Low-dose testosterone treatment decreases oxidative damage in TM3 Leydig cells

Abstract

Testosterone replacement therapy has benefits for aging men and those with hypogonadism. However, the effects of exogenous testosterone on Leydig cells are still unclear and need to be clarified. In this report, we demonstrate that testosterone supplementation can reduce oxidative damage in Leydig cells. The TM3 Leydig cell line was used as an in vitro cell model in this study. Cytoprotective effects were identified with 100-nmol l 21 testosterone treatment, but cytotoxic effects were found with o500-nmol l 21 testosterone supplementation. Significantly reduced reactive oxygen species (ROS) generation, lipid peroxide contents and hypoxia induction factor (HIF)-1a stabilization and activation were found with 100-nmol l 21 testosterone treatment. There was a 1.72-fold increase in ROS generation in the 500-nmol l 21 compared to the 100-nmol l 21 testosterone treatment. A 1.58-fold increase in steroidogenic acute regulatory protein (StAR) expression was found in 50-nmol l 21 testosterone-treated cells (P,0.01). Chemically induced hypoxia was attenuated by testosterone supplementation. Leydig cells treated with low-dose testosterone supplementation showed cytoprotection by decreasing ROS and lipid peroxides, increasing StAR expression and relieving hypoxia stress as demonstrated by HIF-1a stabilization. Increased oxidative damage was found with o500-nmol l 21 testosterone manipulation. The mechanism governing the differential dose effects of testosterone on Leydig cells needs further investigation in order to shed light on testosterone replacement therapy. INTRODUCTIONTestosterone plays an important role in normal growth and development of male sex organs. It is also known to be a key player in glucose homeostasis and lipid metabolism. 1 More recently, gonadotrophinreleasing hormones I and II were demonstrated to stimulate testosterone production in murine Leydig cells. 2 In the testes, Leydig cells synthesize and secrete testosterone in response to luteinizing hormone, which is counter-regulated by feedback influences of testosterone and its metabolites. Testosterone levels notably decline with aging; 3,4 however, a recent report showed no correlation between androgen receptor (AR) polymorphism and the serum concentrations of total and free testosterone in elderly men. 5 The mechanism by which aged Leydig cells lose their steroidogenic function remains unclear. It was proposed that decreases in testosterone levels with aging may reflect reactive oxygen species (ROS) elevation and further disruption of the ability of Leydig cells to produce testosterone. 6,7 Mitochondrial respiration, which typically consumes about 90% of the oxygen utilized by cells, is considered to be the major source of cellular ROS. 8 ROS cause tissue damage by a variety of mechanisms including DNA damage, lipid peroxidation, protein oxidation and carbonylation, depletion of cellular thiols and activation of proinflammatory cytokine release. Mitochondrial-derived ROS were implicated in a number of disease and disorders, including neurodegenerat...

Vildagliptin reduces cardiac ischemic-reperfusion injury in obese orchiectomized rats

“…In addition, low testosterone levels and obese insulin resistance are known as risk factors of cardiac dysfunction (Culic & Busic 2015) due mainly to increased oxidative stress (Hwang et al 2011) in the heart, and leading to depressed HRV (Brook et al 2010). Moreover, previous studies found the association of low testosterone and the increase in the reactive oxygen species (ROS) level (Pongkan et al 2015(Pongkan et al , 2016.…”

“…Although previous studies demonstrated that either testosterone or vildagliptin exerted beneficial effects on cardiac function in HFO and NDO groups in a testosterone-deprived model (Pongkan et al 2015), obese-insulin resistance model (Apaijai et al 2012(Apaijai et al , 2014 and testosterone-deprived with obese-insulin resistance model (Francomano et al 2014), our study is the first to compare the efficacy of testosterone replacement and vildagliptin for their cardioprotection. Regarding the effects of testosterone replacement and vildagliptin on the suppression of mitochondrial ROS production and apoptosis, previous studies demonstrated that either testosterone (Hwang et al 2011, Zhang et al 2013, Pintana et al 2015 or vildagliptin (Avila Dde et al 2013, Apaijai et al 2014 could effectively reduce ROS generation and suppressed oxidative stress. In addition, Alessandro and coworkers reported that testosterone decreased ROS production by binding to cytoplasmic androgen receptor (AR) and promoting its translocation to the nucleus, resulting in enhanced extracellular matrix (ECM) production via the transcription-inducing complex c-FOS/c-JUN (Bertolo et al 2014).…”

Chronic Testosterone Replacement Exerts Cardioprotection against Cardiac Ischemia-Reperfusion Injury by Attenuating Mitochondrial Dysfunction in Testosterone-Deprived Rats

“…This result is consistent with a previous clinical report in men with stable coronary artery disease (CAD) which demonstrated that a high level of blood testosterone was associated with reduced sympathovagal imbalance [ 37 ]. Since depressed HRV is known to be associated with increased oxidative stress [ 38 , 39 ] and that testosterone deprivation has been shown to affect the antioxidant defense system in the left ventricle (LV) [ 40 ] and associated with the increased oxidative stress [ 41 , 42 ], testosterone replacement could play a crucial role in the protection of cardiac sympathovagal imbalance by reducing the oxidative stress and the enhancing of the antioxidant defense system. This hypothesis is supported by the findings of this study that ORX rats had increased cardiac mitochondrial ROS production, and testosterone attenuated ROS level.…”

Chronic stress induces ageing-associated degeneration in rat Leydig cells

“…46 Additionally, low-dose testosterone treatment can decrease ROS production and subsequent oxidative damage in Leydig cells in vitro. 47 ROS generated both from normal metabolism and in the process of steroidogenesis in Leydig cells, followed by ageassociated degeneration and testicular steroidogenesis inhibition. Consistent with previous reports, we showed that ROS levels were increased in Leydig cells from aged rats.…”