The effects of parental carbamazepine and gemfibrozil exposure on sexual differentiation in zebrafish (Danio rerio)

Elucidating the Effects of the Lipids Regulators Fibrates and Statins on the Health Status of Finfish Species: A Review

The most documented fibrates are gemfibrozil, clofibrate and bezafibrate, while for statins, the majority of the published literature focuses on atorvastatin and simvastatin. The present work reviews previously published research concerning the effects of these hypocholesterolaemic pharmaceuticals on fish, with a particular focus on commercially important species, commonly produced by the European aquaculture industry, specifically in recirculated aquaculture systems (RAS). Overall, results suggest that both acute and chronic exposures to lipid-lowering compounds may have adverse effects on fish, disrupting their capacity to excrete exogenous substances, as well as both lipid metabolism and homeostasis, causing severe ontogenetic and endocrinological abnormalities, leading to hampered reproductive success (e.g., gametogenesis, fecundity), and skeletal or muscular malformations, having serious repercussions on fish health and welfare. Nonetheless, the available literature focusing on the effects of statins or fibrates on commonly farmed fish is still limited, and further research is required to understand the implications of this matter on aquaculture production, global food security and, ultimately, human health.

Mapping the past, present and future research landscape of paternal effects

BACKGROUND

Although in all sexually reproducing organisms an individual has a mother and a father, non-genetic inheritance has been predominantly studied in mothers. Paternal effects have been far less frequently studied, until recently. In the last 5 years, research on environmentally induced paternal effects has grown rapidly in the number of publications and diversity of topics. Here, we provide an overview of this field using synthesis of evidence (systematic map) and influence (bibliometric analyses).

RESULTS

We find that motivations for studies into paternal effects are diverse. For example, from the ecological and evolutionary perspective, paternal effects are of interest as facilitators of response to environmental change and mediators of extended heredity. Medical researchers track how paternal pre-fertilization exposures to factors, such as diet or trauma, influence offspring health. Toxicologists look at the effects of toxins. We compare how these three research guilds design experiments in relation to objects of their studies: fathers, mothers and offspring. We highlight examples of research gaps, which, in turn, lead to future avenues of research.

CONCLUSIONS

The literature on paternal effects is large and disparate. Our study helps in fostering connections between areas of knowledge that develop in parallel, but which could benefit from the lateral transfer of concepts and methods.

Paternal Exposure to Carbamazepine Impacts Zebrafish Offspring Reproduction Over Multiple Generations

Chronic low-concentration chemical exposures may have both direct health outcomes on adults and indirect effects on their offspring. Using zebrafish, we examined the impacts of chronic, low-concentration carbamazepine (CBZ) exposure on a suite of male reproductive endpoints in the parents and four generations of offspring reared in clean water. CBZ is one of the most frequently detected pharmaceutical residues in water, is a histone deacetylase inhibitor in mammals, and is reported to lower androgens in mammals and fish. Exposure of adult zebrafish to 10 μg/L CBZ for 6 weeks decreased reproductive output, courtship and aggressive behaviors, 11-ketotestosterone (11KT), and sperm morphology but did not impact milt volume or sperm swimming speed. Pairwise breeding generated lineages of offspring with both parents exposed and two lineages where only one parent was exposed; the control lineage had unexposed parents. Reproductive output and male reproductive indices were assessed in F₁-F₄ offspring to determine whether parental CBZ exposure had transgenerational impacts. The offspring of CBZ-exposed males had lower 11KT, reproductive output, altered courtship, aggression, and sperm morphology compared to the lineage from unexposed parents. Our results indicate that parental carbamazepine exposure history impacts the unexposed progeny up to the F₄ generations and that paternal, but not maternal, exposure is most important for the reproductive health of male offspring.

