Genevieve A. Perono

Halogenated derivatives of polycyclic aromatic hydrocarbons (PAHs), such as chlorinated PAHs (ClPAHs), are an emerging class of contaminants that are being detected in the environment as well as in wildlife and human populations. Previous studies have shown that chemical substitution of PAHs, including chlorination, may alter the toxicity of parent PAHs; however, whether chlorination affects their endocrine-disrupting potential remains unexplored. In this study, we examined the effects of phenanthrene (Phe), one of the most prevalent PAHs, and its chlorinated congeners, 9-chlorophenanthrene (9ClPhe) and 9,10-dichlorophenanthrene (9,10Cl₂Phe), on hormone production in granulosa cells, key hormone-secreting cells of the ovary. We observed that Phe and its chlorinated congeners differentially altered anti-Müllerian hormone (AMH), estradiol (E2), and progesterone (P4) secretion. Since mitochondria are central to steroidogenesis, we further evaluated mitochondrial function. While Phe increased ATP production, both 9ClPhe and 9,10Cl₂Phe increased ROS, decreased mitochondrial membrane potential, and reduced the expression of markers for mitochondrial dynamics and mitophagy without altering ATP levels. We further tested impacts on cell fate and found that neither Phe nor its chlorinated congeners altered granulosa cell apoptosis. Together, these results suggest that chlorination of Phe leads to dose-dependent, differential effects on hormone production and mitochondrial pathways without inducing cell death in granulosa cells. This study highlights the potential adverse impacts of ClPAH exposure on ovarian follicle development and female fertility by disrupting steroidogenesis and mitochondrial quality control.

The expansion of the Alberta Oil Sands Region (AOSR) has increased the deposition of petroleum-derived chemicals into the surrounding environment. Among these, polycyclic aromatic compounds (PACs), including sulfur-containing heterocyclic hydrocarbons, have been detected in exposed local wildlife, yet the reproductive toxicity and genotoxicity of this suite of PACs remain largely unexplored. This study examined the effects of dibenzothiophene (DBT) and its alkylated congener, 2,4,7-trimethyldibenzothiophene (2,4,7-DBT), on estradiol (E2) synthesis and metabolism in granulosa cells (SIGCs). Cells were exposed to DBT or 2,4,7-DBT for 24 h at concentrations detected in AOSR wildlife tissues (0, 0.1, 1 and 10 nM). We measured the gene expression of markers involved in E2 synthesis, signaling and metabolism, E2 output via ELISA and E2 metabolite production via HPLC-MS/MS. Exposure to 2,4,7-DBT, but not DBT, shifted E2 metabolism towards 4-OHE2, a genotoxic E2 metabolite. DNA damage was assessed by γH2Ax expression, alongside DNA repair (Parp1) and survival markers (pAKT). Interestingly, both DBT and 2,4,7-DBT increased DNA damage and triggered apoptosis via a caspase-independent mechanism. Given the critical role of granulosa cells in steroidogenesis and fertility, these findings highlight the endocrine-disruptive effects of sulfur-containing heterocyclic PACs and their potential to compromise reproductive health in exposed mammals.

Altered body condition and diminished growth in wildlife in the Alberta Oil Sands Region (AOSR) are prompting investigations into the impact of oil sands industrial activity on wildlife in the region. Chemical constituents from bitumen-influenced waters, including oil sands process-affected water (OSPW), can disrupt endocrine signaling, leading to aberrant lipid accumulation and altered glycemic control in mammals. This study aimed to investigate the effects of naphthenic acid fraction components (NAFCs), derived from OSPW, on energy homeostasis using the McA-RH7777 rat hepatocyte model. Cells were exposed to NAFCs at nominal concentrations of 0, 0.73, 14.7, and 73.4 mg/L for 24 and 48 h. We assessed gene expression related to lipid and glucose metabolism and measured triglyceride accumulation, glucose, and fatty acid uptake. NAFC exposure (14.7 and 73.4 mg/L) reduced triglyceride levels and glucose uptake and increased fatty acid uptake and the expression of beta-oxidation genes, suggesting a metabolic switch from glucose to fatty acid oxidation. This switch in substrate availability signifies a shift in cellular energy dynamics, potentially linked to altered mitochondrial function. To investigate this, we conducted adenosine triphosphate (ATP), mitochondrial membrane potential, and terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assays to measure cellular ATP levels, mitochondrial membrane potential, and apoptosis, respectively. At both time points, 73.4 mg/L NAFC exposure resulted in increased ATP levels, induced mitochondrial membrane hyperpolarization, and increased apoptosis. These results suggest that mitochondrial efficiency is compromised, necessitating metabolic adaptations to maintain energy homeostasis. Given that cells exhibit metabolic flexibility that allows them to dynamically respond to changes in substrate availability, we further demonstrated that the kynurenine–tryptophan ratio (KTR) serves as a marker for a shift in energy metabolism under these stress conditions. This work provides a mechanistic framework for understanding how bitumen-derived organic contaminants may disrupt metabolic function in wildlife living in the AOSR. These findings further support the use of molecular markers like KTR to evaluate sub-lethal metabolic stress in environmental health monitoring.

