Per- and polyfluoroalkyl substances (PFAS) are highly persistent environmental contaminants that pose potential ecological and health risks to humans and wildlife. This study investigated the comparative toxicity of four PFAS compounds, PFOS, PFOA, PFNA, and PFHxS, using primary hepatocytes isolated from Atlantic salmon. Cells were exposed for 48 h to increasing concentrations (10 µM to 100-150 µM) and cytotoxicity, membrane fluidity, RT-qPCR and untargeted metabolomic profiles were subsequently assessed. The results showed no PFAS-induced cytotoxicity, and no clear dose-dependent effect on membrane fluidity. The transcriptional effect was generally minimal, except for a significant induction of Cyp7a after exposure to 100 µM PFOS. The metabolic profiles for the perfluorinated sulfonic acids PFOS and PFHxS differed from those observed with the perfluorinated carboxylic acids PFOA and PFNA. Pathway analysis revealed convergent effects across all four compounds on mechanisms associated with lipid metabolism, bile acids, cholesterol, mevalonate, extracellular matrix remodeling and biotransformation. Predicted adverse outcomes included dyslipidemia and cholestasis and biliary hyperplasia. In conclusion, this study identified metabolite biomarkers in Atlantic salmon associated with the four PFAS currently regulated under European food legislation and highlights the value of untargeted screening approaches such as metabolomics for detecting PFAS-induced perturbations.

Marine aquaculture uses a wide variety of chemicals that go directly out into waterbodies, but little is known about the combined impact of these substances. As much of salmon aquaculture is situated in fjords where early development occurs for fish and other aquatic organisms, we have used zebrafish larvae as a model organism to assess the impacts of the combined exposure of a common antifoulant (ZnPT) and nanoplastics (NPs). Embryos were exposed to a control, 100 nm NPs (50 mg/L), 0.002 μM ZnPT (635.4 ng/L), and their combination. Zebrafish were studied from fertilization to 116 hpf, and developmental processes, early embryonic movement, heart rate, oxygen saturation, and swimming behavior, as well as DNA methylation and RNA transcriptome, were included as endpoints. We observed higher toxicity in larvae exposed to a combined treatment of ZnPT+NPs, with significant decreases in eye size and body length at 72 hpf, significantly increased burst activity at 24 hpf, significantly decreased oxygen saturation, hypomethylation of 5mC%, and 3054 significantly differentially expressed genes. These differentially expressed genes were mainly associated with immunogenic pathways, such as leukocyte (white blood cell) activation and proliferation, interleukin-1 production, neutrophil migration, interleukin-17 (antimicrobial proteins), cytokine and chemokine-mediated pathways, and C-type lectin receptors. At 72 hpf, co-exposure resulted in significantly stronger effects on developmental parameters (body length and eye size) and behavioral responses (burst activity). By 116 hpf, immunotoxic outcomes were substantially more pronounced in the co-exposure group, while impacts on global methylation levels had decreased in the co-exposure. Overall, these findings demonstrate that simultaneous exposure to ZnPT and NPs produce significantly stronger biological impacts than exposure to either compound alone.

Microplastics (MPs) have been documented in farmed fish and in aquaculture feed. In this dietary exposure experiment, Atlantic salmon (63 ± 2 g) were fed standard feed spiked with five different concentrations of polypropylene (PP) MPs (dietary groups B-F) for 90 days. The nominal exposure concentrations ranged from lower than realistic (B), realistic (C-D), to higher than realistic (E-F). Py-GC/MS analysis of the feed also showed presence of PP-MPs in the control (A). Dietary groups A-D therefore reflect realistic conditions for salmon aquaculture, while the two highest groups, E and F, reflect about twice and five-fold of concentrations expected in aquaculture. After 90 days exposure, no significant differences in PP-MPs levels in liver and muscle of feeding groups A, E and F were detected by μFTIR. Dietary exposure to PP-MPs for 90 days had no effect on survival, growth, or morphology. Plasma chloride levels were increased in fish exposed to the three highest PP-MP concentrations, while plasma parameters albumin, ALP, ALT, creatinine, triglyceride, IgM and total protein were elevated in salmon exposed to the two highest concentrations. A dose-dependent increase in plasma glutathione (GSH) suggested MP-induced oxidative stress, and benchmark modelling suggested that plasma GSH was the most sensitive parameter to dietary MPs. Transcriptomic profiling pointed to responses such as oxidative stress, DNA damage, and metabolic dysregulation in salmon exposed to the highest MP concentrations. In conclusion, the study suggests that exposure to MPs might induce multiple toxicity mechanisms in Atlantic salmon, with realistic MPs concentrations affecting GSH levels.

