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
pentylentetrazole (PM) 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 fiuphenazine-
induced parkinsonism in rats. The beneficial effect of the antiparkinsonian
drug benztropine was , also, deceased by the concomitant administration
of melatonin. The concentrations of acetylcholine, dopamine
and GABA were ass yed in the thalamus, hypothalamus and the whole
brain of the control group as well as the experimentally two animal models.
It was concluded that melatonin has an antiepileptic 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 deceased
dopamine secretion.
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