Prenatal and Postnatal Cocaine Enhances the Induction and Expression of Locomotor Sensitization to Nicotine in Male Rats

Introduction Several studies mention that early consumption of cannabis, alcohol, or even cocaine is related to an increase in the prevalence of daily consumption of tobacco in adulthood. However, other factors, such as genetic comorbidity, social influences, and even molecular, neurochemical, and behavioral alterations induced by prenatal and postnatal cocaine exposure, could also explain these observations, since these factors together increase the vulnerability of the offspring to the reinforcing effects of nicotine. The objective of this study was to determine the effect of prenatal and postnatal exposure to cocaine on nicotine-induced locomotor sensitization in young and adult rats. Aims and Methods The study was divided into two stages: prenatal and postnatal. In the prenatal stage, a group of pregnant female Wistar rats was administered cocaine daily from day GD0 to GD21 (cocaine preexposure group), and another group of pregnant female rats was administered saline daily (saline preexposure group). Of the litters resulting from the cocaine preexposed and saline preexposed pregnant female groups, in the postnatal stage, only the male rats were used for the recording of the locomotor activity induced by different doses of nicotine (0.2, 0.4, and 0.6 mg/kg) during the induction and expression of locomotor sensitization at different postnatal ages (30, 60, 90, and 120 days). Results Prenatal and postnatal cocaine exposure enhanced nicotine-induced locomotor activity and locomotor sensitization. Conclusions This suggests that prenatal and postnatal cocaine exposure can result in increased vulnerability to other drugs of abuse, such as nicotine, in humans. Implications Several studies have shown that the abuse of a drug, such as cannabis, alcohol, or even cocaine, at an early age can progress to more severe levels of use of other drugs, such as nicotine, to adulthood. Our data are consistent with this hypothesis, since prenatal and postnatal cocaine exposure enhanced the nicotine-induced increase in locomotor activity and locomotor sensitization. This suggests that prenatal and postnatal exposure to cocaine enhances the drug's salience.