The pineal gland hormone melatonin has been implicated in so
many diversified events from aging to aggression, from hibernation to
hypertension, from immunodeficiency to tumor growth, and from sleep
to stress. The present study was designed to explore the effect of
melatonin on experimentally two separate animal models of epilepsy and
parkinsonism. It was found that melatonin increased the epilepsy
threshold induced by pentylenetetrazole (PTZ) in mice. Melatonin also
potentiated the anticonvulsant effects of both Valproic acid and
phenobarbitone.
On the other hand, it was found that melatonin enhanced the
Fluphenazine-induced Parkinsonism in rats. The beneficial effect of the
antiparkinsonian drug Benztropine was also decreased by the
concomitant administration of melatonin. The concentrations of
acetylcholine, dopamine and GABA were assayed in the thalamus,
hypothalamus, and whole brain of the control group as well as in the
experimentally two animal models.
It was concluded that melatonin has an ant/epileptic effect which
may be due to its ability to accumulate GABA in the brain, while its
deteriorating effect in Fluphenazine-induced Parkinsonism in rats may
be due to decreased dopamine secretion.
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