STRENGTH OF THE HUMERUS IN STREPTOZOTOCIN-INDUCED DIABETIC RATS OF DIFFERENT AGES

Purpose: to investigate dynamic changes of humerus strength in streptozotocin-induced diabetic rats of different ages.Material and methods. 210 male rats were selected for the experiment and three age groups were formed as follows: infantile animals (aged 1 month, body weight - 45-50 g), juvenile (aged 3 months, body weight - 135-150 g), and of pre-senile age (aged 17-18 months, body weight - 290-310 g). Streptozotocin-induced diabetes was caused by a single intraperitoneal injection of strepto-zotocin in dosage 55 mg/kg (35 animals in each age group). The controls for each group were the intact animals (35 animals in each age group). Robustness testing was performed by means by means of three-point bending loading technique at a loading speed of 10µm per minute. Robustness features were calculated from resulting displacement curves. Results and discussion. Robustness of the humerus in streptozotocin-induced diabetic rats exhibited marked decrease mostly due to decrease of the values of ultimate stress, elasticity modulus, and fracture energy. This decrease grew with time in all age groups. In infantile diabetic rats the above mentioned values by the 90th day of the experiment were lower than those of the controls by 9,73%, 6,67%, and 9,28%. In juvenile diabetic rats these values decreased by 11,97%, 4,53%, and 10,59% and finally in presenile diabetic rats they decreased by 13,05%, 7,19% and 7,90%. Conclusions. Robustness of the humerus in streptozotocin-induced diabetic rats decreases due to decrease of ultimate stress, elasticity modulus, and fracture energy. In infantile rats robustness decrease was observed in the period from the 7th to the 90th day of observation yet beginning from the 60th day restoration signs appeared. In older animals, especially in presenile ones robustness decrease only grew with time.

rats, streptozotocin, diabetes, skeletal system, strength

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