Adolescence is a period in which many are first introduced to cigarettes. With adolescence being a plastic neurodevelopmental period, exposure to addictive substances, like nicotine, may lead to abnormal neural development and consequently, behavioural and cognitive deficits. Importantly, nicotine exposure is linked to various psychiatric conditions including anxiety and depression. To assess the long-term neuropsychiatric-like effects of adolescent nicotine exposure, adolescent (PND 35-44) and early adult (PND 65-74) rats were exposed to nicotine. Once adults (PND 75), or later in adulthood (PND 105), rats were analyzed with a battery of behavioural, cognitive, molecular and cellular assays. Following adolescent, but not adult nicotine exposure, rats develop depressive and anxiety disorder phenotypes including temporal memory and social motivation deficits, relative to controls. Adolescent behavioural results were associated with a hyperdopaminergic, sub-cortical state through the mesolimbic pathway and an upregulation in pERK1/2 and downregulation in D1DR expression levels in the PFC
