Histological effects of Leptin on fracture healing in rats

Leptin is a polypeptide hormone, mainly secreted by white adipose tissue. It is a multifunctional hormone, regulating metabolic rate, energy expenditure and having effects on fertility, immune function, angiogenesis, and even bone formation.In this experimental study, effects of leptin on fracture healing in rats? tibias were histologically and radiologically evaluated. Fifty-four Spraque Dawley rats, aged 16 weeks and a mean body weight of 323 g (range, 295 to 352 g), were used for this study. They were randomly and equally divided into three groups. Their right tibias were broken and intramedullary fixed histologically and radiologically under anesthesia.0.1 µg/kg and 0.3 µg/kg leptin were intraperitonially administered for 0,1 leptin and 0,3 leptin groups respectively, for 14 days. 0.5 ml 0.9% normal saline was given to control group for the same period.These groups were further divided into three groups, composed of 6 rats, to evaluate postoperatively at 14th, 21st, 35th days. Finally 9 groups were obtained. Six rats from each group (ie: control, 0,1 leptin and 0,3 leptin groups) were sacrificed at 14th day, another six rats from each group sacrificed at 21st day and the remaining six were sacrificed at 35th day after the operation. Then their right tibias were radiologically and histologically evaluated and the results of groups were compared.We found leptin has positive effects on fracture healing both 21st and 35th days in histologic evaluation of groups. We also radyologically observed more healing in 0,3 leptin group than control group especially at 35th day.As a result, we established intraperitonial leptin administration has positive effects on fracture healing depending on doses, according to histological and radiological evaluations.