The transport of ions and ammonia in gills may be regulated by neuroendocrine factors. In order to explore the mechanism of dopamine (DA) regulation, we investigated hemolymph neuroendocrine hormones, gill intracellular signaling pathways, ion and ammonia transporters, hemolymph osmolality and ammonia concentration in Litopenaeus vannamei after injection of 10-7 and 10-6 mol DA per shrimp. The data showed a significant increase in crustacean hyperglycemic hormone (CHH) concentration at 1-12 h and a transient significant decrease in corticotrophin-releasing hormone (CRH), adrenocorticotropic hormone (ACTH) and cortisol concentration under DA stimulation. The up-regulation of guanylyl cyclase (GC) mRNA, cyclic guanosine monophosphate (cGMP) and protein kinase G (PKG) concentration, together with the down-regulation of DA receptor D4 mRNA and up-regulation of cyclic adenosine monophosphate (cAMP), protein kinase A (PKA), diacylglycerol (DAG) and protein kinase C (PKC) concentration suggested the activation of complicated intracellular signaling pathways. The expression of cAMP response element-binding protein (CREB), FXYD2 and 14-3-3 protein mRNA was significantly increased by PKA regulation. The increase in Na+/K+-ATPase (NKA) activity and the stabilization of V-type H+-ATPase (V-rATPase) activity were accompanied by an up-regulation of K+ channel, Na+/K+/2Cl- cotransporter (NKCC), Rh protein and vesicle associated membrane protein (VAMP) mRNA, resulting in an increase in hemolymph osmolality and a decrease in hemolymph ammonia concentration. These results suggest that DA stimulates the secretion of CHH and inhibits the release of cortisol, which activates intracellular signaling factors to facilitate ion and ammonia transport across the gills, and may not affect intracellular acidification.
Keywords: Ammonia transport; Biogenic amine; Hormone; Protein kinase; Second messenger.
© 2019. Published by The Company of Biologists Ltd.