Evidence for a mineralocorticoid-like receptor linked to branchial chloride cell proliferation in freshwater rainbow trout

2001 ◽  
Vol 204 (22) ◽  
pp. 3953-3961 ◽  
Author(s):  
Katherine A. Sloman ◽  
Patrick R. Desforges ◽  
Kathleen M. Gilmour
Keyword(s):  
Cell Proliferation ◽  
Rainbow Trout ◽  
Atpase Activity ◽  
Coconut Oil ◽  
Chloride Cell ◽  
Chloride Cells ◽  
Corticosteroid Receptor ◽  
Potent Antagonist ◽  
Mineralocorticoid Hormone

SUMMARY Fish acclimated to ion-deficient water exhibit proliferation of branchial chloride cells. The objective of the present study was to investigate the role of cortisol in this response using the corticosteroid receptor antagonists RU486 and spironolactone. RU486 is a potent antagonist of the glucocorticoid actions of cortisol, whereas spironolactone exhibits high-affinity binding to mineralocorticoid receptors, with a resulting blockade of mineralocorticoid properties in mammals. Untreated rainbow trout, as well as rainbow trout given a single intraperitoneal implant of coconut oil alone, coconut oil containing RU486 (0.5 mg g–1) or coconut oil containing spironolactone (0.1 mg g–1), were exposed to either dechlorinated city-of-Ottawa tapwater or artificial softwater for 7 days. Neither corticosteroid antagonist nor acclimation condition affected circulating plasma cortisol levels, plasma ion concentrations or gill Na+-K+-ATPase activity. Kidney Na+-K+-ATPase activity was significantly higher in softwater-acclimated fish than in fish held in dechlorinated tapwater. In addition, whereas RU486 treatment was found to be without effect on gill morphometrics, treatment with spironolactone inhibited the proliferation of chloride cells normally associated with acclimation to ion-deficient water. The results of the present study provide further evidence for the mineralocorticoid actions of cortisol in freshwater fish, specifically in eliciting chloride cell proliferation. Furthermore, these results support the hypothesis that distinct glucocorticoid and mineralocorticoid receptor populations are present in teleost fish, despite the apparent absence of the classic mineralocorticoid hormone, aldosterone.

Does socially induced stress in rainbow trout cause chloride cell proliferation?

2000 ◽  
Vol 56 (3) ◽  
pp. 725-738 ◽  
Author(s):  
K. A. Sloman ◽  
K. M. Gilmour ◽  
N. B. Metcalfe ◽  
A. C. Taylor
Keyword(s):  
Cell Proliferation ◽  
Rainbow Trout ◽  
Chloride Cell ◽  
Induced Stress

Branchial chloride cell proliferation in the rainbow trout, Oncorhynchus mykiss: implications for gas transfer

1994 ◽  
Vol 72 (8) ◽  
pp. 1395-1402 ◽  
Author(s):  
Shawn D. Bindon ◽  
James C. Fenwick ◽  
Steve F. Perry
Keyword(s):  
Electron Microscopy ◽  
Cell Proliferation ◽  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
Surface Area ◽  
Chloride Cell ◽  
Gas Transfer ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Treated Fish ◽  
Fractional Surface

The effects of branchial chloride cell proliferation on ion transport capability and gill morphometry were evaluated in the rainbow trout, Oncorhynchus mykiss, to test the hypothesis that chloride cell (CC) proliferation benefits ionic regulation at the expense of efficient gas transfer. The extent of hormone-induced CC proliferation (using ovine growth hormone (oGH), cortisol, or a combination of both) on the gill filament epithelium was assessed by determining the fractional surface area of exposed cells using scanning electron microscopy. Cortisol and oGH were equally effective in increasing CC fractional surface area (~2×), owing to the enlargement of individual CCs. The combined cortisol/oGH treatment resulted in an even greater increase in CC fractional area (~6×), as both the size and number of CCs increased. Sham injections were without effect on CC surface area or number. Significant increases in Na+ (Jin Na+) and Cl− uptake (Jin Cl−) were observed after all hormone treatments and were correlated positively with the increases in the CC fractional surface area. These findings support the view that CC proliferation enhances branchial ion transport capability. Lamellar epithelial thickness (measured by transmission electron microscopy) was increased in hormone-treated fish, while lamellar surface area (measured using light microscopy) was unaffected. The area of the interlamellar water channels (calculated from light micrographs) was significantly reduced in hormone-treated fish. These results suggest that, in trout, a compromise is made between the efficiency of ion regulation and gas transfer in which the enlargement/proliferation of CCs may impede gas transfer.

