Absence of positive effect of black cohosh (Cimicifuga racemosa) on fracture healing in osteopenic rodent model.

The healing of predominantly metaphyseal fractures in postmenopausal osteoporosis is delayed and comparatively poor. Due to the potential side effects of HRT, natural alternatives are appealing. The aim of this study was to determine whether Cimicifuga racemosa extract BNO 1055 improves metaphyseal fracture healing in severe osteopenic bone in rats. Thirty-three 12-week-old female rats developed severe osteopenia during 10 weeks after ovariectomy. After metaphyseal tibial-osteotomy and standardized T-plate-osteosynthesis, the healing periods in ovariectomized rats (C), 17-α-estradiol (E) and Cimicifuga racemosa (CR) supplemented diets were assessed for 35 days. Changes in callus morphology were evaluated qualitatively by biomechanical testing and quantitatively in microradiographies and fluorochrome-labeled histological sections. The CR-supplementation slightly improved callus quality and trabecular bone formation. It significantly enhanced the endosteal callus density compared to C group (Cl.Dn.e C: 59.08 ± 21.89, E: 45.95 ± 18.39, CR: 60.85 ± 18.66*), though most of the other morphological parameters examined showed no improvement. The time course of fracture healing did not change due to CR. Estrogen-supplementation enhanced the biomechanical properties of the fracture site. Trabecular bone was improved indicating the physiological endosteal healing process. The CR-supplementation did not exhibit positive effects in severe (senile) osteopenic fracture healing as seen in early (postmenopausal) osteoporosis in rats. Callus formation was slightly improved under CR. Estrogen improved fracture healing in severe osteopenic bone, while the extent of callus formation played a minor role.

Equol but not genistein improves early metaphyseal fracture healing in osteoporotic rats.

Healing of predominantly metaphyseal fractures in postmenopausal osteoporosis is delayed and comparatively poor. Hormone replacement therapy could improve fracture healing, but, because of its potential side effects, natural alternatives are more appealing. The aim of this study was to determine if the soy metabolite equol and the native isoflavone genistein, in comparison to 17beta-estradiol, improve metaphyseal fracture healing in ovariectomy-induced osteoporotic bone of the rat. Forty-eight 12-week-old female rats developed severe osteoporosis ten weeks after ovariectomy. After metaphyseal tibial osteotomy and standardized stable internal fixation, changes in callus morphology were evaluated biomechanically, qualitatively and quantitatively in fluorochrome-labeled histological sections and microradiographs in ovariectomized rats (C) and under standardized 17beta-estradiol (E), equol (EQ) and genistein (G) supplemented rats over a period of five weeks. Estrogen and equol were able to improve the elasticity of callus formation significantly in postmenopausal osteoporotic bone (stiffness of C: 121.40 +/- 47.08 N/mm, E: 147.90 +/- 39.38 N/mm, EQ: 167.8 +/- 59.90 N/mm). The effects of estrogen were more anabolic than those of equol and were visible in changes to the trabecular bone (N.Nd of E: 6.47 +/- 7.68, EQ: 4.25 +/- 3.96). However, in terms of the whole body, equol seemed to induce less of an adverse reaction than estrogen (body weight of C: 342.20 +/- 19.91 g, E: 280.25 +/- 12.05 g, EQ: 308.75 +/- 24.28 g). Genistein as an osteoclast inhibitor influenced callus stiffness (G: 144.50 +/- 61.52 N/mm) and negatively impacted trabecular structure (N.Nd of G: 0.59 +/- 1.01) in severely osteoporotic bones. Estrogen and equol were able to improve fracture healing in ovariectomy-induced osteoporotic bones, and the extent of callus formation played only a minor role. Genistein rather negatively influenced fracture healing. The metaphyseal osteotomy model in ovariectomized rats allows an accurate study of the therapeutic effects of antiosteoporotic substances on the fracture healing process.

Effect of human parathyroid hormone hPTH (1-34) applied at different regimes on fracture healing and muscle in ovariectomized and healthy rats.

Three experiments were conducted to investigate the effect of intermittent administration of parathyroid hormone (PTH) (1-34) applied at different regimes on fracture healing and muscle in healthy and ovariectomized (Ovx at 3 months of age) rats. Five-month old rats underwent bilateral transverse metaphyseal osteotomy of tibia and were divided into groups (12 rats each). In Exp 1, Ovx rats were either treated with PTH (7x/w, 1-35d), with oral estradiol-17beta-benzoate (0.4 mg/kg BW, 1-35d) or untreated. In Exp. 2, there were 3 groups: healthy untreated or treated with PTH (5x/w, 1-35d or 7-35d). In Exp. 3, there were 7 groups: healthy, Ovx, "healthy PTH 5x/w 7-35d", "Ovx PTH 5x/w 7-35d, 14-35d or 14-28d", "Ovx PTH every other day 7-35d". Single dosage of PTH was 40 microg/kg BW. After 35 days of healing one tibia was analyzed by computed tomographical, biomechanical, histological analyses. The other tibia was used in analyses of Alp, Oc, Trap 1, Igf-1, Rankl, Opg genes (Exp.2, 3). Serum Oc and Alp were measured. Body, uterus weight was recorded. M. gastrocnemius was analyzed for weight (Exp. 2), fiber size and mitochondrial respiratory activity (MRA) (Exp.3). Estrogen enhanced uterus weight, prevented body increase, however, did not improve bone healing in Ovx rats (Exp. 1). PTH administration from days 1 and 7 improved bone parameters in all rats regardless of the application frequency (7, 5x/w or every other day) (Exp. 1, stiffness Ovx: 118+13 N/mm, Ovx PTH: 250+/-20 N/mm) being more effective in healthy rats (Exp. 3, stiffness improvement Healthy: 59 to 174 N/mm, Ovx: 52 to 98 N/mm). Serum Oc level was elevated in PTH treated rats. Application from day 14 proved to be less effective (Exp. 3). PTH had no effect (P>0.05) on body, uterus and muscle weight, muscle fiber size, MRA and expression of bone markers. PTH promoted bone healing in Ovx and healthy rats, when it is applied during early stage of healing without having any adverse systemic effect. In perspective, PTH may represent a treatment for enhancement of fracture healing. The findings need to be confirmed by follow-up studies on other animals.