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

Alteration of redox status and fatty acid profile in gills from the green crab (Carcinus aestuarii) following dimethoate exposure

Dimethoate is a broad-spectrum organophosphate insecticide and acaricide. Through various pathways, such as runoff and drift, dimethoate can reach marine environment, and easily impact common organisms in coastal areas, close to agriculture lands, namely crustaceans. The purpose of this study was to investigate the potential effects of dimethoate exposure (50, 100, and 200 μg/l), for 1 day, on a wide range of markers of oxidative stress and neurotransmission impairment, as well as fatty acids composition and histopathological aspect in the gills of the green crab Carcinus aestuarii. A significant increase in n-3 polyunsaturated fatty acids series, namely the eicosapentaenoic acid (C20: 5n3) and its precursor alpha-linolenic acid (C 18: 3n3) in dimethoate-treated crabs was recorded. Concerning n-6 polyunsaturated fatty acids, we noted a high reduction in arachidonic acid (C20:4n-6) levels. Dimethoate exposure increased the levels of hydrogen peroxide, malondialdehyde, lipid hydroperoxides, protein carbonyl, and caused the advanced oxidation of protein products along with enzymatic and non-enzymatic antioxidant-related markers. Acetylcholinesterase activity was highly inhibited following exposure to dimethoate in a concentration-dependent manner. Finally, deleterious histopathological changes with several abnormalities were noted in exposed animals confirming our biochemical findings. The present study offered unique insights to establish a relationship between redox status and alterations in fatty acid composition, allowing a better understanding of dimethoate-triggered toxicity.

Targeting critical pathways in ferroptosis and enhancing antitumor therapy of Platinum drugs for colorectal cancer

Colorectal cancer (CRC) can be resistant to platinum drugs, possibly through ferroptosis suppression, albeit the need for further work to completely understand this mechanism. This work aimed to sum up current findings pertaining to oxaliplatin resistance (OR) or resistance to ascertain the potential of ferroptosis to regulate oxaliplatin effects. In this review, tumor development relating to iron homeostasis, which includes levels of iron that ascertain cells' sensitivity to ferroptosis, oxidative stress, or lipid peroxidation in colorectal tumor cells that are connected with ferroptosis initiation, especially the role of c-Myc/NRF2 signaling in regulating iron homeostasis, coupled with NRF2/GPX4-mediated ferroptosis are discussed. Importantly, ferroptosis plays a key role in OR and ferroptotic induction may substantially reverse OR in CRC cells, which in turn could inhibit the imbalance of intracellular redox induced by oxaliplatin and ferroptosis, as well as cause chemotherapeutic resistance in CRC. Furthermore, fundamental research of small molecules, ferroptosis inducers, GPX4 inhibitors, or natural products for OR coupled with their clinical applications in CRC have also been summarized. Also, potential molecular targets and mechanisms of small molecules or drugs are discussed as well. Suggestively, OR of CRC cells could significantly be reversed by ferroptosis induction, wherein this result is discussed in the current review. Prospectively, the existing literature discussed in this review will provide a solid foundation for scientists to research the potential use of combined anticancer drugs which can overcome OR via targeting various mechanisms of ferroptosis. Especially, promising therapeutic strategies, challenges ,and opportunities for CRC therapy will be discussed.

Influence of Dietary Long-Chain Polyunsaturated Fatty Acids and ω6 to ω3 Ratios on Head Kidney Lipid Composition and Expression of Fatty Acid and Eicosanoid Metabolism Genes in Atlantic Salmon (Salmo salar)

