title: Decreased Bone Volume and Bone Mineral Density in the Tibial Trabecular Bone Is Associated with Per2 Gene by 405 nm Laser Stimulation.
abstract: Low-level laser therapy/treatment (LLLT) using a minimally invasive laser needle system (MILNS) might enhance bone formation and suppress bone resorption. In this study, the use of 405 nm LLLT led to decreases in bone volume and bone mineral density (BMD) of tibial trabecular bone in wild-type (WT) and Per2 knockout (KO) mice. Bone volume and bone mineral density of tibial trabecular bone was decreased by 405 nm LLLT in Per2 KO compared to WT mice at two and four weeks. To determine the reduction in tibial bone, mRNA expressions of alkaline phosphatase (ALP) and Per2 were investigated at four weeks after 405 nm laser stimulation using MILNS. ALP gene expression was significantly reduced in the LLLT-stimulated right tibial bone of WT and Per2 KO mice compared to the non-irradiated left tibia (p < 0.001). Per2 mRNA expression in WT mice was significantly reduced in the LLLT-stimulated right tibial bone compared to the non-irradiated left tibia (p < 0.001). To identify the decrease in tibial bone mediated by the Per2 gene, levels of runt-related transcription factor 2 (Runx2) and ALP mRNAs were determined in non-irradiated WT and Per2 KO mice. These results demonstrated significant downregulation of Runx2 and ALP mRNA levels in Per2 KO mice (p < 0.001). Therefore, the reduction in tibial trabecular bone resulting from 405 nm LLLT using MILNS might be associated with Per2 gene expression.
authors.affiliation: Department of Biomedical Engineering, Yonsei-Fraunhofer Medical Device Laboratory, Yonsei University, Wonju, Gangwon-do 26493, Korea. yyeongm@hanmail.net.
authors.forename: Yeong-Min
authors.initials: YM
authors.lastname: Yoo
authors.affiliation: Division of Biological Science and Technology, Yonsei University, Wonju, Gangwon-do 26493, Korea. blue-me914@hanmail.net.
authors.forename: Myung-Han
authors.initials: MH
authors.lastname: Lee
authors.affiliation: Department of Biomedical Engineering, Yonsei-Fraunhofer Medical Device Laboratory, Yonsei University, Wonju, Gangwon-do 26493, Korea. hyungpump@hanmail.net.
authors.forename: Ji Hyung
authors.initials: JH
authors.lastname: Park
authors.affiliation: Department of Biomedical Engineering, Yonsei-Fraunhofer Medical Device Laboratory, Yonsei University, Wonju, Gangwon-do 26493, Korea. seodongh@gmail.com.
authors.forename: Dong-Hyun
authors.initials: DH
authors.lastname: Seo
authors.affiliation: Department of Biomedical Engineering, Yonsei-Fraunhofer Medical Device Laboratory, Yonsei University, Wonju, Gangwon-do 26493, Korea. sangyeob.lee.90@yonsei.ac.kr.
authors.forename: Sangyeob
authors.initials: S
authors.lastname: Lee
authors.affiliation: Department of Biomedical Engineering, Yonsei-Fraunhofer Medical Device Laboratory, Yonsei University, Wonju, Gangwon-do 26493, Korea. bjung@yonsei.ac.kr.
authors.forename: Byungjo
authors.initials: B
authors.lastname: Jung
authors.affiliation: Department of Biomedical Engineering, Yonsei-Fraunhofer Medical Device Laboratory, Yonsei University, Wonju, Gangwon-do 26493, Korea. hanskim@yonsei.ac.kr.
authors.forename: Han Sung
authors.initials: HS
authors.lastname: Kim
authors.affiliation: Division of Biological Science and Technology, Yonsei University, Wonju, Gangwon-do 26493, Korea. kbae@yonsei.ac.kr.
authors.forename: Kiho
authors.initials: K
authors.lastname: Bae
mesh_terms: D000818:Animals; D015519:Bone Density; D001842:Bone and Bones / Q000378:metabolism* / Q000473:pathology* / Q000528:radiation effects; D005786:Gene Expression Regulation / Q000528:radiation effects; D028022:Low-Level Light Therapy; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D023421:Models, Animal; D056950:Period Circadian Proteins / Q000235:genetics* / Q000378:metabolism; D013977:Tibia / Q000378:metabolism* / Q000473:pathology* / Q000528:radiation effects; D055114:X-Ray Microtomography
chemical_list: C513312:Per2 protein, mouse; D056950:Period Circadian Proteins
keywords: ALP; Per2; Runx; low-level laser therapy; minimally invasive laser needle system; tibia; trabecular bone