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The marijuana legalization trend in the U.S. will likely lead to increased use by younger adults during gestation and postpartum. The current study examined the hypothesis that delta-9-tetrahydrocannabinol (THC) would disrupt voluntary maternal care behaviors and negatively impact offspring development. Rat dams were gavaged with 0, 2, 5, or 10 mg/kg THC from the 1st day of gestation through the 21st postnatal day. Somatic growth and developmental milestones were measured in the offspring, and maternal pup retrieval tests were conducted on postnatal days 1, 3, and 5. THC did not affect body growth but produced transient delays in the righting reflex and eye opening in offspring. However, there was significant pup mortality due to impaired maternal care. Dams in all THC groups took significantly longer to retrieve their pups to the nest and often failed to retrieve any pups. Serum levels of THC and metabolites measured at this time were comparable to those in breastfeeding women who are chronic users. Benchmark doses associated with a 10% reduction of pup retrieval or increased pup mortality were 0.383 (BMDL 0.228) and 0.794 (BMDL 0.442) mg/kg THC, respectively. The current findings indicate that maternal care is an important and heretofore overlooked index of THC behavioral toxicity and should be included in future assessments of THC's health risks. [ABSTRACT FROM AUTHOR]

The marijuana legalization trend in the U.S. will likely lead to increased use by younger adults during gestation and postpartum. The current study examined the hypothesis that delta-9-tetrahydrocannabinol (THC) would disrupt voluntary maternal care behaviors and negatively impact offspring development. Rat dams were gavaged with 0, 2, 5, or 10 mg/kg THC from the 1st day of gestation through the 21st postnatal day. Somatic growth and developmental milestones were measured in the offspring, and maternal pup retrieval tests were conducted on postnatal days 1, 3, and 5. THC did not affect body growth but produced transient delays in the righting reflex and eye opening in offspring. However, there was significant pup mortality due to impaired maternal care. Dams in all THC groups took significantly longer to retrieve their pups to the nest and often failed to retrieve any pups. Serum levels of THC and metabolites measured at this time were comparable to those in breastfeeding women who are chronic users. Benchmark doses associated with a 10% reduction of pup retrieval or increased pup mortality were 0.383 (BMDL 0.228) and 0.794 (BMDL 0.442) mg/kg THC, respectively. The current findings indicate that maternal care is an important and heretofore overlooked index of THC behavioral toxicity and should be included in future assessments of THC’s health risks.

The present study examined the effects of environmentally realistic exposure to atrazine (ATZ) on the behavior of sailfin mollies, Poecilia latipinna. ATZ is one of the most commonly used pesticides in the US and a known endocrine disrupting chemical (EDC). The behavior of sailfin mollies is well documented in the scientific literature. Moreover, they are ecologically important indicators of environmental health, widely distributed among the mangroves along the Gulf Coast of the Southeastern US where significant amounts of ATZ are introduced via runoff and storm water drainage from coastal households, businesses, and farms. Four sets of experiments designed to assess ATZ's impact on various aspects of male and female reproductive behavior, aggression, anxiety, and boldness were conducted following 12 weeks of exposure to 1 or 15 ppb water-borne ATZ, along with a no-exposure control group. Results indicated that the behavior of ATZ-exposed individuals differed from those of controls: ATZ exposure affected which stimulus fish (a male vs. a female) subject females preferred to associate with while also affecting female strength of preference for males of larger body size and their sexual receptivity to conspecific males in general. ATZ-exposed males also showed reduced overall responsiveness to conspecific stimuli and directed significantly less aggression toward their mirror image compared with controls. Finally, ATZ exposure affected multiple aspects of male and female behavior that are often used as proxies for boldness and anxiety. Overall, ATZ exposure resulted in alterations across a variety of behaviors attributed to sexual receptivity, mate choice and motivation to mate, aggression, as well as boldness and anxiety. These ATZ-induced behavioral changes may adversely affect the long-term health of natural populations exposed to similar, environmentally realistic concentrations and add to a growing body of empirical data demonstrating substantial fitness consequences of exposure to sublethal concentrations of this known EDC. [ABSTRACT FROM AUTHOR]