The interaction of dietary eicosapentaenoic acid and docosahexaenoic acid (EPA+DHA) levels with omega-6 to omega-3 ratios (ω6:ω3), and their impact on head kidney lipid metabolism in farmed fish, are not fully elucidated. We investigated the influence of five plant-based diets (12-week exposure) with varying EPA+DHA levels (0.3, 1.0, or 1.4%) and ω6:ω3 (high ω6, high ω3, or balanced) on tissue lipid composition, and transcript expression of genes involved in fatty acid and eicosanoid metabolism in Atlantic salmon head kidney. Tissue fatty acid composition was reflective of the diet with respect to C₁₈ PUFA and MUFA levels (% of total FA), and ω6:ω3 (0.5–1.5). Fish fed 0.3% EPA+DHA with high ω6 (0.3% EPA+DHA↑ω6) had the highest increase in proportions (1.7–2.3-fold) and in concentrations (1.4-1.8-fold) of arachidonic acid (ARA). EPA showed the greatest decrease in proportion and in concentration (by ~½) in the 0.3% EPA+DHA↑ω6 fed fish compared to the other treatments. However, no differences were observed in EPA proportions among salmon fed the high ω3 (0.3 and 1.0% EPA+DHA) and balanced (1.4% EPA+DHA) diets, and DHA proportions were similar among all treatments. Further, the transcript expression of elovl5a was lowest in the 0.3% EPA+DHA↑ω6 fed fish, and correlated positively with 20:3ω3, 20:4ω3 and EPA:ARA in the head kidney. This indicates that high dietary 18:3ω3 promoted the synthesis of ω3 LC-PUFA. Dietary EPA+DHA levels had a positive impact on elovl5a, fadsd5 and srebp1 expression, and these transcripts positively correlated with tissue ΣMUFA. This supported the hypothesis that LC-PUFA synthesis is positively influenced by tissue MUFA levels in Atlantic salmon. The expression of pparaa was higher in the 0.3% EPA+DHA↑ω6 compared to the 0.3% EPA+DHA↑ω3 fed fish. Finally, significant correlations between head kidney fatty acid composition and the expression of eicosanoid synthesis-related transcripts (i.e., 5loxa, 5loxb, cox1, cox2, ptges2, ptges3, and pgds) illustrated the constitutive relationships among fatty acids and eicosanoid metabolism in salmon.

Pesticide residues in honey and their potential reproductive toxicity

Honey is the sweet natural substance produced by honeybees. It may be contaminated with pesticide residues due to its intensive use. Almost no reviews have addressed pesticide residues in honey, calculated a hazard index or discussed their potential reproductive toxicity. The focus of this article is primarily to summarize advances in research related to pesticide residues, estimate daily intake of pesticide residues from consuming honey only and discuss the potential reproductive toxicity associated with those residues. The results showed that 92 pesticide residues were found in honey samples from 27 countries. Six residues belong to class IA toxicity, eight residues belong to class IB toxicity, 42 residues belong to class II, 35 residues belong to class III and one residue belong to class IV toxicity. The calculated hazard indices (HIs) suggest high potential health risk by consuming honey. In addition, residues found in honey are known to impair semen quality among exposed individuals and experimental animal models. In conclusion, consumption of honey as one of many food items contaminated with pesticide residues may induce male and female reproductive toxicity in consumers.

Mixture toxicity of chlorpyrifos-methyl, pirimiphos-methyl, and nonylphenol in Atlantic salmon (Salmo salar) hepatocytes

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Shotgun lipidomics points to combined effects on 18:0 and 18:1 lipid species.

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Combined effects seen on membrane phospholipids and TAG in salmon hepatocytes.

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Inhibited stearoyl CoA desaturase (SCD) and increased Δ6 desaturase (D6D) activity.

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Adjuvants may amend toxicity of active ingredient in pesticide formulations.

Pesticide formulations typically contain adjuvants added to enhance the performance of the active ingredient. Adjuvants may modify the bioavailability and toxicity of pesticides. In this study, the aim was to examine to which degree nonylphenol (NP) may interfere with the toxicity of two organophosphorus pesticides found in aquafeeds, chlorpyrifos-methyl (CPM) and pirimiphos-methyl (PPM). Atlantic salmon liver cells were exposed to these compounds singly or in combinations for 48 h using 3D cell cultures. Cytotoxicity, gene expression (RT-qPCR), and lipidomics endpoints were used to assess toxicity. The dose-response assessment showed that NP was the most toxic compound at equimolar concentrations (100 μM). Shotgun lipidomics pointed to a general pattern of elevated levels of saturated 18:0 fatty acids and declined levels of 18:1 monounsaturated fatty acids by the combined treatment. All three compounds had a distinct effect on membrane phospholipids, in particular on phosphatidylcholine (PC) and phosphatidylethanolamine (PE). Lipid species patterns predicted inhibited stearoyl CoA desaturase (SCD) activity and increased Δ6 desaturase (D6D) activity in co-treated cells. While all three compounds alone mitigated increased triacylglycerol (TAG) accumulation, combined treatment resulted in lower total TAG in the cells. Multivariate analysis with PLS regression showed significant combined effects for nine genes (d5d, d6d, scd, srebf2, vtg, esr1, cyp1, ugt1a, and cat) and four lipid species (FFA 22:5, LPC 18:0, TAG52:1-FA16:0, and TAG52:1-FA18:0). In summary, this study demonstrates that the adjuvant can be the main contributor to the toxicity of a mixture of two organophosphorus pesticides with relatively low toxicity in fish cells.

