ABSTRACT
OBJECTIVE To screen a mouse anxiety model with good reproducibility, little stimulation and user-friendliness by comparing the uncertain empty bottle drinking water stimulation with restraint stress to induce anxiety-like emotion in mice in order to find a suitable pharmacodynamic evaluation model for anti-anxiety drugs which provides an experimental basis. METHODS A mouse anxiety model was established using the uncertain empty bottle drinking water stimulation method. The mice were divided into freely drinking water group, regular drinking water group, physiological stress group and empty bottle stimulation group, with eight mice in each group. The freely drinking water group was free to eat and drink all day, the regular drinking water group mice were given free water for 2 periods per day, while the regular drinking water group mice were given water for 10 min at 2 fixed time with a 12 h interval every day. At the same time, physiological stress group mice had access to drinking water for 10 min once a day, but at another time they were given neither water nor empty bottles. The empty bottle stimulation group mice were given empty bottle stimulation randomly once or twice every day so that they drank water 12 times and empty bottle stimulation 16 times. The experiment lasted 14 d. The mouse anxiety model was established with restraint stress method. The experimental mice were divided into normal control group and restraint stress group, with eight mice in each group. The normal control group was normally reared, while the restraint stress group mice were confined to the tube at 9:00 every morning, headed towards the bottom of the centrifuge tube and were restrained for 2 h on the first day, and then the daily binding strength was extended for 2 h until 8 h every day for 21 d. The changes of body mass in mice after 7 and 14 d of empty bottle stimulation and after 7, 14, and 21 d of restraint stress were observed. At the end of the modeling, the mice were tested for autonomous activities and exploration behaviors through the open field test. The elevated plus maze test was used to detect the number of times they entered the open arms and the time spent in the open arms. The plasma corticosterone (CORT) content and the content of serotonin (5-HT) in the hippocampus of mice were determined by ELISA after 21 d of restraint stress. RESULTS Uncertain empty bottle drinking water stimulation method: compared with the freely drinking water group, the regular drinking water group showed a significant decrease in the residence time in the open arm (P<0.05). Compared with the regular drinking water group, the body mass of the mice decreased significantly after 7 d of empty bottle stimulation (P<0.05). There was no significant change in the behavioral indicators. Restraint stress method: compared with the normal control group, the body mass of mice was significantly decreased after 14 d of restraint stress (P<0.05). There was no significant change in the autonomous activity or exploration behavior of mice. The number of times the mice entered the open arms and the residence time in the open arms were significantly decreased (P<0.05). After 21 d of restraint stress, the body mass of the mice decreased significantly (P<0.05), and plasma CORT content (P<0.01) and 5-HT content in hippocampus (PO.01, P<0.05) of mice were significantly reduced. CONCLUSION The mouse anxiety model established with the uncertain empty bottle drinking water stimulation method results in poor stability and sensitivity, with more uncontrollable factors. The mouse anxiety model was not successfully established until 14 d of stimulation. The restraint stress for 14 d could successfully a establish mouse anxiety model, and the mechanism may be related to HPA axis dysfunction and 5-HT metabolic abnormalities.
ABSTRACT
OBJECTIVE To explore the effect and mechanisms of LW-AFC,a new formula derived from Liuwei Dihuang decoction,on chronic unpredictable mild stress(CUMS)-induced mood and cogni-tion impairment in mice. METHODS C57BL/6J mice were randomly placed into seven groups (n=10):normal control group,CUMS group,Fluoxetine(10 mg·kg-1,once per day)group,Liuwei Dihuang de-coction group(LW,10 g·kg-1,once per day),and LW-AFC(0.8 g·kg-1,1.6 g·kg-1,3.2 g·kg-1,once per day) group. The stressed group was given CUMS for 4 weeks to set up a chronic multiple-stressed model.LW and LW-AFC was oral administered a week prior to CUMS and until the end of the study(a total of 35 d),while fluoxetine was administrated orally for 4 weeks.The anxiety behavior was analyzed using the open field test(OFT)and elevated plus maze test(EPM).The depression behavior was ana-lyzed using the sucrose preference test (SPT) and forced swimming test (FST). Spatial cognition was evaluated using Morris water maze (MWM) test and working memory was evaluated using new object recognition test(NORT). RESULTS CUMS for 28 d increased depressive-and anxiety-like behaviors. LW-AFC (1.6 g·kg-1) significantly increased the numbers of entries into the open arm and time in the open arm of CUMS mice (P<0.05). LW-AFC (3.2 g·kg-1) increased sucrose consumption and de-creased the immobility time of FST (P<0.01) of CUMS mice. The MWM test showed that spatial learning andmemory in CUMS mice were remarkably affected relative to controls,whereas LW-AFC(3.2 g·kg-1)im-proves cognitive functions(P<0.05).CONCLUSION The mood and theability of learning and memory of thestressed group can be affected after exposure to CUS.Oral administration of LW-AFC significant-ly improved CUMS-induced impairments of mood and cognition in mice.