Effect of dexamethasone on the convulsive behavior induced by hyperthermia: Possible role of histamine

Febrile seizures are the most common seizure disorder in childhood and its prevalence is estimated to
be 2 to 5 percent. There is a relationship between the use of corticosteroids and seizures. This study investigated the
effects of dexamethasone pretreatment on convulsive behavior caused by hyperthermia.
Methods: In this study, 24 rats aged 19-20 days were divided into 3 groups (n=8) as control, hyperthermia and
dexamethasone. In the hyperthermia group, rats were placed in the chamber for 30 min and warm wind was blown on
them. In the dexamethasone group, the rats received intraperitoneal dexamethasone before hyperthermia. The body
temperature of the rats was continuously recorded via a rectal probe throughout the experiment. During 30 min of
hyperthermia, behavior of each rat was carefully observed and recorded. Blood sampling was done from the heart and
samples were used to measure histamine blood levels.
Results: All the rats that were exposed to hyperthermia showed convulsive behavior. Dexamethasone potentiated
seizure intensity and significantly increased the rate of tonic-clonic seizure (5.62±1.05 in dexamethasone and 1.37±0.46
in hyperthermia) (p=0.02). Hyperthermia decreased histamine blood levels and dexamethasone potentiated this
reduction (p<0.001).
Conclusion: At least one of the ways that hyperthermia leads to seizure is through the reduction of histamine blood
level. Since histamine has an anticonvulsant effect, reduction of histamine blood level is one reason of hyperthermiainduced
seizure. Dexamethasone leads to a deacrease in histamine blood level and potentiates hyperthermia-induced
seizure