Nigerian bonny light crude oil induces endocrine disruption in male rats.

Exposure to Nigerian bonny light crude oil (BLCO) in the southern part of Nigeria has been reported to be associated with reproductive toxicity, but there is paucity of information on its interference with steroidogenesis. This study investigated the influence of BLCO on testicular steroidogenesis and plasma levels of hormones from the pituitary and thyroid components of the brain-pituitary-testicular axis. Adult male Wistar rats were orally treated with BLCO dissolved in corn oil at 0, 200 and 800 mg/kg for 7 days. Immunoblot analysis revealed that BLCO exposure suppressed steroid acute regulatory protein and androgen-binding protein expression with concomitant decrease in 3ß-hydroxysteroid dehydrogenase (HSD) and 17ß-hydroxysteroid dehydrogenase activities. BLCO exposure significantly decreased plasma concentrations of follicle-stimulating hormone, luteinizing hormone, prolactin and intratesticular testosterone, but elevated thyrotropin, triiodothyronine and thyroxine above the control values. The data presented herein indicate that undue exposure to BLCO has an inhibitory effect on testicular steroidogenesis. The underlying mechanisms for BLCO-induced testicular dysfunction may involve its disruptive effect on the brain-pituitary-testicular axis. These observations highlight the potential risk to public health for a population where, unfortunately, oil spillages occur frequently.

Neurotoxicity of Nigerian bonny light crude oil in rats.

Biometal accumulation may contribute to organ toxicity in individuals using the Nigerian bonny light crude oil (BLCO) for ailment management. We assessed the levels of biometals, antioxidant status, along with histomorphometric analysis to investigate the effect of BLCO, commonly use in folklore medicine, on the brain. Adult male Wistar rats were dosed by gavage with BLCO at 0, 200, and 800 mg/kg(-1) of BLCO for 7 days. Results showed the accumulation of iron, zinc, nickel and lead, in contrast to copper, in BLCO-treated rats. Administration of BLCO disrupted the brain's antioxidant system and significantly increased levels of hydrogen peroxide and lipid peroxidation. Although the Purkinje layer and maximum width of Purkinje cells were not affected, BLCO treatment significantly decreased molecular layer, granular layer, and density of Purkinje cells of the cerebellum. The neurotoxicity of BLCO may be the result of oxidative stress resulting from loss of biometal homeostasis as well as toxicant injury from other constituents of BLCO.

Tissues distribution of heavy metals and erythrocytes antioxidant status in rats exposed to Nigerian bonny light crude oil.

The harmful effects of folkloric uses of Nigerian bonny light crude oil (BLCO) in ailments management may outweigh the expected beneficial effects. We investigated the levels of heavy metal concentrations in the tissues as well as the effect of BLCO on the antioxidant status of erythrocytes of rats after oral exposure to 0, 200 and 800 mg/kg BLCO for 7 days. Analysis of heavy metal concentrations in BLCO showed that Zn > Fe > Pb > Cu > Ni. The trend of accumulation of the metals in the tissues is blood-Fe > Pb >Zn whereas Cu and Ni levels were not affected; Liver-Ni > Zn > Fe > Cu > Pb and Testes-Ni > Cu > Pb > Zn > Fe. The order of concentration of the metals in the tissues is as follows: iron-blood > liver > testes; zinc-liver > blood > testes; lead-blood > liver > testes; copper-testes > liver > blood; nickel-liver > testes > blood. Activities of the antioxidant enzymes of erythrocytes such as superoxide dismutase, catalase, glutathione S-transferase and glutathione peroxidase increased significantly in a dose-dependent manner with significant elevation in hydrogen peroxide and malondialdehyde levels, whereas glutathione level was not significantly decreased in BLCO-treated animals. Collectively, the results showed that BLCO induces oxidative damage to erythrocytes of rats.

Induction of oxidative stress in liver and kidney of rats exposed to Nigerian bonny light crude oil.

