RESUMEN
In the last decade, melatonin has gained recognition as a potent scavenger and an effective antioxidant capable of neutralizing free radicals, including reactive oxygen species. Additionally, it exhibits anti-apoptotic properties. In this review, we will examine a compilation of articles that explore the cellular signaling function of melatonin on spermatogonial stem cells (SSCs) and adjacent cells such as Sertoli and Leydig cells. These cells play a crucial role in the proliferation of SSCs both in vitro and in vivo. In this review, we analyze the function of melatonin in the proliferation of SSCs from other aspects. For this purpose, we examine the articles based on the presence of melatonin on SSCs in four groups: As a supplement in SSCs medium culture, SSCs three-dimensional culture system, SSCs freezing medium, and as a therapeutic factor in vivo. Mechanisms of growth and proliferation of SSCs were considered. The purpose of this study is to investigate the potential effects of melatonin as a powerful antioxidant or growth stimulant for SSCs, both in vivo and in vitro.
RESUMEN
PURPOSE: Polycystic ovary syndrome (PCOS) is the most common endocrine disorder of the reproductive system characterized by polycystic ovaries and androgen excess. Letrozole is a nonsteroidal aromatase inhibitor that is used in experimental research to induce PCOS. Kisspeptin is an essential protein in regulation of cyclicity. Kisspeptin receptor is expressed in the hypothalamus and pituitary glands, and kisspeptin containing neurons are affected from sex steroid hormones. We aimed to investigate the number of kisspeptin-positive cells in the arcuate (Arc) and anteroventral periventricular nuclei (AVPV) of hypothalamus in the letrozole-induced PCOS. METHODS: 40 female Wistar rats were divided into the proestrus control, diestrus control, proestrus vehicle, diestrus vehicle and letrozole. Animals were sacrificed after 3 weeks, and sera, ovary and brain samples were harvested for further evaluations. RESULTS: Letrozole group had high weight gain, high numbers of ovarian follicular cysts, high levels of luteinizing hormone and testosterone and increase number of kisspeptin-positive cells in the Arc nucleus, as compared with the control groups (P ≤ 0.05 vs. proestrus control and proestrus vehicle). Letrozole group showed a decrease in the number of kisspeptin-positive cells in the AVPV nucleus (P ≤ 0.05 vs. proestrus control and proestrus vehicle). CONCLUSION: Our findings show that the number of kisspeptin-positive cells may be affected from letrozole, and that the changes in the number of these cells may be in favor of the appearance of PCOS features in this group.