In the present study, we have examined in Wistar rats the effects of food o
r water deprivation of 3 days on the hypophyso-adrenal axis, vasopressinerg
ic system and activity of Al noradrenergic brain stem cell group, which is
involved in the control of the hypothalamic neuro-endocrine activity. Level
s of adrenocorticotropic hormone (ACTH) and vasopressin (AVP) were determin
ed by radio-immunoassay, and corticosterone level was determined by fluorim
etric method. Plasma levels of ACTH and corticosterone were greatly increas
ed in both groups of rats. In water-deprived rats: plasma AVP (13.83 +/- 1.
63 vs. 3.03 +/- 0.23 pg/ml) and osmolality levels were significantly elevat
ed with a marked decrease of AVP hypophysis content (272 +/- 65 vs. 1098 +/
- 75 ng/mg protein), but not in food-deprived rats in which osmolality did
not change and AVP remained stocked (2082 +/- 216 ng/mg protein) in the hyp
ophysis without release in the plasma (1.11+/-0.23 pg/ml). These observatio
ns indicated that both food-deprivation and water-deprivation stimulated th
e pituitary-adrenal axis thereby suggesting a stress state. AVP production
is stimulated both by fluid and food restriction but is secreted with diffe
rential effects: during food restriction AVP secretion is limited to suppor
ting the hypothalamic-pituitary-adrenal system. (C) 2000 Elsevier Science I
nc. All rights reserved.