The effect of zymosan and the protective effect of various antioxidants on fracture healing in rats.

AIM: To investigate the effects of free oxygen radicals and various antioxidants on bone healing after experimental formation of fracture. MATERIALS AND METHODS: Fifty male rats were used and divided into five groups (ten rats in each). The right forelimbs of the rats were broken by bimanual compression method. One hour before this procedure, 5 ml/kg of intraperitoneal (i.p.) physiologic saline were given to the control Group 1. All 40 rats in the experimental Groups 2, 3, 4 and 5 were treated with i.p. zymosan at a dosage of 100 mg/kg to induce the production of free radicals by stimulating NADPH oxidase in polymorphonuclear leukocytes. Zymosan induction was stopped on the fifth post-fracture day. In addition to the zymosan, i.p. 1 g/kg/day of dimethyl sulfoxide were given to the animals in Group 3, 50 mg/kg/d of Ginko biloba Extract (EGb 761) in Group 4 and 500 mg/kg/day of vitamin C in Group 5. Radiographs of the fractures of all animals were obtained to assess callus formation, remodeling and bridging bone formation under ether anesthetics on postfracture day 7, 14 and 21. All rats were euthanized on day 22, and sections of the radius and ulna were examined both histologically with light and electron microscopy and ultrastructurally. Statistical analysis was made with Kruskal-Wallis variance analyze test and comparison between groups was performed by Dunn's multiple comparison test. RESULTS: An impairment of bone healing was observed in Group 2 inducted with purely zymosan. Variable results were obtained for bone healing in the groups treated with various antioxidants. There was very significant difference of fracture healing between Groups 1 and 2 both histologically and radiologically (P < 0.001). There was significant difference between Groups 2 and 5 radiologically (P < 0.05). CONCLUSION: Free oxygen radicals demonstrate a negative effect on fracture healing and vitamin C (an antioxidant) partially prevents the negative effect of zymosan on fracture healing.

Influence of maternal nicotine exposure on neonatal rat bone: protective effect of ascorbic acid.

Limited research in young adults and immature animals suggests a detrimental effect of tobacco on bone during growth. We aimed to determine the adverse effects of maternal nicotine exposure during pregnancy and lactation on neonatal rat bone development, and to determine a protective effect of ascorbic acid. Gravid rats were assigned into three groups: two experimental and one control (group I). In the first experimental group (group II), pregnant rats received 3 mg/kg/d nicotine subcutaneously during pregnancy from 1 to 21 days of gestation and lactation (until postnatal day 21). The second experimental group (group III) received nicotine and ascorbic acid (1 mg/kg body mass/d). Whole body mineral density (BMD), content (BMC), and area (BA) were measured on postnatal day 21. Histopathologic and morphologic findings of the femur were obtained. Maternal nicotine exposure decreased the body weight of the rat at the birth and postnatal day 21. The values of BMD, BA, and BMC of the groups were similar to each other. Width of the epiphyseal plate and the hypertrophic zone were higher in group III but lower in group II than in group I. Number of apoptotic chondrocytes was significantly increased in group II. The length of femur was higher in group I but lower in group II than in group III. Maternal nicotine exposure during gestation and lactation resulted in decreased body weight and bone lengthening. Ascorbic acid supplementation was found to prevent the adverse effects of maternal nicotine exposure on the growth plate.