MODERATE ANTICONVULSANT ACTION OF BACLOFEN DOES NOT CHANGE DURING DEVELOPMENT

The possible anticonvulsant action of baclofen, a GABAB (gamma-aminobu tyric acid) receptor agonist, was studied using two types of motor sei zures (minimal, clonic and generalized tonicoclonic) elicited by penty lenetetrazol in adult rats and rat pups, 7, 12, 18, and 25 days old. I f baclofen was administered intraperitoneally (only in 12- and 25-day- old rats), no effect could be observed in 25-day-old animals. In 12-da y-old rats, only the 12-mg/kg dose led to a prolongation of the genera lized tonicoclonic seizure latency. Subcutaneous administration of bac lofen (3, 6, or 12 mg/kg 30 min before subcutaneous pentylenetetrazol injection) led to a moderate action against the tonic phase of general ized tonicoclonic seizures: the tonic phase of hind limbs was signific antly suppressed in all age groups, whereas total suppression of the t onic phase was only outlined. Minimal, i.e., clonic, seizures with pre served righting ability were not influenced by baclofen. The conclusio n could be made that the anticonvulsant action of baclofen is dependen t on the model of seizures used and that there is no change of baclofe n action against pentylenetetrazol-induced seizures during postnatal d evelopment in rats.