title: Imaging of zebrafish in vivo with second-harmonic generation reveals shortened sarcomeres associated with myopathy induced by statin.
abstract: We employed second-harmonic generation (SHG) imaging and the zebrafish model to investigate the myopathy caused by statin in vivo with emphasis on the altered microstructures of the muscle sarcomere, the fundamental contractile element of muscles. This approach derives an advantage of SHG imaging to observe the striated skeletal muscle of living zebrafish based on signals produced mainly from the thick myosin filament of sarcomeres without employing exogenous labels, and eliminates concern about the distortion of muscle structures caused by sample preparation in conventional histological examination. The treatment with statin caused a significantly shortened sarcomere relative to an untreated control (1.73±0.09 µm vs 1.91±0.08 µm, P<0.05) while the morphological integrity of the muscle fibers remained largely intact. Mechanistic tests indicated that this microstructural disorder was associated with the biosynthetic pathway of cholesterol, or, specifically, with the impaired production of mevalonate by statins. This microstructural disorder exhibited a strong dependence on both the dosage and the duration of treatment, indicating a possibility to assess the severity of muscle injury according to the altered length of the sarcomeres. In contrast to a conventional assessment of muscle injury using clinical biomarkers in blood, such as creatine kinase that is released from only disrupted myocytes, the ability to determine microstructural modification of sarcomeres allows diagnosis of muscle injury before an onset of conventional clinical symptoms. In light of the increasing prevalence of the incidence of muscle injuries caused by new therapies, our work consolidates the combined use of the zebrafish and SHG imaging as an effective and sensitive means to evaluate the safety profile of new therapeutic targets in vivo.
authors.affiliation: Department of Applied Chemistry, Institute of Molecular Science, National Chiao Tung University, Hsinchu, Taiwan.
authors.forename: Shih-Hao
authors.initials: SH
authors.lastname: Huang
authors.forename: Chung-Der
authors.initials: CD
authors.lastname: Hsiao
authors.forename: Dar-Shong
authors.initials: DS
authors.lastname: Lin
authors.forename: Cho-Yen
authors.initials: CY
authors.lastname: Chow
authors.forename: Chia-Jen
authors.initials: CJ
authors.lastname: Chang
authors.forename: Ian
authors.initials: I
authors.lastname: Liau
mesh_terms: D000818:Animals; D002784:Cholesterol / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005260:Female; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000633:toxicity*; D007091:Image Processing, Computer-Assisted / Q000379:methods; D007814:Larva / Q000187:drug effects / Q000254:growth & development / Q000502:physiology; D008297:Male; D008798:Mevalonic Acid / Q000378:metabolism; D020894:Microfibrils / Q000187:drug effects / Q000502:physiology; D036641:Microscopy, Fluorescence, Multiphoton / Q000379:methods*; D009119:Muscle Contraction / Q000187:drug effects; D018482:Muscle, Skeletal / Q000187:drug effects / Q000378:metabolism / Q000503:physiopathology; D009135:Muscular Diseases / Q000139:chemically induced / Q000378:metabolism / Q000503:physiopathology*; D012518:Sarcomeres / Q000502:physiology*; D013997:Time Factors; D015027:Zebrafish / Q000254:growth & development / Q000502:physiology*
chemical_list: D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D002784:Cholesterol; D008798:Mevalonic Acid