Effects of cortisol and thyroid hormone ....

[Guest guest]

J Endocrinol. 2011 Jan 6. [Epub ahead

of print]

Effects

of cortisol and thyroid hormone on peripheral outer ring deiodination and

osmoregulatory parameters in the Senegalese sole (Solea senegalensis).

Arjona

FJ, Vargas-Chacoff

L, Martín

Del Río MP, Flik

G, Mancera

JM, Klaren

PH.

F Arjona, Animal

Physiology, Radboud University Nijmegen, Nijmegen, 6525 AJ, Netherlands.

Abstract

The

thyroid gland in fish mainly secretes the thyroid prohormone

3,5,3',5'-tetraiodothyronine T4, and extrathyroidal outer ring deiodination

(ORD) of the prohormone to T3 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 T3 is

still a controversial issue in teleosts. In this study we investigated the

regulation of the ORD pathway by cortisol and T3 in different organs (liver,

kidney and gills) of Solea senegalensis and the involvement of T3 in the

control of branchial and renal Na+,K+-ATPase activity, a prime determinant of

the hydromineral balance in teleosts. Animals were treated with

intra-peritoneal slow-release coconut oil implants containing cortisol or T3.

Hepatic and renal ORD activities were up-regulated in cortisol-injected

animals. T3-treated fish showed a prominent decrease in plasma free T4 levels

whereas ORD activities did not change significantly. Branchial and renal

Na+,K+-ATPase activities were virtually unaffected by T3, but were transiently

up-regulated by cortisol. We conclude that cortisol regulates local T3

bioavailability in S. senegalensis via ORD in an organ-specific manner. Unlike

T3, cortisol appears to be directly implicated in the up-regulation of

branchial and renal Na+,K+-ATPase activities.

PMID: 21212093 [PubMed

- as supplied by publisher]

Related

citations