Abstract
We have reported that addition of nicotine to the drinking water of pregnant rats resulted in lighter weight offspring and greater variability in liver lipid content than in control rats given distilled water(l). It was noted that the water intake was lower in the case of the pregnant rats drinking nicotine solution. Food intake was not measured, but the weight gain during the pregnancy was comparable to that of controls. To determine whether the fetal changes resulted from nicotine itself or decreased food intake, a different experimental design was sought in order to give nicotine in multiple small doses throughout the pregnancy with minimal disturbance or trauma to the gravid rat and, at the same time, to maintain a normal food intake.
After testing several types of feeding and drinking patterns, it was found that nicotinediet mixtures were acceptable to the rats at concentrations that permit comparison with the results of our previously reported experiments. In this paper we present the results of experiments in which pregnant rats were maintained on normal food and water intake and yet took in nicotine in amounts comparable to the earlier study. Fetal weight and length were determined on the 20th day of gestation.
Materials and methods. Sprague-Dawley derived rats were used throughout. Virgin females were mated and time of conception was marked from the appearance of the vaginal plug. Distilled water was given ad lib and daily intake was recorded. The food was finely ground Purina Mouse Breeder Chow given ad lib in non-spillable food cups. Food intake was measured at 2-3-day intervals. Nicotine was added to food by injecting a solution containing 25 mg/ml (through a 25 gauge needle) into the powdered food while mixing. The mixture was then stirred mechanically for 2 hours. Diets were freshly prepared weekly and stored at 3-4°C.
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