Glucocorticoid receptors in the gill tissue of fish

Sandor, Thomas; DiBattista, John A.; Mehdi, A.Z.

doi:10.1016/0016-6480(84)90262-4

Cited by 68 publications

(23 citation statements)

References 22 publications

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“…Radioligand binding protocols have identified cortisol receptors in the gills of the eel, two salmonids, and tilapia (57, 88,464,660), and in tilapia, acclimation to seawater is accompanied by an increase in the number of receptors (57). The receptors were localized to two types of MRC (defined by Na ϩ -K ϩ -ATPase immunoreactivity) in chum salmon fry, using both immunological and molecular protocols (763).…”

Section: Cortisolmentioning

confidence: 99%

The Multifunctional Fish Gill: Dominant Site of Gas Exchange, Osmoregulation, Acid-Base Regulation, and Excretion of Nitrogenous Waste

Evans¹,

Piermarini²,

Choe³

2005

Physiological Reviews

2,325

1,788

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The fish gill is a multipurpose organ that, in addition to providing for aquatic gas exchange, plays dominant roles in osmotic and ionic regulation, acid-base regulation, and excretion of nitrogenous wastes. Thus, despite the fact that all fish groups have functional kidneys, the gill epithelium is the site of many processes that are mediated by renal epithelia in terrestrial vertebrates. Indeed, many of the pathways that mediate these processes in mammalian renal epithelial are expressed in the gill, and many of the extrinsic and intrinsic modulators of these processes are also found in fish endocrine tissues and the gill itself. The basic patterns of gill physiology were outlined over a half century ago, but modern immunological and molecular techniques are bringing new insights into this complicated system. Nevertheless, substantial questions about the evolution of these mechanisms and control remain.

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Section: Cortisolmentioning

confidence: 99%

The Multifunctional Fish Gill: Dominant Site of Gas Exchange, Osmoregulation, Acid-Base Regulation, and Excretion of Nitrogenous Waste

Evans¹,

Piermarini²,

Choe³

2005

Physiological Reviews

2,325

1,788

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“…Na+/H + exchange activity was calculated and expressed as a percentage of the maximal ApH e . The concentration of inhibitor required to reduce proton extrusion activity by 50%o (IC 50 ) was obtained by linearization of the competitive inhibition curves using In-logit transformation (Sandor et al 1984).…”

Section: Experimental Protocolmentioning

confidence: 99%

Quantification of presumptive Na+/H+ antiporters of the erythrocytes of trout and eel

Reid

Perry

1994

Fish Physiol Biochem

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The presumptive Na(+)/H(+) exchange sites of trout and eel erythrocytes were quantified using amiloride-displaceable 5-(N-methyl-N-[(3)H]isobutyl)-amiloride ((3)H-MIA) equilibrium binding to further evaluate the mechanisms of i) hypoxia-mediated modifications in the trout erythrocyte β-adrenergic signal transduction system and ii) the marked differences in the catecholamine responsiveness of this system between the trout and eel. MIA was a more potent inhibitor of both trout apparent erythrocyte proton extrusion (IC50 = 20.1 ± 1.1 μmol l(-1), N = 6) activity (as evaluated by measuring plasma pH changes after addition of catecholamine in vitro) and specific (3)H-MIA binding (IC50 = 257 ± 8.2 nmol l(-1), N = 3) than amiloride, which possessed a proton extrusion IC50 of 26.1 ± 1.6 μmol l(-1) (N = 6) and a binding IC50 of 891 ± 113 nmol l(-1) (N = 3). The specific Na(+) channel blocker phenamil was without effect on adrenergic proton extrusion activity or specific (3)H-MIA binding. Trout erythrocytes suspended in Na(+)-free saline and maintained under normoxic conditions possessed 37,675 ± 6,678 (N = 6) amiloride-displaceable (3)H-MIA binding sites per cell (Bmax, presumptive Na(+)/H(+) antiporters) with an apparent dissociation constant (KD) of 244 ± 29 nmol l(-1) (N = 6). Acute hypoxia (PO2 = 1.2 kPa; 30 min) did not affect the KD, yet resulted in a 65% increase in the number of presumptive Na(+)/H(+) antiporters. Normoxic eel erythrocytes, similarly suspended in Na(+)-free saline, possessed only 17,133 ± 3,716 presumptive Na(+)/H(+) antiporters (N = 6), 45% of that of trout erythrocytes, with a similar KD (246 ± 41 nmol l(-1), N = 6). These findings suggest that inter- and intra-specific differences in the responsiveness of the teleost erythrocyte β-adrenergic signal transduction system can be explained, in part, by differences in the numbers of Na(+)/H(+) exchange sites.

