Deterioration in learning and memory of fear conditioning in response to context in aged SAMP8 mice.
This study examined age-dependent deficits in the learning and memory of fear conditioning, using a newly developed senescence-accelerated mouse (SAMP8) model of age-related brain dysfunction and its genetically related inbred strain (SAMR1). The mice were classically conditioned to tone by giving aversive foot shocks in a distinct experimental box (context). After conditioning, fear in response to the original context without the tone and to the tone in a different context were tested with no shocks. Freezing behavior was used as a reliable index of fear. At 4 and 8 months, contextual fear was weaker in the accelerated senescence-prone SAMP8 mice than in the accelerated senescence-resistant SAMR1 mice. However, at 1 and 2 months, both SAMP8 and SAMR1 mice showed significant contextual fear to equivalent levels. Aging did not affect the fear response to tone. These results indicate that SAMP8 mice have age-related learning and memory deficits in their fear response evoked by contextual but not explicit tone stimuli. Age-related hippocampal dysfunction is suggested to be the cause of these age-related deficits in contextual fear conditioning in SAMP8 mice.
Ohta
A
A
Field of Regeneration Control, Institute for Frontier Medical Sciences, Kyoto University, Japan. ota@frontier.kyoto-u.ac.jp
Akiguchi
I
I
Seriu
N
N
Ohnishi
K
K
Yagi
H
H
Higuchi
K
K
Hosokawa
M
M
D000375:Aging / Q000502:physiology*; D000704:Analysis of Variance; D000818:Animals; D001522:Behavior, Animal / Q000502:physiology; D003214:Conditioning, Classical / Q000502:physiology*; D004597:Electroshock; D005239:Fear / Q000502:physiology*; D006624:Hippocampus / Q000503:physiopathology*; D008297:Male; D008569:Memory Disorders / Q000503:physiopathology*; D051379:Mice; D008815:Mice, Inbred Strains; D013016:Sound; D013997:Time Factors