OBJECTIVETo investigate the influence of parathyroid hormone and estrogen on alveolar bone metabolism of castrated female rats.

METHODSSixty-six female Wistar rats which were healthy and 4 months old were divided into two groups, with group SHAM (n = 18) and group ovariectomy (OVX) (n = 48). After 8 weeks of ovariectomy, the osteoporosis model was confirmed by examing 8 ovariectomized and sham-operated rats. The rest 10 rats in group SHAM were the control group (group A). The rest 40 rats in group OVX were divided into ovariectomized group (group B), ovariectomized and treated with estrogen (group C), ovariectomized and treated with parathyroid hormone (group D), ovariectomized and treated with estrogen and parathyroid hormone (group E) at random with 10 in each group. Group A and B injected physiological saline (1 mL x kg(-1)), group C injected estradiol benzoate (10 microg x kg(-1)), group D injected parathyroid hormone (20 microg x kg(-1)), group E injected parathyroid hormone (20 microg x kg(-1)) and estradiol benzoate (10 microg x kg(-1)). The intraperitoneal injection were maken every other day to rats in each group, which continued for 8 weeks. The bone mineral density (BMD), bone histomorphology and serum Ca, P, alkaline phosphatase (ALP) were measured after therapy.

RESULTSAfter 8 weeks of ovariectomy, the lumbar BMD of ovariectomized rats were significantly declined compared with those of the sham-operated rats (P < 0.05). Eight weeks later after the drug use, the BMD, %Tb.Ar, Tb.Th, Tb.N in group C, D, E were slightly elevated compared to group B, especially the group E (P < 0.05). Serum calcium and phosphorus values did not change significantly (P > 0.05). ALP values in group B was significantly higher than that in group A (P < 0.05).

CONCLUSIONIntermittent application of parathyroid hormone in small doses can increase alveolar BMD of castration rats and improve their bone structure. And it can have synergy effects on the treatment of osteoporosis if it is used combining with estrogen.