Factors from the paraventricular nucleus mediate inhibitory effect of alpha-2-adrenergic drugs on ACTH secretion

Neuroendocrinology. 1993;57(2):346-50. doi: 10.1159/000126378.


The controversy about putative stimulatory and inhibitory functions of catecholamines in regulation of ACTH secretion has been recently shifted towards a consensus that during stress catecholamines stimulate corticotropin-releasing factor (CRF-41) containing neurons through alpha 1-adrenoreceptors, while inhibiting their own secretion acting on presynaptic alpha 2-receptors. In this study the effect of the alpha 2-agonist clonidine and the antagonist CH-38083 was studied on exogenous CRF-41/AVP-induced ACTH secretion in rats with/without paraventricular nucleus lesion. Clonidine (30 micrograms/kg) attenuated CRF-41/AVP (1 pmol/10 pmol)-induced ACTH secretion in sham-operated rats, but was ineffective in reducing CRF-41/AVP-induced ACTH secretion in rats with paraventricular nucleus lesion. In sham-operated rats, alpha 2-receptor antagonist CH-38083 slightly elevated the basal, and significantly potentiated the CRF-41/AVP-induced ACTH secretion, while it had no effect on the hypophyseotropic cocktail-induced ACTH response in paraventricular-lesioned rats. Neither the agonist nor the antagonist affected CRF-41/AVP-induced ACTH release from pituitary fragments in vitro. These results suggest that in response to activation of alpha 2-adrenoreceptors a corticotropin release-inhibiting substance is released from the paraventricular nucleus.

MeSH terms

  • Adrenocorticotropic Hormone / metabolism*
  • Animals
  • Berberine / analogs & derivatives
  • Berberine / pharmacology
  • Clonidine / pharmacology
  • In Vitro Techniques
  • Male
  • Paraventricular Hypothalamic Nucleus / physiology*
  • Pituitary Gland, Anterior / drug effects
  • Pituitary Gland, Anterior / metabolism
  • Rats
  • Rats, Wistar
  • Receptors, Adrenergic, alpha / drug effects*
  • Receptors, Adrenergic, alpha / physiology


  • Receptors, Adrenergic, alpha
  • Berberine
  • 7,8-(methylenedioxy)-14-hydroxyberbane
  • Adrenocorticotropic Hormone
  • Clonidine