[The effect of melatonin as anti-convulsant and neuron protector]

Melatonin is the principal hormone secreted by the pineal gland. In human beings the pineal gland is found on the posterior aspect of the midbrain. Melatonin is synthesized from tryptophan following a circadian rhythm, with low levels during the day and high levels during the night. It regulates many biological processes in relation to the cycles of light and darkness.

Its first known function was that of inducing sleep. In experimental animals its effect as a depressor of the central nervous system and its anti-convulsive action have been shown. Few studies have been done in human beings, although there is some evidence of its beneficial effect in epileptic patients, improving both the frequency of the crises and the EEG tracing. In our experience we gave melatonin to a girl with severe myoclonic epilepsy which did not respond to usual treatment, obtaining improvement in both the number of crises daily and in psycho-motor development. Several possible modes of action have been described for melatonin; increase in Gabaergic transmission at a cerebral level, where GABA is the main inhibitory neurotransmitter; interaction with benzodiazepinic cerebral receptors; it may owe its effect to the activity of its metabolites, particularly kinurenic and kinurenic acid; it may induce hormone changes in the organism. Recent studies show the marked anti-oxidant activity of melatonin. Its considerable capacity to accept free radicles resulting from biological processes has been shown and it thus acts as a cell protector.

It seems reasonable to assume that melatonin has anticonvulsant and neuroprotector properties. Further study may define its pharmacological usefulness in these disorders.