title: Hippocampal signaling pathways are involved in stress-induced impairment of memory formation in rats.
abstract: Stress is a potent modulator of hippocampal-dependent memory formation. The aim of the present study was to assess the role of hippocampal signaling pathways in stress-induced memory impairment in male Wistar rats. The animals were exposed to acute elevated platform (EP) stress and memory formation was measured by a step-through type passive avoidance task. The results indicated that post-training or pre-test exposure to EP stress impaired memory consolidation or retrieval respectively. Using western blot analysis, it was found that memory retrieval was associated with the increase in the levels of phosphorylated cAMP-responsive element binding protein (P-CREB), peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α) and its downstream targets in the hippocampus. In contrast, the stress exposure decreased the hippocampal levels of these proteins. In addition, stress-induced impairment of memory consolidation or retrieval was associated with the decrease in the P-CREB/CREB ratio and the PGC-1α level in the hippocampus. On the other hand, the hippocampal level of nuclear factor E2-related factor 2 (Nrf2) and gamma-glutamylcysteine synthetase (γ-GCS) which are the master regulators of defense system were decreased by the stress exposure. The increased hippocampal levels of Nrf2 and it׳s downstream was observed during memory retrieval, while stress-induced impairment of memory consolidation or retrieval inhibited this hippocampal signaling pathway. Overall, these findings suggest that down-regulation of CREB/PGC-1α signaling cascade and Nrf2 antioxidant pathways in the hippocampus may be associated with memory impairment induced by stress.
authors: Department of Animal Biology, School of Biology and Center of Excellence in Phylogeny of Living Organisms, College of Science, University of Tehran, Tehran, Iran.
authors: Maryam
authors: M
authors: Sardari
authors: Department of Animal Biology, School of Biology and Center of Excellence in Phylogeny of Living Organisms, College of Science, University of Tehran, Tehran, Iran. Electronic address: rezayof@khayam.ut.ac.ir.
authors: Ameneh
authors: A
authors: Rezayof
authors: Neuroscience Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
authors: Fariba
authors: F
authors: Khodagholi
mesh_terms: D000199:Actins / Q000378:metabolism; D000704:Analysis of Variance; D000818:Animals; D050882:CREB-Binding Protein / Q000378:metabolism; D002374:Catalase / Q000378:metabolism; D005786:Gene Expression Regulation / Q000502:physiology; D005721:Glutamate-Cysteine Ligase / Q000378:metabolism; D005978:Glutathione / Q000378:metabolism; D051547:Heme Oxygenase-1 / Q000378:metabolism; D006624:Hippocampus / Q000378:metabolism*; D008297:Male; D008569:Memory Disorders / Q000209:etiology* / Q000473:pathology*; D011939:Mental Recall / Q000502:physiology; D051267:NF-E2-Related Factor 2 / Q000378:metabolism; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction; D013315:Stress, Psychological / Q000150:complications*; D014157:Transcription Factors / Q000378:metabolism
chemical_list: D000199:Actins; D051267:NF-E2-Related Factor 2; C495637:Nfe2l2 protein, rat; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; C501429:Ppargc1a protein, rat; D014157:Transcription Factors; D002374:Catalase; D051547:Heme Oxygenase-1; D050882:CREB-Binding Protein; D005721:Glutamate-Cysteine Ligase; D005978:Glutathione
keywords: Acute stress; Hippocampal signaling pathway; Memory formation; Rat(s)