The effect of streptozotocin induced diabetes on sperm function: a closer look at AGEs, RAGEs, MAPKs and activation of the apoptotic pathway

Omolaoye Temidayo S.,Du Plessis Stefan S. 한국독성학회 2021 Toxicological Research Vol.37 No.1

This study was designed to (1) investigate the possible mechanisms through which diabetes-induced advanced glycation end products (AGEs) and receptor for AGEs (RAGE) activation can affect male reproductive function; and (2) corroborate the interaction of previously established independent pathways. Male albino Wistar rats (14-weeks old) weighing 250–300 g received either a single intraperitoneal injection of streptozotocin (30 mg/kg or 60 mg/kg), represented as STZ30 or STZ60 respectively, or citrate buffer (control). Diabetes mellitus (DM) was confirmed if plasma glucose levels were ≥ 14 mmol/L after 1 week. Animals were sacrificed after 8 weeks of treatment by an overdose of sodium pentobarbital (160 mg/kg body weight). The testes and epididymides were harvested. The testes were used for biochemical and Western blot analysis, while sperm was retrieved from the epididymis and analysed with computer-aided sperm analysis. The blood glucose levels of STZ60 animals were above the cut-off point and hence these animals were regarded as diabetic. Diabetic animals presented with a non-significant increase in AGE and RAGE expression. Diabetic animals showed a significant increase in the expression of cleaved caspase 3 compared to control (p < 0.001), and these animals also presented with an increase in the expression of JNK (p < 0.05), PARP (p = 0.059) and p38 MAPK (p = 0.1). Diabetic animals also displayed decreased catalase activity accompanied by a non-significant increase in malondialdehyde levels. Additionally, there was a significant decrease in the percentage of progressively motile spermatozoa (p < 0.05) in diabetic animals. This study has shed some light on the interplay between DM, AGE, RAGE and mitogen-activated protein kinase signalling in the testes of diabetic rats, which can result in altered sperm function and contribute to male infertility. However, more studies are needed to better understand this complicated process.

Effect of Oxidative Stress on Male Reproduction

Ashok Agarwal,Gurpriya Virk,Chloe Ong,Stefan S du Plessis 대한남성과학회 2014 The World Journal of Men's Health Vol.32 No.1

Infertility affects approximately 15% of couples trying to conceive, and a male factor contributes to roughly half of these cases. Oxidative stress (OS) has been identified as one of the many mediators of male infertility by causing sperm dysfunction. OS is a state related to increased cellular damage triggered by oxygen and oxygen-derived free radicals known as reactive oxygen species (ROS). During this process, augmented production of ROS overwhelms the body’s antioxidant defenses. While small amounts of ROS are required for normal sperm functioning, disproportionate levels can negatively impact the quality of spermatozoa and impair their overall fertilizing capacity. OS has been identified as an area of great attention because ROS and their metabolites can attack DNA, lipids, and proteins; alter enzymatic systems; produce irreparable alterations; cause cell death; and ultimately, lead to a decline in the semen parameters associated with male infertility. This review highlights the mechanisms of ROS production, the physiological and pathophysiological roles of ROS in relation to the male reproductive system, and recent advances in diagnostic methods; it also explores the benefits of using antioxidants in a clinical setting.

Environmental Exposure of Sperm Sex-Chromosomes

Ibukun P. Oyeyipo,Michelle van der Linde,Stefan S. du Plessis 한국독성학회 2017 Toxicological Research Vol.33 No.4

Preconceptual sex selection is still a highly debatable process whereby X- and Y-chromosome-bearing spermatozoa are isolated prior to fertilization of the oocyte. Although various separation techniques are available, none can guarantee 100% accuracy. The aim of this study was to separate X- and Y-chromosome-bearing spermatozoa using methods based on the viability difference between the X- and Y-chromosome-bearing spermatozoa. A total of 18 experimental semen samples were used, written consent was obtained from all donors and results were analysed in a blinded fashion. Spermatozoa were exposed to different pH values (5.5, 6.5, 7.5, 8.5, and 9.5), increased temperatures (37℃, 41℃, and 45℃) and ROS level (50 μM, 750 μM, and 1,000 μM). The live and dead cell separation was done through a modified swim-up technique. Changes in the sex-chromosome ratio of samples were established by double-label fluorescent in situ hybridization (FISH) before and after processing. The results indicated successful enrichment of Xchromosome-bearing spermatozoa upon incubation in acidic media, increased temperatures, and elevated H₂O₂. This study demonstrated the potential role for exploring the physiological differences between Xand Y-chromosome-bearing spermatozoa in the development of preconceptual gender selection.

Modulation of Inflammatory Cytokines and Islet Morphology as Therapeutic Mechanisms of Basella alba in Streptozotocin-Induced Diabetic Rats

Dennis S. Arokoyo,Ibukun P. Oyeyipo,Stefan S. Du Plessis,Novel N. Chegou,Yapo G. Aboua 한국독성학회 2018 Toxicological Research Vol.34 No.4

