Effect of long-term administration of ranitidine, a histamine H2 receptor antagonist, on bone metabolism in young growing rats.

BACKGROUND: Histamine regulates function of osteoclasts and osteoblasts, however data regarding the influence of histamine H2 receptors antagonists on bone tissue are ambiguous. Factors that influence growing skeleton may have an important impact on the peak bone mass and future risk of fractures. The aim of our study was the assessment of influence of ranitidine, on growing bones. METHODS: The experiment was carried out on young male Wistar rats divided into two groups receiving either ranitidine (10mg/kg ip) or vehicle. RESULTS: A significant decrease in femoral BMD in ranitidine-treated rats (R) compared to vehicle-treated ones (C) was detected (0.262±0.009g/cm2vs. 0.271 ±0.007g/cm2, p<0.05). In group R we observed elevated serum C-terminated telopeptide of type I collagen (CTX) level with concomitantly lowered serum osteocalcin (OC) concentration comparing to control group (151.2±27.2pg/ml vs. 101.5±55.6, p<0.05 and 229.1±50.0pg/ml vs. 292.0±52.9, p<0.05, respectively). Serum concentration of inorganic phosphorus was lower in group R than in group C (134±13mmol/L vs. 157±28mmol/L, p<0.05). CONCLUSIONS: Long-term administration of ranitidine increases bone resorption and decreases bone formation in growing rats leading to decrease in BMD.

Oral administration of kaempferol inhibits bone loss in rat model of ovariectomy-induced osteopenia.

BACKGROUND: Postmenopausal osteoporosis and osteoporotic fractures constitute an increasing problem in developing countries. Kaempferol, isolated from seeds of Cuscuta chinensis, is an active flavonoid inhibiting in vitro osteoclast activity. The aim of the presented research was an assessment of kaempferol effect on estrogen-deficiency-induced bone structure disturbances in rats. METHODS: The study was performed on 24 Wistar female rats divided into 3 groups: SHAM - rats undergoing a "sham" surgery, OVX-C - control group of animals that underwent ovariectomy, OVX-K - rats undergoing ovariectomy and receiving kaempferol for 8 weeks (from day 56 to day 112). RESULTS: In the OVX-K group, contrary to the OVX-C one, there was no significant decrease in femoral bone mineral density (BMD). A significant increase in Young's modulus was observed in the OVX-K group compared to the OVX-C (15.33±2.51GPa vs. 11.14±1.93GPa, p<0.05). A decreased bone turnover was detected in the OVX-K group. Tissue volume ratio (BV/TV) and trabecular bone perimeter were increased in the OVX-K group compared to the OVX-C one (0.241±0.037 vs. 0.170±0.022, p<0.05 and 15.52±2.78mm vs. 9.67±3.07mm, p<0.05, respectively). CONCLUSION: Kaempferol has a beneficial influence on estrogen-deficiency-induced disturbances of bone structure in rats.