Soy isoflavone daidzein increases the expression of NaPi2a cotransporter in a rat model of the andropause

Abstract

Sodium phosphate cotransporter type 2a (NaPi 2a) is specifically expressed in the brush border membrane of renal proximal tubules and mediates the phosphate reabsorption from the primary urine. One of the main soy isoflavones, daidzein, has been widely studied for its therapeutic potential and already recognized as the bone protective substance. Aim of this study was to investigate the effects of daidzein application on NaPi 2a expression, phosphate and parathormone concentration in a rat model of the andropause. Middle-aged Wistar rats were divided in three groups: sham operated (SO), orchidectomized (Orx) and daidzein treated orchidectomized group (Orx+D). Daidzein (30 mg/kg b.w.) was subcutaneously applicated, while the control groups received the vehicle alone. Expression of NaPi 2a was determined by RT-PCR and Western blot, while the , serum and urine parameters were analysed biochemically. The abundance of NaPi 2a cotransporter expression was decreased in Orx animals in comparison with the SO group, while daidzein treatment enhanced the cotransporter expression when compared to the Orx rats. Serum phosphate concentration was decreased in Orx rats by 13% (p<0.05) in comparison with the SO group. Daidzein treatment elevated the serum phosphate by 10% (p<0.05) when compared to the Orx animals. Serum PTH concentration w1111 increased after Orx in comparison with SO by 24% (p<0.05), while daidzein application decreased the same parameter by 18% (p<0.05) when compared to the Orx animals. Our results demonstrated that daidzein treatment increases NaPi 2a cotransporter expression in the kidney of andropausal rats, which suggests some benefit of daidzein application when it comes to the regulation of mineral metabolism in advanced age.