RESUMO
OBJECTIVE: To analyze the biomechanical and tomographic effects of hormone replacement therapy (HRT) on femurs from rats subjected to induced menopause. METHODS: Forty-five adult Wistar rats were divided equally into three groups. The first and second groups consisted of rats subjected to oophorectomy, and the third was the control group, consisting of nonoophorectomized rates. After verifying that hormone failure had occurred (exfoliative cytological test), only the first group received HRT, over a two-month period. After this period, the femurs were disarticulated and subjected to biomechanical tests in a universal testing machine to evaluate their strength, and were subjected to tomographic evaluation to determine the bone mineral density. RESULTS: The exfoliative cytological test showed that hormone failure was induced in all the oophorectomized animals. A significant difference (p = 0.030) in maximum strength measurements was observed between the groups (higher in the group with HRT). Greater bone fragility was observed in the oophorectomized animals without HRT than in those with HRT (p = 0.010), in relation to the control group (p = 0.0107). There was greater bone strength in the oophorectomized rats with HRT than in those without HRT, and these values were similar to those of the control group (p = 0.179). In the tomographic evaluation, no significant differences were found between the groups (p = 0.625). CONCLUSION: A significant increase in bone strength was observed with the use of HRT. However, treatment with HRT did not show any significant change in bone mineral density.
RESUMO
OBJETIVO: Analisar os efeitos da TRH na avaliação biomecânica e tomográfica dos fêmures de ratas submetidas à menopausa induzida. MÉTODOS: Foram divididas igualmente em três grupos 45 ratas Wistar adultas. O primeiro e o segundo constituíram-se de ratas ooforectomizadas e o terceiro, o grupo controle, de ratas não ooforectomizadas. Após a constatação da falência hormonal (citologia esfoliativa). somente o primeiro grupo recebeu TRH, durante dois meses. Após esse período, os fêmures foram desarticulados e submetidos a testes biomecânicos através de máquina universal de ensaios para avaliação da resistência e submetidos a tomografia para determinação da densidade óssea. RESULTADOS: A citologia esfoliativa demonstrou indução de falência hormonal em todos os animais ooforectomizados. Notou-se diferença significante (p = 0,030) entre os grupos ao se mensurar a força máxima de resistência, maior no grupo que recebeu TRH. Observou-se maior fragilidade óssea nos animais ooforectomizados sem TRH quando comparados com os com TRH (p = 0,010) em relação ao grupo controle (p = 0,0107). Houve aumento da resistência óssea nas ratas ooforectomizadas com TRH em relação às sem TRH e valores semelhantes aos do grupo controle (p = 0,179). Na avaliação tomográfica, não se encontraram diferenças significantes entre os grupos (p = 0,625). CONCLUSÃO: Observou-se aumento significativo da resistência óssea com a utilização de TRH. No entanto, o tratamento com TRH não apresentou alteração significante da densidade mineral óssea.
OBJECTIVE: To analyze the effects of Hormone Replacement Therapy on the biomechanical and tomographic evaluation of femurs of rats submitted to induced menopause. METHODS: Forty-five adult Wistar rats were divided equally into three groups. The first and second groups consisted of rats submitted to oophorectomy, and the third was the control group, consisting of non-oophorectomized rates. After observing hormonal failure (exfoliative cytology), only the first group received HRT, over a two-month period. After this period, the femurs were disarticulated and submitted to biomechanical tests in a universal testing machine to evaluate stamina, and submitted to tomographic evaluation to determine mineral bone density. RESULTS: The exfoliative cytology showed induction of hormonal failure in all the animals oophorectomized. A significant difference (p=0.030) was observed between the groups in the measurements of maximum stamina, which was higher in the group with HRT. Greater bone fragility was observed in the oophorectomized animals that did not receive HRT, compared with those that received HRT (p=0.010) in relation to the control group (p=0.0107). There was in increase in bone strength in the oophorectomized rats with HRT compared with those without HRT, and similar values to the control group (p = 1.179). In the tomographical evaluation, no significant differences were found between the groups (p=0.625). CONCLUSION: A significant increase in bone strength was observed with the use of HRT. However, treatment with HRT did not show any significant alteration in bone mineral density.