Effects of β-diketone antibiotic mixtures on behavior of zebrafish (Danio rerio)

Reviewing the use of zebrafish for the detection of neurotoxicity induced by chemical mixtures through the analysis of behaviour

The knowledge and assessment of mixtures of chemical pollutants in the aquatic environment is a complex issue that is often challenging to address. In this review, we focused on the use of zebrafish (Danio rerio), a vertebrate widely used in biomedical research, as a model for detecting the effects of chemical mixtures with a focus on behaviour. Our aim was to summarize the current status of the ecotoxicological research in this sector. Specifically, we limited our research to the period between January 2012 and September 2023, including only those works aimed at detecting neurotoxicity through behavioural endpoints, utilizing zebrafish at one or more developmental stages, from egg to adult. Additionally, we gathered the findings for every group of chemicals involved and summarised data from all the works we included. At the end of the screening process 101 papers were considered eligible for inclusion. Results show a growing interest in zebrafish at all life stages for this kind of research in the last decade. Also, a wide variety of different assays, involving different senses, was used in the works we surveyed, with exposures ranging from acute to chronic. In conclusion, the results of this study show the versatility of zebrafish as a model for the detection of mixture toxicity although, for what concerns behavioural analysis, the lack of standardisation of methods and endpoints might still be limiting.

Zebrafish (Danio rerio) behavioral phenotypes not underscored by different gut microbiota

Different animal behavioral phenotypes maintained and selectively bred over multiple generations may be underscored by dissimilar gut microbial community compositions or not have any significant dissimilarity in community composition. Operating within the microbiota-gut-brain axis framework, we anticipated differences in gut microbiome profiles between zebrafish (Danio rerio) selectively bred to display the bold and shy personality types. This would highlight gut microbe-mediated effects on host behavior. To this end, we amplified and sequenced a fragment of the 16S rRNA gene from the guts of bold and shy zebrafish individuals (n=10) via Miseq. We uncovered no significant difference in within-group microbial diversity nor between-group microbial community composition of the two behavioral phenotypes. Interestingly, though not statistically different, we determined that the gut microbial community of the bold phenotype was dominated by Burkholderiaceae, Micropepsaceae, and Propionibacteriaceae. In contrast, the shy phenotype was dominated by Beijerinckaceae, Pirelullacaeae, Rhizobiales_Incertis_Sedis, and Rubinishaeraceae. The absence of any significant difference in gut microbiota profiles between the two phenotypes would suggest that in this species, there might exist a stable "core" gut microbiome, regardless of behavioral phenotypes, and or possibly, a limited role for the gut microbiota in modulating this selected-for host behavior. This is the first study to characterize the gut microbial community of distinct innate behavioral phenotypes of the zebrafish (that are not considered dysbiotic states) and not rely on antibiotic or probiotic treatments to induce changes in behavior. Such studies are crucial to our understanding of the modulating impacts of the gut microbiome on normative animal behavior.

The many faces of microbiota-gut-brain axis in autism spectrum disorder

The gut-brain axis is gaining more attention in neurodevelopmental disorders, especially autism spectrum disorder (ASD). Many factors can influence microbiota in early life, including host genetics and perinatal events (infections, mode of birth/delivery, medications, nutritional supply, and environmental stressors). The gut microbiome can influence blood-brain barrier (BBB) permeability, drug bioavailability, and social behaviors. Developing microbiota-based interventions such as probiotics, gastrointestinal (GI) microbiota transplantation, or metabolite supplementation may offer an exciting approach to treating ASD. This review highlights that RNA sequencing, metabolomics, and transcriptomics data are needed to understand how microbial modulators can influence ASD pathophysiology. Due to the substantial clinical heterogeneity of ASD, medical caretakers may be unlikely to develop a broad and effective general gut microbiota modulator. However, dietary modulation followed by administration of microbiota modulators is a promising option for treating ASD-related behavioral and gastrointestinal symptoms. Future work should focus on the accuracy of biomarker tests and developing specific psychobiotic agents tailored towards the gut microbiota seen in ASD patients, which may include developing individualized treatment options.

Toxic Effects of Gemcitabine and Paclitaxel Combination: Chemotherapy Drugs Exposure in Zebrafish

Pharmaceuticals are widely recognized as potentially hazardous to aquatic ecosystems. In the last two decades, the constant intake of biologically active chemicals used in human healthcare has been related to the growing release of these agents into natural environments. As reported by several studies, various pharmaceuticals have been detected, mainly in surface water (seas, lakes, and rivers), but also in groundwater and drinking water. Moreover, these contaminants and their metabolites can show biological activity even at very low concentrations. This study aimed to evaluate the developmental toxicity of exposure to the chemotherapy drugs gemcitabine and paclitaxel in aquatic environments. Zebrafish (Danio rerio) embryos were exposed to doses of gemcitabine 15 μM in combination with paclitaxel 1 μM from 0 to 96 h post-fertilization (hpf) using a fish embryo toxicity test (FET). This study highlights that both gemcitabine and paclitaxel exposure at single non-toxic concentrations affected survival and hatching rate, morphology score, and body length after exposure in combination. Additionally, exposure significantly disturbed the antioxidant defense system and increased ROS in zebrafish larvae. Gemcitabine and paclitaxel exposure caused changes in the expression of inflammation-related, endoplasmic reticulum stress-related (ERS), and autophagy-related genes. Taken together, our findings underline that gemcitabine and paclitaxel increase developmental toxicity in zebrafish embryos in a time-dependent manner.

Do microplastics influence the long-term effects of ciprofloxacin on the polychaete Hediste diversicolor? An integrated behavioral and biochemical approach

Ciprofloxacin (CPX), the most commonly used fluoroquinolone antibiotic, and microplastics (MPs) are two classes of emerging contaminants with severe adverse impacts on aquatic organisms. Previous studies suggest that both CPX and MPs induce deleterious changes in exposed aquatic biota, but the characterization of a chronic and combined ecotoxicological response is not well known, especially in organisms from estuarine ecosystems. Thus, in this study, we investigated the behavioral and biochemical effects of environmentally relevant levels of CPX alone and in combination with polyethylene terephthalate (PET) microplastics over 28 days of exposure, using the polychaete Hediste diversicolor as a model. In addition to behavioral parameters, different biochemical endpoints were also evaluated, namely the levels of metabolic enzymes of phase I (7-ethoxy-resorufin-O-deethylase, EROD), and phase II (glutathione-S-transferase, GSTs), antioxidant defense (catalase, CAT; glutathione peroxidase, GPx; superoxide dismutase, SOD), oxidative damage (lipid peroxidation, by means of levels of thiobarbituric acid reactive substances [TBARS]) and acetylcholinesterase (AChE). Chronic exposure to ciprofloxacin caused a decrease in burrowing time and a significant increase in SOD activity. In animals exposed to the combination of CPX and PET MPs, effects on behavioral traits were also observed, with higher concentrations of MPs leading to a marked delay in the animals' burrowing time. In addition, these animals showed changes in their antioxidant defenses, namely, a significant increase in SOD activity, while GPx activity was severely compromised. For none of the experimental groups, significant alterations were observed in the metabolic enzymes, TBARS or AChE. These findings provide the first insights into the responses of H. diversicolor when exposed to the combination of CPX and PET MPs, highlighting that, although the here studied conditions, there was no evidence of oxidative damage or neurotoxicity, these organisms are not risk-free in co-exposure scenarios, even at low environmental relevant concentrations.