The mechanism of the previously reported antidiabetic effect of Basella alba is unknown. This study investigated the role of B. alba aqueous leaf extract in the modulation of inflammatory cytokines and islet morphology in streptozotocin-induced diabetic rats. Forty male Wistar rats, between 8 and 10 weeks old, were randomly divided into four groups (n = 10) and administered the following treatments: Healthy control (H-c) and Diabetic control (D-c) animals received normal saline 0.5 mL/100 g body weight daily, while Healthy Treatment (H-Ba) and Diabetic Treatment (D-Ba) rats received the plant extract 200 mg/kg body weight daily. All treatments were administered by oral gavage. Diabetes was induced in D-c and D-Ba rats by a single intraperitoneal injection of streptozotocin (55 mg/kg body). The body weight and fasting blood sugar (FBS) levels were recorded every week for 4 weeks, after which the rats were euthanized and samples collected for further analysis. After the experiment, FBS level was significantly reduced (p < 0.0001) in rats in the D-Ba group, but increased (p < 0.001) in rats in the D-c group. The absolute (H-c and H-Ba vs D-c, p < 0.05) and relative (D-Ba vs H-c, p < 0.05; D-Ba vs H-Ba, p < 0.005) weights of the pancreases were significantly higher after the experiment. The rats in the D-c group had significantly higher levels of serum interleukin-1β (p < 0.001 vs H-c; p < 0.05 vs H-Ba and D-Ba) and monocyte chemotactic protein-1 (p < 0.0001), but lower levels of interleukin-10 (p < 0.05) in comparison with the other groups. Histopathological examination revealed severe interstitial congestion, reduced islet area (p < 0.0001), and increased islet cell density in the D-c group compared with those in the D-Ba group. From these findings, it was concluded that the aqueous extract of B. alba stimulates the recovery of beta-islet morphology in streptozotocininduced diabetic rats by modulating the peripheral production of inflammatory cytokines.

Environmental Exposure of Sperm Sex-Chromosomes: A Gender Selection Technique

Oyeyipo, Ibukun P.,van der Linde, Michelle,du Plessis, Stefan S. Korean Society of ToxicologyKorea Environmental Mu 2017 Toxicological Research Vol.33 No.4

Preconceptual sex selection is still a highly debatable process whereby X- and Y-chromosome-bearing spermatozoa are isolated prior to fertilization of the oocyte. Although various separation techniques are available, none can guarantee 100% accuracy. The aim of this study was to separate X- and Y-chromosome-bearing spermatozoa using methods based on the viability difference between the X- and Y-chromosome-bearing spermatozoa. A total of 18 experimental semen samples were used, written consent was obtained from all donors and results were analysed in a blinded fashion. Spermatozoa were exposed to different pH values (5.5, 6.5, 7.5, 8.5, and 9.5), increased temperatures ($37^{\circ}C$, $41^{\circ}C$, and $45^{\circ}C$) and ROS level ($50{\mu}M$, $750{\mu}M$, and $1,000{\mu}M$). The live and dead cell separation was done through a modified swim-up technique. Changes in the sex-chromosome ratio of samples were established by double-label fluorescent in situ hybridization (FISH) before and after processing. The results indicated successful enrichment of X-chromosome-bearing spermatozoa upon incubation in acidic media, increased temperatures, and elevated $H_2O_2$. This study demonstrated the potential role for exploring the physiological differences between X-and Y-chromosome-bearing spermatozoa in the development of preconceptual gender selection.

Smoking and Male Infertility: An Evidence-Based Review

Avi Harlev,Ashok Agarwal,Sezgin Ozgur Gunes,Amit Shetty,Stefan Simon du Plessis 대한남성과학회 2015 The World Journal of Men's Health Vol.33 No.3

Many studies have reported that the contents of cigarette smoke negatively affect sperm parameters, seminal plasma, and various other fertility factors. Nevertheless, the actual effect of smoking on male fertility is not clear. The effect of smoking on semen parameters is based on the well-established biological finding that smoking increases the presence of reactive oxygen species, thereby resulting in oxidative stress (OS). OS has devastating effects on sperm parameters, such as viability and morphology, and impairs sperm function, hence reducing male fertility. However, not all studies have come to the same conclusions. This review sheds light upon the arguable association between smoking and male fertility and also assesses the impact of non-smoking routes of tobacco consumption on male infertility. It also highlights the evidence that links smoking with male infertility, including newly emerging genetic and epigenetic data, and discusses the clinical implications thereof.

Highly Active Antiretroviral Therapy Alters Sperm Parameters and Testicular Antioxidant Status in Diet-Induced Obese Rats

Ibukun P. Oyeyipo,Bongekile T. Skosana,Frans P. Everson,Hans Strijdom,Stefan S. du Plessis 한국독성학회 2018 Toxicological Research Vol.34 No.1

The efficacy of highly active antiretroviral therapy (HAART) has led to an increase demand for therapeutic use, thereby necessitating investigation into drug toxicity. This study was designed to investigate the in vivo effects of HAART on sperm parameters and testicular oxidative stress in lean and obese rats. Wistar rats (males, n = 40, weighing 180~200 g) were assigned randomly into 4 groups and treated accordingly for 16 weeks as follows: Control (C): lean group fed with standard rat chow; Diet induced obesity (DIO): obese animals fed a high caloric diet; C + ART: lean animals treated with HAART; DIO + ART: obese animals treated with HAART. An antiretroviral drug combination of Tenofovir, Emtricitabine and Efavirenz at a dose of 17, 26 and 50 mg/kg/day was administered for the latter 6 weeks via jelly cube feeding. At the end of the experimental period, sperm analysis was performed on sperm collected from the caudal epididymis, while the testis was homogenized for antioxidant enzyme and lipid peroxidation assays. Results showed that HAART significantly decreased sperm motility (p < 0.05) in both lean and obese animals, and viability (p < 0.05) in the DIO group. Testicular glutathione, catalase and superoxide dismutase were significantly decreased (p < 0.05), while Thiobarbituric acid reactive substances (TBARS) levels were significantly increased (p < 0.05) when the DIO+ART group was compared to Control group. Thus, the decreased sperm qualities associated with HAART might be as a result of increased testicular oxidative stress prominent in obese animals.