Microcystin-LR (MCLR) has been reported to cause developmental neurotoxicity in zebrafish, but there are few studies on the mechanisms of MCLR-induced transgenerational effects of developmental neurotoxicity. In this study, zebrafish were exposed to 0, 1, 5, and 25 μg/L MCLR for 60 days. The F1 zebrafish embryos from the above-mentioned parents were collected and incubated in clean water for 120 h for hatching. After examining the parental zebrafish and F1 embryos, MCLR was detected in the gonad of adults and F1 embryos, indicating MCLR could potentially be transferred from parents to offspring. The larvae also showed a serious hypoactivity. The contents of dopamine, dihydroxyphenylacetic acid (DOPAC), serotonin, gamma-aminobutyric acid (GABA) and acetylcholine (ACh) were further detected, but only the first three neurotransmitters showed significant reduction in the 5 and 25 μg/L MCLR parental exposure groups. In addition, the acetylcholinesterase (AChE) activity was remarkably decreased in MCLR parental exposure groups, while the expression levels of manf, bdnf, ache, htr1ab, htr1b, htr2a, htr1aa, htr5a, DAT, TH1 and TH2 genes coincided with the decreased content of neurotransmitters (dopamine, DOPAC and serotonin) and the activity of AChE. Neuronal development related genes, α1-tubulin, syn2a, mbp, gfap, elavl3, shha and gap43 were also measured, but gap43 was the gene only up-regulated. Our results demonstrated MCLR could be transferred to offspring, and subsequently induce developmental neurotoxicity in F1 zebrafish larvae by disturbing the neurotransmitter systems and neuronal development.

1H-HRMAS NMR-based metabolomics was used to better understand the toxic effects on maize root tips of organochlorine pesticides (OCPs), namely lindane (γHCH) and chlordecone (CLD). Maize seedlings were exposed to 2.5 μM γHCH (mimicking basic environmental contaminations) for 7 days and compared to 2.5 μM CLD and 25 μM γHCH for 7 days (mimicking hot spot contaminations). The 1H-HRMAS NMR-based metabolomic profiles provided details of the changes in carbohydrates, amino acids, tricarboxylic acid (TCA) cycle intermediates and fatty acids with a significant separation between the control and OCP-exposed root tips. First of all, alterations in the balance between glycolysis/gluconeogenesis were observed with sucrose depletion and with dose-dependent fluctuations in glucose content. Secondly, observations indicated that OCPs might inactivate the TCA cycle, with sizeable succinate and fumarate depletion. Thirdly, disturbances in the amino acid composition (GABA, glutamine/glutamate, asparagine, isoleucine) reflected a new distribution of internal nitrogen compounds under OCP stress. Finally, OCP exposure caused an increase in fatty acid content, concomitant with a marked rise in oxidized fatty acids which could indicate failures in cell integrity and vitality. Moreover, the accumulation of asparagine and oxidized fatty acids with the induction of LOX3 transcription levels under OCP exposure highlighted an induction of protein and lipid catabolism. The overall data indicated that the effect of OCPs on primary metabolism could have broader physiological consequences on root development. Therefore, 1H-HRMAS NMR metabolomics is a sensitive tool for understanding molecular disturbances under OCP exposure and can be used to perform a rapid assessment of phytotoxicity.

