The key characteristics of cardiotoxicity for the pervasive pollutant phenanthrene

A gold-silver nanostar 2D array composite structure for rapid SERS determination of PAHs

This study developed a portable multi-ring aromatic hydrocarbon (PAH) detection tool using a dual-metal surface-enhanced Raman scattering (SERS) substrate. Gold-silver nanostars (AuNS@Ag) were synthesized by a secondary seed-mediated growth method and assembled into a two-dimensional array by a liquid-phase interface self-assembly method, uniformly deposited on a silicon wafer. The PAHs in water samples were identified using a portable Raman spectrometer. The SERS detection platform has high sensitivity and stability, and can detect pyrene and phenanthrene with concentrations of 10-8 M and 0.5 × 10-8 M, respectively. The stable dual-metal nanomaterial AuNS@Ag 2D array has potential application prospects and can be used for environmental monitoring.

Prenatal exposure to phenanthrene impairs spermatogenesis and fertility by elevating apoptosis, altering gene expression, and disrupting steroidogenesis in adult male mice across two generations

BACKGROUND

Phenanthrene, a polycyclic aromatic hydrocarbon, can enter the human body via various routes and affect reproductive health. Its low molecular weight enables its transfer from the mother to the fetus. However, comprehensive research on its effects on reproductive system development is lacking. This study aimed to examine the impacts of prenatal phenanthrene exposure on the reproductive systems of both the immediate offspring and their progeny.

METHODS

Pregnant mice were divided into three groups: control, sham, and phenanthrene. From the detection of the vaginal plug until pregnancy day 18, mice in the phenanthrene group were administered phenanthrene solution (60 μg/kg), while sham mice received corn oil on alternate days. Following birth, male offspring were maintained without intervention until PND56. After puberty, a portion of these males were bred, while others were euthanized for histological and molecular analyses. The subsequent generation was born and developed under standard conditions without intervention, and underwent procedures similar to those of the first generation.

RESULTS

The study revealed that exposure to phenanthrene during fetal development, across two consecutive generations, led to a reduction in the expression of genes associated with mitosis and meiosis, while simultaneously increasing the rate of cell death. Additionally, the research found that a decline in Leydig cells resulted in decreased serum testosterone levels, which subsequently led to diminished quality and quantity of sperm.

CONCLUSION

Prenatal phenanthrene exposure, by disrupting gene expression and steroidogenesis, causes impaired testicular tissue function, reduced spermatogenesis, and ultimately reduced male fertility rates in the F1 and F2.

Exposure to oxygenated polycyclic aromatic hydrocarbons and endocrine dysfunction: Multi-level study based on hormone receptor responses

Oxygenated polycyclic aromatic hydrocarbons (OPAHs) are a class of emerging environmental contaminants that exhibit high toxicity compared to parent PAHs. In addition to carcinogenic, teratogenic and mutagenic effects, recent studies show their potential to cause endocrine disruption, but the reports are controversial. In this study, we employed hormone receptors (ERα/AR/GRα/TRβ)-mediated dual luciferase reporter gene assay and molecular docking, and found that five typical OPAHs exhibited agonistic activity towards hormone receptors, and hydrogen bonding and hydrophobic interactions were the primary binding forces involved in OPAHs-receptor interactions. Then, we developed a weighted scoring system coupled with computerized screening and clarified that 1,2-benzanthraquinone (BAQ) had the strongest hormonal effects, while anthraquinone (AQ) exhibited the weakest effects. Using the in vivo exposure model, we clarified that BAQ induced hormone receptor-coupled developmental toxicity in zebrafish larvae, evidenced by increased expression of androgen receptors and key genes involved in hormone synthesis, pericardial edema and reduced body length. Importantly, we successfully constructed androgen response element-enhanced green fluorescent protein (ARE-EGFP) transient transfection zebrafish embryos, and confirmed the androgenic potency of BAQ, but not AQ. These findings highlight the endocrine-disrupting effects in the risk management of OPAHs.