Washing of road tunnels is essential for removing accumulated pollutants such as tyre wear particles, brake dust, exhaust residues, and road debris to ensure visibility and safe driving. Tunnel washing generates large volumes of contaminated runoff known as untreated tunnel wash runoff (UTWR). Some countries filter UTWR through a sedimentation process before release to reduce contamination, generating what is known as treated tunnel wash runoff (TWR). This study investigates the potential environmental impact of diluted UTWR (25 %) and TWR (50 %) by evaluating their toxicity in fish and comparing the effect to tyre-particle leachate (TPL, 2 g/L). UTWR was collected during tunnel cleaning, and TWR was collected after 14 days of filtration through sand sediments, from the Bodø tunnel in Norway. Zebrafish larvae, used as a fish model, exposed to contaminated runoff exhibited increased mortality, impaired growth, developmental anomalies, altered swimming behaviour, and changes in gene expression. Both UTWR and TWR exposure induced significant toxicity in zebrafish larvae, though the toxicity caused by TWR was notably lower than that of UTWR. This study shows that current filtration methods of tunnel wash water reduce the levels of most pollutants, however, more research is needed on how tunnel wash-water runoff affect aquatic ecosystems.

With increasing socio-economic importance of the rare earth elements and yttrium (REY), Norway has laid out plans for REY mining, from land-based to deep-sea mining, thereby enhancing REY mobility in the marine ecosystem. Little is known about associated environmental consequences, especially in the deep ocean. We explored the toxicity and modes of action of a light (Nd), medium (Gd) and heavy (Yb) REY-Cl-3 at four concentrations (3, 30, 300, and 3000 mu g L-1) in the Arcto-boreal deep-sea amphipod Tmetonyx cicada. At the highest concentration, REY solubility was limited and increased with atomic weight (Nd < Gd < Yb). Lethal effects were practically restricted to this treatment, with the lighter elements being more acutely toxic than Yb (from similar to 50 % mortality in the Gd-group at dissolved 689-504 mu g L-1 to <20 % in the Yb-group at ca. 2000 mu g L-1), which could be a function of bioavailability. All three REY induced hyperactivity at the low-medium concentrations. Delving into the transcriptome of T. cicada allowed us to determine a whole array of potential (neurotoxic) mechanisms underlying this behaviour. Gd induced the vastest response, affecting serotonin-synthesis; sphingolipid-synthesis; the renin-angiotensin system; mitochondrial and endoplasmic reticulum functioning (Gd, Nd); and lysosome integrity (Gd, Yb); as well as the expression of hemocyanin, potentially governing REY-uptake (Gd, Yb). While Nd and Yb shared only few pathways, suggesting a link between mode of action and atomic weight/radius, almost all discussed mechanisms imply the disruption of organismal Ca-homeostasis. Despite only fragmental genomic information available for crustaceans to date, our results provide novel insight into the toxicophysiology of REY in marine biota. The neurotoxic/behavioural effects in T. cicada at concentrations with potential environmental relevance warn about the possibility of bottom-up ecological consequences in mining exposed fjords and deep-sea ecosystems, calling for follow-up studies and regulatory measures prior to the onset of REY mining in Norway.

Nanoplastics (NPs) and persistent organic pollutants such as polychlorinated biphenyls (PCBs) are ubiquitous aquatic pollutants. The coexistence of these pollutants in the environment emphasises the need to study their combined toxicity. NPs can cross biological membranes and act as vectors for other pollutants, whereas PCBs are known for their ability to bioaccumulate and biomagnify. The present work aimed to study the combined toxicity of polystyrene NPs and PCB-153 using physiological (development, heart rate, respiration), behavioural (swimming behaviour) and molecular (transcriptome) endpoints in zebrafish larvae. The results show that exposure to NPs, PCB and their mixture significantly affected the development and respiration in zebrafish larvae. Larvae co-exposed to NPs and PCB exhibited significant hyperlocomotion, whereas no such effect was observed after exposure to NPs or PCB alone. The transcriptomic results revealed that NPs exposure significantly affected several pathways associated with DNA compaction and nucleosome assembly, whereas PCB exposure significantly affected critical neurogenic pathways. In contrast, co-exposure to NPs and PCB generated multi-faceted toxicity and suppressed neurobehavioural, immune-related and detoxification pathways. The study highlights the complex interplay between NPs and PCBs, and documents how the two toxicants in combination give a stronger effect than the single toxicants alone. Understanding the mixture toxicity of these two pollutants is important to assess the environmental risks and developing effective management strategies, ultimately safeguarding ecosystems and human health.

