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Arginine vasotocin and fish osmoregulation
R J Balment1, J M Warne, M Tierney
1Department of Physiological Sciences, University of Manchester, Manchester, M13 9PT.
Fish Physiology and Biochemistry
|November 9, 2013
Summary
Pituitary arginine vasotocin (AVT) secretion adjusts to environmental salinity changes in fish. While pituitary AVT levels vary, plasma AVT concentrations remain relatively stable, with antidiuretic effects being physiologically significant.
Area of Science:
- Comparative Physiology
- Endocrinology
- Osmoregulation
Background:
- Euryhaline teleosts must adapt to wide salinity fluctuations.
- Pituitary arginine vasotocin (AVT) plays a role in osmoregulation.
- Environmental salinity impacts AVT secretion and action.
Purpose of the Study:
- To investigate the role of pituitary AVT in osmoregulation of euryhaline teleosts.
- To examine plasma and pituitary AVT levels in fish adapted to freshwater (FW) and seawater (SW).
- To explore the physiological significance of AVT receptors in renal and gill tissues.
Main Methods:
- Measurement of pituitary AVT content and plasma AVT concentrations.
- Correlation analysis of plasma AVT with sodium levels.
- Investigation of AVT receptor presence and function in renal and gill tissues.
Main Results:
- Pituitary AVT content is higher in FW-adapted flounders than SW-adapted.
- Plasma AVT concentrations show no consistent differences between FW and SW adaptation.
- Plasma AVT correlates with sodium in SW-adapted flounders; a transient rise in AVT and Angiotensin II occurs during FW to SW acclimation in eels.
- Antidiuretic responses are the most physiologically significant AVT effect on urine production.
- Renal AVT receptors (V1 and V2 types) are present and functional, while gill AVT receptors inhibit cAMP production.
Conclusions:
- Pituitary AVT content, but not plasma concentration, reflects salinity adaptation.
- AVT's primary osmoregulatory role in teleosts is likely antidiuretic.
- The functional significance of AVT receptors in gill tissue requires further investigation.
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