Branchial Morphological and Endocrine Responses of Rainbow Trout (Oncorhynchus mykiss) to a Long-Term Sublethal Acid Exposure In Which Acclimation Did Not Occur

1993 ◽  
Vol 50 (1) ◽  
pp. 198-209 ◽  
Author(s):  
Céline Audet ◽  
Chris M. Wood
Keyword(s):  
Rainbow Trout ◽  
Oncorhynchus Mykiss ◽  
Chloride Cell ◽  
Chloride Cells ◽  
Physiological Data ◽  
Mucous Cells ◽  
Diffusion Distance ◽  
Cell Numbers ◽  
Rainbow Trout Oncorhynchus Mykiss

Changes in branchial morphology and in plasma Cortisol, adrenaline, and noradrenaline were quantified throughout an 81 -d exposure of rainbow trout (Oncorhynchus mykiss) to sublethal acidity (pH 4.8) in artificial soft water and after a 5-h acid challenge (pH 4.0) of naive fish and 81-d acid-preexposed fish. Changes in branchial morphology at pH 4.8 were generally very mild and characterized by slight increases in filamental mucous cells and decreases in lamellar mucous cells. Chloride cell numbers and branchial Na+–K+- and total ATPase activities did not change. The filamental epithelium thickened, but the water–blood diffusion distance in the lamellae decreased during chronic exposure. Cortisol was significantly elevated throughout whereas catecholamines exhibited relatively little response. Response to acute pH 4.0 challenge was similar in naive and 81-d acid-exposed fish: epithelial damage, increase in visible mucous cells, loss of chloride cells by necrosis, and high cortisol levels but no changes in lamellar or filamental epithelial thickness, diffusion distance, ATPase activities, or catecholamine levels. Previously reported physiological data from these same trout demonstrated that sensitization rather than acclimation had occurred. Therefore, these observations support the view that acclimation does not occur in the absence of significant branchial damage and repair.

Angiotensin II receptors in the gill of sea water- and freshwater-adapted eel

1997 ◽  
Vol 18 (1) ◽  
pp. 67-76 ◽  
Author(s):  
S Marsigliante ◽  
A Muscella ◽  
G P Vinson ◽  
C Storelli
Keyword(s):  
Image Analysis ◽  
Angiotensin Ii ◽  
Atpase Activity ◽  
Sea Water ◽  
Anguilla Anguilla ◽  
Chloride Cell ◽  
Chloride Cells ◽  
Angiotensin Ii Receptors ◽  
Receptor Subtypes ◽  
Ang Ii

ABSTRACT Immunocytochemistry of paraffin-embedded and cryostat sections of eel (Anguilla anguilla) gill showed that angiotensin II receptors (Ang II-R) were present in chloride cells, uniformly distributed in the cytoplasm and on surface membranes. Computerised image analysis of these preparations showed that gills from sea water (SW)-adapted animals had a significantly (3-fold) higher Ang II-R concentration compared with freshwater (FW)-adapted eel gills. Isoelectric focusing gel electrophoresis revealed two Ang II-R isoforms with pI 6·5 and 6·6 that were differentially modulated by environmental salinity: they were equally abundant in SW while in FW the pI 6·6/pI 6·5 ratio was 1·66. Using catalytic cytochemistry with image analysis, gill chloride cell membrane Na+/K+ATPase activity was shown to increase 4-fold in response to SW adaptation. Additionally, perfusion of gills for 30 min with 0·1, 10 or with 100 nM Ang II provoked a dose-dependent increment in Na+/K+ATPase activity in FW, and a biphasic response in SW gills in which activity was significantly increased at low Ang II concentrations but was reduced to basal values at 100 nM. The data suggest that adaptation to sea water significantly increases Ang II-R concentration in the chloride cell and, together with the effects of Ang II on Na+/K+ATPase activity, suggest a role for this hormone in gill NaCl retention. The different responses of Na+/K+ATPase to Ang II stimulation in FW and SW may be attributed to the presence of two receptor subtypes that are differently modulated by salinity and that have opposing effects on Na+/K+ATPase.

scholarly journals Metabolic and mitogenic effects of IGF-I and insulin on muscle cells of rainbow trout

