Effects of acute fear stress on hormone levels, abilities of spatial learning and memory of rats

    CHEN Yaoª²Ming, ZHENG Gang, ZHANG Xueª²Ping, LUO Wenª²Jing, ZHANG Yun, CHEN Jingª²Yuan

    Department of Occupational and Environmental Hygiene, School of Military Preventive Medicine, Fourth Military Medical University, Xi¬ðan 710033, China

    ¡¾Abstract¡¿ AIM: To study the effects of acute fear stress on the hormone levels, and the abilities of spatial learning and memory of rats. METHODS: Thirtyª²two adult male SD rats weighing 180-220 g were randomly divided into control group (n=16) and stress group (n=16). Rats of stress group received 30ª²min acute stress including white noise, and foot shock, and then the spatial learning and memory performance was measured by Morris water maze. The hormone levels in plasma and brain were determined by spectrophotofluorometry and radioimmunoassay kit. RESULTS: In water maze task, the time taken for fearª²stressed rats to find the platform (latency) for spatial bias was prolonged(P<0.05), and the frequency of crossing over the platform location was decreased in the probe trail (P<0.01). The stress also resulted in significantly higher plasmic and cerebral noradrenaline, corticosteroid, 5ª²hydroxytryptamine levels, and lower adrenomedulin level in comparison with the controls (P<0.01). CONCLUSION: Acute fear stress leads to abnormalities of learning and memory of rats, and the alteration of hormone levels in this process may be a significant mechanism underlying the effect. ......