ABSTRACT
INTRODUCTION: The primary goal of nicotine replacement therapy (NRT) is to reduce smoking related harms by introducing low nicotine products. In spite of being a potential mode of NRT, there is lack of information on the risks and safety of long term oral nicotine usage on the female reproductive system. METHODS: We evaluated the effects of 30 µg/mL oral nicotine consumption on the estrous cycle, circulating estradiol levels, and uterine and ovarian morphology after 2 or 7 weeks of intake by female Sprague-Dawley rats. RESULTS: Estrous phase frequencies were similar between nicotine treated and control groups throughout the study, no changes were detected in nicotine-treated animals before and during the nicotine exposure period, and circulating estradiol levels were comparable between animals in both groups after 2 weeks of nicotine consumption. Histological examination of uteri from the nicotine group revealed a significant decrease in the height of uterine surface epithelium and an increase in the height of glandular epithelium compared to control animals; yet, the ovaries did not show attrition or changes in follicular appearance due to nicotine. CONCLUSIONS: These preclinical studies suggest that nicotine intake results in structural changes in uterine tissues without disrupting estrous cyclicity or estradiol hormone levels. Though oral nicotine may not be totally risk-free, continuing research on this mode of nicotine administration is worthwhile to determine optimal dosing and duration of consumption for its potential use as an NRT.