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“…Sandor et al 1984, Weisbart et al 1984, Maule & Schreck 1990, Pottinger & Moore 1997, Weyts et al 1998, Marsigliante et al 2000, and full-length glucocorticoids receptor (GR) cDNAs (rainbow trout (Oncorhynchus mykiss): Ducouret et al (1995), Takeo et al (1996); Japanese flounder, Genbank ABO1344) and a partial tilapia GR cDNA (Tagawa et al 1997) have been cloned. Expression of rainbow trout GR (rtGR) transcript is found in a number of tissues (Ducouret et al 1995, Takeo et al 1996, is widely distributed in the brain (Teitsma et al 1997(Teitsma et al , 1998 and has been identified in gill chloride cells (Uchida et al 1998), the cells believed to be responsible for branchial ion movement (Perry 1997).…”

Section: Introductionmentioning

confidence: 99%

Evidence for two distinct functional glucocorticoid receptors in teleost fish

Bury¹,

Sturm²,

Rouzic³

et al. 2003

Journal of Molecular Endocrinology

232

178

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Using RT-PCR with degenerated primers followed by screening of a rainbow trout (Oncorhynchus mykiss) intestinal cDNA library, we have isolated from the rainbow trout a new corticosteroid receptor which shows high sequence homology with other glucocorticoid receptors (GRs), but is clearly different from the previous trout GR (named rtGR1). Phylogenetic analysis of these two sequences and other GRs known in mammals, amphibians and fishes indicate that the GR duplication is probably common to most teleost fish. The open reading frame of this new trout GR (named rtGR2) encodes a protein of 669 amino acids and in vitro translation produces a protein of 80 kDa that appears clearly different from rtGR1 protein (88 kDa). Using rtGR2 cDNA as a probe, a 7·3 kb transcript was observed in various tissues suggesting that this gene would lead to expression of a steroid receptor. In vitro studies were used to further characterize this new corticosteroid receptor. Binding studies with recombinant rtGR1 and rtGR2 proteins show that the two receptors have a similar affinity for dexamethasone (GR1 K d =5·05±0·45 nM; GR2 K d =3·04±0·79 nM). Co-transfection of an rtGR1 or rtGR2 expression vector into CHO-K1 or COS-7 cells, along with a reporter plasmid containing multiple consensus glucocorticoid response elements, shows that both clones are able to induce transcriptional activity in the presence of cortisol and dexamethasone. Moreover, at 10 −6 M 11-deoxycortisol and corticosterone partially induced rtGR2 transactivation activity but were without effect on rtGR1. The other major teleost reproductive hormones, as well as a number of their precursors or breakdown products of these and corticosteroid hormones, were without major effects on either receptor. Interestingly, rtGR2 transactivational activity was induced at far lower concentrations of dexamethasone or cortisol (cortisol EC 50 =0·72±0·87 nM) compared with rtGR1 (cortisol EC 50 =46±12 nM). Similarly, even though RU486 inhibited transactivation activity in both rtGR1 and rtGR2, rtGR1 was more sensitive to this GR antagonist. Altogether, these results indicate that these two GR sequences encode for two functionally distinct GRs acting as ligand-inducible transcription factors in rainbow trout.

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Glucocorticoid receptors in the gill tissue of fish

Cited by 68 publications

References 22 publications

The Multifunctional Fish Gill: Dominant Site of Gas Exchange, Osmoregulation, Acid-Base Regulation, and Excretion of Nitrogenous Waste

The Multifunctional Fish Gill: Dominant Site of Gas Exchange, Osmoregulation, Acid-Base Regulation, and Excretion of Nitrogenous Waste

Quantification of presumptive Na+/H+ antiporters of the erythrocytes of trout and eel

Evidence for two distinct functional glucocorticoid receptors in teleost fish

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