Hexachloronaphthalene (HxCN) is one of the most toxic and most bioaccumulative congeners of polychlorinated naphthalenes (PCNs) known to be present in animal and human adipose tissue. Unfortunately, little data is available regarding the negative effect of PCNs on endocrine function. The aim of the study was to investigate the direct influence of subacute (two and four-week) and subchronic (13-week) daily oral exposure of female rats to 30, 100 and 300 μg kg b.w.⁻¹ HxCN on ovarian, thyroid function and neurotransmitters level. The levels of selected sex hormones (progesterone: P and estradiol: E2) in the serum and uterus, regularity of estrous cycle, levels of thyroid hormones (fT3 and fT4), TSH, γ-aminobutyric acid and glutamate levels in selected brain areas and the activity of CYP1A1 and CYP2B in the liver were examined. Estrogenic action (elevated E2 concentration in the uterus and serum) was observed only after subacute exposure, and antiestrogenic activity (decreased E2 level and uterus weight) after 13 weeks administration of 300 μg kg b.w.⁻¹ day⁻¹. Subchronic administration of HxCN significantly lengthens the estrous cycle, by up to almost 50%, and increases the number of irregular cycles. In addition, increased TSH and decreased fT4 serum levels were observed after all doses and durations of exposure to HxCN. Only subacute exposure led to a significant decrease in the level of examined neurotransmitters in all analyzed structures. Additionally, exposure to low doses of HxCN appears to lead to strong induction of CYP1A1 in a liver. It can be hypothesized that HxCN produces effects which are very similar to those caused by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and dioxin-like compounds (DLCs), particularly concerning endocrine and estrous cyclicity disorders. Therefore, HxCN exposure may exert unexpected effects on female fecundity among the general population.

Gabapentin-lactam (GBP-L) is a transformation product (TP) of gabapentin (GBP), a widely used anti-epileptic pharmaceutical. Due to its high persistence, GBP-L has been frequently detected in the surface water. However, the effects of GBP-L on aquatic organisms have not been thoroughly investigated. In the present study, zebrafish (Danio rerio) embryos as a model organism were used to study the impacts of GBP-L in terms of embryos LC₅₀, spontaneous movement at 24 hpf (hours post fertilization), heartbeat rates at 48 hpf, and body length at 72 hpf, with the concentrations of GBP-L down to 0.01 μg/L, covering its environmental concentrations. Various biomarkers from nervous, antioxidant and immune systems of zebrafish larvae were analyzed, including acetylcholinesterase, acetylcholine, dopamine, gamma-aminobutyric acid, superoxide dismutase, catalase, glutathione S-transferase, C reactive protein, and lysozyme, to assess its toxicity on these systems. RT-qPCR was then used to further verify the results and explain the toxicological mechanism at the gene level. The results demonstrated that GBP-L is much more toxic than its parent compound, and could lead to adverse impacts on the aquatic organisms even at every low concentrations.

Smoke from plastic waste incineration in an open air travels worldwide and is a major source of air pollution particulate matter (PM) that is very withstand to degradation and hazard to human health. Suspension of smoke aerosol components in water occurs during rains and fire extinguishing. Here, water-suspended plastic smoke aerosol (WPS) preparations suitable for biotesting were synthesized. It has been revealed using dynamic light scattering that WPS contained major nano-sized (∼30 nm) PM fraction, and this result was confirmed by electron microscopy. Optical absorption of WPS was in the UV region and an increase in λₑₓ led to a red-shift in fluorescence emission with a corresponding decrease in fluorescence intensity. WPS was analyzed in neurotoxicity studies in vitro using presynaptic rat cortex nerve terminals (synaptosomes). Generation of spontaneous reactive oxygen species (ROS) detected using fluorescent dye 2′,7-dichlorofluorescein in nerve terminals was decreased by WPS (10–50 μg/ml) in a dose-dependent manner. WPS also reduced the H₂O₂-evoked ROS production in synaptosomes, thereby influencing cellular oxidative processes and this effect was similar to that for carbon nanodots. WPS (0.1 mg/ml) decreased the synaptosomal membrane potential and synaptic vesicle acidification in fluorimetric experiments. WPS (1.0 mg/ml) attenuated the synaptosomal transporter-mediated uptake of excitatory and inhibitory neurotransmitters, L-[¹⁴C]glutamate and [³H]GABA, respectively. This can lead to an excessive increase in the glutamate concentration in the synaptic cleft and neurotoxicity via over activation of ionotropic glutamate receptors. Therefore, WPS was neurotoxic and provoked presynaptic malfunction through changes of oxidative activity, reduction of the membrane potential, synaptic vesicle acidification, and transporter-mediated uptake of excitatory and inhibitory neurotransmitters in nerve terminals. In summary, synthesis and emission to the environment of ultrafine PM occur during combustion of plastics, thereby polluting air and water resources, and possibly triggering development of neuropathologies.

