Plasma corticosterone elevations in rats in response to consumption of concentrated sugar solutions.

The results of three experiments indicated that male hooded rats exhibit marked corticosterone elevations when they freely consume .740 mol/l (23.2% w/w) sucrose in tap water while nondeprived or .298 mol/l (9.8% w/w) sucrose when deprived of water for 36 hr. The magnitude of the corticosterone elevation was increased by lengthening the duration of prior water deprivation (2, 24, or 48 hr) and by raising the sucrose solution concentration (.189, .298, or .470 mol/l). Free ingestion of tap water following sucrose consumption accelerated the decline from peak level of corticosterone during the period 60-120 min following the onset of sucrose consumption. Glucose (.470 or 1.166 mol/l) consumption by 36-hr water-deprived rats also elevated corticosterone levels, but less effectively than equimolar sucrose. These data suggest strongly that the pituitary-adrenal system is activated by rapid, acute dehydration. The effect is surprising, considering the minimal effects of water deprivation per se on corticosterone levels and the interpretation of increased pituitary-adrenal activity as a sign of psychological stress.