The effect of Justicia extensa leaf (ethanolic) extract on behavior and histopathology of Clarias gariepinus fingerling was investigated in the present study. The fish specimens were exposed to graded acute concentrations of the plant leaf extract (0.0, 4.0, 6.0, 8.0, 10.0, and 12.0 mL) for 96 h, during which time-dependent (24 h, 48 h, 72 h, 96 h) lethal concentrations of J. extensa, behavior, and histopathological changes in the gill and liver of the grouped specimens were evaluated. Based on the study findings, the respective values; 10.90, 8.60, 7.00 and 6.80 mL were obtained as the 24, 48, 72 and 96 h median lethal concentrations of J. extensa leaf extract to C. gariepinus fingerling. The study further indicate that the plant affected water quality conditions of the test media in a concentration-dependent manner, except for pH. Consequently, J. extensa elicited prominent behavioral aberrations (excessive mucus secretion, air gulping, respiratory distress, erratic swimming and vertical erection) and induced histopathological lesions in the gill (hyperplasia, erosion, fusion and disorganization of secondary lamella, desquamation and cellular degeneration) and liver (hepatic coagulative necrosis, vacuolation of parenchyma, hyperplasia, necrotic hepatocytes and hepatopancreatic tissue lysis) of C. gariepinus after 96 h exposure duration. The use of plant piscicides for fishing should be applied with caution in order to avert catastrophic events in the aquatic ecosystems.

Fluoroquinolones (FQs) and tetracyclines (TCs), the two β-diketone antibiotics (DKAs), are two frequently detected pollutants in the environment; however, little data are available on their combined toxicity to zebrafish (Danio rerio). This study reports that toxicologic effects of combined DKA (FQs-TCs) exposure on zebrafish were comparable with or slightly less than those of TCs alone, showing that TCs played a major toxicologic role in the mixtures. The effects of FQs, TCs, and DKAs on malformation rates of zebrafish were dose dependent, with EC50 values of 481.3, 16.4, and 135.1 mg/L, respectively. According to the combined effects of DKAs on zebrafish hatching, mortality, and malformation rates, the interaction between FQs and TCs was shown to be antagonistic based on three assessment methods: Toxic Unit, Additional Index, and Mixture Toxic Index. The 1.56 mg/L TC and 9.38 mg/L DKA treatments resulted in higher zebrafish basal swimming rate compared with the control group at 120 hours postfertilization (hpf). in both light and light-to-dark photoperiod experiments. Under conditions of no obvious abnormality in cardiac development, the heart beats were decreased significantly because of DKA exposure, such as decreasing by ∼20% at 150 mg/L DKAs. Transmission electron microscopy observation of myocytes from DKA-exposed hearts displayed prominent interruptions and myofibrillar disorganization of the normal parallel alignment of thick and thin filaments, and partial edematous and dissolved membranes of cell nuclear tissues. At 90 mg/L DKAs, the transcriptional levels of the acta1a, myl7, and gle1b genes, related to heart development and skeletal muscle formation, were significantly changed. This is consistent with the swimming behavior and histopathologic results obtained by transmission electron microscopy. In summary, the toxicity of the combined DKAs to zebrafish was comparable with or less than that of TCs alone and had the ability to impair individual behaviors that are of great importance in the assessment of their ecologic fitness. © 2014 Wiley Periodicals, Inc. Environ Toxicol 31: 736-750, 2016.

With the appreciation that behavior represents the integration and complexity of the nervous system, neurobehavioral phenotyping and assessment has seen a renaissance over the last couple of decades, resulting in a robust database on rodent performance within various testing paradigms, possible associations with human disorders, and therapeutic interventions. The interchange of data across behavior and other test modalities and multiple model systems has advanced our understanding of fundamental biology and mechanisms associated with normal functions and alterations in the nervous system. While there is a demonstrated value and power of neurobehavioral assessments for examining alterations due to genetic manipulations, maternal factors, early development environment, the applied use of behavior to assess environmental neurotoxicity continues to come under question as to whether behavior represents a sensitive endpoint for assessment. Why is rodent behavior a sensitive tool to the neuroscientist and yet, not when used in pre-clinical or chemical neurotoxicity studies? Applying new paradigms and evidence on the biological basis of behavior to neurobehavioral testing requires expertise and refinement of how such experiments are conducted to minimize variability and maximize information. This review presents relevant issues of methods used to conduct such test, sources of variability, experimental design, data analysis, interpretation, and reporting. It presents beneficial and critical limitations as they translate to the in vivo environment and considers the need to integrate across disciplines for the best value. It proposes that a refinement of behavioral assessments and understanding of subtle pronounced differences will facilitate the integration of data obtained across multiple approaches and to address issues of translation.