Silver (Ag) is amongst the most well studied nanomaterials (NMs), although most studies have only dealt with a single AgNM at a time and one biological endpoint. We here integrate the results of various testing-tools (endpoints) using a terrestrial worm, the standard ecotoxicological model organism Enchytraeus crypticus. Exposure spanned both water and soil exposure, it covered all life stages (cocoons, juveniles and adults), varying exposure durations (1-2-3-4-5-21 days), and covered 5 biological endpoints: hatching success, survival, reproduction, avoidance and gene expression (qPCR target genes GABA and Acetyl cholinesterase). We tested 4 Ag materials: PVP coated (PVP-AgNM), non-coated (NC-AgNM), the JRC reference Ag NM300K and AgNO₃. Results showed that short-term exposure via water to assess impact on cocoons’ hatching predicted longer term effects such as survival and reproduction. Moreover, if we extended the exposure from 11 to 17 day this allowed discrimination between hatch delay and impairment. Exposure of juveniles and adults via water showed that juveniles were most sensitive with survival affected. Across materials the following toxic ranking was observed: AgNO₃ ≥ Ag NM300K ≫ NC-AgNM ≥ PVP-AgNM. E. crypticus avoided AgNO₃ in a dose-response manner, avoiding most during the first 24 h. Avoidance of Ag NM300K and NC-AgNM only occurred during the first 24 h and the PVP coated AgNM were not avoided at all. The up-regulation of the GABA triggering anesthetic effects, indicated the high ecological impact of Ag materials in soil: Ag affects the GABAergic system hence organisms were not able to efficiently avoid and became intoxicated, this caused impacts in terms of survival and reproduction.

Several works evaluated the toxicity of pharmaceutical drugs and climate related changes in invertebrates but few explored the combined effects of both stressors, namely considering their mode of action (MoA). Carbamazepine (CBZ) and cetirizine (CTZ) are pharmaceutical drugs detected in the environment and the toxicity derived from the combined effects of these drugs with ocean acidification (OA) is poorly explored. Thus, the present study investigated the biochemical parameters related to an oxidative stress response and the transcription of genes related to the MoA of CBZ (1.0 μg/L) and CTZ (0.6 μg/L) in the clam Ruditapes philippinarum chronically exposed (28 days) to control (7.8) and low (7.5) pH conditions. The results obtained showed that despite the clams accumulated both drugs, at low pH the clams exposed to CTZ decreased drug concentration and BCF values (CTZ uptake: 2.0 ± 0.5 ng/g fresh weight; BCF: 3.8 ± 0.9) in comparison with clams exposed to control pH (CTZ uptake: 2.9 ± 0.3 ng/g fresh weight; BCF: 5.5 ± 0.6). No oxidative stress was induced by the exposure to CBZ or CTZ at each pH level, but the transcription of several genes related with the MoA (neurotransmission, immunity and biomineralization) was altered by low pH, drug exposure and the combination of both stressors. At both pH conditions, CBZ increased the transcription of GABA receptor gene (neurotransmission) and CTZ led to a decrease of Perlucin gene (biomineralization) transcription. The transcription of MyD88 gene (immunity) decreased at low pH (7.5) combined with drug exposure (CBZ or CTZ). Thus, it was highlighted that the interaction of drug exposure and low pH conditions can change bivalves’ sensitivity to drugs or alter drugs toxicity.

