mRNA expression analysis of the physiological responses to ammonia infusion in rainbow trout

C. Michele Nawata, Chris M. Wood

Research output: Contribution to journalArticle

41 Citations (Scopus)

Abstract

We recently reported that tissue levels of Rhesus (Rh) mRNA in rainbow trout changed in response to high-external ammonia (HEA). To investigate whether or not these changes could be due to elevated plasma ammonia levels, we infused rainbow trout for 12 h with 140 mmol L-1 NH4HCO3, or with 140 mmol L-1 NaCl as a control for the effects of infusion. We also analyzed the effects of dorsal aortic catheterization alone, without infusion. Catheterization alone resulted in an elevated ammonia excretion rate, a downregulation of Rhbg mRNA in the brain, and mRNA upregulations of Rhbg, Rhcg1, and Rhcg2 in the gill, Rhbg and Rhcg1 in the skin, and Rhag in the erythrocytes. In NH4HCO3-infused fish, plasma cortisol peaked at 6 h, erythrocyte Rhag mRNA was downregulated, gill Rhbg, Rhcg1, and Rhcg2 mRNA were upregulated, and skin Rhbg mRNA was also upregulated. NaCl infusion resulted in elevated plasma ammonia and ammonia excretion rates as well as gill mRNA upregulations of Rhbg, carbonic anhydrase, NHE2, H+-ATPase, Na+/K+-ATPase. Taken together, the results indicated that infusion of NH4HCO3 induced a similar pattern of Rh transcript changes as that seen when fish were exposed to HEA. Second, catheterization alone, as well as isotonic NaCl infusion, significantly altered mRNA levels, highlighting the necessity for careful data interpretation and inclusion of appropriate controls for gene expression studies in fish that have undergone anaesthesia/surgery and infusion procedures. Finally, elevated plasma ammonia and cortisol may both be involved in the signaling mechanism for Rh gene regulation.

Original languageEnglish
Pages (from-to)799-810
Number of pages12
JournalJournal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology
Volume179
Issue number7
DOIs
StatePublished - Sep 1 2009

Fingerprint

Oncorhynchus mykiss
physiological response
Ammonia
rainbow
ammonia
Messenger RNA
catheters
plasma
Catheterization
gills
Fish
Plasmas
Fishes
skin (animal)
excretion
cortisol
Gene expression
skin
erythrocytes
fish

Keywords

  • Ammonia transport
  • Cortisol
  • NHHCO
  • Rhesus glycoproteins

ASJC Scopus subject areas

  • Physiology
  • Ecology, Evolution, Behavior and Systematics
  • Animal Science and Zoology
  • Biochemistry
  • Endocrinology

Cite this

mRNA expression analysis of the physiological responses to ammonia infusion in rainbow trout. / Nawata, C. Michele; Wood, Chris M.

In: Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology, Vol. 179, No. 7, 01.09.2009, p. 799-810.

Research output: Contribution to journalArticle

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