The effec of melatonin hormone on hippocampus of pinealectomized rats

In this experiemntal study, hippocampus tissue samples from pinealectomized rats and melatonin applied rats after pinealectomy were researched.For this purpose, 21 male Wistar-Albino rats weighing about 200-250 gr were divided equally into three groups. Rats in group I were used as control (sham) while rats in group II were pinealectomized. The rats in group III were applied melatonin hormone every day 1mg/kg for three months after pinealectomy.At the end of the study, animals were decapitated and the whole brain were removed. The hippocampus tissues of the right brain hemispheres were used to determinate activities of superoxide dismutase (SOD), glutathion peroxidase (GSH-Px) and assignment of malondialdehyde (MDA) levels. Left brain hemispheres were stained with routine histological methods and examined under the light microscope. After pinealectomy operation, significantly decreasing was established in the SOD and GSH-Px enzyme activities of hippocampus, compared with the sham-control group. In addition to, MDA levels were significant increases in rats with pinealectomy when compared sham-control group. In the histological evaluation, tissue specimens of this group?s hippocampus CA1, CA2 and CA3 areas, a significant increase were detected the number of picnotic cells. In addition to this, increases were observed in the activities of SOD and GSH-Px enzymes and a decrease of MDA levels in pinealectomized rats plus melotonin was observed.In the histological evoluation of hippocampal CA1, CA2, and CA3 areas in brains from pinealectomized rats, significant increases in the number of picnotic cells were detected.Otherwise it was determined that increase of issue of picnotic cells were regressed after melatonin injections.The results of this biochemical and light microscopic examination revealed that pinealectomy induced oxidative tissue damage, histological changes and apoptosis were supressed by melatoninKey words: hippocampus, pinealectomy, melatonin, apoptosis, rat