| BackgroundLearning and memory are the basic functions of the brain. The gradual decline of learning and memory with age is a common phenomenon in human beings and rodents, it was obviously expressed in spatial learning and memory impairment. However, the underlying neuromechanism of the age-related impairment of learning and memory is not yet clear. Nowadays, it is thought that the destruction of synaptic integrity may lead to the the age-related decline in learning and memory. Among the main components of the SNARE complex, SNAP-25 may be involved in regulation of presynaptic and postsynaptic mechanisms, which is recognized as playing an important role in the process of synaptic transmission. The SNAP-25 was also concerned with the growth of dendrites and axons, as well as the synaptic plasticity in injury-related central nervous system. It is found that SNAP-25 expression increases following the induction of long-term potentiation in hippocampus. This evidence indicated that SNAP-25 may play a significant role in the learning and memory. However, the change of the SNAP-25 during normal aging is still not clarified. Due to the limitations of direct study neuromechanism of the aging in human, we turn to Kunming mice and ICR mice to simulate human aging. Objective①To explore the effects of age and sex on the levels of SNAP-25 in different brain regions.②To explore the correlation between spatial learning and memory functions and the levels of SNAP-25 in these brain regions.Methods①Three age groups in the Kunming mice (old group aged 22 months, middle-aged group at age of 11 months and young group aged 6 months) and two age groups in the ICR mice (middle-aged group at 12 months and young group at 7 months) were used;②The ability of spatial learning and memory was evaluated by six-arm radial water maze (RAWM);③The SNAP-25 andβ-actin (reference protein) in dorsal hippocampus, ventral hippocampus, frontal lobe, parietal lobe and olfactory bulb were detected by Western blot, and the ratio of the SNAP-25 to theβ-actin gray-scale value was viewed as the relative content of the SNAP-25.④Using analysis of variance method, experiment parameters of the RAWM and the SNAP-25 relative content was analysed statistically, and the correlation was determined between the both using Spearman's rank correlation.Results①For the Kunming mice, the average number of errors and latency during learning and memory periods were higher in the 22-month-old group than those in the middle-aged and young groups (Ps<0.05),with more significantly in the elderly females (Ps<0.05), and there were no significant differences between the middle-aged and young mice (Ps > 0.05); For the ICR mice, the average number of errors and latency during the same periods in the 12-month-old group were higher than those in the young group (Ps<0.05),with more significantly in the middle-aged females (Ps <0.05).②For the Kunming mice, the relative SANP-25 amount in the dorsal hippocampus in the 22-month-old mice was significantly higher than that in the middle-aged and young mice (Ps <0.05) with more significantly in the older females (Ps<0.05), and that in the middle-aged mice was not significantly different from young mice (Ps > 0.05); In the ICR mice, the relative amount of the SANP-25 in the dorsal hippocampus in the 12-month-old group was significantly higher than that in the young mice (P<0.05), with more significantly in the females (P <0.05).③I n Kunming and ICR mice,positive correlation was confirmed between the relative amount of the SANP-25 in the dorsal hippocampus and the number of errors and latency during learning and memory periods (Ps <0.05).Conclusion①Age-related impairment of spatial learning and memory was confirmed in Kunming and ICR mice, with more significantly in the females.②In Kunming and ICR mice, the amount of the age-related SANP-25 in the dorsal hippocampus significantly increased with more singnificantly in the females.③The increasing of the amount of the SANP-25 in the dorsal hippocampus may be involved in the age-related spatial cognitive impairment. |
