Prenatal Nicotine Exposure Alters Genetic Profiles of Neurons in the Sub-regions of the VTA During Early Postnatal Development
Brain growth occurs during the first two weeks of postnatal development in rats. This developmental period is equivalent to the third trimester of human gestation. Dendritic arborization, axonal growth, and gliogenesis are observed along with a significant maturation of neurotransmission during this critical development period. Furthermore, nicotine exposure during early development causes deficiencies in sensory and cognitive processing in adults. In this study, we further investigated the neuron populations and the influence of perinatal nicotine exposure on gene expressions of neurons within the sub-regions of the ventral tegmental area (VTA) in one week (P7), two week (P14) and three week (P21) old rat pups. We exposed pregnant rats to nicotine perinatally to investigate its effect in rat pups during early neuronal development (P7, P14, and P21). Real time PCR (RT-qPCR) was used to determine the relative expressions of GABA, dopamine (DA), and glutamate neuron markers within the sub-regions of the VTA including the paranigral nucleus (PN), parainterfascicular (PIF), and parabrachial pigmented nucleus (PBP). Our results indicated that during early maturation, the dopamine marker TH was not significantly expressed within the sub-regions of the VTA in the nicotine exposed P7 group. However, TH was significantly expressed within the PN sub-region compared to the PBP sub-region of the VTA in both the P14 and P21 groups and within the PN sub-region compared to the PIF sub-region in the P21 group. These results suggest that following perinatal nicotine exposure, VTA DA neurons, especially within the PN sub-region, are significantly excited after two weeks of maturation.