Parallelism and dissociation in the actions of an Aroclor 1260-based transformer fluid on testicular androgenesis and antioxidant enzymes

The effects of Aroclor 1254 alone and in combination with X-rays on the male mice germ cells quantity and quality

The effects of chemical and physical environmental factors are concerned as the main reason of diminished male fertility. The aim of the study was the investigation of the effects of low doses of Aroclor 1254 or combined exposure to low doses of Aroclor 1254 and low doses of ionizing radiation on the sperm quantity and quality of male germ cells including damage to genetic material of adult male mice. Mice were exposed for 2 weeks, 3 times per week by intraperitoneal injection with Aroclor 1254 diluted in corn oil at doses of 1, 2 and 4 mg/kg bw or to whole body X-rays irradiation at doses 0.05 Gy, 0.10 Gy and 0.15 Gy or to combination of X-rays and Aroclor 1254 at following doses 0.05 Gy + 1 mg/kg bw Aroclor 1254, 0.10 Gy + 2 mg/kg bw Aroclor 1254. The samples for sperm count, motility, morphology and DNA integrity of male germ cells estimation were taken from animals just after the end of exposure and 5 weeks later. Irradiation alone deteriorated sperm count and quality. Aroclor 1254 significantly reduced the sperm motility and increased sperm abnormality and at the highest dose also induced DNA damage of gametes. The combined exposure to 0.10 Gy + 2 mg/kg bw of Aroclor 1254 showed the increase in the sperm concentration and the decrease of percentage of abnormal spermatozoa compared to results after irradiation to 0.10 Gy alone. In conclusion, the low doses of Aroclor 1254 used in this study did not significantly reduce the sperm count, but affected the sperm motility, morphology and sometimes also DNA integrity of gametes. In combination with low doses of irradiation, low doses of Aroclor 1254 may ameliorate the harmful effect of irradiation on the male gametes.

Lipoic acid and Calligonum comosumon attenuate aroclor 1260-induced testicular toxicity in adult rats

Aroclor 1260 is one of the more representative polychlorinated biphenyls found in biota. This study was designed to delineate the testicular toxicity of Aroclor 1260 and to elucidate the potential protective role of Calligonum comosum (C. comosum) and lipoic acid in adult rats. Aroclor 1260 was dissolved in corn oil and given to rats by gavage at doses 0, 20, 40, or 60 mg/kg/day for 15 consecutive days (Groups I, II, III, and IV, respectively). Groups V and VI were pretreated with C. comosum (200 mg/kg/day) and lipoic acid (35 mg/kg/day) respectively 24 h before Aroclor 1260 (40 mg/kg/day) treatment for 15 consecutive days. Aroclor 1260 (20, 40 or 60 mg/kg/day) treatment significantly decreased testes weight, sperm count and motility and daily sperm production. Serum testosterone was significantly decreased in response to treatment with 40 and 60 mg/kg/day of Aroclor 1260. LDH-X activity was significantly decreased at the three dose levels. Hydrogen peroxide (H₂ O₂ ) production (in a dose-related manner) and lipid peroxidation were significantly increased in response to Aroclor 1260 (20, 40, or 60 mg/kg/day) treatment. Aroclor 1260 at the three dose levels decreased the activities of the antioxidant enzymes SOD, CAT, GPx, and GR and the non-enzymatic antioxidant GSH level. CAT, GPx and GSH showed a dose-response effect. These abnormalities were effectively attenuated by pretreatment with C. comosum (200 mg/kg/day) or lipoic acid (35 mg/kg/day). Histopathological examination showed a dose-related increase in morphological abnormalities of the testis in response to Aroclor 1260 treatment. In conclusion, Aroclor 1260 induced testicular toxicity at least, in part, by induction of oxidative stress. By reversal of biochemical and morphological changes towards normalcy, the cytoprotective role of C. comosum and lipoic acid is illuminated. In comparison, lipoic acid was more protective than C. comosum extract against testicular toxicity induced by Aroclor 1260. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 1147-1157, 2017.