The present study examined the effects of environmentally realistic exposure to atrazine (ATZ) on the behavior of sailfin mollies, Poecilia latipinna. ATZ is one of the most commonly used pesticides in the US and a known endocrine disrupting chemical (EDC). The behavior of sailfin mollies is well documented in the scientific literature. Moreover, they are ecologically important indicators of environmental health, widely distributed among the mangroves along the Gulf Coast of the Southeastern US where significant amounts of ATZ are introduced via runoff and storm water drainage from coastal households, businesses, and farms. Four sets of experiments designed to assess ATZ’s impact on various aspects of male and female reproductive behavior, aggression, anxiety, and boldness were conducted following 12 weeks of exposure to 1 or 15 ppb water-borne ATZ, along with a no-exposure control group. Results indicated that the behavior of ATZ-exposed individuals differed from those of controls: ATZ exposure affected which stimulus fish (a male vs. a female) subject females preferred to associate with while also affecting female strength of preference for males of larger body size and their sexual receptivity to conspecific males in general. ATZ-exposed males also showed reduced overall responsiveness to conspecific stimuli and directed significantly less aggression toward their mirror image compared with controls. Finally, ATZ exposure affected multiple aspects of male and female behavior that are often used as proxies for boldness and anxiety. Overall, ATZ exposure resulted in alterations across a variety of behaviors attributed to sexual receptivity, mate choice and motivation to mate, aggression, as well as boldness and anxiety. These ATZ-induced behavioral changes may adversely affect the long-term health of natural populations exposed to similar, environmentally realistic concentrations and add to a growing body of empirical data demonstrating substantial fitness consequences of exposure to sublethal concentrations of this known EDC.

The eco-risk of roxarsone (ROX) was evaluated using multiple responses of earthworm biomarkers under different ROX concentrations for 28 d. With the increasing total arsenic accumulation (TAs-E), biological responses in earthworm generally showed a two-stage changes of homeostasis dysregulation and dose-dependent alterations. At the early periods, ROX stress increased the reactive oxygen species (ROS) and lipid peroxidation (LPO) in a similar manner, and apparently disrupted mitochondrial calcium ([Ca2+]m). But earthworms regulated their mitochondrial and redox homeostasis through stable mitochondrial membrane potential (MMP) and increase of ATP level, superoxide dismutase (SOD) and catalase (CAT). After 14 d, the positively correlated mitochondrial effects of ROS, [Ca2+]m, MMP and ATP were related to the behavioral inhibition of burrow length, depth and reuse rate as well as antioxidant up-regulation of Nrf2, HO-1, sod1 and cat. These results contributed possible biomarkers from the dose-dependent relationship between mitochondrial, antioxidant and behavioral responses. Multiple biological detection in earthworms can better reflect the sub-chronic ecotoxicity of phenylarsenic pollutants in soil.

Numerous byproducts resulting from chlorinated disinfection are constantly being generated during water treatment processes. The potential risks of these new emerging pollutions remain largely unknown. Here, we determined the risks of chlorinated disinfection byproducts of diazepam (DZP) in the cellular and zebrafish exposure experiments. The cytotoxicity of disinfection byproducts (MACB and MBCC) was greater than DZP in macrophage raw 264.7 cells at 10 mg/L. We further found that the effects of MBCC on the metabolism of glycine, serine, threonine and riboflavin were far greater than DZP by the targeted metabolomics methods. Moreover, MBCC significantly decreased the peak amplitude of neuronal action potential in primary embryonic rat (Spragu-Dawley SD) hippocampal neurons. We finally determined behavioral toxicity of DZP and byproducts in zebrafish larvae. MBCC significantly decreased the maximal swim-activity and peak duration of zebrafish after 72 h exposure. Altogether, these findings indicate the MBCC pose serious pressures on public health.

Disrupted behavior and respiratory distress effects of 96-h acute deltamethrin exposures in adult Mozambique tilapia, Oreochromis mossambicus, were investigated using behavioral indices and opercular movement, respectively. Deltamethrin concentrations were found to be associated with toxicological (lethal and sublethal) responses. At 24, 48, 72, and 96 h, the LC50 values and 95% confidence limits were 12.290 (11.174–14.411 µg/L), 12.671 (11.334–15.649 µg/L), 10.172 (9.310–11.193 µg/L), and 8.639 (7.860–9.417 µg/L), respectively. The GUTS-model analysis showed that GUTS-SD (stochastic death) with a narrow tolerance distribution in deltamethrin exposed O. mossambicus populations was more sensitive than the GUTS-IT (individual tolerance) model. Prior to death, exposed fish demonstrated concentration-dependent mortality and disturbed behavioral responses, including uncoordinated swim motions, increased mucus secretion, unbalanced and unpredictable swimming patterns, and inactivity. The altered behavioral patterns and increased opercular movement with increased deltamethrin levels and exposure time are strongly suggestive of neurotoxicity and respiratory distress, respectively. Adverse Outcome Pathways (AOPs), describing biological mechanisms and plausible pathways, highlighted oxidative stress and cholinergic effects as intermediate steps linked to respiratory distress and behavioral toxicity.

