Investigation of the effects of sleep disorders on the hippocampal mediated learning and memory in rats

In this study, the effects of sleep disorders on the hippocampus mediated learning and memory were investigated. forty-eight sprague-dawley male rats in total, weighing 320-360 g were divided into 4 groups including control group (c) (n=12), the rem deprivation group (rd) (n=12), total sleep deprivation group (sd) (n=12) and sleep fragmentation group (sf) (n=12). rats were subjected to swimming training in the morris water maze float assembly (learning period) for 4 times a day for 5 days period. at the 6th day sleep disorders were begun to be implemented and sleep disorders were created for the sd group in the course of 3 days and for the rd and sf groups for 7 days. probe test was applied to the animals for a period of 60 seconds by removing the platform from the assembly. visible platform test was conducted 1 day prior to experiment and 3rd days to the sd group and 1 day prior to experiment and 7th days to the rd and sf groups. as the parameters of memory; swim period (sec) at the platform quadrant (2nd quadrant, target quadrant) swim distance (cm) at the platform quadrant (2nd quadrant, target quadrant), average swim speed (cm/sec), total swim distance (cm), and swimming time (sec) at the outer quadrant were evaluated. for all groups, statistically significant disturbances in the memory patterns were recorded (p<0.05). at the end of the experiment hippocampus tissues were removed and the levels of glutamate, serotonin, acetylcholine, and 8-oh-2’-deoxyguanosine were determined by means of elisa test, glutamatergic nr2a, nr2b, nachr-α7 nicotinic cholinergic and serotonergic 5-ht2a receptor expressions were measured by using western blot analysis, and the levels of no, tbars, ca2+, mg2+ and na+ were measured by a colorimetric method. glutamate levels were found to be significant in sd and rd, sd and sf groups and an increase was observed in rd and sf (p< 0.05). serotonin levels were found to be statistically significant between c and sd, sd and rd, and sd and sf (p< 0.05); while serotonin levels decreased in sd group comparing with control group, they increased in rd and sf groups comparing with sd group. in terms of 5-ht2a receptor expression, significant relationships were found in c and sd, c and rd and c and sf (p< 0.05) and comparing with the controls the expression rates increased. in terms of mg2+ level, statistically significant relationship was detected between c and sf, and it decreased in the sf group (p< 0.05). weights were found to be statistically significant in sd and rd groups (p< 0.05) and the weights gradually diminished. as a conclusion, it can be said that serotonin levels and expressions of serotonin 5-ht2a receptors increased in sleep disorders. compansation of the impairment mechanisms related with memory was realized by this receptor. we conclude that in sleep disorders, serotonin reuptake inhibitor drugs (ssris) and 5-ht2a receptor agonists could be used.