Effects of Single and Combined Ciprofloxacin and Lead Treatments on Zebrafish Behavior, Oxidative Stress, and Elements Content

Even though the toxic effects of antibiotics and heavy metals have been extensively studied in the last decades, their combined adverse impact on aquatic organisms is poorly understood. Therefore, the objective of this study was to assess the acute effects of a ciprofloxacin (Cipro) and lead (Pb) mixture on the 3D swimming behavior, acetylcholinesterase (AChE) activity, lipid peroxidation level (MDA-malondialdehyde), activity of some oxidative stress markers (SOD-superoxide dismutase and GPx-glutathione peroxidase), and the essential elements content (Cu-copper, Zn-zinc, Fe-iron, Ca-calcium, Mg-magnesium, Na-sodium and K-potassium) in the body of zebrafish (Danio rerio). For this purpose, zebrafish were exposed to environmentally relevant concentrations of Cipro, Pb, and a mixture for 96 h. The results revealed that acute exposure to Pb alone and in mixture with Cipro impaired zebrafish exploratory behavior by decreasing swimming activity and elevating freezing duration. Moreover, significant deficiencies of Ca, K, Mg, and Na contents, as well as an excess of Zn level, were observed in fish tissues after exposure to the binary mixture. Likewise, the combined treatment with Pb and Cipro inhibited the activity of AChE and increased the GPx activity and MDA level. The mixture produced more damage in all studied endpoints, while Cipro had no significant effect. The findings highlight that the simultaneous presence of antibiotics and heavy metals in the environment can pose a threat to the health of living organisms.

Antibiotics modulate frequency and early generation of epileptic seizures in zebrafish

Antibiotics have been used for decades to treat various bacterial infections. Apart from bactericidal activities, their potential side effects have not been much studied or evaluated. Neurotoxicity is a major concern in the case of β-lactam and fluoroquinolone families, which can result in convulsions or seizures. Here, we proposed a hypothesis to check whether antibiotic treatment can conclusively enhance anxiety-like behaviours and how seizure behavioural profile gets modulated in pentylenetetrazole (PTZ)-treated zebrafish. Zebrafish were treated with selected antibiotics such as 25 mg/L Penicillin G (PG) and Ciprofloxacin (CPFX), for 7 days and thereafter exposed to PTZ (7.5 mM) for 20 min. The data indicate that PG and CPFX-treated groups exhibited anxiety-like or stressed behavioural phenotypes in the novel tank test (6 min), and also, they were found to promote hyperactivity. Early onset of PTZ-induced seizure-like behavioural scores, the heightened intensity of seizure and reduced latency in different scores were found in PG and CPFX-administered groups. This study substantiates that PG and CPFX as potential seizure modulators in zebrafish. The zebrafish is a well-established and still expanding model organism in many fields. Here, we again reinforce zebrafish as a prominent model to investigate seizure-like neuro-behavioural entities and confirm that chronic antibiotic use has negative consequences that can exacerbate the circumstances of vertebrate species exhibiting seizure-related reactions.

Understanding CNS Effects of Antimicrobial Drugs Using Zebrafish Models

Antimicrobial drugs represent a diverse group of widely utilized antibiotic, antifungal, antiparasitic and antiviral agents. Their growing use and clinical importance necessitate our improved understanding of physiological effects of antimicrobial drugs, including their potential effects on the central nervous system (CNS), at molecular, cellular, and behavioral levels. In addition, antimicrobial drugs can alter the composition of gut microbiota, and hence affect the gut-microbiota-brain axis, further modulating brain and behavioral processes. Complementing rodent studies, the zebrafish (Danio rerio) emerges as a powerful model system for screening various antimicrobial drugs, including probing their putative CNS effects. Here, we critically discuss recent evidence on the effects of antimicrobial drugs on brain and behavior in zebrafish, and outline future related lines of research using this aquatic model organism.

The Effect of Limosilactobacillus reuteri on Social Behavior Is Independent of the Adaptive Immune System

Gut microbes can modulate almost all aspects of host physiology throughout life. As a result, specific microbial interventions are attracting considerable attention as potential therapeutic strategies for treating a variety of conditions. Nonetheless, little is known about the mechanisms through which many of these microbes work. Recently, we and others have found that the commensal bacterium Limosilactobacillus reuteri (formerly Lactobacillus reuteri) reverses social deficits in several mouse models (genetic, environmental, and idiopathic) for neurodevelopmental disorders in a vagus nerve-, oxytocin-, and biopterin-dependent manner. Given that gut microbes can signal to the brain through the immune system and L. reuteri promotes wound healing via the adaptive immune response, we sought to determine whether the prosocial effect mediated by L. reuteri also depends on adaptive immunity. Here, we found that the effects of L. reuteri on social behavior and related changes in synaptic function are independent of the mature adaptive immune system. Interestingly, these findings indicate that the same microbe (L. reuteri) can affect different host phenotypes through distinct mechanisms. IMPORTANCE Because preclinical animal studies support the idea that gut microbes could represent novel therapeutics for brain disorders, it is essential to fully understand the mechanisms by which gut microbes affect their host's physiology. Previously, we discovered that treatment with Limosilactobacillus reuteri selectively improves social behavior in different mouse models for autism spectrum disorder through the vagus nerve, oxytocin reward signaling in the brain, and biopterin metabolites (BH4) in the gut. However, given that (i) the immune system remains a key pathway for host-microbe interactions and that (ii) L. reuteri has been shown to facilitate wound healing through the adaptive immune system, we examined here whether the prosocial effects of L. reuteri require immune signaling. Unexpectedly, we found that the mature adaptive immune system (i.e., conventional B and T cells) is not required for L. reuteri to reverse social deficits and related changes in synaptic function. Overall, these findings add new insight into the mechanism through which L. reuteri modulates brain function and behavior. More importantly, they highlight that a given bacterial species can modulate different phenotypes (e.g., wound healing versus social behavior) through separate mechanisms.