Lipoic acid attenuates Aroclor 1260-induced hepatotoxicity in adult rats

The present study was aimed to investigate the mechanistic aspect of Aroclor 1260-induced hepatotoxicity and its protection by lipoic acid. The adult male Albino rats were divided into six groups. Group I served as control. Group II received lipoic acid (35 mg/kg/day). Aroclor 1260 was given to rats by oral gavage at doses 20, 40, or 60 mg/kg/day (Groups III, IV, and V, respectively). Group VI was pretreated with lipoic acid (35 mg/kg/day) 24 h before Aroclor 1260 (40 mg/kg/day). Treatment in all groups was continued for further 15 consecutive days. Serum alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, and lactate dehydrogenase activities and total bilirubin, total cholesterol, and triglycerides were significantly increased while total protein, total albumin, and high-density lipoprotein were significantly decreased. Hydrogen peroxide production and lipid peroxidation were significantly increased while superoxide dismutase and catalase activities and reduced glutathione (GSH) content was significantly decreased in liver. Caspase-3 & -9 activities were significantly increased in liver. Lipoic acid pretreatment significantly reverted all these abnormalities toward their normal levels. In conclusion, Aroclor 1260 induced liver dysfunction, at least in part, by induction of oxidative stress. Apoptotic effect of hepatic cells is involved in Aroclor 1260-induced liver injury. Lipoic acid could protect rats against Aroclor 1260-induced hepatotoxicity. © 2014 Wiley Periodicals, Inc. Environ Toxicol 31: 913-922, 2016.

Which exposure stage (gestation or lactation) is more vulnerable to atrazine toxicity? Studies on mouse dams and their pups

Either during gestation or lactation, the experimental mouse dams received one of the following treatments: (a) diet free of pesticide; (b) diet enriched with atrazine (ATZ); 31.0 μg kg⁻¹; (c) diet free of pesticide + oral vitamin E (α-tocopherol; 200 mg kg⁻¹ per mouse); and (d) diet enriched with ATZ (31.0 μg kg⁻¹) + oral vitamin E (200 mg kg⁻¹ per mouse). At the weaning, pups and dams were killed and selected organs and blood samples were collected for analyses. Compared with the control results, ATZ induced alteration in a number of biochemical and histopathological parameters either in the dams or their offspring. The ameliorative effect of vitamin E, based on estimating the “Ameliorative Index; AI” to malondialdehyde (MDA) and superoxide dismutase (SOD) ranged between 0.95 and 1.06 (≈1.0) for the dams and the pups either in gestational or lactational exposure routes. In general, the mouse pups were more vulnerable to ATZ toxicity than their mothers and exposure during gestation was suggested to be more effective than during lactation. The findings may support the need to further investigating the adverse effects of exposure to low doses of commonly used pesticides, especially during pregnancy and breast-feeding as well as effects on newborn child.

Atrazine effects on antioxidant status and xenobiotic metabolizing enzymes after oral administration in peripubertal male rat

Previously, we reported that in vivo applied atrazine from postnatal day 23 to 50 induced strong inhibition of testicular steroidogenesis. Therefore, the aim of the present study was to investigate, in the same experimental model, the oxidative status in androgen-producing testicular interstitial compartment characterized by diminished steroidogenesis. In parallel, we determined activities of antioxidative and cytochrome P450 (CYP) xenobiotic-metabolizing enzymes in liver. To confirm the results on atrazine induced-inhibition of testicular androgenesis, we measured ex vivo production of androgen in Leydig cells. The results revealed decreased activity of antioxidant enzymes, especially glutathione S-transferase (GST), but also glutathione peroxidase (GSH-Px) and catalase (CAT) in testicular interstitial cells, in parallel with strongly diminished ex vivo basal and agonist-stimulated Leydig cell androgenesis. In liver, atrazine increased the activity of GSH-Px, GST, and CYP1A1/2 enzyme, but not lipid peroxidation. These results indicate that atrazine markedly affects both antioxidant status and androgenesis in peripubertal rats.

