ULTRASTRUCTURAL CHANGES OF THE PINEAL GLAND IN EPILEPSY

Abstract

Circadian mechanisms modulate neuronal excitability at several levels, and their destruction can cause excessive uncontrolled excitability. Previous studies have shown that epilepsy is associated with melatonin levels. Melatonin is a powerful chronobiotic secreted from the pineal gland; helps to maintain normal circadian rhythms and is used to treat some neurological and psychiatric disorders. Circadian rhythms and sleep/wake mechanisms play role in the epilepsy. Melatonin deficiency can decrease seizure threshold, and hence could increase seizure activity. The aim of the study was to identify ultrastructural changes in the pineal gland in an experimental model of epilepsy. Materials and methods. The experiment was carried out on Wistar rats, 5-6 months of age, weight of about 200 g, 36 experimental and 10 control animals. Electrically provoked experimental epileptic seizures model in rats was reproduced. The rats developed spontaneous generalized seizures after 9-14 stimulations. Material for histological examinations was taken after stable formation (for >1 month) of repeated seizures. Ultrathin sections, after contrast with Reynolds lead citrate, were studied under an electron microscope at an accelerating voltage of 75 kV. The increase was selected adequate to the study and ranged from 20,000 to 60,000 times. Results. Experimental studies have confirmed the presence of stable dystrophic, up to apoptosis of some cells, morphological changes of the pineal gland in the experimental model of epilepsy in rats, which is the reason for the decrease in its functional activity. Conclusions. Our experimental data on the morphological changes of the pineal gland confirm the conclusion about a stable, possibly irreversible, decrease in gland function in epilepsy due to damage and disruption of the structure of its cells. Given the polyfunctionality of melatonin, its deficiency can be one of the causes of changes in neural networks, impaired permeability of synaptic membranes, and as a consequence, increased epileptic activity of neurons.