A Time-course Transcriptional Kinetics of Genes in Behavior, Cortisol Synthesis and Neurodevelopment in Zebrafish Larvae Exposed to Imidacloprid and Thiamethoxam

Agricultural use of neonicotinoid insecticides, neuroactive nitroguanidine compounds, has been detected everywhere in the global, posing significant hazard to nontarget organisms. This work studied the developmental neurotoxicity of zebrafish larvae exposed to imidacloprid (IMI) and thiamethoxam (THM), ranging from 0.05 µg L^- 1 to 50 µg L^- 1 for 35 days. Transcriptions of genes belonging to the behavior, neurodevelopment and cortisol synthesis in zebrafish larvae were monitored. The qPCR data demonstrated that with exposure time increased, the transcription of behavior related genes was down-regulated in both IMI and THM groups, such as macf1, cdh6 and syt10. Additionally, IMI and THM significantly up-regulated the transcriptions of actha, and down-regulated il1rapl1b and pi4k2a at 35 dpf. Importantly, IMI markedly enhanced the transcripiton of gfap, shha, nkx2.2a and nestin in a time dependent manner. This work provided the foundation for understanding zebrafish larvae's neurotoxicity induced by IMI and THM.

Top2a promotes the development of social behavior via PRC2 and H3K27me3

Little is understood about the embryonic development of sociality. We screened 1120 known drugs and found that embryonic inhibition of topoisomerase IIα (Top2a) resulted in lasting social deficits in zebrafish. In mice, prenatal Top2 inhibition caused defects in social interaction and communication, which are behaviors that relate to core symptoms of autism. Mutation of Top2a in zebrafish caused down-regulation of a set of genes highly enriched for genes associated with autism in humans. Both the Top2a-regulated and autism-associated gene sets have binding sites for polycomb repressive complex 2 (PRC2), a regulatory complex responsible for H3K27 trimethylation (H3K27me3). Moreover, both gene sets are highly enriched for H3K27me3. Inhibition of the PRC2 component Ezh2 rescued social deficits caused by Top2 inhibition. Therefore, Top2a is a key component of an evolutionarily conserved pathway that promotes the development of social behavior through PRC2 and H3K27me3.

Study on the toxic-mechanism of triclosan chronic exposure to zebrafish (Danio rerio) based on gut-brain axis

Triclosan (TCS), as a broad-spectrum bactericide, is extensively used in the fine chemical and textile industries. It is recognized as a new type of environmental endocrine disruptor with frequent detection and environmental pollution. However, the toxicity mechanism regarding neurodevelopment and neurobehavior remains unclear. This study is intended to explore the underlying toxic mechanism of TCS based on gut-brain axis. TCS-chronic exposure affected the development of zebrafish, induced feminization, obesity physical signs and abnormal organ index and caused neurobehavioral abnormalities by inhibiting both neurotransmitter acetylcholinesterase and dopamine activity, promoting brain neuron apoptosis and accelerating diencephalic lesions. Meanwhile, TCS-chronic exposure led to gut microbiota dysbiosis and decreased diversity, such as increased pathogenic bacteria and decreased probiotics in adult zebrafish gut, which caused many pathological damages, including partial shedding and ablation of intestinal villi, inflammatory infiltration, thinning of intestinal wall, and increased goblet cell in villus. Based on the communication between intestinal peripheral nerves and CNS, the above histopathological injuries and disorders were well underpinned and illustrated by the changes of biomarkers and the expression of related marker genes in the gut-brain axis. Additionally, short-chain fatty acids (SCFA), as the regulators of intestinal sympathetic nerve activation, are also secreting products of intestinal microflora and play a crucial role in regulating the balance of intestinal flora and protecting intestinal homeostasis. SCFA in low doses can effectively alleviate and rescue the toxic effects under TCS exposure, which evidenced that TCS exerted systemic toxic effects on the gut-brain axis by influencing the composition and diversity of gut flora in zebrafish, and fully demonstrated the interaction effect between intestine and brain. Hence, these findings contribute to the understanding, prevention, and diagnosis of endocrine disrupting diseases caused by environmental pollutants from the perspective of the gut-brain axis, and strengthening the early warning, management and control of TCS pollution.

Hydroxyl radicals can significantly influence the toxicity of ofloxacin transformation products during ozonation

Ozonation is often applied to eliminate the recalcitrant contaminants in water. During the process, toxic transformation products (TPs) can be generated mainly via the reactions with ozone and hydroxyl radicals (^•OH). However, the toxicity difference between the TPs generated from O₃ and ^•OH has not been well elucidated. In this study, we designed ozonation scenarios with different Rct values (the exposure ratio of ^•OH to O₃) via varying pH values, adding a catalyst or a radical scavenger, and investigated the degradation of a popularly used antibiotic ofloxacin (OFX). The microbial oxygen uptake, the development of zebrafish embryos, and the calculation with the Toxicity Estimation Software Tool (T.E.S.T) were applied to evaluate the toxicity of TPs generated from the above reaction scenarios. The toxicity tests demonstrated that TPs formed at high-Rct conditions were less toxic than those at low-Rct conditions. Ten and eleven TPs were identified during ozonation of OFX at pH 3 and 9, respectively, based on which the different pathways were proposed. The piperazine ring's demethylation and opening occurred at both pH values, while the hydroxylation of quinolone and oxazine mainly occurred at pH 9. The study suggests that ^•OH might be more efficient in eliminating the toxicity of OFX than O₃.

Dopamine Level Affects Social Interaction and Color Preference Possibly Through Intestinal Microbiota in Zebrafish

Accumulating researches suggest that the microbiota reside in the gastrointestinal system can influence neurodevelopment of brain and programming of behaviors. However, the mechanism underlining the relationship between shoals' behaviors and intestinal microbiota remain controversial and the roles of responsible neurotransmitters are still unclear. Here we show that shoaling behavior affected the color preference of shoals, indicating that shoals tended to choose a favorable color environment that benefited social contact. Meanwhile, administration of the selective D1-R antagonist, SCH23390, could disrupt the social interaction that led to the deficits of color preference in shoals. More importantly, the altered microbiota caused by an antibiotic oxytetracycline (OTC) exposure decreased the sociability and weakened shoals' preference for all color combinations. When given a supplementation of Lactobacillus rhamnosus GG after OTC exposure, fish maintained the same capability of social cohesion and color preference as normal fish. Our results support a role for dopamine in shaping the color preference in shoals. Our findings show that dopamine level of brain could mediate both social recognition and color preference, and offer a possibility that the production of dopamine is coordinated through gut microbiota.

