Abstract
This study determined the effects of nicotine on serum concentrations of several calciotropic hormones, and bone formation and resorption end-points in 7 month old, adult female rats. Animals were administered either saline (n= 9/group), low dose nicotine at 3.0 mg/kg/day (n=10/group) or high dose nicotine at 4.5 mg/kg/day (n=11/group) by subcutaneous osmotic minipumps. At the end of a three months treatment period, serum concentrations of calcium, phosphorus, parathyroid hormone, calcitonin, 25-hydroxyvitamin D and 1,25- dihydroxyvitamin D were determined. Femora, tibiae, and lumbar vertebrae (3- 5) were collected and bone parameters evaluated included mineral density and content (femora and vertebrae), strength (femora and vertebrae) and histomorphometry (tibiae). Animals given nicotine had significantly lower levels of 25-hydroxyvitamin D than controls [20.8±1.4 ng/ml for the low dose group and 20.7±1.0 ng/ml for the high dose group versus 27.6±1.3 ng/ml for the control group (mean±S.E.M.), P2 versus 6.2±0.2 mm2, P