Hypothalamo-pituitary regulation of thyrotrophin secretion in chronically catheterized Brattleboro rats.
J Endocrinol
; 105(2): 277-83, 1985 May.
Article
em En
| MEDLINE
| ID: mdl-3921647
ABSTRACT
Plasma TSH rhythms were measured in Brattleboro (DI) and control Long-Evans (LE) rats with an intracardiac catheter allowing repeated sampling in conscious unstressed animals. The TSH response to thyrotrophin-releasing hormone (TRH; 500 ng/100 g body weight) was also determined. Finally, hypothalamic and pancreatic TRH concentrations and TRH-degrading activity (TRH-DA) were measured by specific radioimmunoassay. Long-Evans rats had a 24-h rhythm with a major modulatory 8-h component. In DI rats, only the 24-h rhythm was detected. The mean 24-h rhythm-adjusted mean TSH level was higher in DI than in LE rats (1.38 +/- 0.05 and 1.14 +/- 0.06 micrograms/l respectively, P less than 0.01). The peak TSH response to TRH was significantly increased in DI rats while the pituitary concentration of TSH was also higher (0.93 +/- 0.09 vs 0.39 +/- 0.06 micrograms/mg wet weight in LE, P less than 0.001). Hypothalamic TRH and TRH-DA were similar in both strains. The response to propylthiouracil-induced hypothyroidism was identical in both strains. We conclude that DI rats have a normal pituitary sensitivity to tri-iodothyronine but a central dysfunction in the pituitary environment leading to some alterations of TSH secretion.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Hipófise
/
Ratos Brattleboro
/
Ratos Mutantes
/
Tireotropina
/
Hormônio Liberador de Tireotropina
/
Hipotálamo
Limite:
Animals
Idioma:
En
Ano de publicação:
1985
Tipo de documento:
Article