Microbiota-brain interactions: Moving toward mechanisms in model organisms

Changes in the microbiota are associated with alterations in nervous system structure-function and behavior and have been implicated in the etiology of neuropsychiatric and neurodegenerative disorders. Most of these studies have centered on mammalian models due to their phylogenetic proximity to humans. Indeed, the germ-free mouse has been a particularly useful model organism for investigating microbiota-brain interactions. However, microbiota-brain axis research on simpler genetic model organisms with a vast and diverse scientific toolkit (zebrafish, Drosophila melanogaster, and Caenorhabditis elegans) is now also coming of age. In this review, we summarize the current state of microbiota-brain axis research in rodents and humans, and then we elaborate and discuss recent research on the neurobiological and behavioral effects of the microbiota in the model systems of fish, flies, and worms. We propose that a cross-species, holistic and mechanistic approach to unravel the microbiota-brain communication is an essential step toward rational microbiota-based therapeutics to combat brain disorders.

Sub-chronic exposure to antibiotics doxycycline, oxytetracycline or florfenicol impacts gut barrier and induces gut microbiota dysbiosis in adult zebrafish (Daino rerio)

Antibiotics are widely used in the treatment of bacterial infections and as food additives in the livestock industry. The wide usage of antibiotics causes residues in animal products, like milk, eggs and meat. A number of studies have reported that antibiotic residues exist at high concentrations in watercourses around the world. Doxycycline (DH), oxytetracycline (OTCC) and florfenicol (FF) are the three most commonly used veterinary antibiotics in China. However, studies of the toxic effects of DH, OTCC and FF are limited. In this study, six-moth-old healthy male adult zebrafish were exposed to 0, 10, 30, 100 μg/L DH, OTCC or FF for 21 days. After exposure, some biochemical parameters changed significantly, including total cholesterol (TC), triglyceride (TG), pyruvate and acid phosphatase (ACP). In addition, mucus secretion in the gut decreased and the transcription of related genes also decreased significantly. Moreover, the composition of microbiota in the gut changed significantly. DH, OTCC and FF exposure caused the decrease of diversity of gut microbiota. The relative abundance of Proteobacteria increased significantly after OTCC and FF exposure and Fusobacteria decreased in all antibiotic-treated groups. Further functional prediction analysis also suggested changes in gut microbiota in the OTCC and FF-treated groups, especially those linked to metabolism. To support this idea, we confirmed that some glycolipid related genes also increased significantly in the liver of adult zebrafish after antibiotic exposure. According to these results, DH, OTCC or FF exposure could cause the gut microbiota dysbiosis and dysfunction, and hepatic metabolic disorder in adult male zebrafish.

Zebrafish as a Screening Model to Study the Single and Joint Effects of Antibiotics

The overuse of antibiotics combined with the limitation of wastewater facilities has resulted in drug residue accumulation in the natural environment. Thus, in recent years, the presence of antibiotic residues in the environment has raised concerns over the potential harmful effects on ecosystems and human health. The in vivo studies represent an essential step to study the potential impact induced by pharmaceutical exposure. Due to the limitations of traditional vertebrate model systems, zebrafish (Danio rerio) has recently emerged as a promising animal model to study the toxic effects of drugs and their therapeutic efficacy. The present review summarizes the recent advances made on the toxicity of seven representative classes of antibiotics, namely aminoglycosides, β-lactams, macrolides, quinolones, sulfonamides, tetracyclines and polyether antibiotics, in zebrafish, as well as the combined effects of antibiotic mixtures, to date. Despite a significant amount of the literature describing the impact of single antibiotic exposure, little information exists on the effects of antibiotic mixtures using zebrafish as an animal model. Most of the research papers on this topic have focused on antibiotic toxicity in zebrafish across different developmental stages rather than on their efficacy assessment.

Comparison of the chronic toxicities of graphene and graphene oxide toward adult zebrafish by using biochemical and phenomic approaches

Graphene (GR) and graphene oxide (GO) are widely being used as promising candidates for biomedical applications, as well as for bio-sensing, drug delivery, and anticancer therapy. However, their undesirable side effects make it necessary to assess further the toxicity and safety of using these materials. The main objective of the current study was to investigate the toxicities of GR and GO in predicted environmental relevant concentrations in adult zebrafish (Danio rerio), particularly on their behaviors, and conducted biochemical assays to elucidate the possible mechanism that underlies their toxicities. Zebrafish was chronically (∼14 days) exposed to two different doses of GR (0.1 and 0.5 ppm) or GO (0.1 and 1 ppm). At 14 ± 1 days, a battery of behavioral tests was conducted, followed by enzyme-linked immunosorbent assays (ELISA) test on the following day to inspect the alterations in antioxidant activity, oxidative stress, and neurotransmitters in the treated zebrafish brain. An alteration in predator avoidance behavior was observed in all treated groups, while GR-treated fish exhibited abnormal exploratory behavior. Furthermore, altered locomotor activity was displayed by most of the treated groups, except for the high concentration of the GR group. From the ELISA results, we discovered a high concentration of GR exposure significantly decreased several neurotransmitters and cortisol levels. Meanwhile, elevated reactive oxygen species (ROS) were displayed by the group treated with low and high doses of GR and GO, respectively. These significant changes would possibly affect zebrafish behaviors and might suggest the potential toxicity from GR and GO exposures. To sum up, the present study presented new evidence for the effects of GR and GO in zebrafish behavioral dysregulation. We hope these assessments can contribute to our understanding of graphene and graphene oxide biosafety.

Antibiotic drugs alter zebrafish behavior

Antibiotics are widely used drugs in human and veterinary health as well as in the food industry. The majority of these compounds are, however, excreted unchanged and found as contaminants in water bodies. Although the toxicity of these drugs was previously studied in aquatic organisms, the behavioral effects of these pollutants have not been fully explored. Here we exposed adult zebrafish to environmentally relevant concentrations of different classes of antibiotics (Chlortetracycline, Ciprofloxacin, and Ceftazidime) and assessed zebrafish exploratory, cognitive, aggressive, and social behaviors. Ciprofloxacin, Chlortetracycline, and Ceftazidime exposure induced hyperlocomotion, which was characterized by an increase in the distance traveled in zebrafish. These antibiotics promoted cognitive decline and exacerbated aggressive behavior. In summary, this study shows that antibiotic contamination may impact zebrafish behavior in a short-time manner.

