Memory changes in rats following repeated blast-induced neurotrauma

Aim. To determine the characteristics of memory changes in associative and spatial memory in the dynamics of repeated blast-induced neurotrauma (rBINT) in rats. Materials and methods. The study was conducted on 36 sexually mature male rats, in accordance with the current legislation on the humane treatment of animals. The selected rats were randomly divided into 2 groups for assessment using the conditioned passive avoidance response (CPAR) test (I) and the Barnes maze (II). In each of these groups, three subgroups were formed: Experimental – subjected to 3-fold exposure to a blast wave with an excess pressure of 31.6 ± 4.8 kPa; Control – exposed only to halothane and fixation; Intact. The study was conducted on the 1st, 3rd, 7th, 14th, 21st and 28th days after the blast wave exposure. Results. Experimental reproduction of rBINT on the 1st, 3rd, 7th, 14th, 21st day showed a significant decrease in the time spent by rats in the light compartment in the CPAR test as compared to the control and intact groups, indicating a deterioration in associative memory. The study using the Barnes maze demonstrated significantly increased latency to find the target hole and the number of errors in experimental animals throughout the observation period as compared to the control and intact groups, indicating a deterioration in spatial memory. Conclusions. Experimental modeling of repeated blast-induced neurotrauma in rats has revealed a significant decrease in associative memory within the first 14 days after the exposure with partial recovery from day 21 to 28. Spatial memory remained impaired throughout the observation period, as evidenced by increased time to locate the hidden platform and the number of errors in the Barnes maze. The detected impairments suggest the impact of the blast wave on cognitive functions, and could be associated with hippocampal pathologies, neuroinflammation, and prefrontal cortex dysfunction.