SODIUM-FLUORIDE DOES NOT BUILD BONE IN AGED OVARIECTOMIZED RATS

Sodium fluoride builds bone in young intact rats and young ovariectomized (OVX) rats. Here we show that NaF does not build bone in aged OVX rats. Wistar rats were OVX at nine months old and fed with regular rodent chow and de-ionized water ad libitum. After three months of conditioning, they were divided into four groups (five rats per group) and treated for four months as follows: (1) no treatment (control); (2) NaF solution (4 mmol/l) instead of water (NaF); (3) subcutaneous injections of pamidronate (0.25 mg/kg/d; 5 d/w) (APD); and (4) both NaF solution and pamidronate injections (APD+NaF). After four months, the OVX control had significantly less cancellous bone than a sham-operated control, but the NaF treated group has significantly less cancellous bone than the OVX control. Both APD and APD +NaF groups were not significantly different from the OVX control or the sham control. Biochemical analysis of rat urine showed that NaF treated group had significantly higher pyridinoline/ creatinine values than all other groups, indicating that the lack of bone gain was due to excessive resorption. We have shown that NaF does not have an anabolic effect on bone in aged OVX rats. On the contrary, it shows a catabolic effect due to excessive resorption which is inhibited by APD. This adverse finding of NaF on aged rats (12 month old rats ovariectomized for 3 months) does not agree with previous observations made in young rats.