Here we evaluated the gill epithelial cell line ASG-10 from Atlantic salmon, as an in vitro model for research on known water quality challenges in aquaculture. Ammonia/ammonium (NH3/NH4+), a recognized challenge in water-intensive recirculating aquaculture systems (RAS), induced lysosomal vacuolization, reduced protein degradation and cell migration of the ASG-10 cells. Aluminium (Aln+), another challenge in freshwater aquaculture facilities had only minor effects. Next, we investigated the tolerance for direct water exposure of ASG-10. The cells tolerated water with osmolarity between 169 and 419 mOsmol/kg for 24 h. However, cells exposed for 3 h to water at 863 mOsmol/kg changed cellular morphology and induced gene expression related to stress (gpx1, casp3, hsp70), and after 24 h exposure cellular viability was severely reduced. Nevertheless, when the cells were grown in transwell inserts, they tolerated 863 mOsmol/kg for 3 h and induction of stress response associated genes was considerably reduced. Lastly, the ASG-10 cells were exposed to water samples, with no known quality issues, from different aquaculture facilities. The cells showed no differences in viability or morphology compared to their representative control. In conclusion, the ASG-10 cell line is a promising in vitro model to study water quality challenges and whole water samples.

Seafood fraud has become a global issue, threatening food security and safety. Adulteration, substitution, dilution, and incorrect labeling of seafood products are fraudulent practices that violate consumer safety. In this context, developing sensitive, robust, and high-throughput molecular tools for food and feed authentication is becoming crucial for regulatory purposes. Analytical approaches such as proteomics mass spectrometry have shown promise in detecting incorrectly labeled products. For the application of these tools, genome information is crucial, but currently, for many marine species of commercial importance, such information is unavailable. However, when combining proteomic analysis with spectral library matching, commercially important fish species were successfully identified, differentiated, and quantified in pure muscle samples and mixtures, even when genome information was scarce. This study further tested the previously developed spectral library matching approach to differentiate between 29 fish species from the North Sea and examined samples including individual fish, laboratory-prepared mixtures and commercial products. For authenticating libraries generated from 29 fish species, fresh muscle samples from the fish samples were matched against the reference spectral libraries. Species of the fresh fish samples were correctly authenticated using the spectral library approach. The same result was obtained when evaluating the laboratory-prepared mixtures. Furthermore, processed commercial products containing mixtures of two or three fish species were matched against these reference spectral libraries to test the accuracy and robustness of this method for authentication of fish species. The results indicated that the method is suitable for the authentication of fish species from highly processed samples such as fish cakes and burgers. The study shows that current and future challenges in food and feed authentication can efficiently be tackled by reference spectral libraries method when prospecting new resources in the Arctic.

Plastic pollution, including micro- and nanoplastics, is a growing concern. Tyre-wear particles (TWPs) are the second largest source of microplastics in the ocean following abrasion of synthetic fibres. In addition to the particles themselves, TWPs contain many harmful chemicals, including 6PPD. This chemical reacts with atmospheric ozone and forms the toxic compound 6PPD-quinone (6PPDq), which poses a danger to aquatic life. There is a knowledge gap in understanding risks associated with the combined toxicity of nanoplastics (NPs) and 6PPDq. The present study aimed to investigate the toxicity of NPs and 6PPDq on adult zebrafish using phenotypic (behaviour, histology) and transcriptomic endpoints. Zebrafish were exposed to four treatments: control (contaminant-free), 50 μg/L 6PPDq, 3 mg/L polystyrene (PS)-NPs, and a combination of 50 μg/L 6PPDq and 3 mg/L PS-NPs. We did not observe locomotory dysregulation in zebrafish exposed to NPs. However, we found significant hyperlocomotion in zebrafish exposed to 6PPDq and this effect was even more substantial after co-exposure with PS-NPs. This study explores the molecular mechanisms behind these effects, identifying genes associated with neurotransmitters and fatty acid metabolism that were dysregulated by the co-exposure. Transcriptomic analysis further showed that both 6PPDq and PS-NPs impacted cellular processes associated with sterol biosynthesis, cholesterol metabolism, and muscle tissue development. The effects on these mechanisms were stronger in co-exposed zebrafish, indicating a heightened risk to cellular integrity and mitochondrial dysfunction. These results highlight the significance of mixture toxicity when studying the effects of NPs and associated chemicals like 6PPDq.

