Effects of withdrawal from long-term barbital treatment on open-field behaviour and seizure susceptibility of rats.

Rats withdrawn from long-term barbital treatment were tested both for their activity in an open-field and for their sensitivity to convulsant stimuli. Barbital withdrawal induced a significant increase on locomotion and rearing frequency. Drug removal also made the rats more sensitive to convulsions elicited by sound and maximal electroshock. A positive correlation was found between locomotion plus rearing frequency and audiogenic-induced seizures 3, 4 and 5 days after barbital withdrawal. The results show that exploratory behaviour evaluated through the open-field method can be used as a reliable method to show barbital withdrawal in rats. Taken together, the results suggest that long-term barbital treatment might develop a supersensitivity state, in noradrenergic neurons in the central nervous system.