Beneficial effects of desacyl-ghrelin, hexarelin and EP-80317 in models of status epilepticus

It has been reported that ghrelin exerts anticonvulsive effects in models of epilepsy. In this study we aimed to characterize the anticonvulsive activity of ghrelin and other growth hormone secretagogue receptor 1a (GHSR1a) ligands in rats exposed to status epilepticus induced by pilocarpine or kainate. Firstly, in three independent experiments, before receiving pilocarpine (380 mg/kg, i.p.), rats were pretreated with one among ghrelin (1.5 mg/kg), desacyl-ghrelin (1.5 mg/kg), hexarelin (330 μg/kg), EP-80317 (330 μg/kg), JMV-1843 (330 μg/kg), JMV-2959 (330 μg/kg) or saline. Secondly, in the fourth experiment, rats were pretreated with i.p. ghrelin, desacyl-ghrelin, hexarelin, EP-80317 or saline, followed by kainate (15 mg/kg, i.p.). We evaluated: induction of generalized seizures, latency to generalized seizures, status epilepticus, latency to status epilepticus (the time lag between the first tonic-clonic convulsion and the switch to continuous seizures) and mortality. In the pilocarpine model, 60% of rats pretreated with EP-80317 (P < 0.05) showed no seizure. Hexarelin and EP-80317 were both able to prevent progression to status epilepticus in pilocarpine-treated rats (P < 0.05). When status epilepticus was induced by kainate, seizures developed with few exceptions. However, latency to status epilepticus was significantly (P < 0.01) longer in rats pretreated with desacyl-ghrelin, whereas hexarelin and EP-80317 did not display any effect. Almost all GHSR1a ligands prevented pilocarpine-induced mortality, which was observed only in rats pretreated with saline or JMV-2959. After kainate administration, all rats survived to status epilepticus. These findings demonstrate that desacyl-ghrelin, hexarelin and EP-80317 but not other GHSR1a ligands display relevant anticonvulsive properties in models of limbic seizures.