Survival and chemotaxis of Clonorchis sinensis newly excysted juveniles to bile acidsflash

초록

The effects of bile and bile acids on newly excysted juvenile C. sinensis (CsNEJs) were studied in terms of survival. The survival rate of the NEJs was not significantly affected in low than 0.05% bile, but the NEJs were deteriorated rapidly in higher than 0.1% bile. All bile acids and conjugatedbile salts were found favorable to CsNEJ survival, except for lithocholic acid (LCA), which was toxic to CsNEJs. It is, therefore, proposed that bile acids enhance the activity of CsNEJs, but LCA is deteriorative to CsNEJs. Neuro-receptors associated with bile-chemotactic behavior of CsNEJs were analyzed by neuropeptides and inhibitors of glutamate, serotonin, dopamine and acetylcholine neuron groups. The CsNEJs migrated toward 0.001-0.01% bile but away from 0.05-0.1% bile. The CsNEJs showed strong chemotactic behavior to cholic acid, but chemorepellent to lithocholic acid. The bile chemotaxis was inhibited strong by dopamine receptor antagonists D1 (SKF 83566 and LE-300), D2 (AMI-193, Nemonapride and RS-(+/-)-sulpiride), D3 (GR 10369 and NGB) and dopamine uptake inhibitor (BTCP), but showed chemo-repellent to 1 and 10 μM of AMI-193 and NGB. The bile chemotactic migration was inhibited by serotonin, glutamate and acetylcholine receptor inhibitors at high concentration. Collectively, chemotaxis of CsNEJs toward cholic acid is considered to be a driving factor of migration to the bile ducts in the final hosts. It is proposed that dopamine neurons play a major role of bile-chemotactic behavior of C. sinensis, and serotonin and acetylcholine neurons may take minor parts for the chemotactic responses.