Exogenous arachidonate restores the dimethoate-induced inhibition of steroidogenesis in rat interstitial cells

The present work studies the potential restorative effect of polyunsaturated fatty acids (PUFA, 5 μM/24 h) on the dimethoate (DMT)-induced inhibition of testosterone biosynthesis in Leydig cells isolated from rat testes. Various fatty acids (FA) from the n-6 (18:2, 20:3, 20:4, 22:4 and 22:5) and n-3 (18.3, 20:5, 22:5, 22:6) series were assayed in Leydig cells, alone (as delipidated BSA complexes) and in combination with DMT (1 ppm). The n-6 FA stimulated lipid peroxidation (LPO) and inhibited the activities of steroidogenic enzymes (3β- and 17β-hydroxysteroid dehydrogenases). The n-3 FA exerted an anti-oxidant effect, decreasing the production of thiobarbituric-acid reactive substances (TBARS) and inhibiting phospholipase A(2) activity. The biosynthesis of testosterone in DMT-treated cultures was completely normalized by ARA (20:4n-6) and partially restored by the addition of 20:3n-6, increasing ARA content inside the mitochondria. The other FA assayed failed to restore androgenesis. COX-2 protein and prostaglandin F2α and E2 production were stimulated by 20:3n-6, ARA, 18:3n-3 and 20:5 n-3. COX-2 protein decreased upon addition of 22:5n-3 and 22:6n-3. StAR protein was increased by ARA and partially increased by 20:3n-6, likely due to its metabolic conversion into ARA. Both FA increased the mitochondrial cholesterol pool available for testosterone biosynthesis. The rate of androgenesis is likely the result of various regulatory factors acting concomitantly on the physiology of Leydig cells.

Involvement of lipids in dimethoate-induced inhibition of testosterone biosynthesis in rat interstitial cells

The mechanism involved in the inhibition of testosterone (Te) biosynthesis after a sub-chronic exposure to low doses of dimethoate (D) was studied in rat interstitial cells (IC). Expression of COX-2 in IC isolated from D-treated rats increased by 44% over C data, while transcription of StAR decreased by approx. 50% and the expression of this protein was diminished by approximately 40%. PGE(2) and PGF(2alpha) were increased by 61 and 78%, respectively. Te concentration decreased by 49% in IC homogenates. Concomitantly, plasma concentration of LH and FSH both increased. Araquidonate (ARA) and C(22) fatty acyl chains in phospholipids from IC mitochondrial fraction decreased by approx. 30% after D treatment. Protein carbonyls, lipoperoxides and nitrite content increased while alpha-tocopherol and the antioxidant capacity of the soluble cellular fraction decreased significantly. Stimulation with h-CG 10 nM overnight failed to overcome the inhibition caused by D on both Te biosynthesis and 3beta- and 17beta-hydroxysteroid dehydrogenases. Decreased Te biosynthesis may be attributed to (1) inhibition of StAR protein activity due to the stimulation of COX-2 and the overproduction of PGF(2alpha), (2) decreased stimulatory effect of ARA on StAR with a subsequent reduction in the availability of CHO for the androgenic pathway, and/or (3) indirect inhibition of steroidogenic enzymes by a lower transcriptional rate caused by elevated PGF(2alpha). Rofecoxib administration prevents the deleterious effect(s) exerted by D.

Aroclor 1254 induced cytotoxicity and mitochondrial dysfunction in isolated rat hepatocytes

