Effects of nicotine on bone and calciotropic hormones in growing female rats.

Limited research in young adults and immature animals suggests a detrimental effect of tobacco on bone during growth. This study investigated the effects of nicotine, the major alkaloid component of tobacco, on calciotropic hormone concentrations and bone status in growing female rats. One-month-old animals received either saline (n = 10), nicotine at 3.0 mg/kg/day (n = 10), or nicotine at 4.5 mg/kg/day (n = 10) administered subcutaneously via osmotic minipumps for either 2 or 3 months. Sera, femora, tibiae, and lumbar vertebrae (3-5) were collected at necropsy. The concentrations of serum calcium, phosphorus, 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D, parathyroid hormone, calcitonin, and insulin-like growth factor-I were determined. Bone variables evaluated included mineral content and density (vertebrae and femora), cancellous and cortical histomorphometry (tibiae), and bone strength (vertebrae and femora). Statistically significant differences in serum mineral and hormone concentrations were not associated with nicotine dose or exposure time. No significant nicotine treatment effects were detected for bone mineral content and density, bone histomorphometry, or bone strength. We conclude that nicotine treatment for 2 or 3 months at serum concentrations in the upper range of those found in smokers has no detrimental effect on bone mass, volume, or strength in the growing rat.