The antioxidant defense system of isolated guinea pig Leydig cells

Abstract

Utilization of highly enriched preparations of steroidogenic Leydig cells have proven invaluable for studying the direct effects of various hormones and agents on Leydig cell function in vitro. However, recent work indicates that isolated Leydig cells are often subjected to oxygen (O2) toxicity when cultured at ambient (19%) oxygen concentrations. Because intracellular antioxidants play an important role in protecting cells against oxygen toxicity, we have investigated the intracellular antioxidant defense system of isolated Leydig cells. The cellular levels of several antioxidants including catalase, glucose-6-phosphate dehydrogenase (G-6-PDH), superoxide dismutase (SOD) of the Cu/Zn & Mn variety, glutathione peroxidase, glutathione reductase and total glutathione were quantitated using enriched populations of Leydig cells isolated from adult male guinea pig testes. Compared to whole testicular homogenates, Leydig cells contained significantly (P < 0.01) less G-6-PDH, total SOD, glutathione reductase and total glutathione, but significantly (P < 0.001) more glutathione peroxidase. Compared to hepatic values previously reported in the guinea pig, Leydig cells contain nearly 400 times less catalase, about 14 times less glutathione peroxidase and almost 11 times less glutathione reductase. Since G-6-PDH and glutathione reductase are both necessary to regenerate reduced glutathione (GSH) which couples with glutathione peroxidase to breakdown hydrogen peroxide (H2O2) under normal conditions, it is plausible that the oxygen toxicity observed in isolated Leydig cells is due to the intracellular accumulation of H2O2.(ABSTRACT TRUNCATED AT 250 WORDS)

Antioxidant system in rat testicular cells

“…Data on antioxidant enzyme activity in whole rat and guinea pig testes [31,50] have been previously reported. As compared to the liver, rat testes express equivalent SOD activity but only 5% of the GPx liver levels and 2% of the liver catalase activity [31].…”

“…As compared to the liver, rat testes express equivalent SOD activity but only 5% of the GPx liver levels and 2% of the liver catalase activity [31]. Testicular guinea pig SOD levels were found to be about twice as high as liver SOD in the same species, whereas GPx, GR and catalase were about 60, 5, 300 times less, respectively [50]. The previous studies on testicular tissues did not investigate the precise cellular distribution of these enzymatic activities.…”

Expression of Selenoprotein-P Messenger Ribonucleic Acid in the Rat Testis

“…However, in the testis, their activities are very low, 5% and 2%, respectively, as compared with activity in the liver (whereas the superoxide dismutase activity is similar) [5]. Similarly, in cultured guinea pig Leydig cells, lower activities of catalase, GPx, and glutathione reductase are observed, and these Leydig cells are susceptible to H 2 0 2 [4]. In contrast, high expression of PHGPx, which is an antioxidant against phospholipid peroxidation, is observed in the peripheral part of the cytoplasm, the nuclear membrane, and mitochondria in maturating spermatogenic cells in the rat testis [12].…”

Changes in the Plasma Testosterone Level and Testicular Superoxide Dismutase Activity of 5 Azoospermic Beagles after GnRH Analogue Injections

“…High plasma levels of LH and FSH stimulate Leydig and Sertoli cells, respectively, in the testis. SOD has been reported that to be produced by both Leydig cells [8] and Sertoli cells [11]. The increase in SOD production in the testes of the AZ-dogs may have been directly caused by the high plasma LH and FSH levels or indirectly caused by the increase in T secretion by Leydig cells.…”

“…Superoxide dismutase (SOD) is known to be the most important antioxidant enzyme in seminal plasma [5], and SOD activity has been detected in canine seminal plasma [2]. Leydig [8] and Sertoli cells [11] have been reported to produce SOD in the testis. Low SOD activity in seminal plasma causes infertility in humans [14].…”