Mitochondrial Function in Leydig Cell Steroidogenesis

Abstract

The first and rate-limiting step in the biosynthesis of steroid hormones is the transfer of cholesterol into mitochondria, which is facilitated by the steroidogenic acute regulatory (StAR) protein. Recent studies of Leydig cell function have focused on the molecular events controlling steroidogenesis; however, few studies have examined the importance of the mitochondria. The purpose of this investigation was to determine which aspects of mitochondrial function are necessary for Leydig cell steroidogenesis. MA-10 tumor Leydig cells were treated with 8-bromo-cAMP (cAMP) and site-specific mitochondrial disrupters, pro-oxidants, and their effects on progesterone synthesis, StAR expression, mitochondrial membrane potential (delta psi(m)) and ATP synthesis were determined. Dissipating delta psi(m) with CCCP inhibited progesterone synthesis, even in the presence of newly synthesized StAR protein. The electron transport inhibitor antimycin A significantly reduced cellular ATP, inhibited steroidogenesis, and reduced StAR protein expression. The F0/F1 ATPase inhibitor oligomycin reduced cellular ATP and inhibited progesterone synthesis and StAR protein expression, but had no effect on delta psi(m). Disruption of pH with nigericin significantly reduced progesterone production and StAR protein, but had minimal effects on delta psi(m). Sodium arsenite at low concentrations inhibited StAR protein but not mRNA expression and inhibited progesterone without disrupting delta psi(m). The mitochondrial Ca2+ inhibitor Ru360 also inhibited StAR protein expression. These results demonstrate that delta psi(m), ATP synthesis, delta pH and [Ca2+]mt are all required for steroid biosynthesis, and that mitochondria are sensitive to oxidative stress. These results suggest that mitochondria must be energized, polarized, and actively respiring to support Leydig cell steroidogenesis and alterations in the state of mitochondria may be involved in regulating steroid biosynthesis.

Antioxidant Systems and Oxidative Stress in the Testes

“…At the level of the isolated spermatozoon, ROS attack can induce lipid peroxidation and DNA fragmentation disrupting both the motility of these cells and their ability to support normal embryonic development. [176][177][178][179][180][181][182] At the level of the testes, oxidative stress is capable of disrupting the steroidogenic capacity of Leydig cells 183 as well as the capacity of the germinal epithelium to differentiate normal spermatozoa. 184 A large number of independent clinical studies have demonstrated a correlative relationship between male infertility and evidence of oxidative stress in the ejaculate.…”

Therapeutic effects of quercetin against bisphenol A induced testicular damage in male Sprague Dawley rats

“…Subcutaneous administration of adult male rats with a dose of 3 mg BPA/kg/bw per day significantly lowered the level of testosterone (T) and elevated the level of luteinizing hormone (LH) in both serum and testis [Sun et al 2006]. At the testicular level, oxidative stress caused disruption of steroidogenic activity of Leydig cells [Hales et al 2005]. Some activities of BPA are attributed to its ability to bind to membrane estrogen receptors [Alonso-Magdalena et al 2005;Watson et al 2005;Alonso-Magdalena et al 2008] along with the G-protein coupled receptor 30 (GPR30) [Thomas and Dong 2006].…”

Black Grape Seed Extract Modulates Fluoxetine-Induced Oxidative Stress and Cytotoxicity in the Mouse Testis

“…It is believed that OS development negatively impacts fertilization rates and pregnancy outcomes through the sperm membrane and DNA damage, and the prevention of OS is vital for the preservation of normal reproductive function (8). Furthermore, at the testis level, OS is involved in steroidogenesis impairment and germinal epithelium differentiation disruption (9,10). Growing evidence demonstrates that the black grape (Vitis vinifera) and its seed possess a broad spectrum of pharmacological properties, including free-radical scavenging (11), antitumor (12), antifibrotic (13), anti-apoptotic (14), and anti-inflammatory activities (15).…”