Inflammatory markers are associated with inhibitory avoidance memory deficit induced by sleep deprivation in rats

► Memory deficit and weight loss are classic consequences of sleep deprivation in rats. ► Sleep deprivation increases the levels of many inflammatory mediators. ► LPS attenuated the memory deficit in the inhibitory avoidance task. ► Anti-IL-6 antibody did not alter animal performance in the inhibitory avoidance task. ► Anti-IL-6 attenuated the weight loss of the sleep-deprived rats. Sleep deprivation (SD) causes detrimental effects to the body, such as memory impairment and weight loss. SD also changes the concentration of inflammatory mediators such as cytokines, which, in turn, can affect cognitive functioning. Thus, the objective of this study was to investigate the involvement of these inflammatory mediators in inhibitory avoidance memory deficit in sleep-deprived rats. Male Wistar rats were deprived of sleep by the modified multiple platform method for 96 h, while their respective controls remained in their housing cages. To assess memory after SD, all animals underwent training, followed by the inhibitory avoidance task test 24 h later. Also, the weight of each animal was recorded daily. In the first experiment, animals received an acute administration of lipopolysaccharide (LPS, 50 or 75 μg/kg i.p.) 3 h before the inhibitory avoidance training. In the experiment 2, the animals received acute or chronic administration of anti-IL-6 antibody (Ab, 2 μg/kg i.p.). The acute administration was performed 3 h before the inhibitory avoidance training, while the chronic treatment administrations were performed daily during the SD period. The 75 μg/kg dose of LPS, but not the 50 μg/kg dose, caused a significant attenuation of memory impairment in the sleep-deprived animals. Although the treatments with the anti-IL-6 Ab did not produce any significant changes in cognitive performance, the Ab attenuated weight loss in sleep-deprived animals. Taken together, these results suggest the involvement of inflammatory mediators in the modulation of memory deficit and weight loss that are observed in sleep-deprived rats.