AGE-RELATED-CHANGES IN LEARNING AND MEMORY AND CHOLINERGIC NEURONAL FUNCTION IN SENESCENCE-ACCELERATED MICE (SAM)

The senescence-accelerated mouse (SAM) has been established as a murin e model of accelerated aging. We investigated learning ability and mem ory in various tasks in a SAM strain, SAMPlTA, and in a control strain of SAMRlTA at the ages of 20, 30 and 40 weeks. We also measured choli ne acetyltransferase (ChAT) and cholinesterase (ChE) activity in the b rains of these mice at the same ages. In a Y-maze task, in which short -term memory can be examined, there was no difference in learning abil ity between SAMPlTA and SAMRlTA at any age. Ability in latent learning and passive-avoidance tasks was less in SAMPlTA at 30 weeks of age th an in age-matched SAMRlTA. The level of ChAT activity in the striatum of SAMPlTA was lower, than that of SAMRlTA at the ages of 20 and 30 we eks. At the ages of 40 and 50 weeks, ChE activity in the striatum of S AMPlTA was lower than that of SAMRlTA. These results suggest that SAMP lTA has a deficit, with cholinergic neuronal dysfunction, in learning ability and memory, as shown by impairment of performance in latent le arning and long-term memory, but not in short-term memory.