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Master's Dissertation
DOI
10.11606/D.17.2017.tde-07062017-165223
Document
Author
Full name
Jéssica Suzuki Yamanaka
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
Ribeirão Preto, 2016
Supervisor
Committee
Shimano, Antonio Carlos (President)
Azevedo, Aline de
Carvalho, Leonardo César
Paula, Francisco Jose Albuquerque de
Title in Portuguese
Efeitos da dieta hiperlipídica na estrutura e consolidação de tíbias de ratas em crescimento
Keywords in Portuguese
Consolidação da fratura
Dieta hiperlipídica
Osso
Osteotomia
Abstract in Portuguese
O acúmulo de gordura corporal é considerado um problema de saúde pública com diversas consequências negativas, inclusive relacionado à redução da qualidade do osso, que afeta cada vez mais indivíduos jovens. São crescentes as investigações que buscam esclarecer a relação entre massa gorda e massa óssea. Portanto, o objetivo deste estudo foi investigar o efeito do consumo excessivo de lipídios na estrutura e no processo de consolidação óssea em tíbias de ratas em crescimento. Foram utilizadas cinquenta e duas ratas Wistar com 21 dias de vida, distribuídas em quatro grupos (n=13), sendo: animais submetidos à dieta padrão (DP), animais submetidos à dieta hiperlipídica (DH), animais submetidos à dieta padrão e osteotomia (DPO) e animais submetidos à dieta hiperlipídica e osteotomia (DHO). Cada um deles com período experimental de 5 semanas. Os animais dos grupos DP e DH foram mantidos sem intervenção, enquanto os animais dos grupos DPO e DHO foram submetidos à osteotomia da tíbia esquerda na terceira semana experimental. Durante o experimento a massa corporal e o consumo de ração dos animais foram avaliados. Um dia precedente à eutanásia foi realizado o teste de tolerância à insulina em 5 animais de cada grupo. Após a eutanásia a tíbia esquerda de cada rata foi dissecada, limpa das partes moles e submetidas a análises macroscópica, densitometria, ensaio mecânico, histomorfometria, estereologia do osso neoformado e imunohistoquímica. Os dados foram analisados por teste estatístico em modelo linear geral com ajuste para múltiplas comparações de Bonferroni para comparação entre as variáveis, e teste T-Student e Mann-Whitney para comparação entre dois grupos. Ao final do experimento os animais alimentados com dieta hiperlipídica apresentaram massa corporal similar aos animais alimentados com dieta padrão (p=0,115), no entanto tiveram consumo reduzido de ração (p<0,001) e menor sensibilidade à insulina (p=0,018). A variável cirurgia afetou o consumo de ração sendo que animais operados consumiram menos ração do que animais não operados (p=0,017). Os animais alimentados com dieta hiperlipídica tiveram tíbias mais compridas (p=0,041), menor força máxima (p<0,001) e rigidez relativa (p=0,003) quando comparados aos animais alimentados com dieta padrão, embora a densidade mineral óssea (DMO) tenha sido similar (p=0,958). Os animais operados tiveram menor força máxima (p<0,001), rigidez (p=0,020) e menor quantidade de colágeno proximal (p=0,029) quando comparados aos não operados. O volume de osso neoformado das tíbias submetidas à osteotomia tendeu a ser menor no grupo DHO ao grupo DPO (p=0,054). A avaliação imunohistoquímica não revelou diferença entre os grupos DHO e DPO (p<0,05). Concluímos que a dieta hiperlipídica prejudicou a resistência mecânica das tíbias e causou uma redução do volume de osso neoformado, prejudicando dessa forma a estrutura e consolidação óssea das tíbias de ratas em crescimento
Title in English
Effects of high-fat diet on structure and bone healing in tibias of growing rats
Keywords in English
Bone
Diet
Fracture healing
High-fat
Osteotomy
Abstract in English
The body fat accumulation have been considered a public health issue with several negative consequences, including reduction of bone quality, that affects young people increasingly. The studies that seek to clarify the relationship between fat mass and bone mass have been increasing. Therefore the aim of this study was to investigate the effect of high consumption of lipids on bone structure and bone healing in growing rats. Fifty-two female Wistar rats 21 days old were used, divided into four groups (n=13), as follows: animals treated with standard diet (SD), animals treated with high-fat diet (HFD), animals treated with standard diet and osteotomy (SDO) and animals treated with high-fat diet and osteotomy (HFDO). Experimental period was of 5 weeks for every groups. The SD and HFD animals were maintained without intervention, while SDO and HFDO groups were submitted to osteotomy in left tibia at third experimental week. Animal body mass and feed intake were assessed during experimental period. One day before euthanasia insulin tolerance test was performed in 5 animal of each group. After euthanasia, the left tibia of each rat was dissected and cleaned of soft tissues and submitted to macroscopy analysis, densitometry, mechanical analysis, histomorphometry, stereology of newly formed bone and immunohistochemistry. Data were analyzed by general linear model with adjustment to multiple comparisons of Bonferroni for comparisons between variables and TStudent e Mann-Whitney test for comparisons between two groups. At end of the experiment the high-fat diet fed animals had body mass similar to standard diet fed animals (p=0.115), however they had lower feed intake (p<0.001) and lower insulin sensibility (p=0.018). Surgery affected feed intake, operated animals had lower feed intake than non-operated animals (p=0.017). High-fat diet fed animals had longer tibias (p=0,041), lower maximal load (p<0.001) and lower stiffness (p=0,003) than standard diet fed animals, although bone mineral density (BMD) had been similar (p=0,958). Operated animals had lower maximal load (p<0.001), stiffness (p=0.020) and lower collagen quantity (p=0.029) than non-operated animals. Newly formed bone of tibias submitted to osteotomy trended to be lower in HFDO group than SDO group (p=0.054). Immunohistochemistry presented no difference between HFDO e SDO group (p<0.05). We concluded high-fat diet affected bone in order to harm tibia strength and caused a decrease in the newly formed bone volume, impairing structure and bone healing
 
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Publishing Date
2017-08-11
 
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