Parental gemfibrozil exposure impacts zebrafish F1 offspring, but not subsequent generations

Gemfibrozil (GEM) is a fibrate lipid regulator and one of the most commonly occurring fresh water pharmaceuticals. The negative effects of fibrates including GEM on fish reproduction have been frequently reported including effects of F₀ GEM exposure on reproduction of the unexposed F₁ offspring. We predicted that chronic, direct exposure of zebrafish with low concentrations of GEM would adversely affect parental male reproduction and unexposed offspring for multiple generations. Adult zebrafish were exposed to 10 μg/L GEM for 6 weeks and a range of reproductive indices were analyzed. The F₁-F₄ offspring were reared in clean water from 3 distinct lineages where only a single or both parents were exposed and compared to a control lineage where parents were unexposed. Reproductive indices were examined in unexposed F₁-F₄ offspring to test the hypothesis of multi- or trans- generational impacts. Exposure to GEM caused a decline in breeding success and mean embryo production in F₀ parents and a reduction in whole body 11-ketotestosterone (11-KT), altered male courtship, aggression and sperm morphology. Our results indicate that paternal exposure alone is sufficient to result in reproductive effects in unexposed male offspring but that effects are mostly limited to F₁. We suggest that GEM may act as a reproductive endocrine disruptor in fish and that chronic exposure reduced male reproductive fitness but not over multiple generations.

Sublethal psychotropic pharmaceutical effects on the model organism Danio rerio: Oxidative stress and metal dishomeostasis

Contaminants of emerging concern have become an important environmental problem, especially pharmaceutically active compounds (PhACs), since, after use, these drugs return to the environment, contaminating aquatic ecosystems. Some may display the ability to bioaccumulate and biomagnify throughout the food chain, leading to potential environmental and human deleterious effects which are, however, still largely unknown. In this context, the aim of the present study was to evaluate the effect of two psychotropic drugs commonly found in the environment, carbamazepine (CBZ) and clonazepam (CZP), both isolated and co-administrated, on oxidative stress biomarkers and essential metal homeostasis in Danio rerio fish specimens. No studies are available to data in this regard concerning CZP effects on fish. Reduced Glutathione (GSH), Metallothionein (MT), Catalase (CAT) and Glutathione S-Transferase (GST) were determined, as well as essential metals in fish liver, kidney and brains. Significant oxidative stress effects were observed for several biomarkers, where brain GST activity was the most affected, mainly with regard to CBZ exposure, while GST and CAT activity in the liver were downregulated in the co-administration mixture. In addition, dishomeostasis of several essential elements was detected in all analyzed organs, with a synergistic action of CBZ and CZP in brain, decreasing basal Mg, Al, K, Fe, Co, Ni and Cu levels in this organ, the target site for these drugs in humans. The brain organ was the most affected as observed by altered GST activity and metal dyshomeostasis concerning exposure to both compounds. These compounds, thus, present health risks to the aquatic biota, due to the evidenced deleterious effects and their constant release into the environment due to widespread use. Steps are needed to implement adequate legislation for risk analysis and decision-making in order to mitigate the effects of these emerging contaminants on aquatic ecosystem health.

Ecotoxicological Effect of Single and Combined Exposure of Carbamazepine and Cadmium on Female Danio rerio: A Multibiomarker Study

In aquatic environments, organisms are exposed to mixtures of pollutants which may change the toxicity profile of each contaminant, compared to its toxicity alone. Carbamazepine (CBZ) and cadmium (Cd) are among the pollutants that co-occur in aquatic environments. To date, most research about their toxicity towards aquatic vertebrates is based on single exposure experiments. The present study aims to evaluate single and combined effects of CBZ and Cd on biomarkers in female Danio rerio (zebrafish) by exposing them to environmentally relevant concentrations of these two pollutants for ten days. Four kinds of biomarkers involved in antioxidant systems, energy metabolism, nervous system, and endocrine disruption, respectively, were studied. Our research results coincided with those of former studies in single exposure experiments. However, the combined exposure of CBZ and Cd exerted different responses from other studies in which these two contaminants were examined alone in zebrafish. The present study evidenced the need to conduct more coexposure studies to enhance the environmental relevance of these experimental results.