Acute Stress Exposure Preceding Global Brain Ischemia Accelerates Decreased Doublecortin Expression in the Rat Retrosplenial Cortex
Background: Psychological distress is a risk factor of stroke in humans and worsens the behavioral and neurological outcomes. In rats, acute stress exposure preceding ischemic events attenuates learning and memory. The retrosplenial cortex (RS) plays an important role in these functions, and global brain ischemia (GBI) or acute stress exposure can induce a decrease in expression of the immature neuronal marker, doublecortin (DCX), in the RS. However, little is known about the DCX expression in the RS after stress exposure prior to GBI. Methods: Eighteen male Sprague–Dawley rats were used. Acute stress exposure was applied as the forced swim paradigm and GBI was induced by bilateral common carotid arterial occlusion for 10 min. The rats were divided into three groups: GBI model preconditioned by stress (n = 6, Group P), GBI model preconditioned by non-stress (n = 6, Group G), and controls (n = 6, Group C). We performed immunohistochemistry to observe and analyze the DCX-expressing cells and Fluoro-Jade B (FJB) staining to detect cell death in the RS after GBI in each group. Results: The total number of DCX-expressing cells was 1,032, 1,219, and 1,904 in Group P, Group G, and Group C, respectively. The mean number of DCX-expressing cells per unit area was significantly lower in Group P and Group G than in Group C (P < 0.001). Moreover, the number was significantly lower in Group P than in Group G (P < 0.05). In each group, no FJB positive cells were observed. Conclusion: DCX plays an important role in various cytoskeletal changes. Preconditioning by acute stress exposure accelerated the decrease in DCX expression in the RS after GBI.
KeywordsIschemia Lactate Paraformaldehyde
The authors thank Professor Shin Aizawa (Division of Anatomical Science, Department of Functional Morphology, Nihon University School of Medicine) for excellent technical support. This work was supported in part by a Grant-in-Aid for Scientific Research (C-20591725) and by the Strategic Research Program for Brain Science (MEXT); a grant from the Ministry of Education, Culture, Sports, Science and Technology of Japan (C-18591614); a Nihon University School of Medicine Alumni Association 60th Anniversary Fund Research Grant (2012); and a Grant for the Promotion of Industry-University Collaboration at Nihon University.
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