Ammonia-N exposure alters neurohormone levels in the hemolymph and mRNA abundance of neurohormone receptors and associated downstream factors in the gills ofLitopenaeus vannamei

Abstract

Effects of ammonia-N (0.05, 2, 10 and 20 mg l −1 ) on the neuroendocrine regulation of ammonia transport were investigated in Litopenaeus vannamei. The results showed that corticotrophinreleasing hormone, adrenocorticotropic hormone, dopamine, noradrenaline and 5-hydroxytryptamine concentrations in all ammonia-N groups increased significantly between 3 and 12 h. Cortisol increased significantly between 3 and 24 h. All hormones except crustacean hyperglycemic hormone were reduced to control levels. mRNA abundance of guanylyl cyclase increased significantly during the experiment. Dopamine receptor D 4 and α 2 adrenergic receptor mRNA abundance in treatments decreased significantly at the beginning, and eventually returned to the control level, whereas mRNA abundance of the 5-HT 7 receptor increased significantly only within the first 12 h. Changes in protein kinase (PKA, PKG) mRNA abundance were similar to the patterns of biogenic amines and crustacean hyperglycemic hormone, peaking at 6 and 12 h, respectively, whereas PKC mRNA abundance decreased within 24 h. 14-3-3 protein, FXYD2 and cAMP-response element binding protein mRNA abundance increased significantly and peaked at 6 h. β-catenin and T-cell factor mRNA abundance increased significantly throughout the experiment and peaked at 12 h. The upregulation of Rh protein, K + channel, Na + /K + -ATPase, V-type H + -ATPase and vesicle associated membrane protein (VAMP) mRNA, together with downregulation of Na + /K + /2Cl − cotransporter mRNA, indicated an adjustment of general branchial ion-/ammonia-regulatory mechanisms. Meanwhile, hemolymph ammonia concentration was significantly increased in most ammonia-N exposure groups. Histological investigation revealed the hepatopancreatic damage caused by ammonia-N. Results suggest that hormones, biogenic amines and Wnt/β-catenin play a principal role in adapting to ammonia-N exposure and facilitating ammonia transport.

Evidence that dopamine is involved in neuroendocrine regulation, gill intracellular signaling pathways and ion regulation in Litopenaeus vannamei

“…Chang (2005) recorded an increase in hemolymph CHH of Homarus americanus under conditions of acute hypoxia, elevated temperature and altered salinity. Our group also detected a significant increase in CHH concentration of hemolymph in L. vannamei under ammonia-N stress (Si et al, 2019). Therefore, it can be speculated that under salinity and ammonia-N stress, some hormones may participate in ion regulation together with biogenic amines and are associated with ammonia acclimation.…”

“…In addition, there have been many studies on the hypothalamicpituitary-interrenal (HPI) axis of fish. Exposure to ammonia-N enhanced the levels of CRH, ACTH and cortisol in Scophthalmus maximus and L. vannamei (Jia et al, 2017;Si et al, 2019). Moreover, it has been reported that cortisol plays a major role in acclimation to hypersalinity in teleost fish (Gonzalez, 2012).…”

Neuroendocrine‐immune regulation mechanism in crustaceans: A review

“…203 Recently, in crustacean, it has also been reported that after perceiving the low salinity and ammonia-N stress in L. vannamei lead to the secretion of CRH, ACTH and stimulate the release of DA, NE and 5-HT through CRH-ACTH-biogenic amine axis. 171,204 Moreover, Liu et al 71 annotated ACTH-related factors in the brain of L. vannamei after eyestalk ablation by transcriptome technology. In short, these findings emphasize the great similarity with CRH-ACTH-induced BA and glucocorticoid release-related events in invertebrates and vertebrates, respectively.…”

Effects of ammonia on shrimp physiology and immunity: a review

“…2). For instance, exposure of L. vannamei to ammonia or low salinity stress results in the secretion of corticotrophin‐releasing hormone (CRH) and adrenocorticotropic hormone (ACTH) into the haemolymph to stimulate the release of biogenic amines, such as DA, NE and 5‐HT (Jia et al, 2016; Si et al, 2019a). Following the release of these biogenic amines, the membrane receptors, such as D 4 receptor (for DA) and 5‐HT 7 receptor (for 5‐HT), then transduce the signals onto haemocytes to modulate the concentrations of cAMP and cGMP, thereby regulating the levels of intracellular PKA and PKC (Zhao et al, 2016; Zhang et al, 2018a).…”