Tris (1-chloro-2-propyl) phosphate exposure to zebrafish causes neurodevelopmental toxicity and abnormal locomotor behavior

The organophosphate flame retardant, tris (1-chloro-2-propyl) phosphate (TCPP), is ubiquitous in environmental matrices; however, there is a paucity of information concerning its systemic toxicity. Herein, we investigated the effects of TCPP exposure on zebrafish neurodevelopment and swimming behavior to elucidate the underlying molecular mechanisms of neurotoxicity. Under TCPP gradient concentration exposure, the hatching rates were declined by up to 33.3% in 72 hpf, and the malformation rates increased from 15% to 50%. Meanwhile, TCPP led to abnormal behaviors including decreased locomotive activity in the dark and slow/insensitive responses to sound and light stimulation of larvae. TCPP caused excessive apoptosis and ROS accumulation in early embryonic development, with hair cell defects and structural deformity of neuromast. Abnormal expression of neurodevelopment (pax6a, nova1, sox11b, syn2a, foxo3a and robo2) and apoptosis-related genes (baxa, bcl2a and casp8) revealed molecular mechanisms regarding abnormal behavioral and phenotypic symptoms. Chronic TCPP exposure led to anxiety-like behavior and excessive panic, lower capacity for discrimination and risk avoidance, and conditioned place preference in adults. Social interaction tests demonstrated that long-term TCPP stress resulted in unsociable, eccentric, lonely and silent behaviors in adults. Zebrafish memory and cognitive function were severely reduced as concluded from T-maze tests. Potential mechanisms triggering behavioral abnormality were attributed to histopathological injury of diencephalon, abnormal changes in nerve-related genes at transcription and expression levels, and inhibited activity of AChE by TCPP stress. These findings provide an important reference for risk assessment and early warning to TCPP exposure, and offer insights for prevention/mitigation of pollutant-induced nervous system diseases.

Maternal antibiotic administration during a critical developmental window has enduring neurobehavioural effects in offspring mice

Rates of perinatal maternal antibiotic use have increased in recent years linked to prophylactic antibiotic use following Caesarean section delivery. This antibiotic use is necessary and beneficial in the short-term; however, long-term consequences on brain and behaviour have not been studied in detail. Here, we endeavoured to determine whether maternal administration of antibiotics during a critical window of development in early life has lasting effects on brain and behaviour in offspring mice. To this end we studied two different antibiotic preparations (single administration of Phenoxymethylpenicillin at 31 mg/kg/day; and a cocktail consisting of, ampicillin 1 mg/mL; vancomycin 0.5 mg/mL; metronidazole 1 mg/mL; ciprofloxacin 0.2 mg/mL and imipenem 0.25 mg/mL). It was observed that early life exposure to maternal antibiotics led to persistent alterations in anxiety, sociability and cognitive behaviours. These effects in general were greater in animals treated with the broad-spectrum antibiotic cocktail compared to a single antibiotic with the exception of deficits in social recognition which were more robustly observed in Penicillin V exposed animals. Given the prevalence of maternal antibiotic use, our findings have potentially significant translational relevance, particularly considering the implications on infant health during this critical period and into later life.

Bioaccumulation, Biotransformation, and Multicompartmental Toxicokinetic Model of Antibiotics in Sea Cucumber (Apostichopus japonicus)

Extensive application of antibiotics leads to their ubiquitous occurrence in coastal aquatic environments. However, it remains largely unknown whether antibiotics can be bioaccumulated and biotransformed in major mariculture organisms such as sea cucumbers and toxicokinetic models for Echinodermata are lacking. In this study, laboratory exposure experiments on juvenile sea cucumber (Apostichopus japonicus) were performed for seven antibiotics (sulfadiazine, sulfamethoxazole, trimethoprim, enrofloxacin, ofloxacin, clarithromycin, and azithromycin). Field sea cucumber and surrounding seawater samples were also analyzed. Results show that the sea cucumbers tend to accumulate high concentrations of the antibiotics with kinetic bioconcentration factors (BCFs) up to 1719.7 L·kg^-1 for ofloxacin. The BCFs determined in the laboratory agree well with those estimated from the field measurements. Seven biotransformation products (BTPs) of the antibiotics were identified, four of which were not reported previously in aquatic organisms. The BTPs were mainly found in the digestive tract, indicating its high capacity in the biotransformation. A multicompartmental toxicokinetic model based on the principles of passive diffusion was developed, which can successfully predict time-course concentrations of the antibiotics in different compartments of the juvenile sea cucumbers. The findings may offer a scientific basis for assessing health risks and guiding healthy mariculture of sea cucumbers.

You've got male: Sex and the microbiota-gut-brain axis across the lifespan

Sex is a critical factor in the diagnosis and development of a number of mental health disorders including autism, schizophrenia, depression, anxiety, Parkinson's disease, multiple sclerosis, anorexia nervosa and others; likely due to differences in sex steroid hormones and genetics. Recent evidence suggests that sex can also influence the complexity and diversity of microbes that we harbour in our gut; and reciprocally that our gut microbes can directly and indirectly influence sex steroid hormones and central gene activation. There is a growing emphasis on the role of gastrointestinal microbiota in the maintenance of mental health and their role in the pathogenesis of disease. In this review, we introduce mechanisms by which gastrointestinal microbiota are thought to mediate positive health benefits along the gut-brain axis, we report how they may be modulated by sex, the role they play in sex steroid hormone regulation, and their sex-specific effects in various disorders relating to mental health.