Acid mine drainage (AMD) is widely acknowledged as a substantial threat to the biodiversity of aquatic ecosystems. The present study aimed to study the toxicological effects of Cu-rich AMD from the Sulitjelma mine in zebrafish larvae. The AMD from this mine was found to contain elevated levels of dissolved metals including Mg (46.7 mg/L), Al (20.2 mg/L), Cu (18.3 mg/L), Fe (19.8 mg/L) and Zn (10.6 mg/L). To investigate the toxicological effects, the study commenced by exposing zebrafish embryos to various concentrations of AMD (ranging from 0.75% to 9%) to determine the median lethal concentration (LC50). Results showed that 96 h LC50 for zebrafish larvae following AMD exposure was 2.86% (95% CI: 2.32–3.52%). Based on acute toxicity results, zebrafish embryos (<2 hpf) were exposed to 0.1% AMD (Cu: 21.7 µg/L) and 0.45% AMD (Cu: 85.7 µg/L) for 96 h to assess development, swimming behaviour, heart rate, respiration and transcriptional responses at 116 hpf. Light microscopy results showed that both 0.1% and 0.45% AMD reduced the body length, eye size and swim bladder area of zebrafish larvae and caused phenotypic abnormalities. Swimming behaviour results showed that 0.45% AMD significantly decreased the locomotion of zebrafish larvae. Heart rate was not affected by AMD exposure. Furthermore, exposure caused a significant increase in oxygen consumption indicating vascular stress in developing larvae. Taken altogether, the study shows that even heavily diluted AMD with environmentally relevant levels of Cu caused toxicity in zebrafish larvae.

Lufenuron is a benzoylurea insecticide currently in use to combat sea lice infestation in salmon aquaculture in Chile. With pending approval in Norway, the aim of this work was to study the uptake and toxicity of lufenuron in liver tissue of Atlantic salmon. Juvenile salmon weighing 40 g were given a standard 7-day oral dose, and bioaccumulation and transcriptional responses in the liver were examined 1 day after the end-of-treatment (day 8) and after 1 week of elimination (day 14). Bioaccumulation levels of lufenuron were 29 ± 3 mg/kg at day 8 and 14 ± 1 mg/kg at day 14, indicating relatively rapid clearance. However, residues of lufenuron were still present in the liver after 513 days of depuration. The exposure gave a transient inhibition of transcription in the liver at day 8 (2437 significant DEGs, p-adj < .05), followed by a weaker compensatory response at day 14 (169 significant DEGs). Pathways associated with RNA metabolism such as the sumoylation pathway were most strongly affected at day 8, while the apelin pathway was most profoundly affected at day 14. In conclusion, this study shows that lufenuron easily bioaccumulates and that a standard 7-day oral dose induces a transient inhibition of transcription in liver of salmon.

The demand for mineral resources is increasing mining activities worldwide. In Norway, marine tailing disposal (MTD) is practiced, introducing mineral particles into fjord ecosystems. We investigated the effects of two concentrations (high and low) of fine tailings from a CaCO3 processing plant on early life stages of the marine copepod Calanus finmarchicus. Results show that the exposure did not significantly impact hatching success or development in non- and early feeding life stages. However, feeding stage nauplii ingested tailings, which caused a significantly slower development in later nauplii stages in high exposure groups, with most individuals being two stages behind the control group. Further, high mortality occurred in late nauplii and early copepodite stages in low exposure groups, which could be caused by insufficient energy accumulation and depleted energy reserves during development. Individuals exposed to high exposure concentrations seemed to survive by arresting development and potentially by reduced activity, thereby conserving energy reserves. In nature, slower development could affect lipid storage buildup and reproduction.

