Effects of ammonia-N exposure on the concentrations of neurotransmitters, hemocyte intracellular signaling pathways and immune responses in white shrimpLitopenaeus vannamei


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Abstract

The effects of ammonia-N exposure (transferred from 0.07 to 2, 10 and 20 mg L−1) on the mechanism of neuroendocrine-immunoregulatory network were investigated in Litopenaeus vannamei. The results showed that biogenic amines (dopamine, noradrenaline, 5-hydroxytryptamine) concentrations in treatment groups increased significantly within 12 h. The gene expression of guanylyl cyclase increased significantly from 3 h to 24 h. And dopamine receptor D4 and α2 adrenergic receptor gene expression in treatment groups decreased significantly within 12 h, whereas the mRNA expression of 5-HT7 receptor increased significantly within 3 h and reached the peak levels at 6 h. The second messengers (cAMP, cGMP) and Calmodulin (CaM) increased significantly in treatment groups after 3 h. The concentrations of protein kinases (PKA, PKG) shared a similar trend in cAMP and cGMP which were up-regulated and reached the peak value at 6 h, while the PKC decreased within 3 h and arrived at its bottom at 6 h. The nuclear factor kappa-b and cAMP-response element binding protein mRNA expression levels of treatment shrimps increased sharply and reached maximum values at 6 h. The total hemocyte count, phagocytic activity, antibacterial activity in treatment groups decreased dramatically within 48 h. Whereas the phenoloxidase activities slightly up-regulated. Then it was decreased significantly up to 48 h. α2-macroglobulin activity decreased at the first 3 h-stress. Then they up-regulated significantly in 6 h. The results suggest that there are two crucial neuroendocrine substances (biogenic amine and CHH), which play a principal role in adapting to ammonia-N exposure and cause immune response through cAMP-, CaM- and cGMP-dependent pathways.HighlightsBiogenic amine involved in the immune response in L. vannamei exposed to ammonia-N.Biogenic amine and CHH cause immune response through PKA, PKC and PKG pathways.Phagocytic activity is though PKA and PKC pathways and PKG pathway directly.Exocytosis activity is though PKC pathway and affected by CHH indirectly.

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