

Juliana R de Castro; Eugen M N de Souza; Yun-Jong Park; Luana de Campos; Seunghee Cha; Victor E Arana-Chavez; José Nicolau; Alyne Simões

doi:10.1002/jbio.201700179

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

J Biophotonics. 2018 Apr;11(4):e201700179. doi: 10.1002/jbio.201700179. Epub 2018 Jan 18.

Authors

Juliana R de Castro¹, Eugen M N de Souza¹, Yun-Jong Park², Luana de Campos^{1

3}, Seunghee Cha², Victor E Arana-Chavez¹, José Nicolau¹, Alyne Simões¹

Affiliations

¹ Laboratory of Oral Biology, Department of Biomaterials and Oral Biology, School of Dentistry, University of São Paulo, São Paulo, Brazil.
² Oral Maxillofacial Diagnostic Sciences, College of Dentistry, University of Florida, Gainesville, Florida.
³ Department of Oral Medicine, Brazilian Institute for Cancer Control, São Paulo, Brazil.

PMID: 29112328
DOI: 10.1002/jbio.201700179

Abstract

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.

Keywords: diabetes; lipid droplets; low-power laser; salivary glands.

Publication types

Research Support, N.I.H., Extramural
Research Support, Non-U.S. Gov't

MeSH terms

Animals
Calcium / metabolism
Diabetes Mellitus, Experimental / pathology*
Diabetes Mellitus, Experimental / therapy*
Female
Intracellular Space / metabolism
Intracellular Space / radiation effects
Lipid Droplets / metabolism*
Lipid Droplets / radiation effects*
Low-Level Light Therapy*
Parotid Gland / pathology*
Parotid Gland / radiation effects*
Rats
Rats, Wistar

Substances

Calcium