The Journal of Neuroscience, September 15, 1999, 19(18):8122-8133
Sex Dimorphisms in the Rate of Age-Related Decline in Spatial
Memory: Relevance to Alterations in the Estrous Cycle
Alicja L.
Markowska
Neuromnemonics Laboratory, Department of Psychology, The Johns
Hopkins University, Baltimore, Maryland 21218
The present experiments demonstrate the existence of sex
differences in the rate of development and the magnitude of
age-dependent impairments in cognitive and sensorimotor abilities.
Although no sex differences were found in spatial reference memory at a young age, the mnemonic ability of female rats deteriorated more rapidly than that of male rats. A major drop in reference memory of the
females occurred at the age of 12 months, whereas in the males the
onset of impairments occurred later, at the age of 18 months. In
spatial working memory, on the other hand, the magnitude of decline was
greater in females than in males, although the onset of these
impairments occurred at the age of 24 months in both sexes. A sexual
dimorphism-aging interaction also was observed in sensorimotor
performance. Up to the age of 18 months the females outperformed the
males. Subsequently, by the age of 24 months, the performance of the
females declined to a level similar to that of the males. The deficits
observed in reference and working memory seem to be cognitive in origin
and not attributable to alterations in sensory and motor abilities. In
addition, the earlier onset of reference memory impairments in females
generally coincides with the onset of alterations in the estrous cycle,
suggesting that a decline in the estrogenic milieu of the females could
be a factor in accelerating the rate of age-related cognitive
impairments in the female rat.
Key words:
sex dimorphism; spatial memory; estrous cycle; aging; Fischer-344 rats; estrogen
Copyright © 1999 Society for Neuroscience 0270-6474/99/19188122-12$05.00/0
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