Corticosteroid feedback resistance in rats genetically selected for increased dopamine responsiveness.
J Neuroendocrinol
; 7(2): 153-61, 1995 Feb.
Article
em En
| MEDLINE
| ID: mdl-7767328
ABSTRACT
Pharmacogenetically selected Wistar rat lines were used to investigate the implication of either high or low responsiveness of the dopamine system for the activity of the hypothalamus-pituitary-adrenal (HPA) axis. As selection criterion the gnawing response induced by the dopamine agonist apomorphine was used. This criterion allows to distinguish apomorphine susceptible (apo-sus) rats which show a vigorous gnawing response from apomorphine unsusceptible (apo-unsus) rats. The present study, using male animals of the 9-12th generation of the two rat lines, revealed the following characteristics of the stress response system (i) in apo-sus rats under basal conditions corticotrophin-releasing hormone (CRH) mRNA level in the paraventricular nucleus (PVN) and plasma adrenocorticotropin (ACTH) concentration were significantly higher; total corticosterone (B) plasma level was similar but free B level was lower; (ii) exposure to a novel environment resulted in a higher and prolonged plasma ACTH and total B response in the apo-sus rats. Moreover, the elevated free B level was also prolonged; (iii) apo-sus rats had increased CRH-induced pituitary ACTH release and B secretion was also increased, but not as prolonged as during novelty. (iv) In dexamethasone-pretreated rats an intravenous ACTH1-24 injection resulted in a similar plasma B response in rats of both lines; (v) In vitro, ACTH1-24 produced a significantly higher B secretion by adrenocortical cells of apo-sus rats reflecting the higher in vivo ACTH priming of the adrenal glands in these animals. (vi) apo-sus rats had higher body and thymic weight.(ABSTRACT TRUNCATED AT 250 WORDS)
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Sistema Hipófise-Suprarrenal
/
Seleção Genética
/
Dopamina
/
Corticosteroides
/
Receptores de Mineralocorticoides
/
Sistema Hipotálamo-Hipofisário
Limite:
Animals
Idioma:
En
Revista:
J Neuroendocrinol
Assunto da revista:
ENDOCRINOLOGIA
/
NEUROLOGIA
Ano de publicação:
1995
Tipo de documento:
Article
País de afiliação:
Holanda
País de publicação:
EEUU
/
ESTADOS UNIDOS
/
ESTADOS UNIDOS DA AMERICA
/
EUA
/
UNITED STATES
/
UNITED STATES OF AMERICA
/
US
/
USA