Study of bone characteristics and muscle quality in metabolic disorders

Bozkurt, Özlem
Although the effects of diabetes on bone mineral content has been studied, little is known about the structural alterations in collagen, maturation of apatite crystals and carbonate content in diabetic bone. The first part of this study aimed to investigate the mineral and organic properties of cortical, trabecular and growth plate regions of rat femur tissues in type I diabetes using FTIR microspectroscopy and Vickers microhardness test. A decrease in mineral content (degree of mineralization), decrease in microhardness, increase in carbonate content, increase in size and maturation of hydroxyapetite crystals, which are the implications of increased osteoporosis, were observed in diabetic bone. In addition, a decreased carbonate substitution into bone apatite and an increase in labile type carbonate was observed in diabetic bone. There was a decrease in the level of crosslinking of collagen in cortical and trabecular regions of diabetic femurs, implying a decrease in bone collagen quality that may contribute to bone fragility. Recent evidence implies that intramyocellular lipid accumulation is directly correlated with insulin resistance, a key parameter in the generation of obesity. The second part of this study is mainly focused on the determination of the structural and compositional characterization of macromolecules of longissimus dorsi and quadriceps muscles of Berlin fat mouse inbred (BFMI) lines using ATR-FTIR spectroscopy and FTIR microspectroscopic imaging, together with the quantification of fiber specific distribution of lipids in these muscles by the use of confocal microscopy. The study groups included 10 weeks old standard breeding diet fed (juvenile) and 20 weeks old high fat diet fed control and BFMI lines. The results revealed the loss of unsaturation in lipids, increased triglyceride content, increased amount of lipids having shorter chain length, increased lipid peroxidation and fiber specific accumulation of lipids in type IIa and intermediate fibers in skeletal muscles of both 10 weeks old and 20 weeks old BFMI lines, emphasizing their obese phenotype. However, the alterations were more prominent in skeletal muscles of 20 weeks old high fat diet fed BFMI lines, displaying a more severe obesity phenotype. The results of the characterization revealed that BFMI860 and BFMI861 lines are convenient models for the study of spontaneous obesity and studies to enlighten the genetic basis of obesity.
Citation Formats
Ö. Bozkurt, “Study of bone characteristics and muscle quality in metabolic disorders,” Ph.D. - Doctoral Program, Middle East Technical University, 2012.