Non-target organisms in aquatic environments may experience lethal or sublethal effects following exposure to contaminants. Most protocols and regulations, however, are designed to provide protection from lethal effects and are thus based on conventional estimates of population lethality. The relative lack of reliable behavioral endpoints makes it challenging to implement regulations that are similarly protective against sublethal toxicity. The objective of this study was to quantify the avoidance behavior of Hyalella azteca when exposed to three insecticides—bifenthrin (B), chlorpyrifos (C), and permethrin (P)—at a range of estimated lethal concentrations. A two-choice behavioral arena was used for each chemical to quantify H. azteca activity and time spent in either uncontaminated sediment or sediment spiked at concentrations reflecting estimated 48-h lethal concentrations (LC 50 , LC 25 , and LC 10). For all three insecticides, naïve H. azteca demonstrated a preference for the uncontaminated sediment over the contaminated sediment at the LC 50 (B: 312 ng/g OC ; C: 1265 ng/g OC ; P: 5042 ng/g OC) and LC 25 (B: 230 ng/g OC ; C: 859 ng/g OC ; P: 3817 ng/g OC), spending significantly more time in the uncontaminated side of the arena. H. azteca did not avoid sediment at LC 10 (B: 204 ng/g OC ; C: 609 ng/g OC ; P: 1515 ng/g OC) levels, indicating the existence of a potential threshold of detection. Despite the lack of substrate preference at this exposure level, H. azteca were nevertheless more active (i.e., increased zone-switching) when exposed to bifenthrin at the LC 10 , suggesting a possible irritation response (e.g., movement after exposure) to this chemical. Our results provide evidence that H. azteca exhibit innate avoidance responses to sediments contaminated with common insecticides at concentrations below those represented by traditional toxicological endpoints (e.g., LC 50). The sensitivity and ease with which this behavioral endpoint can be assayed demonstrates the potential utility of behavioral endpoints in toxicological assessments using model organisms. [Display omitted] • Avoidance behavior is a sensitive endpoint with population-level consequences. • Hyalella azteca avoided insecticides in sediment at and below the LC 50 and LC 25. • Avoidance was not detected at insecticide concentrations equal to the LC 10. • Increased activity at the bifenthrin LC 10 suggest a threshold of detection. • We advocate for the utility of avoidance as an informative behavioral endpoint. [ABSTRACT FROM AUTHOR]

Keywords: suicidality; Black Box; activation syndrome; behavioral toxicity; antidepressants EN suicidality Black Box activation syndrome behavioral toxicity antidepressants 1 3 3 05/05/20 20200430 NES 200430 In a recent issue of Frontiers in Psychiatry, Spielmans et al. ([1]) defend the 2004 decision of the Food and Drug Administration (FDA) to issue a Black Box warning on the potential risk of suicidality in youth being administered antidepressant medications. As various neural correlates (e.g., amygdala connectivity) have predicted attenuated antidepressant treatment response ([9], [10]), it is possible that such developmental alterations in brain maturation also relate to increased possibility of SSRI-induced behavioral side effects. [Extracted from the article]

This study examined the effects on neurobehavioral function of exposure to low-level mercury vapor (Hg0), methylmercury (MeHg) in female mice and the combination of Hg0 and MeHg during postnatal development. Postnatal mice were exposed to Hg0 at a mean concentration of 0.188 mg/m3 Hg0 and supplied with food containing 3.85 μg/g of MeHg from day 2 to day 28 after delivery. The combined exposure group was exposed to both Hg0 and MeHg, using the same procedure. When their offspring reached the age of 11 weeks, behavioral analyses were performed. The behavioral effects in mice were evaluated based on locomotive activity and rate of center entries in the open field (OPF), learning activity in the passive avoidance response (PA) and spatial learning ability in the radial maze (RM). Total locomotive activity in the OPF significantly decreased in the Hg0, MeHg and combined exposure groups compared with the control group. The proportion of entries to central area in the OPF was significantly higher in the combined exposure group than in the control group, while those in the Hg0 or MeHg exposure group did not differ from the control group. Other behavioral tests did not reveal significant differences among the groups. Behavioral anomalies were more distinctive after combined exposure compared to Hg0 or MeHg exposure alone. The brain Hg concentration of offspring, immediately after exposure, was highest in the combined exposure group, exceeding 2 μg/g, followed by the MeHg and Hg0 exposure groups. Thus, the enhancement of neurobehavioral effects in the combined exposure group was associated with higher brain mercury concentration. [ABSTRACT FROM AUTHOR]

