| Sea urchin embryo and larvae in the early developmental stages is an ideal modelfor the research about developmental neurotoxicity. Dopaminergic nervous system ismore sensitive to neurotoxic effects than cholinergic system, and also can regulate themorphogenesis and swimming behaviors of sea urchin embryo and larvae earlier thanserotonergic system. Organophosphate pesticides can interfere with the dopaminergicnervous system in sea urchin, but the underlying mechanisms of howorganophosphate pesticides affect the development of this system are still not clear.Dopamine (DA) neurotransmitter and it’s receptors’ formation is the important basisof dopaminergic nervous system development, and they can regulate and control themorphogenesis in sea urchin early developmental stages together with other nervoussystems. The dopaminergic neuron precursor cell period (pre-dopaminergic nervoussystem) comes after the synthesis of DA and it’s receptors, as the importantmorphological basis of the dopaminergic control in sea urchin embryo and larvae’swimming behavior, DA and dopamine receptor1(DRD1) both exist and combine inthe form of granule whose diameter is1-2μm (DA/DRD1-Gs), and they are alsolinked with with the cilia substrate from rotational blastula stage to metamorphosisstage. Change of DA neurotransmitter content is the result of comprehensiveregulation of all the metabolic process, also under the physiological status, DR areregulated retrospectively by change of DA content. Therefore, the influence oforganophosphate pesticides to dopaminergic nervous system development mayberelated to DA and DRD1as well as important metabolic enzymes or transport proteinin the metabolic process of DA neurotransmitter. In this research, we incubated seaurchin embryo and larvae of Hemicentrotus pulcherrimus to7key developmentalstages (12-hpf early blastulae stage,15-hpf swimming blastulae stage,18-hpf early gastrulae stage,24-hpf late gastrulae stage,30-hpf early prism stage,36-hpf prismstage, and48-hpf early two-arm pluteus stage) with0.01,0.10and1.00mg/L40%moncrotophos (MCP) pesticide and control, and investigated the influences of MCPpesticide to DA content and the DRD1mRNA expression as well as important factorsin DA metabolic process, we analyzed the influence and it’s mechanism of MCPpesticide to the development of dopaminergic nervous system.These results mainly indicated that:(1) Under the physiological status, DA content and DRD1mRNA expression inearly developmental stages of H. pulcherrimus both have none significant changes.The stabilization of TH mRNA expression level and DAT content are the importantreason for DA having none significant changes in early developmental stages of H.pulcherrimus. In addition, there exist some varying pattern in MAO activity andMAO-A mRNA expression. MCP pesticide disturbed DA content and DRD1mRNAexpression, TH mRNA expression and DAT content, as well as MAO activity andMAO-A mRNA expression in early developmental stages of H. pulcherrimus.(2) In12-hpf,18-hpf and36-hpf, MCP pesticide can disturb TH mRNA expressionand DAT content, and then up/down-regulate DA content, also caused the abnormaldevelopment of dopaminergic nervous system and it’s function regulation. Also, MCPpesticide could upregulate DAT content and then suppress DRD1mRNA expression in48-hpf early two-arm pluteus stage.For the other stages (15-hpf swimming blastulaestage,24-hpf late gastrulae stage and30-hpf early prism stage), although MCPpesticide has no effect to DA content and DRD1mRNA expression, it can disorder THmRNA expression and DAT content, MAO activity and MAO-A mRNA expression.In conclusion, MCP pesticide could disorder TH mRNA expression and DATcontent, which interfere with DA neurotransmitter metabolic process, and thenup/down-regulated DA content and DRD1mRNA expression, also caused theabnormal development of dopaminergic nervous system and it’s function regulation inearly developmental stages of H. pulcherrimus. |
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