Glucocorticosteroid-induced behavioral changes during endotoxinemia in rats

BACKGROUND: Experimental endotoxemia, based on the injection of lipopolysaccharide, is used to study systemic inflammation. Glucocorticosteroids, such as methylprednisolone and dexamethasone, play a key role in modulating inflammation. They affect inflammatory mediators and cellular components, penetrating the blood-brain barrier. However, the cerebral effects of glucocorticosteroids are not well studied. The assessment of behavioral changes induced by lipopolysaccharide and glucocorticosteroids using the “open field” test will help explore the neurobiological mechanisms of inflammation and stress.

AIM: Study of the effect of glucocorticosteroids on behavioral and physiological changes induced by experimental endotoxinemia in rats.

METHODS: Six groups of Wistar rats, 10 males in each group, were used in the experiment. The first group was injected once intraperitoneally with physiological solution, the second group was injected with lipopolysaccharide (1 mg/kg), the 3rd group was injected with i/p dexamethasone, 2 mg/kg; the 4th group was injected with i/p dexamethasone, 2 mg/kg, 2 h before lipopolysaccharide injection; the 5th group was injected with i/p methylprednisolone, 2 mg/kg; the 6th group was injected with i/p methylprednisolone, 2 mg/kg, 2 h before lipopolysaccharide injection. During the first 4 h of the experiment, deep body temperature of the rats was measured every 30 min and after 24 h to construct a temperature curve. At several time points, the behavior and locomotor activity of the rats were evaluated in the open-field test.

RESULTS: The results obtained demonstrate that lipopolysaccharide administration causes changes in behavioral patterns such as stance, minking, locomotion, act of grooming and frizzing. No differences were found in the effects of glucocorticosteroid depending on the drug. Application of glucocorticosteroid promotes restoration of motor activity of animals, elimination of negative effects of lipopolysaccharide.

CONCLUSION: The studied glucocorticosteroid drugs dexamethasone and methylprednisolone had comparable anti-inflammatory effect in terms of severity, caused normalization of body temperature and eliminated behavioral changes caused by lipopolysaccharide.