Electron microscopic study on the effects of melatonin on early spennatids in the rat testis

Abstract

Melatonin is a neuroendocrine hormone secreted principally at night by pineal gland and regulates biological rhythms. Exogenous melatonin is used as a potential treatment for insomnia, sleep disorders and depression. The present investigation was undertaken to characterize the morphological defects in spennatids during early phases of spermiogenesis in melatonin-treated rats using electron microscopy. A single melatonin dose of either 0.05 or 0.1 mg kg-1 body weight was orally administrated to adult rats. They were killed either 2 or 10 days post-treatment. The primary defects were the fragmentation of the head caps, abnormal vesicles that failed to fuse to developing acrosomes, lack of acrosomic granules and disruption of golgi apparatus. In later stages, cytoplasmic vacuolization and mitochondrial and nuclear malformation were apparent. These changes were particularly prominent with the higher dose and the longer post-treatment interval. The results indicate that the treatment of rats with the exogenous melatonin produces a variety of acrosomal abnormalities as well as other cellular changes during early spermiogenesis. The possible mechanisms leading to these melatonininduced morphological defects in early spermatids are discussed. © Medwell Journals, 2011.