The frequent detection of progestins in various aquatic environments and their potential endocrine disruptive effects in fish have attracted increasing attention worldwide. However, data on their effects on thyroid function and neurotoxicity in fish are limited, and the underlying mechanisms remain unclear. Here, the effects of gestodene (GES, a common progestin) on the thyroid endocrine and nervous systems of mosquitofish (Gambusia affinis) were studied. Adult female fish were exposed to GES at environmentally relevant concentrations (4.4–378.7 ng/L) for 60 days. The results showed that exposure to 378.7 ng/L GES caused a significant decrease in fish growth compared with the control and a marked reduction in the total distance traveled (50.6%) and swimming velocity (40.1–61.9%). The triiodothyronine (T3) levels were significantly increased by GES in a dose-dependent manner, whereas those of tetraiodothyronine (T4) were significantly decreased only at the G500 concentration. The acetylcholinesterase (AChE) activity was decreased significantly in the 4.42 ng/L GES treatments, but increased significantly at 378.67 ng/L. In the brain, a strong increase in the transcriptional levels of bdnf , trh , and dio2 was observed in fish after the 378.7 ng/L treatment. In addition, chronic exposure to GES caused colloid depletion with a concentration-dependent manner in the thyroid, and angiectasis, congestion, and vacuolar necrosis in the brain. These findings provide a better understanding of the effects of GES and associated underlying mechanisms in G. affinis. [Display omitted] • The effects of gestodene exposure on thyroid endocrine disruption and neurotoxicity were investigated in G. affinis. • The levels of thyroid hormone T3 was increased, while T4 was decreased in G. affinis. • Gestodene caused colloid depletion in the thyroid, and angiectasis, congestion and vacuolar necrosis in the cerebellum. [ABSTRACT FROM AUTHOR]

Bisphenol A (BPA) is an environmental endocrine disrupter (EED). Previous studies by our group showed that pre- and postnatal administration of low-level BPA induced depression-like behavior in rats. In this study, we evaluated the effects of prenatal BPA on behavioral responses to a predator odor by using a novel cross-form apparatus consisting of 4 plastic chambers. On the first day, nothing was placed into the chambers (Session 1). On the second day, a predator odor (fox odor) was located in separate chambers at 2 opposite corners of the apparatus (Session 2). Pregnant Wistar rats were exposed to low-dose BPA (less than the reference dose) during the 7 days just before birth, and the offspring of the treated rats were evaluated as adults. The locomotor activity and avoidance response of each rat on both test days were compared. The control and BPA groups showed reduced locomotor activity in the presence of the predator odor, but the odor-avoidance response was significant only in the BPA rats. The BPA-exposed rats were obviously sensitive to the predator odor. These results suggest that prenatal BPA exposure has an amplifying effect on avoidance responses to predator odor stress. [ABSTRACT FROM AUTHOR]

Disrupted behavior and respiratory distress effects of 96-h acute deltamethrin exposures in adult Mozambique tilapia, Oreochromis mossambicus , were investigated using behavioral indices and opercular movement, respectively. Deltamethrin concentrations were found to be associated with toxicological (lethal and sublethal) responses. At 24, 48, 72, and 96 h, the LC50 values and 95% confidence limits were 12.290 (11.174-14.411 µg/L), 12.671 (11.334-15.649 µg/L), 10.172 (9.310-11.193 µg/L), and 8.639 (7.860-9.417 µg/L), respectively. The GUTS-model analysis showed that GUTS-SD (stochastic death) with a narrow tolerance distribution in deltamethrin exposed O. mossambicus populations was more sensitive than the GUTS-IT (individual tolerance) model. Prior to death, exposed fish demonstrated concentration-dependent mortality and disturbed behavioral responses, including uncoordinated swim motions, increased mucus secretion, unbalanced and unpredictable swimming patterns, and inactivity. The altered behavioral patterns and increased opercular movement with increased deltamethrin levels and exposure time are strongly suggestive of neurotoxicity and respiratory distress, respectively. Adverse Outcome Pathways (AOPs), describing biological mechanisms and plausible pathways, highlighted oxidative stress and cholinergic effects as intermediate steps linked to respiratory distress and behavioral toxicity., Competing Interests: The authors declare no conflict of interest.

Based on laboratory studies under controlled conditions, we have appraised the toxicological impact of dead leaf leachate from four angiosperm species: Populus nigra, Salix babylonica, Acer monspessulanum and Platanus acerifolia, as well as dead needles of a gymnosperm species, Taxus baccata, on the quality of water of Vittel spring (Tizguit, Ifrane region). The results show that at 25° C the toxicity changes with the duration of leaching, the initial concentration, type of treatment of leaves and dead needles and leaf species. Lethal toxicity tests conducted on Artemia salina larvae and fry of Gambusia affinis show that the If and Saule are the most toxic of water ventilated. [ABSTRACT FROM AUTHOR]