Seasonal remodelling of the fish heart alters sensitivity to petrochemical pollutant, 3-methylphenanthrene

Exploitation of offshore oil reserves, heightened traffic in marine transportation routes, and the release of petrochemicals from the thawing of permafrost and glaciers is increasing the bioavailability of polycyclic aromatic hydrocarbons (PAHs) to aquatic organisms. This availability may also change with the seasons as temperature changes accessibility of Arctic transport routes and the degree of land- and ice-melt and thus run-off into coastal ecosystems. Seasonal temperature change also remodels the ion channels in the heart of fish to facilitated preserved cardiac function across a range of temperatures. How this seasonal cardiac remodelling impacts vulnerability to pollutants is currently unknown. In this study we accessed the electrical activity of navaga cod (Eleginus nawaga) ventricular cardiomyocytes under the dual influence of seasonal change and varying concentrations of a pervasive PAH pollutant, 3-methylphenanthrene (3-MP). We used whole-cell patch-clamp to elucidate the effect of various doses of 3-MP on action potential (AP) parameters and the main ion currents (IKr, IK1, INa, ICa) in ventricular cardiomyocytes isolated from navaga cod in winter and summer at the White Sea, close to the Russian Arctic circle. Navaga cod ventricular cardiomyocytes were particularly vulnerable to 3-MP during the winter season. Exposure to 300 nM 3-MP resulted in significant changes in AP duration in winter-acclimatized fish, whereas no such changes were observed in summer-acclimatized fish. The IKr current was the most sensitive to 3-MP, with a winter IC50 of 49.7 nM and a summer IC50 of 53 μM. The INa current also exhibited seasonal shifts in sensitivity to 3-MP, with IC50 values of 2.39 μM in winter-acclimatized fish and 7.73 μM in summer-acclimatized fish. No significant differences were observed in the effect of 3-MP on the peak ICa current, although 3 μM of 3-MP caused a pronounced decrease in charge transferred by ICa (e.g. QCa) in both seasons. The IK1 current was insensitive to 3-MP in both winter and summer fish. These findings highlight how remodelling of the fish heart with changing season alters the potency of PAH pollution. This paper lays the groundwork for future research on the molecular mechanisms that drive the altered seasonal potency of pollutants in navaga cod and other species.

Developmental toxicity of alkylated PAHs and substituted phenanthrenes: Structural nuances drive diverse toxicity and AHR activation

Polycyclic aromatic hydrocarbons (PAHs) are a diverse class of chemicals that occur in complex mixtures including parent and substituted PAHs. To understand the hazard posed by complex environmental PAH mixtures, we must first understand the structural drivers of activity and mode of action of individual PAHs. Understanding the toxicity of alkylated PAHs is important as they often occur in higher abundance in environmental matrices and can be more biologically active than their parent compounds. 104 alkylated PAHs were screened from 11 different parent compounds with emphasis on substituted phenanthrenes and their structurally dependent toxicity differences. Using a high-throughput early life stage zebrafish assay, embryos were exposed to concentrations between 0.1 and 100 μM and assessed for morphological and behavioral outcomes. The aryl hydrocarbon receptor (AHR) is often implicated in the toxicity of PAHs and the induction of cytochrome P4501A (cyp1a) is an excellent biomarker of Ahr activation. Embryos were evaluated for cyp1a induction using a fluorescence reporter line. Alkyl and polar phenanthrene derivatives were further assessed for spatial cyp1a expression and Ahr dependence of morphological effects. In the alkyl PAH screen 35 (33.7%) elicited a morphological or behavioral response and of those 23 (65%) also induced cyp1a. 31 (29.8%) of the chemicals only induced cyp1a. Toxicity varied substantially in response to substitution location, the amount of ring substitutions and alkyl chain length. Cyp1a induction varied by parent compound group and was a poor indicator of morphological or behavioral outcomes. Polar phenanthrenes were more biologically active than alkylated phenanthrene derivatives and their toxicity was not dependent upon the Ahr2, Ahr1a or Ahr1b when tested individually, despite cyp1a induction by 50% of polar phenanthrenes. Our results demonstrated that induction of cyp1a did not always correlate with PAH toxicity or Ahr dependence and that the type and location of phenanthrene substitution determined potency.

