Bone Loss in Experimental Diabetes

Summary

Osteopenia occurs in diabetes mellitus. Since bone status is altered in Inflammation Mediated Osteopenia (IMO), it was appropriate to study its course in diabetic animals in order to investigate the mechanism of diabetic osteopenia. To this end, we compared the bone loss in streptozotocin (STZ) diabetes with that of IMO. Female rats were studied in total of 8 groups: Control, IMO, Diabetes, IMO with Diabetes (IMO-DIA) on the 3rd and similar groups on the 6th week after induction of IMO with 8 s.c. injections of talcum suspension. Femoral mineral content as reflected by ash weight per femoral volume after 3 weeks was lower in IMO compared to control rats (p<0.05) while after 6 weeks this difference was not significant. The femur ash weight per volume of diabetic rats was lower than the one of intact rats with and without IMO both after 3 and 6 weeks. Diabetic rats with and without IMO exhibited no difference in this respect. Spleen weight as a measure of the extent of inflammation per body weight was increased only in the IMO group. The diabetic rats with and without IMO did not differ significantly with regard to spleen weight. Similar changes were observed 6 weeks after the induction of IMO. However the difference between IMO and diabetes rats was of borderline significance and no difference existed between the IMO and IMO-diabetic group. The serum calcium levels of intact, IMO and diabetic rats showed no change during both experimental periods. Those of diabetic rats with IMO were higher than those of the diabetic and IMO animals after 6 weeks. In conclusion, IMO as well as STZ diabetes lead to bone loss in the rat. The combination of both conditions aggravated the osteopenia induced by inflammation although the spleen weight did not reach the increase observed after IMO. Since in contrast to control and IMO rats, no gain of mineral content occurred in diabetic rats with and without IMO between the 3rd and 6th week after induction of IMO the role of diabetes was decisive. Our findings indicate that possibly diabetic osteopenia is not inflammation mediated.

Key words

Experimental Diabetes - Osteopenia