Free amino acid concentrations and nitrogen (N) isotopic composition in new current-year (new), mature current-year (middle-aged) and previous-year (old) Masson pine (Pinus massoniana Lamb.) needles were determined to indicate atmospheric N deposition in Guiyang (SW China). In different areas, free amino acids (especially arginine) concentrations in new and middle-aged needles were higher than in old needles, and the variation of free amino acids (especially arginine) concentrations in new and middle-aged needles was also greater than in old needles. This indicate that free amino acids in new and middle-aged needles may be more sensitive to N deposition compared to old needles. Moreover, concentrations of total free amino acids, arginine, histidine, γ-aminobutyric acid and alanine in middle-aged needles exhibited a strong relationship with N deposition (P < 0.05). Needle δ¹⁵N values showed a strong gradient from central Guiyang to the rural area, with more positive δ¹⁵N (especially in old needles) in the city center (0–5 km) and more negative δ¹⁵N (especially in old needles) in rural area (30–35 km). These suggest that N deposition in the urban center may be dominated by ¹⁵N-enriched NOx-N from traffic exhausts, while it is dominated by isotopically light atmospheric NHx-N from agriculture in rural area. Soil δ¹⁵N decreased slightly with distance from the city center, and the difference in δ¹⁵N values between the soil and needles (especially for old needles) increased significantly with the distance gradient, indicating that atmospheric N deposition may be an important N source for needles. This study provides novel evidence that free amino acids in needles and age-dependent needle δ¹⁵N values are useful indicators of atmospheric N deposition.

This study investigated the anti-estrogenic effects of chronic exposure to a new marine pollutant, semicarbazide (SMC; 1, 10, and 100μg/L), in female Paralichthys olivaceus, as well as the associated mechanism. After 130days of exposure, plasma 17β-estradiol and testosterone concentrations, and hepatic estrogen receptors, vitellogenin, and choriogenin mRNA levels decreased significantly in SMC-exposed groups. Moreover, down-regulation of genes in the hypothalamic-pituitary-gonadal axis, including gonadotropin-releasing hormone, gonadotropic hormones and their receptors, the steroidogenic acute regulatory protein, 17α-hydroxylase, 17β-hydroxysteroid dehydrogenase, and cytochrome P450 19A, was observed after SMC exposure. Furthermore, the kisspeptin/g protein-coupled receptor 54 (kiss/gpr54) system and gamma-aminobutyric acid-ergic (GABAergic) system were also affected by SMC: SMC significantly down-regulated mRNA expression of kiss2, gpr54, and the GABA synthesis enzyme gad67. Our results demonstrated for the first time that environmentally relevant concentrations of SMC exerted anti-estrogenicity in female flounders, providing theoretical support for ecological risk assessments of SMC in marine environments.

Gamma-aminobutyric acid (GABA) is a well-known feed supplement for its capability of reducing the adverse effect of stress in chickens. Several studies using GABA supplementation as a mitigatory measure have been published. However, it remains difficult to draw a general conclusion since these studies have been done under different experimental conditions. Therefore, the objective of this study was to quantify the response (growth performances, immune responses, and blood biochemical parameters) of chickens to GABA supplementation under various stressful conditions through a meta-analysis approach. A total of 19 articles published from 2011 to 2020, including 30 treatments, were used. A mixed-model ANOVA was used to assess how the growth parameters varied based on the GABA mode of supplementation. Linear mixed models and general linear models were used to evaluate the effects of the GABA doses and the duration of the supplementation on the growth performances and the immune parameters. Results indicated that supplementation of GABA via drinking water was more effective than dietary supplementation for reducing the feed conversion ratio in heat-stressed birds (P < 0.01). In addition, an increase in the GABA doses resulted in an augmentation (P < 0.01) of the body weight gain while a longer duration of supplementation resulted in increasing (P<0.01) the feed intake. Furthermore, increasing the duration of the supplementation reduced the immunoglobulin (P < 0.0001) and bursa’s relative weight (P < 0.0001), while increasing blood CD8+ count (P < 0.001) and spleen’s relative weight (P < 0.0001). Finally, blood total protein content was increased (P < 0.0001) by a longer duration of supplementation. This study showed that the doses and the duration of the GABA supplementation can affect the growth performances of chickens under stressful conditions. However, the effect of GABA on immune responses and blood parameters is perceived with a relatively longer supplementation duration.