Scopolamine And Mifepristone After Reactivation Reverses Cage Changes Stress Induced Retrieval Impairment Of Novel Object Recognition Memory

The cage changes is routine operation to keep environment clean in animal feed. Because of the high sensitivity to environment, the rats generate abnormally behavioral and cardiovascular parameters with the changes from the habitual dirty cage to the clean one. So, the cage changes will be considered as a stress for the rats.We have explored the impacts of cage changes on consolidation of novel object recognition memory in SD and Wistar rats. The cage changes failed to impact the consolidation of the novel recogniton memory in SD and Wistar rats.We have explored the impacts of cage changes on reconsolidation of novel object recognition memory in SD and Wistar rats. The cage changes seem failed to impact the reconsolidation of the novel recogniton memory in SD and Wistar rats, and tend to disrupted the retrieval after reactivation. To determine the impacts of cage changes on reconsolidation and retrieval of the memory, we have executed Experiment 1.5. The cage changes failed to impact the reconsolidation of the memory, but disrupted the retrieval after reactivation. To determine the involvement of muscarinic receptor on the effects which induced by cage changes, we used system administration of scopolamine. The results indicate that scopolamine 0.5mg/kg and scopolamine 2.0mg/kg before cage change successfully block the impairment of the novel object recognition memory. To explore the mechanism of scopolamine before cage change block the impairment of the novel object recognition memory, we have conducted Experiment 2.2 and 2.3. The results indicate that, the scopolamine failed to impact the reconsolidation of the novel recogniton memory, indicated that scopolamine block the impairment of the memory which induced by cage changes not through enhance the reconsolidation. To assess whether scopolamine 2mg/kg enhances the novel object recognition memory through consolidation, we have designed Experiment 2.4 and Experiment 2.5.The results indicate that, the scopolamine disrupted the consolidation of the novel recogniton memory, indicated that scopolamine block the impairment of the memory which induced by cage changes not through enhance the consolidation. To determine the the effects of scopolamine on locomotor activity of the Wistar rats, we have executed Experiment 3.6, and found that scopolamine has not affect locomotor activity of the rats. To determine the involvement of glucocorticoid receptor on the effects which induced by cage changes, we used system administration of mifepristone in Experiment 3. The results indicate that mifepristone 20mg/kg before cage change successfully block the impairment of the novel object recognition memory. Together, our results suggest that cage changes specifically impair the retrieval after reactivation, and administration of scopolamine or mifepristone before cage change can block the impairment of the novel recognition memory.