Differential changes in the quantity of the hippocampal glial connexins mRNAs during memory consolidation

Introduction:It is known that glial cells are crucial for memory formation.Glial cells and neurons interconnect via gap junction channels made of connexin (Cx) proteins.Glial connexins were shown to be involved in memory formation.However, the expression profile of different glial connexins was not measured during memory consolidation.Cx43 and Cx30 are expressed in astrocytes, whereas Cx32 is expressed in oligodendrocytes.We quantified the messenger RNA (mRNA) levels of the hippocampal Cx30, Cx32, and Cx43 throughout the consolidation stage of fear or spatial memory.Methods: Male Wistar rats were distributed into eight groups of four each.To assess the spatial or fear memory consolidation, the Morris water maze and passive avoidance task were utilized.At different time intervals (one, three, and twenty-four hours) following the training sessions, rats were sacrificed and the hippocampi were isolated and frozen instantly in liquid nitrogen.A quantitative real-time polymerase chain reaction (PCR) was employed to measure mRNA levels of the target genes. Results:The results revealed that Cx43 and Cx32 downregulated significantly, one or three hours after training in the inhibitory avoidance model.In the Morris water maze, Cx43 expression was upregulated three hours after training.The expression of Cx30 did not exhibit significant alterations in either of the experimental assays. Conclusion:The results indicate the crucial, but differential role of the hippocampal Cx32 and Cx43 during fear or spatial memory consolidation.The exact outcomes of these potential changes need to be clarified.