AJP - Regulatory, Integrative and Comparative Physiology, Vol 264, Issue 6 1200-R1205, Copyright © 1993 by American Physiological Society
In vitro sensitivity of median preoptic neurons to angiotensin II, osmotic pressure, and temperature
K. A. Travis and A. K. Johnson
Department of Psychology, University of Iowa, Iowa City 52242.
In vivo experiments suggest an interaction of the mechanisms involved in
the regulation of body fluid balance and body temperature. Increases in
plasma osmolality initiate drinking and increase the thermal set point for
sweating. The median preoptic nucleus (MnPO) has anatomical connections
with brain areas important in fluid balance and cardiovascular regulation
and, with the preoptic-anterior hypothalamus, a thermoregulatory region.
The present experiments employed in vitro single-unit recordings to
determine the sensitivity of MnPO neurons to angiotensin II (ANG II),
changes in osmotic pressure, and changes in temperature. One-fifth (11 of
55) of the MnPO neurons responded with changes in firing rate during the
ANG II treatment, one-fourth (19 of 75) responded to changes in perfusate
osmolality, and there was a significant effect of osmolality and ANG II on
the thermosensitivity of 25% of the neurons tested.
