Effects of Gestational Exposure to Nicotine on Levels of Monoamine Neurotransmitters in Brain Tissues of Rat Offspring

Objective To evaluate the effects of gestational exposure to nicotine on the levels of monoamine neurotransmitters in various brain regions of rat offspring.

Methods Twenty-four pregnant SD rats were randomly divided into four groups and treated with nicotine saline at dose of 0.0, 1.0, 2.0, and 4.0 mg/kg daily through subcutaneous injection starting from the seventh gestational day until delivery. At the age of 5 weeks, the body and brain weights of offspring were measured, brain organ coefficient was calculated, and the levels of norepinephrine (NE), dopamine (DA), and 5-hydroxytryptamine (5-HT) in cerebral cortex and hippocampus of offspring were detected.

Results The brain weight and brain organ coefficient of the 4.0 mg/kg nicotine treatment group were significantly lower than those of the other three groups (P < 0.05). In offspring cerebral cortex, the levels of NE, DA, and 5-HT of the three nicotine exposed groups were significantly lower than those of the control group (P < 0.05); the level of NE of the 4.0 mg/kg nicotine treatment group was significantly lower than those of the other two nicotine exposed groups (P < 0.05); the levels of DA of the 2.0 mg/kg and 4.0 mg/kg nicotine exposed groups were significantly lower than that of the 1.0 mg/kg nicotine exposed group (P < 0.05); the level of 5-HT of the 4.0 mg/kg nicotine exposed group was significantly lower than that of the 1.0 mg/kg nicotine exposed group (P < 0.05). In offspring hippocampus, the levels of NE and DA of the three nicotine exposed groups were significantly lower than those of the control group (P < 0.05); a dose-effect relationship was found between the DA level and the dose of nicotine treatment (P < 0.05); the level of 5-HT in the 4.0 mg/kg nicotine exposed group was significantly lower than those of the control group (P < 0.05).

Conclusion Gestational exposure to nicotine could influence the levels of monoamine neurotransmitters in the cerebral cortex and hippocampus of rat offspring, which might participate the neurodevelopmental toxicity induced by nicotine.