Transcriptional Activity of Genes Regulating Neurogliogenesis and Apoptosis in Rats Trained in Morris Water Maze: the Influence of Stress and Spatial Memory Formation

The formation of new neural networks and the modification of pre-existing synaptic contacts underlying learning and memory, largely depend on the transcriptional activity of genes involved in the regulation of associated processes of neurogliogenesis and apoptosis. At the same time, the identification of changes in genome activity, specific to cognitive functions, requires a stressor appraisal as an integral component of all learning models in laboratory animals. The aim of the present study was to compare the expression of genes regulating neurogliogenesis (S100a6, Ascl1) and apoptosis (Apaf1, Bax, Casp3, Bcl2) in animals trained for a spatial skill in the Morris water maze (MWM) and exposed to forced swimming in accordance with the training regimen. Experiments were conducted on young adult male Wistar rats divided into the following groups: Training (rats trained to find a hidden platform in the MWM over 4 days), Control (rats forced to swim in the MWM without a platform over 4 days), and Naïve (rats remaining in home cages). In hippocampal, frontal cortex, and cerebellar tissues sampled 24 h after the end of MWM experiments, the expression of the above genes was determined via a real-time polymerase chain reaction. It was found that cognitive activity reduces the expression of pro-apoptotic genes, which increases under stress conditions, and conversely, stimulates the activity of genes regulating neurogliogenesis and synaptogenesis in structures relevant to various stages of memory trace formation. The obtained results, along with their theoretical contribution, are of interest for identifying targets for the goal-directed therapy of cognitive impairments.