Effect of Nicotine on RANKL and OPG and Bone Mineral Density

WOS: 000344484200002PubMed ID: 24830656Aim: The signaling pathway OPG/RANK/RANKL is a key in maintaining the balance between the activity of osteoblasts and osteoclasts in order to prevent bone loss. In this study, our aim was to assess the effects of long-term nicotine exposure on plasma RANKL and OPG levels, tissue RANKL and OPG immunoreactivities, and bone mineral density (BMD) scores in rats. Materials and Methods: Thirty-six Swiss Albino rats weighing 70 +/- 10 g were divided into three groups. While the controls (n = 12) were only given normal drinking water, for low-dose nicotine (LDN) group (n = 12) 0.4 mg/kg/day; for high-dose nicotine (HDN) group (n = 12), 6.0 mg/kg/day nicotine was added to drinkingwater for a year. At the end of 12th month, BMD scores were measured using an Xray absorptiometry and bone turnover was assessed by measuring plasma RANKL and OPG levels and RANKL and OPG immunoreactivities in tail vertebrae of the rats. Results: There was no statistically significant difference in BMD scores of lumbar spine and femoral regions of the nicotine groups in comparison to controls. Plasma OPG levels were found to be significantly higher in HDN group, in comparison to the controls and LDN groups (p = .001) unlike plasma RANKL levels. Tissue RANKL and OPG immunoreactivities decreased significantly in the LDN and HDN groups (p < .001, p < .01, respectively). Conclusions: The results of this study show that nicotine is not primarily responsible for the decrease in BMD frequently seen in smokers. Measuring plasma RANKL and OPG levels did not reflect tissue immunoreactivities.Ege UniversityEge University [BAP TIP 09TIP020]; Celal Bayar UniversityCelal Bayar University [BAP 2008/112]Thanks to Prof. Kamil Kumanlioglu and his technicians (Ebru Akgungor and Huseyin Atmaca) for measuring BMD scores in the Department of Nuclear Medicine, Faculty of Medicine, Ege University, Turkey. Our study was supported by Ege University Scientific Research Projects Funding BAP TIP 09TIP020 and Celal Bayar University Scientific Research Projects Funding BAP 2008/112