Abstract: Cadmium selenium (CdSe) quantum dots (QDs) are semiconductor nanocrystals that hold wide range of applications and substantial production volumes. Due to unique composition and nanoscale properties, their potential toxicity to aquatic organisms has increasingly gained a great amount of interest. However, the impact of CdSe QDs exposure on zebrafish embryo and larvae remains almost unknown. Therefore, the lab study was performed to determine the developmental and behavioral toxicities to zebrafish under continuous exposure to low level CdSe QDs (0.05–31.25mgL−1) coated with mercaptopropionic acid (MPA). The results showed MPA–CdSe exposure from embryo to larvae stage affected overall fitness. Our findings for the first time revealed that: (1) The 120h LC50 of MPA–CdSe for zebrafish was 1.98mgL−1; (2) embryos exposed to MPA–CdSe resulted in malformations incidence and lower hatch rate; (3) abnormal vascular of FLI-1 transgenic zebrafish larvae appeared after exposure to MPA–CdSe including vascular junction, bifurcation, crossing and particle appearance; (4) larvae behavior assessment showed during MPA–CdSe exposure a rapid transition from light-to-dark elicited a similar, brief burst and a higher basal swimming rate; (5) MPA–CdSe induced embryos cell apoptosis in the head and tail region. Results of the observations provide a basic understanding of MPA–CdSe toxicity to aquatic organisms and suggest the need for additional research to identify the toxicological mechanism. [Copyright &y& Elsevier]

Abstract: This study investigated the possible effects of a commonly used foliar herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) formulation on medulla spinalis of lebistes. Fish were exposed to 2,4-D (15, 30, 45mgL−1), behavioral changes were monitored. Fish were fixed, histopathological examination was carried out on sections taken from the upper parts of the fish body. Histopathology showed increase in neuronal loss, swelling indicating formation of intracellular edema, vacuolization noticed as the formation of vacuoles within or adjacent to cells, deformation in the Nissl granules, pyknosis and gliosis in medulla spinalis. Behavioral changes were decreased general activity, grouping, shortness in breath, sudden rotations and jumping, loss of equilibrium and colour. In conclusion, this commercial formulation of 2,4-D is considerably neurotoxic to lebistes. Fish constitute the last link in the chain of the feeding cycle in aquatic eco-system, number of studies investigating acute and chronic neurotoxicity of various herbicides in fish should be increased. [Copyright &y& Elsevier]

The eco-risk of roxarsone (ROX) was evaluated using multiple responses of earthworm biomarkers under different ROX concentrations for 28 d. With the increasing total arsenic accumulation (TAs-E), biological responses in earthworm generally showed a two-stage changes of homeostasis dysregulation and dose-dependent alterations. At the early periods, ROX stress increased the reactive oxygen species (ROS) and lipid peroxidation (LPO) in a similar manner, and apparently disrupted mitochondrial calcium ([Ca2+] m). But earthworms regulated their mitochondrial and redox homeostasis through stable mitochondrial membrane potential (MMP) and increase of ATP level, superoxide dismutase (SOD) and catalase (CAT). After 14 d, the positively correlated mitochondrial effects of ROS, [Ca2+] m , MMP and ATP were related to the behavioral inhibition of burrow length, depth and reuse rate as well as antioxidant up-regulation of Nrf2, HO-1, sod1 and cat. These results contributed possible biomarkers from the dose-dependent relationship between mitochondrial, antioxidant and behavioral responses. Multiple biological detection in earthworms can better reflect the sub-chronic ecotoxicity of phenylarsenic pollutants in soil. [Display omitted] ● Bioenergetic, burrowing and antioxidant responses in earthworm are related. ● Mitochondrial calcium, membrane potential and ATP are sensitive biomarkers. ● Gene expression of antioxidases reflect ROX stress more directly than enzymes. [ABSTRACT FROM AUTHOR]

In this study two indices of swimming behavior (horizontal and vertical swimming activity) in a gammaridean amphipod (Gammarus lawrencianus) were examined for their sensitivity to Cd exposure. G. lawrencianus were exposed for 72 h to a variety of Cd concentrations [background (∼12), 62, 125, 250 and 500 μg l-1] at 20 ppt. Subsequent to exposure, video surveillance of survivors held within grooved rings or clear boxes was used to assess horizontal swimming activity (percentage of time mobile) and vertical swimming activity (number of surfacings), respectively. Results show that control amphipods were quite active, being mobile ∼61% of the time, with horizontal swimming activity decreasing (P < 0.01) to ∼0.3% between a Cd exposure concentration of 125 and 500 μg l-1. Vertical swimming activity in amphipods was also impacted by Cd exposure (P < 0.001), with the greatest decrease occurring between background (∼12 μg l-1) and 62 μg l-1 (60 versus ∼26 surfacings, respectively), which is approximately four-fold lower than the estimated 72 h LC50 (250 μg l-1) for G. lawrencianus. Based on fluid dynamic considerations, it is speculated that of the two behaviors, vertical swimming activity is more sensitive to Cd exposure because of the presumed greater energetic costs associated with producing enough thrust to attain the lift required to make a vertical ascent into the water. [Copyright &y& Elsevier]