Cannabis use during pregnancy has continued to rise, particularly in developed countries, as a result of the trend towards legalization and lack of consistent, evidence-based knowledge on the matter. While there is conflicting data regarding whether cannabis use during pregnancy leads to adverse outcomes such as stillbirth, preterm birth, low birthweight, or increased admission to neonatal intensive care units, investigations into long-term effects on the offspring’s health are limited. Historically, studies have focused on the neurobehavioral effects of prenatal cannabis exposure on the offspring. The effects of cannabis on other physiological aspects of the developing fetus have received less attention. Importantly, our knowledge about cannabinoid signaling in the placenta is also limited. The endocannabinoid system (ECS) is present at early stages of development and represents a potential target for exogenous cannabinoids in utero. The ECS is expressed in a broad range of tissues and influences a spectrum of cellular functions. The aim of this review is to explore the current evidence surrounding the effects of prenatal exposure to cannabinoids and the role of the ECS in the placenta and the developing fetus.

Introduction: Serotonin produced in the periphery has been shown to affect glucose and lipid homeostasis. The availability of the amino acid tryptophan, the precursor of serotonin, affects serotonin availability. In addition, the metabolism of tryptophan via the kynurenine pathway produces physiologically active metabolites which have been shown to be altered under conditions of increased adiposity and dysglycemia. There is now evidence demonstrating some environmental xenobiotics, known to affect glucose and lipid homeostasis, can also alter serotonin production and key components of the kynurenine pathway. Recent evidence suggests that exposure to compounds present in petroleum and wastewaters from oil and gas extraction sites can impact endocrine signaling and result in aberrant lipid accumulation and altered glycemic control. However, whether any of these changes can be causally ascribed to altered serotonin synthesis/signaling or tryptophan metabolism remains unknown. The goal of this study was to determine the effects of exposure to naphthenic acid (NA), a key toxicant found in wastewater from bitumen (thick crude oil present in oil sands deposits) extraction on the enzymes involved in tryptophan metabolism and serotonin production. Methods: McA-RH7777 rat hepatoma cells, were exposed to a technical NA mixture for 48 hours at concentrations within the reported range of NA found in wastewaters from oil extraction. We assessed mRNA expression for key rate-limiting enzymes involved in tryptophan metabolism that lead to either serotonin [Tph1] and/or kynurenine [Ido2 and Tdo2] production, as well as downstream enzymes in the kynurenine pathway [Afmid, Kyat1, Aadat, Kyat3, Kmo, Haao, Acmsd, Qprt]. We also examined the effects of NA on prostaglandin synthesis [Ptgs1, Ptgs2, Ptges] and signalling [Ptger2, Ptger4] as prostaglandins have been shown to be induced by serotonin and are linked to hepatic fat accumulation. Results: NA treatment significantly increased Tph1 and Ido2 expression; this occurred in association with a significant increase in the expression of the inducible prostaglandin synthase Ptgs2 (COX-2), prostaglandin E synthase Ptges, and prostaglandin receptors Ptger2 and Ptger4. Acmsd was the only downstream enzyme in the kynurenine pathway that was significantly altered by NA treatment. Conclusion: These results provide proof-of-concept that compounds associated with oil sands extraction have the potential to perturb key components of serotonin synthesis (Tph1) and tryptophan metabolism (Ido2, Acmsd). Furthermore, we found that the increase in Tph1 expression paralleled expression of Ptgs2. As increased prostaglandin production has been reported in association with nonalcoholic steatohepatitis, these data provide a potential mechanism by which exposure to NA and other petroleum-based compounds may increase the risk of metabolic disease.