| BackgroundWith rapid socio-economic development, the aging population increase quickly andit becomes a serious society problem. The grim situation of the aging has precipitatedmany researchers to focus on the aging-related study, but up to date there is only a fewways to delay aging, in particular drugs therapy. Currently, the study trend of anti-agingis to search naturally occurring drugs. Abound evidences indicates that the activeingredients of variety Chinese herbal medicines has displayed a good anti-aging effects.Recently, the function of the mulberry leaf extract has also been widely concerned.1-deoxynojirimycin (DNJ), one of the active ingredients of the mulberry leaf extract,has been found to show many effects such as the role of the alpha-glycosidase inhibitor,loss in weight, suppressing postprandial hyperglycemia, enhancing insulin sensitivity,anti-virus, and inhibiting tumor metastasis, which suggests that DNJ may have potentialeffect of delaying the process of aging. However, there is no direct evidence about theanti-aging of DNJ.ObjectiveTo investigate the effects of DNJ on age-related changes in sensorimotor abilityand anxiety in the senescence-accelerated prone strains8(SAMP8) miceMethodsSAMP8mice were used in this study, and they were randomly divided into threegroups: control, low-dose DNJ (10mg/kg·d) and high-dose DNJ (20mg/kg·d) groups.At the age of3months, DNJ-treated mice were orally administered DNJ mixed with drinking water for6months until the behavioral tests began, and the control mice werereceived normal drinking water. All animals were allowed free access to a standardrodent diet. In order to adjust the concentration of DNJ, drinking water consumptionwas monitored dynamically in mice. At age of9months, behavioral changes, includingsensorimotor ability (beam walking, tightrope) and anxiety (open field, black-whitealley, elevated plus maze), were assessed. The final number of mice was13(6males,7females) in control group,15(8male,7females) in10mg/kg·d DNJ group and12(6male,6female)20mg/kg·d DNJ group. Moreover, another12(6male,6female)4-month-old SAMR8mice were set as the young control and conducted the samebehavioral testing.Results1) The effect of DNJ on the body weight inSAMP8miceAmong the control, low-dose DNJ and high-dose DNJ groups, there were nosignificant difference in body weight (F（2,66）=0.182，P=0.908). But, the total bodyweight of female mice was significantly lower than the male mice (F（1,38）=395.683，P<0.001), and body weight of the female mice were also significantly lower thanmale mice in each group (Ps<0.05).2) The effects of age and DNJ on the sensorimotor abilityIn the beam walking and tightrope tasks, the performance (equilibrium time andtransformed score) of the control mice was significantly worse than that of the youngmice (Ps<0.05), but these changes were lessened by DNJ treatment. The high-dosegroup was significantly better than the blank control group (Ps<0.05) in the two tasks,and the low-dose group was significantly better than the control group only in thetightrope task. There was no significant difference between the two DNJ-treatedgroups.3) The effects of age and DNJ on the anxiety ○1Open field task: Compared to the young group, the latency, squares crossedand peripheral time of the control group significantly reduced (Ps<0.05), but therearing significantly increased (P<0.05). After DNJ treatment, the squares crossed,rearing of the low-dose group were significantly less than the blank control group(Ps<0.05).○2Elevated plus maze task: Compared to the young group, the number of enterinto open arms and the time spent in open arms of the control group significantlyincreased (Ps<0.05). After the DNJ treatment, the low-dose group mice showedsignificant reduction in the number of enter into open arms and the time spent inopen arms compared to the control group (Ps<0.05).○3Black-white alley task: Compared to the young group, the total time spent inwhite side of the control group significantly shortened (P=0.032), but the latency andthe number of enter into white side from black side showed insignificant differencein between the two groups (Ps<0.05). After the DNJ treatment, the total time spent inwhite side in the low-dose group significantly increased compared to the blankcontrol group (P<0.05).Conclusion1) SAMP8mice show age-related reduction in sensorimotor ability and the changeof anxiety was task-dependent, anxiety reduced in the open field and elevated plus mazetasks but increased in the black-white alley task.2) Long-term feeding DNJ may delay age-related changes in sensorimotor abilityand anxiety. That is, DNJ treatment can strengthen sensorimotor ability and alleviate thechange of anxiety. |
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