Figure 3

Vitamin D, calcium and phosphorus status and muscle VDR expression in old rats. At the beginning (A) and the end (B) of the experimental period, blood from control and depleted rats was collected and plasma was separated. Then, plasma 25(OH) D was measured using an ELISA kit according to the manufacturer’s instructions (n = 7 for control group and n = 9 for depleted group). 25(OH) D concentrations were similar at the beginning of the protocol and showed a severe drop in vitamin D status in depleted rats compared to controls after the depletion period. Data presented are means ± SEM; *p < 0.05 and **p < 0.01. (C) VDR protein expression was analyzed in muscle by western blotting and quantified using Multi Gauge V3.2 software. Expression of the total amount of p38 was used to normalize protein loading between samples (n = 7 for control group and n = 9 for depleted group). VDR protein expression was down-regulated in the skeletal muscle of the depleted group. A.U. = arbitrary units. Data presented are means ± SEM; *p < 0.05. At the end of the experiment, blood from control and depleted rats was collected and serum was separated. Then, serum calcium (D) and phosphorus (E) were measured using an automat Konelab 20 (n = 7 for control group and n = 9 for depleted group). Calcium and phosphorus concentrations were similar between control and depleted groups. Data presented are means ± SEM; *p < 0.05.