The effects of 6 weeks of oral exposure to propoxur (PR; at doses of 0.851 and 8.51 mg/kg body wt.), methylparathion (MP; at doses of 0.218 and 0.872 mg/kg body wt.), and their combinations were investigated in male Wistar rats. Measurement endpoints of the investigation were certain general toxicological parameters (body weight gain, organ weights), plaque-forming cell (PFC) count from the spleen, open field (OF) behavior, auditory startle response (ASR), prepulse inhibition (PPI), rotarod performance, somatosensory and auditory cortical evoked potentials, and peripheral nerve conduction velocity. The treated rats did not show any sign of acute intoxication during the 6 weeks of exposure. The higher dose of PR, but not of MP, significantly decreased the relative liver weight. Both agents produced a significant dose-dependent increase of OF activity, with larger expression after 2 weeks than after 6 weeks. The number of ASR responses and the ASR amplitude increased. The amplitude after PPI was increased by MP but only minimally altered by PR and the combinations. There was a small, but with high-dose PR significant, increase in the latency of the somatosensory evoked potentials. Neither of the two substances alone had any effect on the PFC response. The effect of the combination of high-dose PR and low-dose MP was significantly different from that of high-dose PR alone on the liver weight, on the ASR amplitude, and on the PFC/106 cell and PFC/spleen counts. With high-dose MP and low-dose PR, no such interaction was observed. According to the results, the noneffective dose of MP can influence the toxicity of the effective dose of PR in a combined exposure situation. [Copyright &y& Elsevier]

Numerous byproducts resulting from chlorinated disinfection are constantly being generated during water treatment processes. The potential risks of these new emerging pollutions remain largely unknown. Here, we determined the risks of chlorinated disinfection byproducts of diazepam (DZP) in the cellular and zebrafish exposure experiments. The cytotoxicity of disinfection byproducts (MACB and MBCC) was greater than DZP in macrophage raw 264.7 cells at 10 mg/L. We further found that the effects of MBCC on the metabolism of glycine, serine, threonine and riboflavin were far greater than DZP by the targeted metabolomics methods. Moreover, MBCC significantly decreased the peak amplitude of neuronal action potential in primary embryonic rat (Spragu-Dawley SD) hippocampal neurons. We finally determined behavioral toxicity of DZP and byproducts in zebrafish larvae. MBCC significantly decreased the maximal swim-activity and peak duration of zebrafish after 72 h exposure. Altogether, these findings indicate the MBCC pose serious pressures on public health. [Display omitted] • The cytotoxicity of disinfection byproducts is greater than DZP. • The effect of MBCC on riboflavin metabolism is far greater than diazepam. • MBCC disturb action potential propagation and decrease the peak amplitude of neuronal action potential. • MBCC decrease the maximal physical activity of zebrafish at low concentration. [ABSTRACT FROM AUTHOR]

With the appreciation that behavior represents the integration and complexity of the nervous system, neurobehavioral phenotyping and assessment has seen a renaissance over the last couple of decades, resulting in a robust database on rodent performance within various testing paradigms, possible associations with human disorders, and therapeutic interventions. The interchange of data across behavior and other test modalities and multiple model systems has advanced our understanding of fundamental biology and mechanisms associated with normal functions and alterations in the nervous system. While there is a demonstrated value and power of neurobehavioral assessments for examining alterations due to genetic manipulations, maternal factors, early development environment, the applied use of behavior to assess environmental neurotoxicity continues to come under question as to whether behavior represents a sensitive endpoint for assessment. Why is rodent behavior a sensitive tool to the neuroscientist and yet, not when used in pre-clinical or chemical neurotoxicity studies? Applying new paradigms and evidence on the biological basis of behavior to neurobehavioral testing requires expertise and refinement of how such experiments are conducted to minimize variability and maximize information. This review presents relevant issues of methods used to conduct such test, sources of variability, experimental design, data analysis, interpretation, and reporting. It presents beneficial and critical limitations as they translate to the in vivo environment and considers the need to integrate across disciplines for the best value. It proposes that a refinement of behavioral assessments and understanding of subtle pronounced differences will facilitate the integration of data obtained across multiple approaches and to address issues of translation., Competing Interests: Authors SM and MB were employed by company Social & Scientific Systems, Inc. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Harry, McBride, Witchey, Mhaouty-Kodja, Trembleau, Bridge and Bencsik.)

