en سم شناسی Toxicology پژوهشي Original Research <strong>Background: </strong>Dipentyl phthalate (DPeP) is a plasticizer compound commonly used in polyvinylchloride plastic to enhance softness and flexibility. They are not bound covalently to plastic polymers; therefore, they can dissolve into the environment and adversely affect the health of humans and animals.<br> <strong>Objectives:</strong> The aim of this study was to investigate the effect of DPeP on cognition and protective effects of N-acetylcysteine (NAC) on DPeP induced alteration in cognitive behaviour and oxidative stress markers in mice.<br> <strong>Methods:</strong> Mice were orally treated with 2 doses (33 mg/kg and 100 mg/kg) of DPeP for 28 days. Cognitive functions were assessed using spatial navigation tasks on the Morris water maze and the step-down latency in the passive avoidance apparatus. Oxidative stress was assessed by examining the levels of malondialdehyde, glutathione, ferric reducing antioxidant power, and 8-hydroxy-deoxyguanosine levels in the whole brain of mice.&nbsp;<br> <strong>Results: </strong>There was a significant increase in latency in spatial navigation tasks and a significant decline in the step-down latency in passive avoidance apparatus in the DPeP-treated group compared to the control groups. There was also a significant increase in the levels of oxidative stress following DPeP administration as seen with the rise in the levels of malondialdehyde, 8-hydroxy-deoxyguanosine, and a fall in glutathione and ferric reducing antioxidant power levels.<br> <strong>Conclusion:</strong> The present study demonstrated that DPeP adversely affects learning and memory functions in mice by oxidative stress-mediated neuronal damage. These effects were attenuated by pretreatment with N-acetylcysteine. Phthalate, Oxidative stress, N-acetylcysteine, Reactive oxygen species 179 188 http://pbr.mazums.ac.ir/browse.php?a_code=A-10-510-3&slc_lang=en&sid=1 Sandhya Rani Gautam sandhya8522@gmail.com 100319475328460010194 100319475328460010194 No Department of Pharmacology, University College of Medical Sciences & GTB Hospital, Delhi. Seema Jain dr.seemajain@gmail.com 100319475328460010195 100319475328460010195 No Department of Pharmacology, University College of Medical Sciences & GTB Hospital, Delhi. Proteesh Rana proteesh@gmail.com 100319475328460010196 100319475328460010196 Yes Department of Pharmacology, University College of Medical Sciences & GTB Hospital, Delhi. Basudev Banerjee banerjeebd@hotmail.com 100319475328460010197 100319475328460010197 No Department of Biochemistry, University College of Medical Sciences & GTB Hospital, Delhi. Pramod Kumari drpramod_k@yahoo.com 100319475328460010198 100319475328460010198 No Department of Pharmacology, University College of Medical Sciences & GTB Hospital, Delhi.