2004 ◽  
Vol 286 (5) ◽  
pp. R935-R941 ◽  
Author(s):  
Juan Castillo ◽  
Marta Codina ◽  
María Laura Martínez ◽  
Isabel Navarro ◽  
Joaquim Gutiérrez
Keyword(s):  
Cell Proliferation ◽  
Rainbow Trout ◽  
Muscle Metabolism ◽  
Muscle Cells ◽  
Fish Muscle ◽  
Thymidine Uptake ◽  
Igf I ◽  
Vitro Model

The relative function of IGF-I and insulin on fish muscle metabolism and growth has been investigated by the isolation and culture at different stages (myoblasts at day 1, myocytes at day 4, and myotubes at day 10) of rainbow trout muscle cells. This in vitro model avoids interactions with endogenous peptides, which could interfere with the muscle response. In these cells, the effects of IGF-I and insulin on cell proliferation, 2-deoxyglucose (2-DG), and l-alanine uptake at different development stages, and the use of inhibitors were studied and quantified. Insulin (10-1,000 nM) and IGF-I (10-100 nM) stimulated 2-DG uptake in trout myocytes at day 4 in a similar manner (maximum of 124% for insulin and of 142% for IGF-I), and this stimulation increased when cells differentiated to myotubes (maximum for IGF-I of 193%). When incubating the cells with PD-98059 and especially cytochalasin B, a reduction in 2-DG uptake was observed, suggesting that glucose transport takes place through specific facilitative transporters. IGF-I (1-100 nM) stimulated the l-alanine uptake in myocytes at day 4 (maximum of 239%), reaching higher values of stimulation than insulin (100-1,000 nM) (maximum of 160%). This stimulation decreased when cells developed to myotubes at day 10 (118% for IGF-I and 114% for insulin). IGF-I (0.125-25 nM) had a significant effect on myoblast proliferation, measured by thymidine incorporation (maximum of 170%), and required the presence of 2-5% fetal serum (FBS) to promote thymidine uptake. On the other hand, insulin was totally ineffective in stimulating thymidine uptake. We conclude that IGF-I is more effective than insulin in stimulating glucose and alanine uptake in rainbow trout myosatellite cells and that the degree of stimulation changes when cells differentiate to myotubes. IGF-I stimulates cell proliferation in this model of muscle in vitro and insulin does not. These results indicate the important role of IGF-I on growth and metabolism of fish muscle.

scholarly journals The effect of salinity on osmoregulation and development of the juvenile fat snook, Centropomus parallelus (POEY)

2013 ◽  
Vol 73 (3) ◽  
pp. 609-615 ◽  
Author(s):  
FC. Sterzelecki ◽  
E. Rodrigues ◽  
E. Fanta ◽  
CAO. Ribeiro
Keyword(s):  
Atpase Activity ◽  
Salt Water ◽  
Cell Ultrastructure ◽  
Chloride Cell ◽  
Chloride Cells ◽  
Secretory Cells ◽  
Salinity Change ◽  
Short Term ◽  
Short Term Exposure

Eurihaline fish support waters with different salt concentration. However, numerous studies have shown that salinity can affect fish development. Thus, the effect of salinity change from 20 to 5 and 35 on survival, weight, length, gill chloride cell ultrastructure and gill Na+, K+ ATPase activity was evaluated in Centropomus parallelus following short-term (6, 24 and 96 hours) and long-term exposure (30 and 60 days). Salinity did not affect C. parallelus survival, final weight and length. The quantity of chloride cells increased visibly at salinities of 5 and 35, with the cells exhibiting the typical features of uptake and secretory cells, respectively. Na+, K+ ATPase activity in the gill of the C. parallelus was significantly greater at a salinity of 5 than at a salinity of 20 or 35 after 96 hours, but not after 30 or 60 days. These results indicate that salinity change from high to low salt water induces gill chloride cell and Na+, K+ ATPase activity adaptations after short-term exposure. However, after long-term exposure at salinity 5, gill Na+, K+ ATPase activity is no more necessary at high levels. The increase in salinity to 35 does not induce significant change in gills. Juveniles of C. parallelus may thus be capable of acclimating to salinities of 5 to 35 for 60 days without significant effects on development.

scholarly journals Teleost chloride cell. I. Response of pupfish Cyprinodon variegatus gill Na,K-ATPase and chloride cell fine structure to various high salinity environments.

