The effect of zymosan and the protective effect of various antioxidants on fracture healing in rats.
OBJECTIVE
To investigate the effects of free oxygen radicals and various antioxidants on bone healing after experimental formation of fracture.


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).


CONCLUSIONS
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.
Duygulu
Fuat
F
Department of Orthopedics, Erciyes University Medical Faculty, Kayseri, Turkey. fuatduygulu@hotmail.com
Yakan
Birkan
B
Karaoglu
Sinan
S
Kutlubay
Recep
R
Karahan
Okkes I
OI
Ozturk
Ahmet
A
D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D001205:Ascorbic Acid / Q000494:pharmacology*; D004121:Dimethyl Sulfoxide / Q000494:pharmacology; D004195:Disease Models, Animal; D017102:Fracture Healing / Q000187:drug effects*; D016166:Free Radical Scavengers / Q000494:pharmacology; D005609:Free Radicals / Q000009:adverse effects*; D020441:Ginkgo biloba; D008297:Male; D010936:Plant Extracts / Q000494:pharmacology; D011885:Radius Fractures / Q000378:metabolism / Q000473:pathology; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D012107:Research Design; D018709:Statistics, Nonparametric; D013997:Time Factors; D014458:Ulna Fractures / Q000378:metabolism / Q000473:pathology; D015054:Zymosan / Q000009:adverse effects*; D000096983:Ginkgo Extract
D000975:Antioxidants; D001205:Ascorbic Acid; D004121:Dimethyl Sulfoxide; D016166:Free Radical Scavengers; D005609:Free Radicals; D010936:Plant Extracts; D015054:Zymosan; C063170:Ginkgo biloba extract; D000096983:Ginkgo Extract