Daily exposure to chlordecone, an organochlorine pesticide, increases cardiac fibrosis and atrial fibrillation vulnerability

CONTEXT

Chlordecone (CLD) is a carcinogenic organochlorine pesticide. CLD was shown to disturb the activity of cardiac Na+-K+-ATPase and Ca2+-Mg2+-ATPase. Conditions affecting these transmembrane pumps are often associated with cardiac arrhythmias (CA). However, little is known about the role of CLD on atrial fibrillation (AF) incidence, the most common type of CA.

HYPOTHESES

1) Daily ingestion of CLD induces arrhythmogenic cardiac remodeling. 2) A phase of CLD withdrawal can reduce CLD-induced AF susceptibility.

METHODS

Adult male Wistar rats (250 g-275 g) ingested daily-doses of CLD (0 μg/L, 0.1 μg/L, or 1 μg/L) diluted in their quotidian water for 4 weeks. From day (D)29 to D56, all rats received CLD-free water. Vulnerability to AF and cardiac function were evaluated at D28 and D56 by electrophysiological study, echocardiography, and optical-mapping. Levels of genes and proteins related to inflammation, fibrosis, and senescence were quantified by qPCR and immunoassays.

RESULTS

Twenty-eight days of CLD exposure were associated with significantly increased AF vulnerability compared to CLD-free rats. Contamination with 1 μg/L CLD significantly reduced atrial conduction velocity (ERP, APD). CLD-weaning normalized food consumption and weight intake. However, after the CLD-withdrawal period of 28 days, AF inducibility, atrial inflammation (IL6, IL1β), and atrial fibrosis (Masson's trichrome staining) remained significantly higher in rats exposed to 1 μg/L CLD compared to 0 μg/L.

CONCLUSIONS

Prolonged CLD ingestion provokes atrial conduction slowing and increased risk of AF. Although CLD-weaning, some persistent damages occurred in the atrium like atrial fibrosis and atrial senescence signals, which are accompanied by atrial inflammation and arrhythmogenicity.

3-Methyl-phenanthrene (3-MP) disrupts the electrical and contractile activity of the heart of the polar fish, navaga cod (Eleginus nawaga)

Alkylated polycyclic aromatic hydrocarbons are abundant in crude oil and are enriched during petroleum refinement but knowledge of their cardiotoxicity remains limited. Polycyclic aromatic hydrocarbons (PAHs) are considered the main hazardous components in crude oil and the tricyclic PAH phenanthrene has been singled out for its direct effects on cardiac tissue in mammals and fish. Here we test the impact of the monomethylated phenanthrene, 3-methylphenanthrene (3-MP), on the contractile and electrical function of the atrium and ventricle of a polar fish, the navaga cod (Eleginus nawaga). Using patch-clamp electrophysiology in atrial and ventricular cardiomyocytes we show that 3-MP is a potent inhibitor of the delayed rectifier current IKr (IC50 = 0.25 μM) and prolongs ventricular action potential duration. Unlike the parent compound phenanthrene, 3-MP did not reduce the amplitude of the L-type Ca2+ current (ICa) but it accelerated current inactivation thus reducing charge transfer across the myocyte membrane and compromising pressure development of the whole heart. 3-MP was a potent inhibitor (IC50 = 4.7 μM) of the sodium current (INa), slowing the upstroke of the action potential in isolated cells, slowing conduction velocity across the atrium measured with optical mapping, and increasing atrio-ventricular delay in a working whole heart preparation. Together, these findings reveal the strong cardiotoxic potential of this phenanthrene derivative on the fish heart. As 3-MP and other alkylated phenanthrenes comprise a large fraction of the PAHs in crude oil mixtures, these findings are worrisome for Arctic species facing increasing incidence of spills and leaks from the petroleum industry. 3-MP is also a major component of polluted air but is not routinely measured. This is also of concern if the hearts of humans and other terrestrial animals respond to this PAH in a similar manner to fish.