Efeito da insulinoterapia na estrutura macroscópica, nas propriedades mecânicas e na microestrutura de tíbias em ratos diabéticos

Abstract

The aim of the present study was to evaluate macroscopic structure, mechanical properties and microarchitecture of tibiae in rats with type 1 diabetes mellitus (T1DM). Nine animals were divided into three groups (n=3): Healthy (H), Diabetic (D) and Insulinized (I). T1DM was induced in D and I groups through administration of intravenous streptozotocin (STZ) (60mg/kg) and in group I, insulin was administered daily (4UI). The animals were euthanized 35 days after T1DM induction. Then, the tibiae were removed and different analyses were performed: Macroscopic, micro–computed tomography (µCT) and three-point bend test. In Macroscopic analysis, it was measured the length (proximal-distal) and thickness (antero-posterior and lateral-medial), in the middle of the diaphysis and near the distal and proximal epiphysis. The parameters evaluated in µCT were: closed porosity, tissue mineral density and cortical thickness. The three-point bend test analyses: maximum strength, energy and stiffness. The macroscopic analysis showed that group D presented smaller measures of length (PD) and thicknesses (AP e AP-P) compared to S and I. Besides, larger measurements were also observed in ML and AP-D thicknesses in group I compared to group D. In the analysis of μCT, group I presented greater cortical thickness in relation to group D. In the mechanical analyses, the strength was lower in group D compared to the other groups. According to the results, it is possible to conclude that T1DM reduces bone growth and mechanical resistance, and insulin therapy in diabetic rats improves longitudinal and thick bone growth making it similar to normoglycemic animals.