Melatonin Protects Mouse Type A Spermatogonial Stem Cells against Oxidative Stress via The Mitochondrial Thioredoxin System.

OBJECTIVE: Mitochondrial oxidative stress is an important factor in infertility. The mitochondrial thioredoxin system plays an important role in this condition. N-acetyl-5-methoxy tryptamine (melatonin) plays a role in reducing oxidative stress and apoptosis in spermatogonial stem cells (SSCs). In this study, we explore the probable protective effects of melatonin on the mitochondrial thioredoxin system [thioredoxin 2 (Trx2)/Txnip] in SSCs under oxidative stress. MATERIALS AND METHODS: In this experimental study, SSCs were co-cultured two-dimensionally (2D) with Sertoli cells in DMEM culture medium that contained 10% fetal bovine serum (FBS), 1% antibiotics, and 10 ng/ml glial cell-derived neurotrophic factor (GDNF) for 30 days. The cultured cells were subsequently divided into four groups: control; melatonin (250 µM, 24 hours); melatonin (250 µM, 24 hours)+hydrogen peroxide (H2O2, 50 µM, 24 hours); and H2O2 (50 µM, 24 hours). Intracellular reactive oxygen species (ROS) production was determined by flow cytometry. Malondialdehyde (MDA) levels were measured by Fluorometry. The expressions of apoptotic and antioxidant genes and nuclear factor erythroid 2-related factor 2 (Nrf2), Trx2, and nicotinamide nucleotide transhydrogenase (NNT) proteins were determined by quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot. Adenosine triphosphate (ATP) levels were measured by fluorometry. RESULTS: Melatonin reduced H2O2-induced ROS levels and apoptosis in the SSCs. Melatonin also increased mRNA expression of Nrf2, Trx2, NNT, Sirtuin 3 (Sirt3), and decreased mRNA expression of Txnip, and increased protein expressions of Nrf2, Trx2, NNT thereby increasing activity of the mitochondrial thioredoxin system. In addition, melatonin increased ATP levels. CONCLUSION: Melatonin increased Trx2 expression through the Nrf2 pathway. This study suggests that melatonin may protect SSCs from oxidative stress in diseases related to infertility.

Overview of biological effects of melatonin on testis: A review.

Infertility is a major global health issue and male factors account for half of all infertility cases. One of the causes of male infertility is the loss of spermatogonial stem cells, which may occur because of chemotherapy, radiotherapy or genetic defects. In numerous animal species, the evidence suggests the pineal gland and melatonin secretion in their reproductive activities are involved. Recently, considerable attention has pointed to the usage of melatonin in the treatment of diseases. Melatonin is associated with the regulation of circadian and seasonal rhythmic functions, immune system functions, retinal physiology, spermatogenesis and inhibition of tumour growth in different species. Several studies demonstrated that melatonin acts as an anti-apoptotic, anti-inflammatory, anticancer and antioxidant agent. Melatonin can also protect testicles and spermatogonia against oxidative damage, chemotherapy drugs, environmental radiation, toxic substances, hyperthermia, ischemia/reperfusion, diabetes-induced testicular damage, metal-induced testicular toxicity, improve sperm quality and it affects the testosterone secretion pathway by affecting Leydig cells. Therefore, the objective of this study is to investigate the biological effects of melatonin as a natural antioxidant on testicles and their disorders.

Evaluating Chondroitin Sulfate and Dermatan Sulfate Expression in Glial Scar to Determine Appropriate Intervention Time in Rats.

INTRODUCTION: The proteoglycans of the extracellular matrix increases in the glial scar during spinal cord injury and significantly affects the inhibition of axonal regeneration. METHODS: The results of injury therapies are limited due to the lack of identifying a timely therapeutic intervention. The present study aimed to investigate the glial scar Chondroitin Sulfate (CS) and Dermatan Sulfate (DS) levels at different post-injury times to determine the appropriate time for therapeutic intervention. RESULTS: By this experimental study, 72 Wistar rats were randomly divided into 12 groups, as follows: control, sham, injured animals at 1, 2, 4, and 8 days, as well as 2, 4, 8, 12, 16, and 20 weeks post-injury. The animals in the injured groups were contused in the T10 segment of the spinal cord. The motor function of animals was assessed using the Basso, Beattie, and Bresnahan (BBB) test. Besides, the histological assessment was performed using Luxol Fast Blue and Bielshovisky Staining. The CS and DS levels of lesions were measured using the Enzyme-Linked Immunosorbent Assay (ELISA) method. CONCLUSION: The motor function assessment indicated a relative recovery over time. Histological results confirmed some regeneration in the injury site at 20 weeks post-injury. The ELISA results demonstrated a much higher level of DS than that of CS in the glial scar. Considering high levels of DS, compared to CS in the glial scar and its reduction from second weeks after SCI onwards, the second week after SCI seems to be the best time for therapeutic interventions in terms of scar permeability.