Brennan M J, Dallob A, Friedman E
Neurobiol Aging. 1981 Fall;2(3):199-203. doi: 10.1016/0197-4580(81)90021-x.
The effect of aging on exploratory behavior was investigated in adult (5 month) and aged (28 month) CB6F1 mice. During the first 10 minutes of the test session, aged mice made fewer head dip responses and spent less time exploring the novel stimuli. Because the aged mice were observed to subsequently increase their duration of exploration, it was suggested that the initial differences in exploration reflected a suppression of exploratory behavior by the aged mice. Immediately after behavioral testing, mice were sacrificed and hippocampal serotonin (5HT) and 5-hydroxyindoleacetic acid (5-HIAA) concentrations were determined. While 5HT concentrations were not found to be significantly altered with age, significant increases in 5-HIAA concentrations and in the ratio of 5-HIAA/5HT were observed in the aged mice. Further, the elevation in the 5-HIAA/5HT ratio was found to be significantly correlated with age-related differences in the duration, but not the frequency, of head dip responses. In view of this finding, it was suggested that alterations in serotonergic function with age may selectively affect specific aspects of an animal's response to novel stimuli.
在成年（5个月）和老年（28个月）的CB6F1小鼠中研究了衰老对探索行为的影响。在测试阶段的前10分钟内，老年小鼠的头部浸入反应较少，探索新刺激的时间也较少。由于观察到老年小鼠随后增加了探索时间，因此有人认为探索行为的初始差异反映了老年小鼠对探索行为的抑制。行为测试后立即处死小鼠，测定海马中血清素（5HT）和5-羟吲哚乙酸（5-HIAA）的浓度。虽然未发现5HT浓度随年龄有显著变化，但在老年小鼠中观察到5-HIAA浓度以及5-HIAA/5HT比值显著增加。此外，发现5-HIAA/5HT比值的升高与头部浸入反应持续时间（而非频率）的年龄相关差异显著相关。鉴于这一发现，有人认为血清素功能随年龄的改变可能选择性地影响动物对新刺激反应的特定方面。