Polychlorinated biphenyls (PCBs) are widespread persistent environmental contaminants that display a complex spectrum of toxicological properties, including hepatotoxicity. Although Aroclor 1254 is ubiquitous in the environment, its potential cytotoxic effect on rat hepatocytes and the mechanism underlines its cytotoxicity are not fully investigated. Therefore, the present study was conducted to investigate: (1) the potential cytotoxicity of Aroclor 1254 in rat hepatocytes, and (2) characterization of the molecular mechanisms involved in the Aroclor 1254-induced hepatotoxicity, particularly the role of mitochondria, possibly a primary target in such event, could greatly explain the cytotoxic effect of Aroclor 1254 in rat hepatocytes. Hepatocytes were isolated from adult male albino rats and incubated for 24h in a fresh media containing 0, 20, 30, 40, 50 or 60muM of Aroclor 1254. At the end of incubation, hepatocytes and hepatocyte mitochondria were used for the assay. Our results showed cytotoxicity of Aroclor 1254 in rat hepatocytes starting at a concentration of 30muM as manifested by increased lactate dehydrogenase (LDH) leakage, decreased cell viability (MTT assay) and increased lipid peroxidation. As mitochondria are known to be one possible site of the cell damage, the effects of Aroclor 1254 on hepatocyte mitochondria was investigated. Aroclor 1254 induced reactive oxygen species (ROS) generation in hepatocyte mitochondria, inhibited mitochondrial respiratory chain complexes I and III and beta-oxidation of free fatty acids, depletion of mitochondrial antioxidant enzymes GPx and GR and the non-enzymatic antioxidant reduced glutathione, inhibited mitochondrial membrane potential (Deltapsi(m)), decreased mitochondrial aconitase and cardiolipin content, and elevated levels of cytochrome P450 subfamily, CYP1A and CYP2B activities as indicated by ethoxyresorufin O-deethylase (EROD) and pentoxyresorufin O-deethylase (PROD). Therefore, we can conclude that Aroclor 1254 induced rat hepatocyte toxicity and our findings provide evidence to propose that mitochondria are one of the most important and earliest cell targets in Aroclor 1254-mediated toxicity and delineate several mitochondrial processes at least, in part, by induction of oxidative stress. These findings can be useful in future cytoprotective therapy approaches. Since mitochondrial events appear to be targeted in hepatocellular damage induced by Aroclor 1254, an antioxidant therapy targeted to mitochondria may constitute an interesting strategy to ameliorate its toxicity.

In vivo and in vitro effects of PCB126 and PCB153 on rat testicular androgenesis

In this study we compared the effects of PCB126 and PCB153 on adult rat testicular androgenesis and the status of antioxidant enzymes in the interstitial cell compartment 96h after local intratesticular application. Obtained results indicated PCB126-induced inhibition of conversion of progesterone (P) and Δ(4)-androstenedione (A(4)) to testosterone (T), and stimulation of conversion of P to T induced by PCB153, while combined application had no effect. Activities of antioxidant enzymes were unchanged, except of decreased activity of SOD in PCB126-treated group. In parallel experiments, adult purified Leydig cells challenged with PCB congeners were incubated for 2h in the presence of corresponding steroid substrates. Results demonstrated that in the presence of subsaturating substrate concentrations PCB126 induced inhibition of conversion of P and A(4) to T at nM to μM doses, while PCB153 caused stimulation at nM concentrations. Further studies should indicate possible mechanism(s) of modulation of androgenesis by tested PCB congeners.

Effect of a PCB-based transformer oil on testicular steroidogenesis and xenobiotic-metabolizing enzymes

Pyralene is a PCB-based transformer oil with a unique PCB congener profile when compared to other mixtures. We studied the influence of Pyralene on testicular steroidogenesis and the status of xenobiotic-metabolizing enzymes in the testis and liver of rats during oral exposure (10 and 50 mg/kg body weight, p.o. daily for 1 week) and a 3-week post-treatment recovery period. As expected, Pyralene induced a rapid and sustained increase in mRNA transcripts for CYP1A1 and CYP2B1 in hepatocytes that was associated with a dramatic increase in ethoxyresorufin-O-deethylase (EROD) and pentoxyresorufin-O-deethylase (PROD) activities. Testicular androgenesis and the conversion of progesterone to testosterone in testicular microsomes were bidirectionally affected. An increase in these parameters was observed 24h after the initial administration of Pyralene, followed by inhibition that lasted until the fourth post-treatment day. Expression PCR analysis revealed a significant decrease in 17beta-hydroxysteroid dehydrogenase (17betaHSD) transcript abundance at 48 h after Pyralene administration. In contrast, transcripts for several other steroidogenic enzymes and for testicular CYP1A1, CYP1B1, and CYP2B1 were unaffected under the same conditions. These results in the rat indicate that a sub-chronic exposure to Pyralene disrupted testicular steroidogenesis and suggest the mechanism may involve direct action on the regulation of specific steroidogenic enzymes such as 17betaHSD.

