The Effect of Melatonin in the Testes and Ovaries of Animal Models

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Addis Abeba University


Melatonin (N-acetyl-5-methoxytryptamine) is a neurohormone synthesized and secreted primarily by the pineal gland during the dark hours at night. Other tissues and cells are also involved in its synthesis in the retina, gastrointestinal tract, lymphocytes and the skin. There has been increasing evidence that extrinsic doses of melatonin cause certain pharmaceutical, biochemical and physiological effects on the mammalian genital organs (such as in the testes and ovaries). It has an inhibitive effect on hypothalamus-hypophysis-gonads system. Furthermore, it increases the secretion of opioid peptides, which in turn decrease the secretion of gonadotropin-releasing hormone (GnRH). This project paper is designed to review and discuss scientific research articles regarding the effect of melatonin on the testes and ovaries of animal models. For these purpose different animal models, different time of exposure and different doses of melatonin administration was employed. As a result, the experimental animals treated with melatonin displayed inhibited spermatogenesis, tubular degeneration and necrosis, obstruction in tubular lumen and lymphocytic infiltration. In addition, melatonin administration caused marked reductions in absolute and relative testicular weight, size, serum testosterone concentration, atretic follicles and sperm of experimental animals. Though there was no difference in ovarian volume and relative ovarian weights, a differential count of various follicles has revealed significantly higher number of primordial, primary, secondary and antral follicles in melatonin treated rats. In the 90-day-old ovary, there was almost double the number of corpora lutea between control and melatonin programmed rats. Moreover, the histological effect of the testicular and ovarian damage increased with increased dosage of melatonin administration and with increased days after exposure to different doses of melatonin. Keywords: Antral follicles, Atretic follicles, Corpora lutea, Melatonin, Ovaries, spermatogenesis, Testes.



Antral follicles, Atretic follicles, Corpora lutea, Melatonin, Ovaries, Spermatogenesis, Testes