Diabetes mellitus (DM), as chronic stress activates the hypothalamo-pituitary-adrenocortical axis. We examined whether
arginine vasopressin (AVP) and the hypothalamic paraventricular nucleus (PVN) participate in DM-induced chronic stress symptoms. AVP-deficient Brattleboro or PVN-lesioned Wistar rats were used with heterozygous or
sham-operated controls. The rats were studied 2 wk after a single injection of
streptozotocin. The appearance of DM (enhanced water consumption and
blood glucose elevation) and the chronic stress-like somatic
changes (body weight decrease, thymus involution, adrenal gland
hypertrophy) were not influenced by the lack of AVP. By contrast, PVN lesion significantly attenuated DM-induced thymus involution and adrenal gland
hypertrophy as well as the increase in water consumption. The
corticotropin-releasing hormone mRNA in PVN was diminished by DM and elevated by the lack of AVP without interaction. DM elevated the
proopiomelanocortin (
POMC)
mRNA in the anterior lobe of the pituitary. The lack of AVP had no effect, whereas lesioning the PVN significantly diminished the elevation. The elevated basal
corticosterone plasma levels detectable in DM were influenced neither by the lack of AVP nor by lesioning the PVN. Thus the lack of AVP had no influence on DM-induced chronic stress symptoms, but lesioning the PVN attenuated part of them. However, the lack of elevation in
POMC mRNA after PVN lesion, together with the maintained
corticosterone elevation, suggests that direct adrenal gland activation occurs in untreated DM.