Project Summary There have been several reported cases of seizures in youths following electronic nicotine delivery systems (ENDS) use, prompting an investigation by the Federal Drug Administration. Although reports show that ENDS aerosols contain fewer numbers and lower levels of toxicants than conventional cigarettes, there is evidence of adverse biological effects in humans, and the long-term effects of ENDS exposure with nicotine (NIC) and flavorings such as menthol on seizure susceptibility are unknown. The reports of illnesses associated with ENDS challenge the concept that they are a healthier alternative to traditional cigarettes and underscore the urgent need for studies to elucidate the health effects of ENDS. Seizures are linked to smoking through genetic mutations and by exposure to high levels of nicotine, but the effects of NIC exposure via ENDS use is unknown. Using our rodent-validated vapor inhalation system, our preliminary data indicates that inhalation of NIC leads to changes in body weight, locomotor activity, and somatic signs of dependence and causes profound changes in glutamate regulatory proteins, suggesting increased neuronal activity. The central hypothesis of the current proposal is that exposure to ENDS disrupts neuronal function and increases seizure susceptibility via alteration in glutamate homeostasis. This hypothesis will be tested by pursuing two Specific Aims: 1) To test the hypothesis that exposure to ENDS with menthol increases seizure susceptibility and 2) To test the hypothesis that ENDS with menthol exposure increases neuronal hyperexcitability. Given the dramatic increase in ENDS use, the need for fundamental research on its health effects is imperative. The proposed research will lead to a greater understanding of the fundamental effects of ENDS use with nicotine on neuronal hyperexcitability and seizure susceptibility. These data will provide critical first step towards understanding the effect of ENDS use, which will help guide individuals and policy makers in making informed decisions about ENDS use.