Effect of cortisol on the in vitro hepatic conversion of thyroxine to triiodothyronine in brook charr (Salvelinus fontinalis Mitchill)

Vijayan, M. M.; Flett, Peter; Leatherland, J. F.

doi:10.1016/0016-6480(88)90151-7

Cited by 56 publications

(28 citation statements)

References 29 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Indeed, osmotic challenges changed peripheral ORD activities in S. senegalensis and Sparus auratus but did not result in altered plasma fT 3 levels (Klaren et al 2007b, Arjona et al 2008. In S. fontinalis, circulating T 4 and T 3 remained unaltered after a cortisol treatment that had increased hepatic T 4 -ORD activities (Vijayan et al 1988). A plausible explanation is that traffic of T 3 out of cells is regulated by the activity of membrane transporters, preventing T 3 from entering plasma.…”

Section: Discussionmentioning

confidence: 96%

See 1 more Smart Citation

Effects of cortisol and thyroid hormone on peripheral outer ring deiodination and osmoregulatory parameters in the Senegalese sole (Solea senegalensis)

Arjona¹,

Vargas‐Chacoff²,

Río³

et al. 2011

Journal of Endocrinology

View full text Add to dashboard Cite

The thyroid gland in fish mainly secretes the thyroid prohormone 3,5,3 0 ,5 0 -tetraiodothyronine (T 4 ), and extrathyroidal outer ring deiodination (ORD) of the prohormone to 3,5,3 0 -triiodothyronine (T 3 ) is pivotal in thyroid hormone economy. Despite its importance in thyroid hormone metabolism, factors that regulate ORD are still largely unresolved in fish. In addition, the osmoregulatory role of T 3 is still a controversial issue in teleosts. In this study, we investigated the regulation of the ORD pathway by cortisol and T 3 in different organs (liver, kidney, and gills) of Solea senegalensis and the involvement of T 3 in the control of branchial and renal Na C , K C -ATPase activity, a prime determinant of the hydromineral balance in teleosts. Animals were treated with i.p. slow-release coconut oil implants containing cortisol or T 3 . Hepatic and renal ORD activities were up-regulated in cortisol-injected animals. T 3 -treated fish showed a prominent decrease in plasma-free T 4 levels, whereas ORD activities did not change significantly. Branchial and renal Na C , K C -ATPase activities were virtually unaffected by T 3 , but were transiently up-regulated by cortisol. We conclude that cortisol regulates local T 3 bioavailability in S. senegalensis via ORD in an organ-specific manner. Unlike T 3 , cortisol appears to be directly implicated in the up-regulation of branchial and renal Na

show abstract

Section: Discussionmentioning

confidence: 96%

“…Cortisol stimulated the conversion, by ORD, of T 4 to T 3 in Salvelinus fontinalis liver in vitro (Vijayan et al 1988), and enhanced liver D1 and D2 activities in Fundulus heteroclitus (Orozco et al 1998). Negative results have also been reported, i.e.…”

Section: Introductionmentioning

confidence: 99%

Effects of cortisol and thyroid hormone on peripheral outer ring deiodination and osmoregulatory parameters in the Senegalese sole (Solea senegalensis)

Arjona¹,

Vargas‐Chacoff²,

Río³

et al. 2011

Journal of Endocrinology

View full text Add to dashboard Cite

show abstract

“…Stimulatory effects of cortisol on the HPT axis have also been suggested in teleost fish. In brook charr (Salvelinus fontinalis) long-term exposure to cortisol increased the hepatic conversion of T 4 to T 3 (Vijayan et al 1988) and in Japanese flounder (Paralichthys olivaceus) cortisol augmented the effects of THs on the resorption of the dorsal fin ray (de Jesus et al 1990). Experimental data on the effects of THs on the HPI axis in teleosts are scarce.…”

Section: Introductionmentioning

confidence: 99%

Central and peripheral integration of interrenal and thyroid axes signals in common carp (Cyprinus carpio L.)

Geven

Flik²,

Klaren

2008

Journal of Endocrinology

View full text Add to dashboard Cite

In teleostean fishes the hypothalamic-pituitary-thyroid axis (HPTaxis) and the hypothalamic-pituitary-interrenal axis (HPI axis) regulate the release of thyroid hormones (THs) and cortisol respectively. Since many actions of both hormones are involved in the regulation of metabolic processes, communication between both signal pathways can be anticipated. In this study, we describe central and peripheral sites for direct interaction between mediators of both neuroendocrine axes in the common carp (Cyprinus carpio). Despite suggestions in the literature that CRH is thyrotropic in some fish; we were not able to establish stimulatory effects of CRH on the expression of the pituitary TSHb subunit gene. In preoptic area tissue incubated with 10 K7 M thyroxine (T 4 ) a 2 . 9-fold increase in the expression of CRH-binding protein (CRHBP) was observed. Thus, T 4 could reduce the bioavailable hypothalamic crh via the up regulation of crhbp expression and hence down regulate the HPI axis. At the peripheral level, cortisol (10 K6 M), ACTH (10 K7 M), and a-MSH (10 K7 M) stimulate the release of T 4 from kidney and head kidney fragments, which contain all functional thyroid follicles in carp, by two-to fourfold. The substantiation of three pituitary thyrotropic factors, viz. TSH, ACTH, and a-MSH, in common carp, allows for an integration of central thyrotropic signals. Clearly, two sites for interaction between the HPT axis, the HPI axis, and a-MSH are present in common carp. These interactions may be key to the proper regulation of general metabolism in this fish.

