Synergistic interaction of corticotropin releasing factor and arginine vasopressin on adrenocorticotropin and cortisol secretion in Macaca fuscata.

Plasma immunoreactive CRF measured by radioimmunoassay decreased rapidly after intravenous injection of synthetic ovine corticotropin releasing factor (CRF) and showed a bi-exponential decay curve in five macaca fuscatas. Half lives of plasma immunoreactive CRF were 5.8 +/- 1.4 (Mean +/- SEM) min for the fast component and 38.3 +/- 2.4 min for the slow component. A bolus injection of 5 micrograms/kg CRF significantly increased the plasma cortisol level. CRF at 5 micrograms/kg induced a delayed response of ACTH and cortisol. Arginine vasopressin (AVP) at 0.5 micrograms/kg induced a slight increase in plasma ACTH and cortisol, but AVP at 0.1 micrograms/kg evoked no significant increase. When 0.5 micrograms/kg CRF and 0.1 micrograms/kg AVP were administered simultaneously, significant ACTH and cortisol responses occurred. The results indicate that CRF and AVP act synergistically to stimulate ACTH secretion in vivo.