ABSTRACT
OBJECTIVE Microgravity exerts several negative effects on the learning and memory of astro-nauts during space flight.Rg1 and Rb1,the key steroidal components of ginseng,have shown potent neuroprotec-tive effects with a high safety profile.The object of the current study is to investigate the influence of Rg1 and Rb1 on simulated microgravity-induced memory and learning dysfunction in the hindlimb suspension(HLS)rat model.METHODS The HLS rats were orally administered Rg1(30 and 60 μmol·kg-1)or Rb1(30 and 60 μmol·kg-1)for four weeks.The Morris water maze test(MWM)and reward operating conditioning reflex test(ROCR)were conducted to evaluate spatial and associative learning and memory.After the behavior tests,the serum and the prefrontal cortex(PFC)were dissected to measure the mechanism.RESULTS Rg1 and Rb1 treatment amelio-rated the cognitive deficits of HLS-exposure rats in MWM and ROCR,reduced reactive oxygen species generation and increased antioxidant enzyme activity.Rg1 and Rb1 also assisted in the recovery of mitochondrial complex Ⅰ(NADH dehydrogenase)activities and Mfn2,and decrea-sed Drp-1 expression.Furthermore,Rg1 and Rb1 reduced the ratio of Bax/Bcl-2 and the expression of cleaved-cas-pase 3,cytochrome c,increased the levels of SYN,PSD95 and activated BDNF-TrkB/PI3K-Akt pathway in the PFC.CONCLUSION Rg1 and Rb1 treatment attenuated cog-nitive deficits induced by HLS,mitigated mitochondrial dysfunction,attenuated oxidative stress,inhibited apopto-sis,and increased the synaptic plasticity,which was partly mediated by the modulation of the BDNF-TrkB/PI3K-Akt signaling.
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Objective To develop a computer-aided-controlling and analysis system for light/dark box in mice and rats with a high degree of automation and intelligence.Methods Video recording and image processing were applied to develop the computer-aided-controlling and image analysis system for light/dark box test in mice and rats. The artificial environment was developed. The stability and reliability of the system was validated by male rats. Results The percentage of time spent in the lit chamber in total time was above 79.40%. The data showed that the artificial environment was successful. When the threshold was set at 18 cm/s, the data showed a high correlation coefficient of movement time between the computer and manual recordings(r > 0.99). Classical indexes including transition and time spent in both the lit and dark chambers also showed a high correlation. The model group showed a significantly decrease in the transitions and time spent in the lit chamber compared with the control group, indicating a high stability and reliability of the light/dark box test. Conclusions A stable and highly intelligent computer-aided-controlling and image analysis system for light/dark box test of mice and rats has been developed,and it could be used for pathological mechanism studies of anxiolytics.
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Objective To develop a multi-mode,detailed and sensitive object recognition method for learning and memory research,including novel object recognition task,object location recognition task,temporal order memory task and object context recognition task in animals based on their spontaneous behavior. Methods Two strains of mice(KM and ICR)and four patterns were used to establish the object recognition method and several relative factors,such as time of test phase,delay between test phase and familiar phase were investigated. Results It was stable and reasonable to set the time of familiar phase as 5 min,the interval between test phase and familiar phase as 10 min,and the time of test phase as 3-5 min,under the precondition of habituation for three days and selecting the appropriate object pairs. Conclusions Object recognition test including four patterns has been systematically established as a stable, reliable and normative way for the research of animal learning and memory and drug development.
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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.
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Objective To investigate the relationship between different brain developmental stages and changes of cognitive function in rats. Methods 1-month, 2-month and 8-month-old rats were selected to imitate the juvenile, adolescent and adulthood, respectively, and their behavioral functions were compared. The reward operant conditioning and Morris water maze task were used to investigate the differences in exploration interest, executive and recognition ability, spatial learning and memory of the rats at different ages. Results In the reward operant conditioning and Morris water maze task, there was no significant difference in the cognitive function between 1-month and 2-month-old rats. In the reward conditioning phase, the nose pokes numbers of 8-month-old rats were significantly decreased compared with the 1-month-old rats (P＜ 0. 01). There was no significant difference in nose pokes accuracy. During the operant conditioning phase, the lever press numbers and accuracy of 8-month-old rats were significantly decreased ( P ＜ 0. 05 or P ＜ 0. 01) and the press latency was longer (P ＜ 0. 05). At the phase of visual identification, the press and reward numbers, and the visual identification index were significantly decreased ( P ＜ 0. 05 or P ＜ 0. 01). In the Morris water maze test, compared with the 1-month-old rats, the total swimming distance and escape latency of the 8-month-old rats were significantly increased (P＜ 0. 05), as well as average swimming speed ( P ＜ 0. 05 or P ＜ 0. 01) in spatial learning phage. In spatial memory phage, the swimming distance and time spent in the target quadrant were obviously decreased (P＜ 0. 01). Conclusions The cognitive functions of rats at different brain developmental stages are different. The juvenile and adolescent rats have similar cognitive functions, but 8-month-old adult rats appear decline in the exploration interest, executive and recognition ability, and spatial learning and memory function.