1976 ◽  
Vol 70 (1) ◽  
pp. 144-156 ◽  
Author(s):  
K J Karnaky ◽  
S A Ernst ◽  
C W Philpott
Keyword(s):  
Cell Surface ◽  
Atpase Activity ◽  
High Salinity ◽  
Cell Structure ◽  
Chloride Cell ◽  
Salt Transport ◽  
Chloride Cells ◽  
Osmotic Gradient ◽  
Cyprinodon Variegatus ◽  
Very High

Certain euryhaline teleosts can tolerate media of very high salinity, i.e. greater than that of seawater itself. The osmotic gradient across the integument of these fish is very high and the key to their survival appears to be the enhanced ability of the gill to excrete excess NaCl. These fish provide an opportunity to study morphological and biochemical aspects of transepithelial salt secretion under conditions of vastly different transport rates. Since the cellular site of gill salt excretion is believed to be the "chloride cell" of the branchial epithelium and since the enzyme Na,K-ATPase has been implicated in salt transport in this and other secretory tissues, we have focused our attention on the differences in chloride cell structure and gill ATPase activity in the variegated pupfish Cyprinodon variegatus adapted to half-strength seawater (50% SW), seawater (100% SW), or double-stregth seawater (200% SW). The Na,K-ATPase activity in gill homogenates was 1.6 times greater in 100% SW. When 50% SW gills were compared to 100% SW gills, differences in chloride cell morphology were minimal. However, chloride cells from 200% SW displayed a marked hypertrophy and a striking increase in basal-lateral cell surface area. These results suggest that there are correlations among higher levels of osmotic stress, basal-lateral extensions of the cell surface, and the activity of the enzyme Na,K-ATPase.

Role of Na-K-ATPase in chloride cell function

1980 ◽  
Vol 238 (3) ◽  
pp. R246-R250 ◽  
Author(s):  
F. H. Epstein ◽  
P. Silva ◽  
G. Kormanik
Keyword(s):  
Cell Function ◽  
Chloride Transport ◽  
Basolateral Membrane ◽  
Chloride Cell ◽  
Chloride Cells ◽  
Ion Movement ◽  
Gill Filaments ◽  
Ion Movements ◽  
Ion Species

In seawater eels the efflux of sodium (and chloride) across the gill is directly proportional to the activity of Na-K-ATPase in homogenates of gill filaments. The rate of ion movement, however, is substantially greater than at the temperature of seawater. Na-K-ATPase is localized predominantly on the basolateral surface of the chloride cell so that ouabain inhibits from the blood side rather than from the apical or mucosal surface of chloride cells. Chloride, rather than sodium, is probably the actively transported ion species, and an attractive hypothesis for active chloride transport is one that invokes the cotransport of chloride with sodium across the basolateral membrane, the energy for which is supplied indirectly by the operation of the Na-K-ATPase pump. Exposure to freshwater sharply dissociates ion movements from Na-K-ATPase activity, possibly by changing the permeability of cell membranes to chloride movements.

scholarly journals IMMUNOLOCALIZATION OF H+-ATPase IN THE GILL EPITHELIA OF RAINBOW TROUT

1994 ◽  
Vol 195 (1) ◽  
pp. 169-183 ◽  
Author(s):  
H Lin ◽  
D Pfeiffer ◽  
A Vogl ◽  
J Pan ◽  
D Randall
Keyword(s):  
Rainbow Trout ◽  
Freshwater Fish ◽  
Immunofluorescence Microscopy ◽  
Polyclonal Antibodies ◽  
Bovine Brain ◽  
Chloride Cells ◽  
Mammalian Brain ◽  
Proton Pumps ◽  
Rainbow Trout Oncorhynchus Mykiss

The localization of proton pumps (H+-ATPase) in gill epithelia of rainbow trout [Oncorhynchus mykiss (Walbaum)] was elucidated by immunofluorescence microscopy, using rabbit polyclonal antibodies against the 70 kDa subunit of H+-ATPase purified from clathrin-coated vesicles of bovine brain. In the gill epithelia of freshwater trout, the immunostaining was uniformly distributed along the lamellae and generally concentrated in apical regions. It is concluded, therefore, that H+-ATPase is located in the apex of both chloride cells and epithelial cells of freshwater fish. Hypercapnic treatment resulted in a non-polarized and restrictive distribution of H+-ATPase in the chloride cell. No fluorescent staining was observed in the gill epithelium of seawater-adapted rainbow trout, except in some unidentified anucleate surface material. The presence of the 70 kDa subunit in fish gill epithelia was confirmed by Western blot. These results support the proposed role of a proton pump in sodium uptake in freshwater fish and demonstrate that the H+-ATPase in fish gills is of the vacuolar type, antigenically similar to the H+-ATPase in mammalian brain and kidney.

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