Effects of cadmium, manganese, and lead on locomotor activity and neurexin 2a expression in zebrafish

Abstract

The synaptic adhesion protein Neurexin 2a (Nrxn2a) plays a key role in neuronal development and is associated with cognitive functioning and locomotor behavior. Although low-level metal exposure poses a potential risk to the human nervous system, especially during the developmental stages, little is known about the effects of metal exposures on nrxn2a expression during embryonic development. We therefore exposed wild-type zebrafish embryos/larvae to cadmium (CdCl ), manganese (MnCl ), and lead ([CH COO] Pb), to determine their effect on mortality, malformation, and hatching rate. Concentrations of these metals in zebrafish were detected by inductively coupled plasma mass spectrometry analysis. Locomotor activity of zebrafish larvae was analyzed using a video-track tracking system. Expression of nrxn2a was assessed by in situ hybridization and quantitative polymerase chain reaction. The results showed that mortality, malformation, and bioaccumulation increased as the exposure dosages and duration increased. Developmental exposure to these metals significantly reduced larval swim distance and velocity. The nrxn2aa and nrxn2ab genes were expressed in the central nervous system and downregulated by almost all of the 3 metals, especially Pb. These data demonstrate that exposure to metals downregulates nrxn2a in the zebrafish model system, and this is likely linked to concurrent developmental processes. Environ Toxicol Chem 2017;36:2147-2154. © 2017 SETAC.

Iron and Manganese Retention of Juvenile Zebrafish (Danio rerio) Exposed to Contaminated Dietary Zooplankton (Daphnia pulex)—a Model Experiment

“…Marins et al in their fresh study from 2019 found that long-term exposure to Fe and Mn in a concentration commonly found in groundwater may cause damage to chromosome levels and changes in locomotor and exploratory behaviors of adult zebrafish [61]. It was further concluded by Tu H. et al that developmental exposure to Mn along with Cd and Pb statistically reduced the velocity and distance of the larval swim of zebrafish [62]. Altenhofen et al studied the effect of MnCl 2 exposure on cognition and exploratory behavior in adult and larval zebrafish.…”

Zinc Chloride Exposure Inhibits Brain Acetylcholine Levels, Produces Neurotoxic Signatures, and Diminishes Memory and Motor Activities in Adult Zebrafish

“…Behavioral response was applied for decades as an indicator of toxicological impact within neurons [ 47 , 48 , 49 ]. Previous studies reported behavioral and locomotor activity alterations influenced by divalent zinc and/or other heavy metals in different species; however, only developmental toxicity of ZnCl 2 in zebrafish embryos was addressed [ 50 , 51 , 52 ]. In contrast, our pioneer study demonstrated, for the first time, that adult zebrafish exposed to ZnCl 2 had reduced locomotor behavior, average speed, entries to the upper zone, and total distance traveled.…”

Morphological and Molecular Alterations Induced by Lead in Embryos and Larvae of Danio rerio

“…In zebrafish embryos and larvae, available studies on Pb toxicity mainly focused on neurotoxicity, neurodevelopmental, and neurobehavior effects [40,[43][44][45][46][47][48]. Surprisingly, morpho-functional investigations during the sensitive phase of development are scarce, and only a few studies have furnished an overall morphological evaluation [45,[49][50][51][52][53].…”

“…In zebrafish embryos and larvae, available studies on Pb toxicity mainly focused on neurotoxicity, neurodevelopmental, and neurobehavior effects [40,[43][44][45][46][47][48]. Surprisingly, morpho-functional investigations during the sensitive phase of development are scarce, and only a few studies have furnished an overall morphological evaluation [45,[49][50][51][52][53]. Moreover, all available information on fish deals with high lead concentrations, and there is a lack of research on the adverse effects of lead at environmentally relevant concentrations [53].…”