AJP - Regulatory, Integrative and Comparative Physiology, Vol 236, Issue 1 117-R125, Copyright © 1979 by American Physiological Society
Inhibition of osmotic thirst by electric stimulation of the basal forebrain in dogs
E. Szczepanska-Sadowska, J. Sobocinska, B. Sadowski and S. Kosowski
The effect of electrical brain stimulation (ESB; 50 Hz, 50-150 microA sine
wave, 5 s on/5 s off) on osmotic thirst was examined in 10 conscious dogs
chronically implanted with electrodes aimed at the anteromedial part of the
basal forebrain. Suppression of osmotic thirst (SOT) was observed during
stimulation through 18 of 41 electrodes located in the olfactory tubercle,
the nucleus accumbens, the caudate nucleus, the medial septum, and the
lateral preoptic-anterolateral hypothalamic area (PrA/ALH). Mean increment
in plasma osmolality necessary to cause drinking rose from 9.0 +/- 1.5
mosmol (X +/- SE; n = 15) under control conditions to 15.8 +/- 2.6 mosmol
(n = 18) during ESB in SOT placements. Threshold cellular dehydration
eliciting drinking increased from 2.70 +/- 0.50% of intracellular water
(ICW;n = 16) to 4.77 +/- 0.68% of ICW (n = 18), respectively. The strongest
SOT was found during ESB in the nucleus accumbens, and the PrA/ALH. The
same stimulation failed to inhibit feeding, support self-stimulation or
produce appreciable changes of dog's gross behavior. The results give
evidence for the existence in the basal forebrain of the dog a widely
distributed neural system suppressing osmotic thirst. The nucleus accumbens
and the PrA/ALH seem to play an important role in this system.