A Western diet elevates the circulating lipoprotein and triglyceride levels which are the major risk factors in cardiovascular disease (CVD) development. Consumption of long-chain omega-3 fatty acids can stall the disease progression. Although these fatty acids can significantly impact the intestine under a hypercholesterolemic condition, the associated changes have not been studied in detail. Therefore, we investigated the alterations in the intestinal transcriptome along with the deviations in the plasma lipids and liver histomorphology of zebrafish offered DHA- and EPA-rich oil. Fish were allocated to 4 dietary treatments: a control group, a high cholesterol group and microbial oil groups with low (3.3%) and high (6.6%) inclusion levels. We quantified the total cholesterol, lipoprotein and triglyceride levels in the plasma. In addition, we assessed the liver histology, intestinal transcriptome and plasma lipidomic profiles of the study groups. The results suggested that higher levels of dietary microbial oil could control the CVD risk factor indices in zebrafish plasma. Furthermore, microbial oil-fed fish had fewer liver vacuoles and higher mRNA levels of genes involved in β-oxidation and HDL maturation. Analyses of the intestine transcriptome revealed that microbial oil supplementation could influence the expression of genes altered by a hypercholesterolemic diet. The plasma lipidomic profiles revealed that the higher level of microbial oil tested could elevate the long-chain poly-unsaturated fatty acid content of triglyceride species and lower the concentration of several lysophosphatidylcholine and diacylglycerol molecules. Our study provides insights into the effectiveness of microbial oil against dyslipidemia in zebrafish.

In the North Sea and North Atlantic coastal areas, fish experience relatively high background levels of persistent organic pollutants. This study aimed to compare the mode of action of environmentally relevant concentrations of mixtures of halogenated compounds in Atlantic cod. Juvenile male cod with mean weight of 840 g were exposed by gavage to dietary mixtures of chlorinated (PCBs, DDT analogs, chlordane, lindane, and toxaphene), brominated (PBDEs), and fluorinated (PFOS) compounds for 4 weeks. One group received a combined mixture of all three compound groups. The results showed that the accumulated levels of chemicals in cod liver after 4 weeks of exposure reflected concentrations found in wild fish in this region. Pathway analysis revealed that the treatment effects by each of the three groups of chemicals (chlorinated, brominated, and fluorinated) converged on activation of the unfolded protein response (UPR). Upstream regulator analysis predicted that almost all the key transcription factors (XBP1, ERN1, ATF4, EIF2AK3, and NFE2L2) regulating the UPR were significantly activated. No additive effect was observed in cod co-treated with all three compound groups. In conclusion, the genome-wide transcriptomic study suggests that the UPR pathway is a sensitive common target of halogenated organic environmental pollutants in fish.

Dyslipidemia is often associated with unhealthy dietary habits, and many mammalian studies have explored the mode of action of certain bioactive compounds such as β-glucans and n-3 PUFAs to understand their potential to normalize the lipid metabolism. There are only a few investigations that adopted omic approaches to unveil their combined effect on hypercholesterolemia. Zebrafish (Danio rerio) was used as a model organism to reveal the efficacy of Schizochytrium oil and β-glucans (from Euglena gracilis and Phaeodactylum tricornutum) against cholesterol-rich diet induced dyslipidemia. One of the folowing four diets was fed to a particular group of fish: a control high-cholesterol diet, a Schizochytrium oil diet or one of the two diets containing the oil and β-glucan. The plasma HDL, expression of hepatic genes linked to, among others, ferric ion binding and plasma phosphatidylcholines were higher and plasma cholesterol esters and triacylglycerols were lower in the microbial oil-fed fish compared to the fish fed high cholesterol diet. While the fish fed a mix of microbial oil and Euglena β-glucan had lower plasma triacylglycerols and expression of hepatic genes linked to PPAR signaling pathway and enriched biosynthesis of plasma unsaturated fatty acids, the fish fed microbial oil-Phaeodactylum β-glucan combination had lower abundance of triacylglycerols rich in saturated and mono-unsaturated fatty acids and cholesterol esters in the plasma.

Anthropogenic releases of plastics, persistent organic pollutants (POPs), and heavy metals can impact the environment, including aquatic ecosystems. Nanoplastics (NPs) have recently emerged as pervasive environmental pollutants that have the ability to adsorb POPs and can cause stress in organisms. Among POPs, DDT and its metabolites are ubiquitous environmental pollutants due to their long persistence. Despite the discontinued use of DDT in Europe, DDT and its metabolites (primarily p,p'-DDE) are still found at detectable levels in fish feed used in salmon aquaculture. Our study aimed to look at the individual and combined toxicity of NPs (50 mg/L polystyrene) and DDE (100 μg/L) using zebrafish larvae as a model. We found no significant morphological, cardiac, respiratory, or behavioural changes in zebrafish larvae exposed to NPs alone. Conversely, morphological, cardiac and respiratory alterations were observed in zebrafish larvae exposed to DDE and NPs + DDE. Interestingly, behavioural changes were only observed in zebrafish larvae exposed to NPs + DDE. These findings were supported by RNA-seq results, which showed that some cardiac, vascular, and immunogenic pathways were downregulated only in zebrafish larvae exposed to NPs + DDE. In summary, we found an enhanced toxicological impact of DDE when combined with NPs.

