Repeated Restraint Stress Decreases Na,K-ATPase Activity via Oxidative and Nitrosative Damage in the Frontal Cortex of Rats

Chronic psychogenic stress can increase neuronal calcium influx and generate the intracellular accumulation of oxidative (ROS) and nitrosative (RNS) reactive species, disrupting synaptic transmission in the brain. These molecules impair the Na,K-ATPase (NKA) activity, whose malfunction has been related to neuropsychiatric disorders, including anxiety, depression, schizophrenia, and neurodegenerative diseases. In this study, we assessed how 14 days of restraint stress in rats affect NKA activity via oxidative/nitrosative damage in the frontal cortex (FCx), a crucial region for emotional and cognitive control. One day after the last stress session (S14 + 1d), but not immediately after the last stress session (S14), alpha 2,3-NKA activity was significantly reduced in the FCx, without changes in the protein levels. The S14 + 1d animals also showed increased lipid peroxidation, iNOS, and AP-1 activities, as well as TNF-alpha protein levels, evidencing oxidative stress and neuroinflammation. No cellular death or neurodegeneration was observed in the FCx of S14 + 1d animals. Pharmacological inhibition of iNOS or COX-2 before each stress session prevented lipid peroxidation and the alpha 2,3-NKA activity loss. Our results show that repeated restraint exposure for 14 days decreases the activity of alpha 2,3-NKA in FCx 24 h after the last stress, an effect associated with augmented inflammatory response and oxidative and nitrosative damage and suggest new pathophysiological roles to neuroinflammation in neuropsychiatric diseases. (C) 2018 IBRO. Published by Elsevier Ltd. All rights reserved.