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[Amyloid β protein suppressed hippocampal theta rhythm and induced behavioral disinhibition and spatial memory deficit in rats.] [Article in Chinese]

YUE Xing-Hua, LIU Xiao-Jie, WU Mei-Na, CHEN Jin-Yuan, QI Jin-Shun

Department of Physiology, Key Laboratory for Cellular Physiology of Ministry of Education； Functional Center of Medical Experiment, Shanxi Medical University, Taiyuan 030001, China

Abstract

Hippocampal neuronal network oscillation is closely related to the memory, anxiety and behavioral inhibition of mammalian. The cognitive decline and behavioral disinhibition in the patients with Alzheimer's disease (AD) may be relevant to amyloid β protein (Aβ)-induced impairment in hippocampal neuronal cooperative activity. However, it is not well known whether intrahippocampal injection of Aβ could induce behavioral disinhibition and neuronal network disorder, as well as cognition decline in animals. In the present study, we observed the effects of intracerebral injection of Aβ_1-42 on the spatial memory and behavioral inhibition of rats by using Morris water maze and elevated plus-maze tests. Further, we analyzed hippocampal theta rhythm by recording hippocampal local field potential. The results showed that: (1) bilateral hippocampal injection of Aβ_1-42 reduced the anxious behavior of rats, with a significant behavioral disinhibition in the elevated plus-maze test, representing as an increase in the mean entering times and mean residence time in the open arm; (2) Aβ_1-42 injection resulted in a significant impairment of spatial memory in rats, with significantly increased mean escape latencies in hidden platform test; (3) Aβ_1-42 disrupted the induction of theta rhythm induced by tail pinch, with a significant reduction in the peak power, not the peak power frequency of the theta rhythm. These experimental results indicate that intrahippocampal injection of Aβ_1-42 can induce behavioral disinhibition and theta rhythm suppression, as well as spatial memory impairment in rats, which suggests that the cognition deficits and behavior impairments in AD are probably associated with the Aβ-induced disruption of hippocampal theta rhythm and consequent down-regulation of synaptic plasticity.

Key words: amyloid β protein; hippocampal theta rhythm; behavioral disinhibition; spatial learning and memory

Received: 2013-09-25　　Accepted: 2013-12-13

Corresponding author: 祁金顺　　E-mail: jinshunqi@sohu.com

Citing This Article：

YUE Xing-Hua, LIU Xiao-Jie, WU Mei-Na, CHEN Jin-Yuan, QI Jin-Shun. [Amyloid β protein suppressed hippocampal theta rhythm and induced behavioral disinhibition and spatial memory deficit in rats.] [Article in Chinese]. Acta Physiol Sin 2014; 66 (2): 97-106 (in Chinese with English abstract).