Arginine Vasotocin, an Osmoregulatory Hormone, as a Potential Indicator of Acid Stress in Fish

Brook trout (Salvelinus fontinalis) exposed for 1 wk to pH 5.6 (sublethal acidity) exhibited higher forebrain and pituitary arginine vasotocin (AVT) levels and lower plasma Na+ levels than fish exposed to pH 6.7 (control). Addition of 300 μg total Al/L to water at pH 5.6 did not augment the effect on either the plasma Na+ or the AVT levels. Exposure to demineralized water for 1 wk lowered the plasma Na+ and increased AVT in the forebrain but had no effect on pituitary AVT. The increased AVT levels could be used as early warning indicators of sublethal acid stress in the brook trout. Such indicators, used in wild fish, might become important tools in management of trout lakes in areas threatened by acidification.

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Elevated Levels of Arginine Vasotocin in the Brain of Brook Trout (Salvelinus fontinalis) from Acid Lakes: A Field Test of a Potential Biomarker for Acid Stress

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f93-193 ◽

1993 ◽

Vol 50 (8) ◽

pp. 1717-1727 ◽

Cited By ~ 4

Author(s):

A. Hontela ◽

J. B. Rasmussen ◽

K. Lederis ◽

H. V. Tra ◽

G. Chevalier

Keyword(s):

Body Size ◽

Field Test ◽

Brook Trout ◽

Salvelinus Fontinalis ◽

Acid Stress ◽

Low Ph ◽

Arginine Vasotocin ◽

Potential Biomarker ◽

Different Seasons ◽

The Relationship

The levels of arginine vasotocin (AVT), an osmoregulatory peptide, were determined by radioimmunoassay in brain tissue of brook trout (Salvelinus fontinalis) of a wide size range (50–380 mm) from softwater Laurentian lakes ranging in pH from 5.0 to 6.9 at different seasons. Multivariate models (ANCOVA) were developed to quantify the relationship between AVT, pH, body size, and season. Brain AVT levels increased with body size, and the allometric slope was highest in the low-pH lakes (pH 5.0-5.5). Although brook trout > 150 mm had higher brain AVT levels at low pH, no significant differences were detected for brook trout < 150 mm. We hypothesize that the sensitivity of brook trout at the parr stage to acid stress may be linked to their inability to mobilize a hormonal response involving AVT. The seasonal variation in brain AVT levels was similar in all the lakes studied, summer levels being the highest. Although this field study revealed that AVT levels depend also on factors other than acid stress (body size and season), our ANCOVA models allow adjustment for the effects of these covariables. Analyses of this type can be used to field test and calibrate biomarkers for use in ecotoxicology.

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Endocrine Responses as Indicators of Sublethal Toxic Stress in Fish from Polluted Environments

Water Quality Research Journal ◽

10.2166/wqrj.1993.042 ◽

1993 ◽

Vol 28 (4) ◽

pp. 767-780 ◽

Cited By ~ 12

Author(s):

Alice Hontela ◽

Joseph B. Rasmussen ◽

Gaston Chevalier

Keyword(s):

Brook Trout ◽

Acid Stress ◽

Aquatic Organisms ◽

River System ◽

Toxic Stress ◽

Physiological Processes ◽

Vital Functions ◽

Early Warning Indicators ◽

Warning Indicators ◽

St Lawrence River

Abstract Development of new methods for detection of sublethal toxic effects of pollutants in aquatic organisms has become a focus of interest in ecotoxicology. The endocrine response to pollutants is an integral part of the homeostatic physiological processes activated in response to environmental stressors including pollutants. Changes in concentrations of hormones, particularly those regulating vital functions such as osmoregulation, energy metabolism, reproduction, or growth, may have potential as early warning indicators of toxic stress in fish. We review the recent literature in fish endocrine toxicology and illustrate the use of hormonal indicators in detection of acid stress in the brook trout. Salvelinus fontinalis, from lakes in the Canadian Shield, and of general toxic stress in the pike, Esox lucius, and the perch, Perca flavescens, from the St. Lawrence River system polluted by a mixture of chemicals.

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