show abstract

“…The fact that total trout liver 5Ј-deiodinase activity saturates at low T 4 concentrations (10 nm) is probably the explanation for the previous failure to clearly identify type I activity in teleostean liver and for the observation that ORD had a low (7,26) or ultra-low T 4 -K m type I activity (8). Nevertheless, present results in trout liver and previous reports in tilapia kidney (22,25) have clearly shown the presence of rT 3 -ORD activity with the kinetic characteristics of mammalian type I.…”

Section: Discussionmentioning

confidence: 99%

“…On the contrary, the single component is a reflection of the relatively low type I-mediated T 4 ORD and of the limitations imposed by the specific activity of 125 I-T 4 to measure the release of 125 I when the predominant pathway of deiodination is the type II. Thus, it has been demonstrated previously that T 4 -ORD can be detected in trout liver at higher substrate concentrations if the activity is measured by the production of T 3 by RIA (7,21,22), which would not be possible if the activity were measured by the release of 125 I, because, at high substrate concentrations, the fractional rate deiodination is very low (Fig. 2).…”

Section: Discussionmentioning

confidence: 99%

Rainbow Trout Liver Expresses Two Iodothyronine Phenolic Ring Deiodinase Pathways with the Characteristics of Mammalian Types I and II 5'-Deiodinases

Orozco¹

1997

Endocrinology

View full text Add to dashboard Cite

Deiodinases are major determinants of thyroid hormone tissue availability and disposal. The knowledge of the expression of these enzymes in lower species is important to understand evolutionary and ontogenetic aspects of thyroid hormone action and metabolism. Here we have studied outer ring deiodination in the trout liver using both reverse T 3 (rT 3 ) and T 4 as substrates. The use of rT 3 disclosed two enzymatic components with the characteristics of mammalian types I and II 5Ј-deiodinases. The high rT 3 -K m type I 5Ј-deiodinase activity (180 nM) has a low cofactor requirement (5 mM dithiothreitol) and is relatively sensitive to propylthiouracil inhibition, whereas the low rT 3 -K m activity was akin to the outer ring deiodination of T 4 in these regards. The use of T 4 exhibited only a single type of activity with a low K m (0.63 nM), a relatively high cofactor requirement (25 mM dithiothreitol), and propylthiouracil-resistance. Teleosts constitute a unique example of type II activity expression in the liver of an adult vertebrate. Furthermore, the V max of this enzyme is as high as that found in comparable homogenates from hypothyroid mammalian tissues, whereas the V max of the type I activity is lower than that of mammalian liver. These findings are in consonance with the peculiar kinetics of T 3 in trout liver, kinetics remarkably similar to those of the mammalian pituitary, cerebral cortex, and brown adipose tissue, which also preferentially express type II deiodinase. (Endocrinology 138: 254 -258, 1997) T HE THYROID gland secretes predominantly T 4 , which functions primarily as a prohormone because it is largely converted to T 3 in peripheral tissues. T 3 is about 10 times more active than T 4 and is produced in an organspecific manner by enzymatic outer ring deiodination (ORD) of its precursor. In mammalian species, ORD is catalyzed by two distinct enzymes, well characterized in operational terms and tissue distribution: the type I and type II 5Ј-deiodinases (1-3).The complement of deiodinases present in vertebrate liver varies with the species and developmental stage of the organism. In fetal rats, for example, the liver expresses both type II and type III (an inner ring deiodinase), whereas, after birth, type I activity predominates (Aceves, C., unpublished data from our laboratory). Chicken embryo liver exhibits types I and II (4), whereas, in developing tadpoles, only type III is expressed (5). However variable the expression of deiodinases could be during ontogeny, adult liver of vertebrate species expresses predominantly, if not exclusively, type I deiodinase activity. In fish liver, it seems that two ORD processes are present, but it is not clear whether they correspond to the types I and II mammalian deiodinase activities (6 -8). In trout, for example, enzyme kinetic analyses have demonstrated vastly differing K m values for hepatic T 4 -ORD. Whereas initial studies reported K m values of 190 nm (6) and 13 nm (7), a subsequent report by Mac Latchy and Eales (8) has suggested that tw...

show abstract

Effect of cortisol on the in vitro hepatic conversion of thyroxine to triiodothyronine in brook charr (Salvelinus fontinalis Mitchill)

Cited by 56 publications

References 29 publications

Effects of cortisol and thyroid hormone on peripheral outer ring deiodination and osmoregulatory parameters in the Senegalese sole (Solea senegalensis)

Effects of cortisol and thyroid hormone on peripheral outer ring deiodination and osmoregulatory parameters in the Senegalese sole (Solea senegalensis)

Central and peripheral integration of interrenal and thyroid axes signals in common carp (Cyprinus carpio L.)

Rainbow Trout Liver Expresses Two Iodothyronine Phenolic Ring Deiodinase Pathways with the Characteristics of Mammalian Types I and II 5'-Deiodinases

Contact Info

Product

Resources

About