Behavioral Impairments and Oxidative Stress in the Brain, Muscle, and Gill Caused by Chronic Exposure of C70 Nanoparticles on Adult Zebrafish

There is an imperative need to develop efficient whole-animal-based testing assays to determine the potential toxicity of engineered nanomaterials. While previous studies have demonstrated toxicity in lung and skin cells after C70 nanoparticles (NPs) exposure, the potential detrimental role of C70 NPs in neurobehavior is largely unaddressed. Here, we evaluated the chronic effects of C70 NPs exposure on behavior and alterations in biochemical responses in adult zebrafish. Two different exposure doses were used for this experiment: low dose (0.5 ppm) and high dose (1.5 ppm). Behavioral tests were performed after two weeks of exposure of C70 NPs. We found decreased locomotion, exploration, mirror biting, social interaction, and shoaling activities, as well as anxiety elevation and circadian rhythm locomotor activity impairment after ~2 weeks in the C70 NP-exposed fish. The results of biochemical assays reveal that following exposure of zebrafish to 1.5 ppm of C70 NPs, the activity of superoxide dismutase (SOD) in the brain and muscle tissues increased significantly. In addition, the concentration of reactive oxygen species (ROS) also increased from 2.95 ± 0.12 U/ug to 8.46 ± 0.25 U/ug and from 0.90 ± 0.03 U/ug to 3.53 ± 0.64 U/ug in the muscle and brain tissues, respectively. Furthermore, an increased level of cortisol was also observed in muscle and brain tissues, ranging from 17.95 ± 0.90 pg/ug to 23.95 ± 0.66 pg/ug and from 3.47 ± 0.13 pg/ug to 4.91 ± 0.51 pg/ug, respectively. Increment of Hif1-α level was also observed in both tissues. The elevation was ranging from 11.65 ± 0.54 pg/ug to 18.45 ± 1.00 pg/ug in the muscle tissue and from 4.26 ± 0.11 pg/ug to 6.86 ± 0.37 pg/ug in the brain tissue. Moreover, the content of DNA damage and inflammatory markers such as ssDNA, TNF-α, and IL-1β were also increased substantially in the brain tissues. Significant changes in several biomarker levels, including catalase and malondialdehyde (MDA), were also observed in the gill tissues. Finally, we used a neurophenomic approach with a particular focus on environmental influences, which can also be easily adapted for other aquatic fish species, to assess the toxicity of metal and carbon-based nanoparticles. In summary, this is the first study to illustrate the adult zebrafish toxicity and the alterations in several neurobehavior parameters after zebrafish exposure to environmentally relevant amounts of C70 NPs.

Microbiota and the social brain

Sociability can facilitate mutually beneficial outcomes such as division of labor, cooperative care, and increased immunity, but sociability can also promote negative outcomes, including aggression and coercion. Accumulating evidence suggests that symbiotic microorganisms, specifically the microbiota that reside within the gastrointestinal system, may influence neurodevelopment and programming of social behaviors across diverse animal species. This relationship between host and microbes hints that host-microbiota interactions may have influenced the evolution of social behaviors. Indeed, the gastrointestinal microbiota is used by certain species as a means to facilitate communication among conspecifics. Further understanding of how microbiota influence the brain in nature may be helpful for elucidating the causal mechanisms underlying sociability and for generating new therapeutic strategies for social disorders in humans, such as autism spectrum disorders (ASDs).

The Microbiota-Gut-Brain Axis

The importance of the gut-brain axis in maintaining homeostasis has long been appreciated. However, the past 15 yr have seen the emergence of the microbiota (the trillions of microorganisms within and on our bodies) as one of the key regulators of gut-brain function and has led to the appreciation of the importance of a distinct microbiota-gut-brain axis. This axis is gaining ever more traction in fields investigating the biological and physiological basis of psychiatric, neurodevelopmental, age-related, and neurodegenerative disorders. The microbiota and the brain communicate with each other via various routes including the immune system, tryptophan metabolism, the vagus nerve and the enteric nervous system, involving microbial metabolites such as short-chain fatty acids, branched chain amino acids, and peptidoglycans. Many factors can influence microbiota composition in early life, including infection, mode of birth delivery, use of antibiotic medications, the nature of nutritional provision, environmental stressors, and host genetics. At the other extreme of life, microbial diversity diminishes with aging. Stress, in particular, can significantly impact the microbiota-gut-brain axis at all stages of life. Much recent work has implicated the gut microbiota in many conditions including autism, anxiety, obesity, schizophrenia, Parkinson’s disease, and Alzheimer’s disease. Animal models have been paramount in linking the regulation of fundamental neural processes, such as neurogenesis and myelination, to microbiome activation of microglia. Moreover, translational human studies are ongoing and will greatly enhance the field. Future studies will focus on understanding the mechanisms underlying the microbiota-gut-brain axis and attempt to elucidate microbial-based intervention and therapeutic strategies for neuropsychiatric disorders.

The zebrafish subcortical social brain as a model for studying social behavior disorders

Social behaviors are essential for the survival and reproduction of social species. Many, if not most, neuropsychiatric disorders in humans are either associated with underlying social deficits or are accompanied by social dysfunctions. Traditionally, rodent models have been used to model these behavioral impairments. However, rodent assays are often difficult to scale up and adapt to high-throughput formats, which severely limits their use for systems-level science. In recent years, an increasing number of studies have used zebrafish (Danio rerio) as a model system to study social behavior. These studies have demonstrated clear potential in overcoming some of the limitations of rodent models. In this Review, we explore the evolutionary conservation of a subcortical social brain between teleosts and mammals as the biological basis for using zebrafish to model human social behavior disorders, while summarizing relevant experimental tools and assays. We then discuss the recent advances gleaned from zebrafish social behavior assays, the applications of these assays to studying related disorders, and the opportunities and challenges that lie ahead.

Dietary Lactobacillus plantarum ST-III alleviates the toxic effects of triclosan on zebrafish (Danio rerio) via gut microbiota modulation

The probiotics, Lactobacillus plantarum ST-III, plays an important role in modulating microbiota and alleviating intestinal metabolic disorders. Herein, we reported that Lactobacillus increases biodiversity of zebrafish gut flora, and attenuates toxic effects from chronic triclosan (TCS) exposure. Lactobacillus-feeding recovered the species and amount of microorganisms in the intestines of zebrafish, and inhibited toxin production by saprophytic bacterial growth. Abnormal physiological indexes and malonaldeyhde content resulting from TCS exposure were effectively alleviated. Additionally, lipid-metabolism disorders, such as increased triglyceride and total cholesterol levels, were attenuated by a probiotics diet. The number of CD4⁺ T cell lymphocytes in the lamina propria of the duodenal mucosa was decreased in zebrafish receiving a Lactobacillus diet compared to the TCS-exposed group, showing a consistent expression trend for six immune genes (NF-κB, IL-1β, TNF-α, lysozyme, TLR4α, IL-10) in the intestinal mucosa. Histopathological observations of intestines, spleen and kidney showed that TCS exposure produced severe damage to the morphology and structure of immune and metabolism-related organs. Lactobacillus was capable of mitigating this damage, but bile salt hydrolase, an active extract of Lactobacillus, was not an effective mitigation strategy. The Lactobacillus-induced decrease in the number of inflammatory cells confirmed its role in preventing inflammatory injury. Three behavioral tests (T-maze, bottom dwelling and social interaction) indicated that a probiotics diet improved zebrafish movement and learning/memory capacity, effectively alleviating anxiety behavior due to TCS exposure. These findings inform development of beneficial strategies to alleviate intestinal metabolic syndromes and neurodegenerative diseases resulting from exposure to environmental contaminants through modifying gut flora with a probiotics diet.

