Efeitos da suplementação de zinco e do treinamento físico sobre o metabolismo e a densidade óssea de ratas ovariectomizadas

Abstract

Osteoporosis is a serious public health problem, and increasingly is recognized as a disease limiting quality of life, especially for the elderly. The role of zinc in human nutrition has been extensively studied. Several hormones and zinc-dependent enzymes are involved in bone metabolism. Physical activity has been advocated as a means to increase and maintain bone mineral density (BMD). Thus, this study aims to determine the effects of zinc supplementation and/or physical training with limited impact on the aquatic environment in bone metabolism and bone mineral density (BMD) in ovariectomized rats. Sixty (60) Wistar female rats were divided into 5 groups: Sham (S), ovariectomized control (Cox), zinc (Z), physical training (PT) and zinc + physical training (ZTF). The groups Z and ZTF received daily zinc supplementation (25 mg/kg of body weight) in the form of ZnSO4.7H2O by gavage for 9 weeks. Groups TF and ZTF performed a progressive loading exercise program of jumps in water three times a week for 10 weeks. The parameters were analyzed using Student t test and one-way ANOVA with post hoc Newman-Keuls. When necessary, ANOVA one way was replaced by its equivalent non-parametric Kruskal-Walli. A significance level of 5% was adopted for all tests. Serum alkaline phosphatase was higher in Cox (p <0.01) when compared to the groups C (p <0.01) and ZTF (p <0.05). The BMD analysis showed that it was greater for TF (p <0.05) and ZTF (p <0.05) when compared to Cox and Z groups for the femoral head and femoral neck surgery. Therefore, zinc supplementation was not effective in increasing bone turnover and BMD, but the physical training protocol was able to enhance the osteogenic response in osteopenic rats in a region dependent way, and may constitute a more effective therapeutic modality for use in the treatment and prevention of bone loss.