ABSTRACT
Objective To Study the depression-like behavior and impairment of learning and memory induced by chronic injection of corticosterone in mice. Methods Forty male C57BL/6J mice were divided into four groups, the control group, and the corticosterone groups(20,40,80 mg/kg). The mice received subcutaneous injection of corticosterone once a day for 21 days. The depression-like behaviors were detected by open field test(OFT), tail suspension test(TST)and forced swimming test(FST). To select the most effective dose of corticosterone, TST, FST, object location recognition test, and Morris water maze(MWM)test were used to study the corticosterone-induced depression-like behaviors and impairment of learning and memory in the mice. Results Compared with the control group, the movement distance and duration were significantly decreased in the corticosterone injection groups(40,80 mg/kg)(P< 0.01 or P< 0.05). In the TST group,the immobilization time was significantly increased in the corticosterone injection group(40,80 mg/kg)(P< 0.05). The TST and FST showed that the immobilization time of the corticosterone injection group(40 mg/kg)was significantly increased(P < 0.05). The object recognition test showed that the discrimination indexes of the object location recognition were decreased in the corticosterone injection group(40 mg/kg). The MWM test showed that the escape latency was increased(P< 0.05),and the number of crossing in target quadrant and the velocity in target quadrant were decreased(P< 0.05)in the corticosterone injection group(40 mg/kg). Conclusions Chronic injection of corticosterone can induce depression accompanied with learning and memory impairment in mice.
ABSTRACT
Objective To study the effects of different color light stimulus, duration of stimulus and day/night training on the incentive conditioned reflex of rats,and to provide a data basis for the methodology of incentive conditional reflection experiments. Methods Three experiments were included in this study. During the experiment 1, a total of 30 male 8-week-old Wistar rats were divided into three groups:red light stimulation group,yellow light stimulation group and blue light stimulation group. During the experiment 2, a total of 32 male 8-week-old Wistar rats were divided into three groups:the group I(with a light stimulation duration of 10 s), the group II(with a light stimulation duration of 30 s), and the group III(with a light stimulation duration of 60 s). During the experiment 3,a total of 16 male 8-week-old Wistar rats were randomly divided into two groups,of which the first group was trained at 9:00 a.m. every day, and the second group was trained at 21:00 every day. All the laboratory animals were given reward conditioned reflex training, and indicators such as the number of correct nose pokes,the number of incorrect nose pokes,the ratio of correct nose pokes and so on were counted and calculated. Results During the experiment 1,there was no significant difference in the numbers of correct nose pokes and incorrect nose pokes,movement distances and average speeds of the rats among the three groups. During the experiment 2,compared with the group with a light duration of 10 s,the rats in the groups with a light duration of 30 s or 60 s had a higher number of correct nose pokes(P< 0.05). Moreover,on the 13th and 14th days,the ratio of correct nose pokes of the group with a light duration of 30 s was significantly higher than that of the group with a light duration of 10 s(P< 0.001). During the experiment 3,there were no significant differences in the number of correct nose pokes and the nose poke accuracy of the rats between the two groups. Conclusions In the reward conditioned reflex test, red,yellow and blue light stimuli have similar reward prediction effect. When stimulated with the same light, the time of stimulation has an impact on the learning ability of the rats,and an appropriate extension of stimulation is beneficial to the formation of conditioned reflex in them. The day/night training has no effect on the learning and memory ability of the rats.
ABSTRACT
Objective To investigate the antidepressant effect of DS-1226, a hydrolysate of ginsenosides, on a mouse model of depression induced by chronic sleep interruption, and provide scientific evidence for the research and de?velopment of antidepressant drugs. Methods 72 male ICR mice were divided into control group, model group, positive control group (paroxetine hydrochloride, 10 mg/kg) and 3 treatment groups (20 mg/kg, 40 mg/kg, 80 mg/kg of DS?1226). Except the control group, the other mice were put into a rotary roller (parameter settings:1 min/rev;rest 2 min af?ter 1 rev) for 3 days of drum adaptation, 3 h/d. Then making model for 14 days in the roller( parameter settings:1 min/rev;rest 2 min after 1 rev) . The antidepressant effects of DS?1226 were evaluated by weight monitoring, open?field test, tail suspension test, and forced swimming test. Results After 14 d sleep disturbance, compared with the control group,the body weight, immobility time in tail suspension test and forced swimming test were significantly decreased in the model group. Compared with the model group, DS?1226(40 mg/kg)significantly reversed the weight loss caused by sleep disturb?ance. Paroxetine significantly reduced the immobility time of tail suspension test. DS?1226 (40 mg/kg, 80 mg/kg)signifi?cantly decreased the immobility time of tail suspension test, and DS?1226 (80 mg/kg) significantly decreased the immobil?ity time of forced swimming test. Conclusion The hydrolysate of ginsenosides DS?1226 shows antidepressant effect on mouse model of depression induced by chronic sleep interruption.