Effect of Arsenic in Realgar on Rat Ability in Novel Objects Recognition Test / 中国实验方剂学杂志

Objective:To determine the contents of inorganic arsenic（iAs），monomethylarsonic acid（MMA） and dimethylarsinic acid（DMA） in brain tissues and blood by using hydride generation-cold trap-atomic absorptionspectrometry（HG-CT-AAS）， and to explore the toxic effects of Realgar on central nervous system of rats. Method:The 96 Wistar rats were randomly divided into 4 groups：normal control group，0.3，0.9 and 2.7 g·kg^-1 Realgar groups. They then received intragastric administration for 14，28 and 42 days respectively， so a total of 12 groups were formed， with 8 animals in each group. The normal group was given the same dose of sodium carboxymethyl cellulose （CMC-Na） by gavage. The contents of iAs，MMA and DMA in blood and brain tissues were determined by HG-CT-AAS. The novel object recognition test was conducted to observe the learning and memory ability of rats. The changes of hippocampal neuron ultrastructure were observed by transmission electron microscopy. Result:There was no difference in the growth，weight and hippocampal coefficient of the experimental animals. The method of HG-CT-AAS showed a good linearity，precision，accuracy and recovery in content determination of arsenic （at various forms） in rat brain and blood. MMA and DMA were detected in the brain of realgar groups at time-dose-effect relationship. iAs，MMA and DMA were detected in the blood of Realgar groups. The nuclear membrane， mitochondria and endoplasmic reticulum in hippocampus neurons of rats were gradually damaged with the increase of Rhubarb exposure dose and time. After 14 days of exposure to Realgar，compared with the normal control group，there was no significant difference in the novel object recognition index among Realgar groups. After 28 days of exposure，only 2.7 g·kg^-1 Realgar group showed statistically significant difference with the control group （<italic>P</italic><0.05）. After 42 days of exposure， the novel object recognition index of 0.9 and 2.7 g·kg^-1 Realgar groups was significantly lower than that in normal control group（<italic>P</italic><0.05）. Conclusion:The metabolites of Realgar in rats are iAs，MMA and DMA. MMA and DMA can be accumulated in the brain tissue through the blood-brain barrier，causing the decline of the ability of learning and memory and leading to damage of hippocampal neurons.

Sirtuin-2 inhibition affects hippocampal functions and sodium butyrate ameliorates the reduction in novel object memory, cell proliferation, and neuroblast differentiation / 한국실험동물학회지

We investigated the effects of the sirtuin-2 (SIRT2) inhibitor AK-7 on novel object memory, cell proliferation, and neuroblast differentiation in the dentate gyrus. In addition, we also observed the relationships with sodium butyrate, a histone deacetylase inhibitor, on the hippocampal functions. To investigate the effects of AK-7 on hippocampal functions, 10-week-old C57BL/6 mice were daily injected intraperitoneally with 20 mg/kg AK-7 alone or in combination with subcutaneous administration of 300 mg/kg sodium butyrate, a histone deacetylase inhibitor, for 21 days. A novel object recognition test was conducted on days 20 (training) and 21 (testing) of treatment. Thereafter, the animals were sacrificed for immunohistochemistry for Ki67 (cell proliferation) and doublecortin (DCX, neuroblast differentiation). AK-7 administration significantly reduced the time spent exploring new objects, while treatment in combination with sodium butyrate significantly alleviated this reduction. Additionally, AK-7 administration significantly reduced the number of Ki67-positive cells and DCX-immunoreactive neuroblasts in the dentate gyrus, while the treatment in combination with sodium butyrate ameliorated these changes. This result suggests that the reduction of SIRT2 may be closely related to age-related phenotypes including novel object memory, as well as cell proliferation and neuroblast differentiation in the dentate gyrus. In addition, sodium butyrate reverses SIRT2-related age phenotypes.

Effects of chronic restraint stress on learning and memory in SD and Wistar rats / 中国实验动物学报

Objective To investigate the effects of chronic restraint stress on learning and memory in Wistar and Sprague-Dawley (SD) rats.Methods Healthy adult male Wistar rats (n=6) and Sprague-Dawley rats (n=6) were subjected to restraint stress 10 h daily for 28 days.After that, all rats were tested for recognition memory by novel object recognition test , and spatial memory and working memory by Morris water maze test .Results After restraint for 10 h daily for 28 days, the restraint rats of the two strains demonstrated lower discrimination index (DI)than the control group, but on-ly SD rats showed significant difference ( P<0.05 ) .The restraint SD rats showed higher escape latency than the control rats, and on the 5th day the difference became significant (P<0.05), and there was no significant difference between Wistar restraint and control rats .The working memory test showed that restraint SD rats exibited longer escape latency than the control rats (P<0.05), while Wistar rats didn’t show significant difference between the two groups .Conclusions The results of this study demonstrate that the impairments of learning and memory in SD rats subjected to restraint 10 hour per day for 28 days are more serious than that in the Wistar rats .Therefore , SD rats may be a better choice as an animal model to study the effects of chronic restraint stress on learning and memory impairment .

The Effect of Fluoxetine on Behaviors in Transient Forebrain Ischemic Gerbil / 대한정신약물학회지

OBJECTIVE: This study aims to explore the effect of fluoxetine on memory, locomotor and depressive behavior in transient forebrain ischemic model of gerbil. METHODS: Doses of fluoxetine (10, 40 mg/kg) or vehicle were intraperitoneally administered once 30 min before ischemic surgery in gerbil. Novel object recognition test, spontaneous motor activity, learned helplessness test were performed 4 days, 8 days, or 9 days, respectively, after sham or ischemic surgery. RESULTS: Fluoxetine treatment (40 mg/kg) significantly reduced recognition memory in sham operated gerbil. However, fluoxetine (10, 40 mg/kg) did not affect ischemia-induced impairment in recognition memory. The treatment of fluoxetine (10, 40 mg/kg) significantly inhibited locomotor hyperactivity induced by transient ischemia even though fluoxetine (40 mg/kg) did not affect spontaneous motor activity in the sham operated gerbils. Fluoxetine did not affect depressive behavior in sham and ischemic gerbils. CONCLUSION: The treatment of fluoxetine inhibited ischemia-induced hyperactivity, but did not affect memory and depressive behavior in transient forebrain ischemic gerbils.