Hyperbaric oxygen preconditioning ameliorates anxiety-like behavior and cognitive impairments via upregulation of thioredoxin reductases in stressed rats

The present study examined the protective effect of hyperbaric oxygen preconditioning (HBO-PC) and the role of thioredoxin reductase (TrxR) in a post-traumatic stress disorder (PTSD)-induced rat model by using single prolonged stress (SPS). Rats were randomly divided into Sham, HBO, SPS and HBO + SPS groups. HBO-PC was conducted by exposing rats to 100% oxygen at 2.5 atm absolute for 1 h each day for 5 consecutive days. SPS was performed 24 h after the last HBO-PC conditioning event. At 1 h, 6 h, 12 h, 24 h and 72 h after SPS, TrxR mRNA expression was analyzed in the hippocampus; Nissl and TUNEL staining were performed at 72 h after SPS. The results indicated that HBO-PC was able to significantly preserve viable neurons in the CA1 subfield of hippocampus following SPS exposure, as evidenced by reduced amounts of CA1 neuronal apoptosis. Furthermore, HBO-PC upregulate the expression of TrxR-1 and TrxR-2 mRNA in the hippocampus at 6 h and 12 h after SPS exposure and ameliorated anxiety-like behavior and cognitive impairments normally induced by SPS. Taken together, these findings suggest that HBO-PC is beneficial for the improvement of anxiety-like behavior and cognitive impairments induced by SPS exposure, and this effect might be associated with inhibition of neuronal apoptosis via upregulation of TrxR in stressed rats. (C) 2010 Elsevier Inc. All rights reserved.