Studies on the protective role of vitamin C and E against polychlorinated biphenyl (Aroclor 1254)--induced oxidative damage in Leydig cells

Free radical production and lipid peroxidation are potentially important mediators in testicular physiology and toxicology. Polychlorinated biphenyls (PCBs) are global environmental contaminants that cause disruption of the endocrine system in human and animals. The present study was conducted to elucidate the protective role of vitamin C and E against Aroclor 1254-induced changes in Leydig cell steroidogenesis and antioxidant system. Adult male rats were dosed for 30 days with daily intraperitoneal (ip) injection of 2 mg/kg Aroclor or vehicle (corn oil). One group of rats was treated with vitamin C (100 mg/kg bw/day) while the other group was treated with vitamin E (50 mg/kg bw/day) orally, simultaneously with Aroclor 1254 for 30 days. One day after the last treatment, animals were euthanized and blood was collected for the assay of serum hormones such as luteinizing hormone (LH), thyroid stimulating hormone (TSH), prolactin (PRL), triiodothyronine (T(3)), thyroxine (T(4)), testosterone and estradiol. Testes were quickly removed and Leydig cells were isolated in aseptic condition. Purity of Leydig cells was determined by 3beta-hydroxysteroid dehydrogenase (3beta-HSD) staining method. Purified Leydig cells were used for quantification of cell surface LH receptors and steroidogenic enzymes such as cytochrome P(450) side chain cleavage enzyme (P(450)scc), 3beta-hydroxysteroid dehydrogenase (3beta-HSD) and 17beta-hydroxysteroid dehydrogenase (17beta- HSD). Leydig cellular enzymatic antioxidants superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), gamma-glutamyl transpeptidase (gamma-GT), glutathione-S-transferase (GST) and non-enzymatic antioxidants such as vitamin C and E were assayed. Lipid peroxidation (LPO) and reactive oxygen species (ROS) were also estimated in Leydig cells. Aroclor 1254 treatment significantly reduced the serum LH, TSH, PRL, T(3), T(4), testosterone and estradiol. In addition to this, Leydig cell surface LH receptors, activities of the steroidogenic enzymes such as cytochrome P(450)scc, 3beta-HSD, 17beta-HSD, antioxidant enzymes SOD, CAT, GPX, GR, gamma-GT, GST and non-enzymatic antioxidants such as vitamin C and E were significantly diminished whereas, LPO and ROS were markedly elevated. However, the simultaneous administration of vitamin C and E in Aroclor 1254 exposed rats resulted a significant restoration of all the above-mentioned parameters to the control level. These observations suggest that vitamin C and E have ameliorative role against adverse effects of PCB on Leydig cell steroidogenesis.

The inhibitory effects of polychlorinated biphenyl Aroclor 1254 on Leydig cell LH receptors, steroidogenic enzymes and antioxidant enzymes in adult rats

Polychlorinated biphenyls (PCBs) are global pollutants of major concern to human and animal reproductive health. The present study has examined the impact of Aroclor 1254 exposure on oxidative stress and testicular Leydig cell function. Adult albino male rats of the Wistar strain were dosed for 30 days with daily intraperitoneal injections of 2 mg/kg Aroclor 1254 or vehicle (corn oil). One day after the last treatment, animals were euthanized and blood collected for the assay of serum testosterone and estradiol. Testes were removed and Leydig cells were isolated for the assay of luteinizing hormone (LH) receptors, steroidogenic enzymes cytochrome P450 side chain cleavage enzyme (P450 scc), 3beta-hydroxysteroid dehydrogenase (3beta-HSD) and 17beta-hydroxysteroid dehydrogenase (17beta-HSD). Cellular antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPX), glutathione reductase (GR), and glutathione-S-transferase (GST) were also assayed. Lipid peroxidation (LPO) and reactive oxygen species (ROS) were quantified. Results showed that Aroclor 1254 exposure lowered serum testosterone and estradiol levels. Leydig cell LH receptor density, activities of the steroidogenic enzymes P450 scc, 3beta-HSD, 17beta-HSD, antioxidant enzymes SOD, CAT, GPX, GR, and GST were significantly diminished whereas, LPO and ROS significantly elevated. Taken together, these results suggest that inefficient LH receptors, steroidogenic enzymes and antioxidant enzymes are possible mechanisms by which Aroclor 1254 treatment disrupts Leydig cell steroidogenesis.