Melatonin's role as an anticonvulsant and neuronal protector: experimental and clinical evidence.

The pineal gland classically has been considered as a vestigial and mystic organ. In the last decades, and with the incorporation of new methodologic procedures, it could be proved that it also has physiologic actions that vary depending on the level of the phylogenetic scale. Its best-known secretion, melatonin, has been related to many different actions, such as sleep promotion, control of biologic rhythms, hormonal inhibition, and an inhibiting action on central nervous system regulation mechanisms. In animal experimentation, there are papers even accepting an anticonvulsant effect. In humans, evidence is reduced to few experiences. In addition to this clinical experience, there is other evidence that clearly relates melatonin to convulsive phenomena. This relationship must be mediated by the following mechanisms attributed to melatonin: altered brain GABAergic neurotransmission, its known interaction with benzodiazepinic brain receptors, through tryptophan metabolite activity (kynurenine, kynurenic acid), or even by its efficacy as a free-radical scavenger.