Gadolinium (Gd) is one of the rare earth elements (REY) and is widely used in magnetic resonance imaging (MRI) contrast agents. Anthropogenic Gd enrichment has frequently been found in wastewater treatment plant effluents in industrialised countries, rising concerns regarding effects on aquatic biota. This study investigates the acute toxicity and sublethal effects of Gd in two forms, as inorganic salt (GdCl3) and as Gd-based contrast agent (GBCA), on early life stages of zebrafish (Danio rerio). Nominal exposure concentrations ranged from 3 to 3000 μg L−1, with an exposure duration of 96 h. None of the two tested compounds were acutely toxic to embryos and larvae. Similarly, we did not observe any effects on larval development and locomotive behaviour. However, we found significant changes in the brain activity of larvae exposed to the highest concentrations of GdCl3 and the GBCA. Our findings show that Gd can have sublethal effects on developing fish at lower concentrations than reported previously, highlighting the necessity of investigating the long-term fate and effects of GBCAs released into the aquatic environment.

Soybean meal evokes diet-induced intestinal inflammation in certain fishes. Although the molecular aspects of soybean-induced intestinal inflammation in zebrafish are known, the impact of the inflammatory diet on fish behavior remain largely underexplored. We fed zebrafish larvae with three diets - control, soybean meal and soybean meal with β-glucan to gain deeper insight into the behavioral changes associated with the soybean meal-induced inflammation model. We assessed the effect of the diets on the locomotor behavior, morphological development, oxygen consumption and larval transcriptome. Our study revealed that dietary soybean meal can reduce the locomotor activity, induce developmental defects and increase the oxygen demand in zebrafish larvae. Transcriptomic analysis pointed to the suppression of genes linked to visual perception, organ development, phototransduction pathway and activation of genes linked to the steroid biosynthesis pathway. On the contrary, β-glucan, an anti-inflammatory feed additive, counteracted the behavioral and phenotypic changes linked to dietary soybean. Although we did not identify any differentially expressed genes from the soybean meal alone fed group vs soybean meal + β-glucan-fed group comparison, the unique genes from the comparisons of the two groups with the control likely indicate reduction in inflammatory cytokine signaling, inhibition of proteolysis and induction of epigenetic modifications by the dietary glucan. Furthermore, we found that feeding an inflammatory diet at the larval stage can lead to long-lasting developmental defects. In conclusion, our study reveals the extra-intestinal manifestations associated with soybean meal-induced inflammation model.

Consumption of lipid-rich foods can increase the blood cholesterol content. β-glucans have hypocholesterolemic effect. However, subtle changes in their molecular branching can influence bioactivity. Therefore, a comparative investigation of the cholesterol-lowering potential of two β-glucans with different branching patterns and a cholesterol-lowering drug, namely simvastatin was undertaken employing the zebrafish (Danio rerio) model of diet-induced hypercholesterolemia. Fish were allocated to 5 dietary treatments; a control group, a high cholesterol group, two β-glucan groups, and a simvastatin group. We investigated plasma total cholesterol, LDL and HDL cholesterol levels, histological changes in the tissues, and explored intestinal transcriptomic changes induced by the experimental diets. Dietary cholesterol likely caused the suppression of endogenous cholesterol biosynthesis, induced dysfunction of endoplasmic reticulum and mitochondria, and altered the histomorphology of the intestine. The two β-glucans and simvastatin significantly abated the rise in plasma cholesterol levels and restored the expression of specific genes to alleviate the endoplasmic reticulum-related effects induced by the dietary cholesterol. Furthermore, the distinct patterns of transcriptomic changes in the intestine elicited by the oat and microalga β-glucans impacted processes such as fatty acid metabolism, protein catabolic processes, and nuclear division. Oat and microalgal β-glucans also altered the pattern of lipid deposition in the liver. Our study provides insights into the effectiveness of different β-glucans to alleviate dysfunctions in lipid metabolism caused by dietary cholesterol.