Genome-wide identification and differentially expression analysis of lncRNAs in tilapia

Background

Long noncoding RNAs (LncRNAs) play important roles in fundamental biological processes. However, knowledge about the genome-wide distribution and stress-related expression of lncRNAs in tilapia is still limited.

Results

Genome-wide identification of lncRNAs in the tilapia genome was carried out in this study using bioinformatics tools. 103 RNAseq datasets that generated in our laboratory or collected from NCBI database were analyzed. In total, 72,276 high-confidence lncRNAs were identified. The averaged positive correlation coefficient (r_mean = 0.286) between overlapped lncRNA and mRNA pairs showed significant differences with the values for all lncRNA-mRNA pairs (r_mean = 0.176, z statistics = − 2.45, p value = 0.00071) and mRNA-mRNA pairs (r_mean = 0.186, z statistics = − 2.23, p value = 0.0129). Weighted correlation network analysis of the lncRNA and mRNA datasets from 12 tissues identified 21 modules and many interesting mRNA genes that clustered with lncRNAs. Overrepresentation test indicated that these mRNAs enriched in many biological processes, such as meiosis (p = 0.00164), DNA replication (p = 0.00246), metabolic process (p = 0.000838) and in molecular function, e.g., helicase activity (p = 0.000102) and catalytic activity (p = 0.0000612). Differential expression (DE) analysis identified 99 stress-related lncRNA genes and 1955 tissue-specific DE lncRNA genes. MiRNA-lncRNA interaction analysis detected 72,267 lncRNAs containing motifs with sequence complementary to 458 miRNAs.

Conclusions

This study provides an invaluable resource for further studies on molecular bases of lncRNAs in tilapia genomes. Further function analysis of the lncRNAs will help to elucidate their roles in regulating stress-related adaptation in tilapia.

Electronic supplementary material

The online version of this article (10.1186/s12864-018-5115-x) contains supplementary material, which is available to authorized users.

Response mechanisms to joint exposure of triclosan and its chlorinated derivatives on zebrafish (Danio rerio) behavior

Triclosan (TCS), 2,4,6-trichlorophenol (2,4,6-TCP) and 2,4-dichlorophenol (2,4-DCP) frequently co-exist in real-world aquatic environments; the latter two contaminants contributing to TCS photolytic products or chlorinated derivatives. There is a paucity of information regarding their joint toxicity to aquatic organisms leading us to study their effects on the swimming behavior of zebrafish (Danio rerio). Herein, we reported that 0.28 mg/L TDT exposure (mixtures of TCS, 2,4,6-TCP and 2,4-DCP) enhanced 24-hpf embryonic spontaneous movement frequency, 96-hpf larval activity; however, the 0.56 and 1.12 mg/L TDT treatments decreased all of these behavioral endpoints. All adult behavioral tests demonstrated that chronic TDT exposure (0.14 mg/L) led to hyperactivity and restlessness in adult zebrafish. A 0.14 mg/L TD DATE /@ "M/d/yyyy" 11/21/2017T treatment led to anxiety-like behavior in a bottom dwelling test and excessive panic and low hedging capacity in a conditioned place preference test. Social interaction test demonstrated that zebrafish preferred quiet and isolated space in response to TDT stress. Zebrafish memory was significantly decreased in a T-maze experiment. Whole mount in situ hybridization of pax2a and bcl2l11 genes revealed that their differential expression in the brain and skeleton were related to the corresponding phenotypic behavioral abnormality. A series of biomarker and estrogen receptor assays demonstrated that TDT acute exposure caused abnormal energy metabolism and neurological diseases. AO staining revealed that TDT exposure produced vascular ablation in the head, as well as the occurrence of massive apoptosis in the brain. TEM observation showed pyknosis of nucleus following TDT exposure. These results allow assessment of mechanisms for zebrafish abnormal behavior in response to TDT exposure, and are useful for early intervention and gene therapy of contaminant-induced diseases.

Reproductive toxicity of β-diketone antibiotic mixtures to zebrafish (Danio rerio)

So far, few data are available on the reproductive toxicological assessment of β-diketone antibiotics (DKAs), a class of ubiquitous pseudo-persistent pollutant, in zebrafish (Danio rerio). Herein, we reported the reproductive effects of DKAs by means of transcriptome analysis (F1-zebrafish), changes in a series of reproductive indices (F0-zebrafish) and histopathological observations. A total of 1170, 983 and 1399 genes were found to be differentially expressed when compared control vs. 6.25mg/L, control vs. 12.5mg/L and 6.25 vs. 12.5mg/L DKA-exposure treatments, respectively. Among three comparison groups, 670, 569 and 821 genes were respectively assigned for GO analyses based on matches with sequences of known functions. In 149 KEGG-noted metabolic pathways, the preferential one was the MAPK (mitogen-activated protein kinase) signaling pathway, followed by oxidative phosphorylation, neuroactive ligand-receptor interaction and so on. By qPCR verification, 6 genes (c6ast4, igfbp1b, mrpl42, tnnc2, emc4 and ddit4) showed consistent gene expression with those identified by transcriptome sequencing. Due to DKA-exposure, the concentrations of plasma estradiol and testosterone, and the gonado-somatic index were significantly dose-dependently declined. Also, DKA-exposure led to declining in zebrafish reproductive capacity, reflecting in fertilization, hatchability and egg production. Histopathological observations demonstrated that zebrafish ovary and testis suffered serious damage after DKA-exposure. The 4-oxo-TEMP signals increased obviously with increasing DKA-exposed concentrations, implying disruption of balance between generation and clearance of ¹O₂. In summary, DKAs not only produce reproductive toxicological effects on F0-zebrafish, but also result in adverse consequences for growth and development of F1-zebrafish.

