ABSTRACT
RATIONALE: Environmental enrichment (EE) could influence brain plasticity and behavior in rodents. Whether the early EE may predispose individuals to a particular social hierarchy in the social dominance tube test (SDTT) at adulthood is still unknown. OBJECTIVE: The present study directly investigated the influence of EE on competitive success in the SDTT among adult rats. METHODS: Male rats were maintained in EE from postnatal days 21 to 35. Social dominance behavior was determined by SDTT, competitive food foraging test, and mate preference test at adulthood. IBA-1 expression in the hypothalamus was examined using immunohistochemistry and western blot. RESULTS: EE rats were prone to become submissive during a social encounter with standard environment (SE) rats in the SDTT. No difference was found in food foraging in the competitive food foraging test between SE and EE rats. Male EE rats were more attractive than the SE to the female rats in the mate preference test. IBA-1 expression was found to be decreased in the hypothalamus of EE rats compared to SE group. Infusion of a microglia inhibitor reduced percentage of forward in SE rats in the SDTT. Infusion of DNA methyltransferase inhibitor prevented the development of subordinate status in EE rats and restored the expression of IBA-1 in the hypothalamus. CONCLUSIONS: The results suggest that early EE did not lead to reduced social hierarchy in the male rat. However, EE caused a reduction in the percentage of forward in the SDTT, which might be associated with reduced number of microglia in the hypothalamus.
Subject(s)
Social Dominance , Social Environment , Animals , Animals, Newborn , Blotting, Western , Calcium-Binding Proteins/metabolism , Competitive Behavior , Female , Hierarchy, Social , Hypothalamus/physiology , Immunohistochemistry , Male , Microfilament Proteins/metabolism , Microglia/physiology , Rats , Rats, Sprague-Dawley , Social BehaviorABSTRACT
OBJECTIVE: To explore the effect on radiosensitivity of arsenic trioxide (As203) in conjunction with hyperthermia on the esophageal carcinoma EC-1 cell line. METHOD: Inhibition of EC-1 cell proliferation at different concentrations of As203 was assessed using the methyl thiazolyl blue colorimetric method (MTT method), with calculation of IC50 value and choice of 20% of the IC50 as the experimental drug concentration. Blank control, As203, hyperthermia, radiotherapy group, As203 + hyperthermia, As203 + radiotherapy, hyperthermia + radiotherapy and As203 + hyperthermia + radiotherapy groups were established, and the cell survival fraction (SF) was calculated from flat panel colony forming analysis, and fitted by the 'multitarget click mathematical model'. Flow cytometry (FCM) was used to detect changes in cell apoptosis and the cell cycle. RESULTS: As203 exerted inhibitory effects on proliferation of esophageal carcinoma EC-1 cells, with an IC50 of 18.7 µmol/L. After joint therapy of As203 + hyperthermia + radiotherapy, the results of FCM showed that cells could be arrested in the G2/M phase, and as the ratio of cells in G0/G1 and S phases decreased, cell death became more pronounced. CONCLUSION: As203 and hyperthermia exert radiosensitivity effects on esophageal carcinoma EC-1 cells, with synergy in combination. Mechanistically, As203 and hyperthermia mainly influence the cell cycle distribution of EC-1 esophageal carcinoma cells, decreasing the repair of sublethal damage and inducing apoptosis, thereby enhancing the killing effects of radioactive rays.