Corticotropin-releasing hormone and pituitary-adrenocortical responses in chronically stressed rats

Regul Pept. 1988 Nov;23(2):117-26. doi: 10.1016/0167-0115(88)90019-5.

Abstract

Brain corticotropin-releasing hormone (CRH) concentration and pituitary adreno-cortical responses were examined in chronically stressed rats: body restraint stress (6 h/day) for 4 or 5 weeks. Stressed rats showed a reduction in weight gain. CRH concentration in the median eminence and the rest of the hypothalamus were not different between control and chronically immobilized rats. The anterior pituitary adenocorticotropic hormone (ACTH) concentration was elevated in chronically stressed rats, whereas plasma ACTH and corticosterone levels did not differ from the control values. The median eminence CRH concentration was reduced to the same extent at 5 min after onset of ether exposure (1 min) in chronically immobilized rats and controls. However, plasma ACTH and corticosterone showed greater responses to ether stress in chronically immobilized rats than in control rats. Plasma ACTH and corticosterone responses to exogenous CRH were not different between control and chronically immobilized rats, while the response to arginine vasopressin (AVP) was significantly greater in chronically immobilized rats. These results suggest that chronic stress caused an increase in the ACTH-secreting mechanism and that pituitary hypersensitivity to vasopressin might at least be partly responsible for this.

MeSH terms

  • Adrenocorticotropic Hormone / blood*
  • Adrenocorticotropic Hormone / metabolism
  • Animals
  • Arginine Vasopressin / pharmacology
  • Brain Chemistry
  • Corticosterone / blood
  • Corticosterone / metabolism
  • Corticotropin-Releasing Hormone / analysis*
  • Corticotropin-Releasing Hormone / metabolism
  • Male
  • Pituitary-Adrenal Function Tests
  • Rats
  • Rats, Inbred Strains
  • Stress, Physiological / metabolism*

Substances

  • Arginine Vasopressin
  • Adrenocorticotropic Hormone
  • Corticotropin-Releasing Hormone
  • Corticosterone