Screening and functional identification of lncRNAs under β-diketone antibiotic exposure to zebrafish (Danio rerio) using high-throughput sequencing

Long non-coding RNAs (lncRNAs) have attracted considerable research interest, but so far no data are available on the roles of lncRNAs and their target genes under chronic β-diketone antibiotic (DKAs) exposure to zebrafish (Danio rerio). Herein, we identified 1.66, 3.07 and 3.36×10⁴ unique lncRNAs from the 0, 6.25 and 12.5mg/L DKA treatment groups, respectively. In comparison with the control group, the 6.25 and 12.5mg/L treatments led to up-regulation of 2064 and 2479 lncRNAs, and down-regulation of 778 and 954 lncRNAs, respectively. Of these, 44 and 39 lncRNAs in the respective 6.25 and 12.5mg/L treatments displayed significant differential expression. Volcano and Venn diagrams of the differentially expressed lncRNAs were constructed on the basis of the differentially expressed lncRNAs. After analyzing 10 lncRNAs and potential target genes, a complex interaction network was constructed between them. The consistency of 7 target genes (tenm3, smarcc1b, myo9ab, ubr4, hoxb3a, mycbp2 and CR388046.3), co-regulated by 3 lncRNAs (TCONS_00129029, TCONS_00027240 and TCONS_00017790), was observed between their qRT-PCR and transcriptomic sequencing. By in situ hybridization (ISH), abnormal expression of 3 lncRNAs was observed in hepatic and spleen tissues, suggesting that they might be target organs for DKAs. A similar abnormal expression of two immune-related target genes (plk3 and syt10), co-regulated by the 3 identified lncRNAs, was observed in liver and spleen by ISH. Histopathological observations demonstrated hepatic parenchyma vacuolar degeneration and clot formation in hepatic tissues, and uneven distribution of brown metachromatic granules and larger nucleus in spleen tissues resulting from DKA exposure. Overall, DKA exposure led to abnormal expression of some lncRNAs and their potential target genes, and these genes might play a role in immune functions of zebrafish.

Effects of β-diketone antibiotics on F1-zebrafish (Danio rerio) based on high throughput miRNA sequencing under exposure to parents

The toxicity of β-diketone antibiotics (DKAs), a class of ''pseudo-persistent'' environmental pollutants, to F0-zebrafish (Danio rerio) was investigated using 7-dpf F1-zebrafish miRNA sequencing and bioinformatics analyses. Based on relative expression, 47, 134 and 118 of 193 mature miRNAs were differentially expressed between control vs 6.25 mg/L, control vs 12.5 mg/L and 6.25 vs 12.5 mg/L treatments, respectively. Utilizing three databases, 2523 potential target genes were predicted, and they were assigned to 19 high-abundance KEGG pathways and 20 functional categories by COG analysis. Among 11 significantly differential expression and high-abundance miRNAs, the expression levels for 7 miRNAs (miR-144, -124, -499, -125b, -430b, -430c and -152) assessed by qRT-PCR were consistent with those determined by sRNA-seq. A potential network was plotted between 11 miRNAs and their target genes based on differential expression and binding effectiveness. The high degree of connectivity between miRNA-gene pairs suggests that these miRNAs play critical roles in zebrafish development. The expression of miR-124 and miR-499 in whole-mount in situ hybridization was in general agreement with those from qRT-PCR and miRNA-seq and were DKA concentration-dependent. DKA exposure induced severe histopathological changes and damage in F0-zebrafish ovary tissue, as reflected by an increased number of early developmental oocytes, irregular cell distribution, decreased yolk granules, cytoplasmic shrinkage, cell lysis in mature oocytes, and dissolution of internal corona radiata. Chronic DKA exposure affected reproduction of F0-zebrafish and development of F1-zebrafish. These observations demonstrate the toxic effect transfer relation across parent and their offspring, and enhance our understanding of drug-induced diseases.

Screening on the differentially expressed miRNAs in zebrafish (Danio rerio) exposed to trace β-diketone antibiotics and their related functions

The toxicity of β-diketone antibiotics (DKAs) to larval and adult zebrafish (Danio rerio) was investigated by miRNA sequencing and bioinformatics analyses. In control and DKA-exposed groups, 215 differentially expressed miRNAs were screened, and 4076 differential target genes were predicted. Among 51 co-differentially expressed genes, 45 were annotated in KOG functional classification, and 34 in KEGG pathway analysis. The homology analysis of 20 miRNAs with human hsa-miRNAs demonstrated 17 high homologous sequences. The expression levels of 12 miRNAs by qRT-PCR were consistent with those by sRNA-seq. A regulatory network for 4 positive miRNA genes (dre-miR-10, -96, -92 and -184) was plotted, and the high-degree of connectivity between miRNA-gene pairs suggests that these miRNAs play critical roles during zebrafish development. The consistent expression of dre-miR-184 and dre-miR-96 was proved in 120-hpf zebrafish brain, gill, otoliths and lateral line neuromast by qRT-PCR, miRNA-seq, W-ISH and ISH. DKA-exposure led to vacuolation of interstitial cells, reduced number of neurons, glial cell proliferation and formation of glial scar, and the obvious abnormality of cell structure might result from abnormal expression of differentially expressed miRNAs. In general, chronic DKA-exposure resulted in comprehensively toxic effects on larval and adult zebrafish tissues, especially for nervous system.

Perinatal sulfamonomethoxine exposure influences physiological and behavioral responses and the brain mTOR pathway in mouse offspring

Sulfamonomethoxine (SMM) is widely used in the veterinary field in China. Although some clinical surveys have revealed that sulfonamide antibiotics cause adverse nervous system symptoms, the related mechanisms of maternal SMM exposure on the neurobehavioral development of offspring remain unclear. Here, we investigated the effects of perinatal SMM exposure on the physiological and behavioral responses of pubertal offspring mice and the underlying mechanisms. We randomly allocated pregnant mice into the groups treated with SMM at different doses and the saline-treated groups. Maternal mice were orally administered SMM daily from gestational day 1 to postpartum day 21. On postnatal day (PND) 22, the parameters of growth, endocrine hormones, and brain amino acid composition were assessed, as well as the brain transcript levels of key genes involved in the mammalian target of rapamycin (mTOR) signaling pathway. From PND 50 to 55, a battery of behavioral tests relevant to anxiety and memory were then administered. Analysis of the results indicated that the pups, particularly the pubertal female offspring, showed anxiety-like behavior. Moreover, the pubertal offspring showed cognitive impairments and fat accumulation. Furthermore, the relative mRNA expression of genes involved in the mTOR signaling pathway in females on PND 22 was elevated, whereas the expression of N-methyl-d-aspartate receptor 2B (NR2B) was reduced. Together, the results showed that perinatal SMM exposure perturbs neuroendocrine functions, and further alters gene expression in the mTOR pathway and NR2B gene expression early in life, which may contribute to brain dysfunction in pubertal life.