The local population of Niger-Delta in the Southern part of Nigeria have used bonny light crude oil (BLCO) as a remedy for various ailments and are exposed to some extent to this widespread environmental contaminant or its metabolites through the food chain. BLCO's hepatorenal toxicity was studied using oxidative stress indices to elucidate the precise nature and mechanism of action. BLCO was orally administered at concentrations of 0, 200, 400, and 800 mg kg⁻¹ to adult male rats for 7 days. After exposure, kidney weight was unaffected, but liver weight decreased significantly at 800 mg kg⁻¹ only compared with control. BLCO exposure resulted in dose-dependent elevation of serum aminotransferases, total bilirubin, urea, and creatinine. Activities of superoxide dismutase and catalase decreased significantly, whereas γ-glutamyltransferase activity and the level of glutathione increased significantly in BLCO-treated animals compared with control in both liver and kidney of rat. Renal activities of glucose-6-phosphatase and 5'-nucleotidase markedly decreased in a dose-dependent manner in BLCO-exposed rats. In addition, the levels of hydrogen peroxide and lipid peroxidation significantly increased, dose dependently, in liver and kidney of BLCO-treated rats compared with control. BLCO-treated rats showed marked degeneration of kidney evident in cortical hemorrhages, tubular necrosis, protein casts, and cellular infiltration. However, no treatment-related liver histopathology was observed. The results suggested that BLCO elicits disruption of antioxidant status and concomitant elevation of hydrogen peroxide and lipid peroxidation differentially in liver and kidney of rats. The hepatorenal toxicity of BLCO could be due to induction of oxidative stress in liver and kidney.

Nigerian Bonny light crude oil disrupts antioxidant systems in testes and sperm of rats.

Nigerian Bonny light crude oil (BLCO) is commonly used by the local population in folklore medicine for the management of various forms of gastrointestinal problems and male reproductive capacity. The study investigated the effects of BLCO on the antioxidant systems of the testes and epidydimal sperm in rats by oral exposure to 0, 200, 400 and 800 mg/kg BLCO for 7 days. In testes and sperm, BLCO treatment at all doses significantly (p<0.05) decreased superoxide dismutase (SOD), catalase (CAT), and glutathione S-transferase (GST) activities, whereas it markedly increased glucose 6-phosphate dehydrogenase (G6PD) and gamma glutamyl transferase (GGT) activities as well as increased glutathione (GSH), hydrogen peroxide, and malondialdehyde (MDA) levels in all treatment groups. Although epididymal sperm number (ESN), daily spermatozoa production (DSP), and sperm motility were significantly decreased, total sperm abnormalities were significantly increased without affecting sperm viability at all dose levels compared with controls. The adverse effect of BLCO on TSN was noted at the 800 mg/kg dose only. Histopathology results showed treatment-related lesions of the testes characterized by severe congestion of interstitial vessels, decreased germinal epithelium, and increased number of vacuolization. These results suggest that exposure to BLCO, such as its use in ailment management, may promote infertility by altering the function of the testes and sperm, particularly by way of induction of oxidative stress.

Sperm functional parameters and erythrocytes oxidant-antioxidant imbalance during municipal landfill leachate treatment withdrawal in rats.

Adequate information on how leachates affect hematological and reproductive functions is necessary to help in linking causality with predictable response. The present study investigated the effects of Olushosun municipal landfill leachate (OMLL) exposure and withdrawal on sperm characteristics and erythrocytes oxidant-antioxidant balance in rats. Adult male Wistar rats were exposed to 0%, 12.5% and 25% OMLL in drinking water for 28 days. One-half of the rats in each group were sacrificed on day 29 while the remaining one-half stayed an additional 28 days without treatment. OMLL exposure significantly decreased sperm functional parameters, disrupted antioxidant systems with concomitant elevation in hydrogen peroxide and malondialdehyde levels in erythrocytes and sperm. Following withdrawal of treatment, OMLL-mediated decrease in sperm count and daily sperm production were reversed to near control. However, erythrocytes and sperm oxidative damage, increased sperm abnormalities, decreased epididymis weight, sperm progressive motility and testicular sperm number persisted and were consistent with results obtained from rats sacrificed immediately after OMLL treatment. Collectively, OMLL-induced irreversible oxidative damage to erythrocytes and sperm in rats within the time course of investigation. These findings highlight potential adverse effects of OMLL on individuals unduly exposed to leachates contaminated substances.