Maternal and postnatal high-fat diets with high ω6 : ω3 ratios affect the reproductive performance of male offspring in the mouse

High-fat diets (HFDs) are an acknowledged risk factor for male subfertility, but the underlying mechanisms remain unclear. In the present study we compared the effects of two HFDs with different ω6:ω3 ratios, one enriched with soy oil (SOD; ω6:ω3=9.62) and another enriched with sunflower oil (SFOD; ω6:ω3=51.55), with those of a commercial diet (CD; ω6:ω3=19.87), supplied from pregnancy to adulthood, on morphometric parameters and reproductive performance in adult male mice (recommended ω6:ω3 for rodents=1-6). Bodyweight was significantly higher in the SFOD than CD group, and relative testicular weight was significantly lower in the SFOD than the other two groups. SFOD altered sperm performance: it reduced sperm viability (mean±s.e.m.; 76.00±1.35% vs 82.50±1.45% and 80.63±1.00% in the SFOD vs CD and SOD groups respectively; P<0.05) and increased the percentage of immature spermatozoa (71.88±7.17% vs 51.38±5.87% and 48.00±5.72% in the SFOD vs CD and SOD groups respectively; P<0.05). The epididymal ω6:ω3 ratio was higher in the SFOD versus CD and SOD groups, whereas the unsaturation index was higher in the SOD and SFOD groups than in CD group. Sperm membrane integrity was diminished in both the SOD and SFOD groups, but there was no difference in sperm reactive oxygen species production in these two groups compared with the CD group. The fertilisation rate was lower in the SFOD compared with the CD and SOD groups. In conclusion, although both HFDs affected sperm quality, the fertilising ability was more altered by the excessive dietary ω6:ω3 ratio than by the net ω6 content.

Steroidogenesis in Leydig cells: effects of aging and environmental factors

Serum testosterone (TS) levels decrease with aging in both humans and rodents. Using the rat as a model system, it was found that age-related reductions in serum TS were not due to loss of Leydig cells, but rather to the reduced ability of the Leydig cells to produce TS in response to luteinizing hormone (LH). Detailed analyses of the steroidogenic pathway have suggested that two defects along the pathway, LH-stimulated cAMP production and cholesterol transport to and into the mitochondria, are of particular importance in age-related reductions in TS production. Although the mechanisms involved in these defects are far from certain, increasing oxidative stress appears to play a particularly important role. Interestingly, increased oxidative stress also appears to be involved in the suppressive effects of endocrine disruptors on Leydig cell TS production.

Pesticide-induced decrease in rat testicular steroidogenesis is differentially prevented by lipoate and tocopherol

We have previously demonstrated that the sub-chronic administration of low doses of Toc or α-Toc, glyphosate and zineb to rats (i.p. 1/250 LD50, three times a week for 5 weeks) provoked severe oxidative stress (OS) in testicles. These effects were also reflected in plasma. Lipoic acid (LA) and α-tocopherol are considered as antioxidants due to their ability to neutralize reactive oxygenated species (ROS) and reset endogenous antioxidant levels. To investigate the possible protective effect on reproductive function, LA and Toc (i.p. 25, 50 and 100mg/kg) were administered simultaneously with the pesticide mixture (PM) for 5 weeks. Both drugs prevented OS and the damage to proteins and lipids caused by PM in a dose-dependent manner. The PM-induced increase levels of prostaglandins E2 and F2α was completely restored by LA but not by Toc. Similarly, only LA was able to restore the inhibition of testosterone production, the decrease of 3β- and 17β-hydroxysteroid dehydrogenases activities, and the elevation of gonatropins (FSH and LH) levels produced by PM. Furthermore, LA was more efficient than Toc in normalizing the histological alterations produced by PM administration, suggesting that pesticides act though other mechanisms that generate oxidative stress. In our experimental model LA displayed a higher protective role against pesticide-induced damage than that observed by Toc administration. Our results suggest that LA administration is a promising therapeutic strategy for coping with disorders suspected to be caused by OS generators - such as pesticides - in male reproductive system.