Nowadays, silica nanoparticles (SiNPs) as one of the most productive nano-powder, has been extensively applied in various filed. The potential harm of SiNPs has previously received severe attention. A bulk of researches have proven the adverse effect of SiNPs on the health of ecological organisms and human. However, neurotoxic impacts of SiNPs, still remain in the stage of exploration. The potential neurotoxic effects of SiNPs need to be further explored. And the toxic mechanism needs comprehensive clarification. Herein, the neurotoxicity of SiNPs of various concentrations (100, 300, 1000 μg/mL) on adult zebrafish was determined by behavioral phenotyping and confirmed by molecular biology techniques such as qPCR. Behavioral phenotype revealed observable effects of SiNPs on disturbing light/dark preference, dampening exploratory behavior, inhibiting memory capability. Furthermore, the relationship between neurotoxic symptom and the transcriptional alteration of autophagy- and parkinsonism-related genes was preliminarily assessed. Importantly, further investigations should be carried out to determine the effects of SiNPs to cause neurodegeneration in the brain as well as to decipher the specific neurotoxic mechanisms. In sum, this work comprehensively evaluated the neurotoxic effect of small-sized SiNPs on overall neurobehavioral profiles and indicated the potential for SiNPs to cause Parkinson's disease, which will provide a solid reference for the research on the neurotoxicity of SiNPs. • Neurobehavioral toxicity of SiNPs was comprehensively determined. • SiNPs caused anxiety behavior and suppressed exploratory behavior. • SiNPs inhibited memory capability. • SiNPs disturbed autophagy- and parkinsonism-related genes expression in the brain. [ABSTRACT FROM AUTHOR]

The interpretation of the literature on lead and child development is presented with open peer commentary from the Neuroepidemiology Unit, Children’s Hospital, Harvard Medical School, Boston, and other centers.

Mercury, and particularly its organic form, methylmercury (MeHg), is a ubiquitous environmental contaminant with documented dosage-dependent adverse effects on endpoints spanning many levels of biological organization. However, relatively little is known about the sublethal impacts of environmentally-relevant exposures on behavioral characteristics that may impact predator-prey relationships, and thus the potential for Hg bioaccumulation within food webs due to behavioral impairments. This study investigated the potential for dietary mercury exposure to impair two behavioral outcomes in the highly invasive rusty crayfish, Faxonius rusticus, which are expected to influence interactions with their fish predators: the tail-flip escape response and chelae pinch strength. Field-caught animals were randomly assigned to four dietary treatments with mean (±1 SE) dry-weight total Hg (THg) concentrations of 3.52 ± 0.57, 114.01 ± 4.05, 274.10 ± 0.38, and 565.79 ± 1.33 ng/g in the control, low, moderate and high exposure treatments, respectively, for 16 weeks. After initial observations, exposures began and mass and behavior were measured every two weeks. At the end of the experiment, THg concentrations in tail muscle tissue were significantly higher in the high exposure treatment than in the control and low exposure treatments (Tukey's HSD, family-wise α = 0.05). Exposure-dependent declines in survival, mass, pinch strength, or tail-flip escape response velocity were not detected within the 12- to 16-week experimental exposure period, which represents one season of the crayfish's 3–4 year lifespan. This suggests that crayfish may be relatively tolerant of dietary exposure to sublethal concentrations of mercury within a single season. Further investigation of the physiological underpinnings of this tolerance is warranted. • Highlights for Review. • Crayfish were exposed to THg using diets that ranged between <3 and 566 ng THg/g dw. • THg exposure did not affect behavioral startle responses or chelae pinch strength. • THg exposure did not result in diminished growth or survivorship in single season. [ABSTRACT FROM AUTHOR]

This study examined the effects on neurobehavioral function of exposure to low-level mercury vapor (Hg 0 ), methylmercury (MeHg) in female mice and the combination of Hg 0 and MeHg during postnatal development. Postnatal mice were exposed to Hg 0 at a mean concentration of 0.188 mg/m 3 Hg 0 and supplied with food containing 3.85 μg/g of MeHg from day 2 to day 28 after delivery. The combined exposure group was exposed to both Hg 0 and MeHg, using the same procedure. When their offspring reached the age of 11 weeks, behavioral analyses were performed. The behavioral effects in mice were evaluated based on locomotive activity and rate of center entries in the open field (OPF), learning activity in the passive avoidance response (PA) and spatial learning ability in the radial maze (RM). Total locomotive activity in the OPF significantly decreased in the Hg 0 , MeHg and combined exposure groups compared with the control group. The proportion of entries to central area in the OPF was significantly higher in the combined exposure group than in the control group, while those in the Hg 0 or MeHg exposure group did not differ from the control group. Other behavioral tests did not reveal significant differences among the groups. Behavioral anomalies were more distinctive after combined exposure compared to Hg 0 or MeHg exposure alone. The brain Hg concentration of offspring, immediately after exposure, was highest in the combined exposure group, exceeding 2 μg/g, followed by the MeHg and Hg 0 exposure groups. Thus, the enhancement of neurobehavioral effects in the combined exposure group was associated with higher brain mercury concentration.