Mp. Rosasarellano et al., GLUTAMATE STIMULATION OF ARCUATE NUCLEUS INHIBITS RESPONSES OF SUBFORNICAL ORGAN NEURONS TO PLASMA HYPERNATREMIA AND ANGIOTENSIN-II, Neuroscience letters, 198(3), 1995, pp. 201-204
Experiments were done in urethane anesthetized rats to investigate the
effect of glutamate (Glu) stimulation of arcuate nucleus of the hypot
halamus (Are) on the discharge rate of subfornical organ (SFO) neurons
during changes in plasma sodium concentration and angiotensin II (ANG
II) levels. Extracellular recordings were made from 67 histologically
verified single neurons within SFO. Of these, 17 (25.4%) were excited
by intracarotid infusion of hypertonic NaCl and 21 (31.3%) by intraca
rotid ANG II infusion. Five (29.4%) of the units excited by hypertonic
NaCl were also excited by Glu stimulation of Are. Similarly, seven (3
3.3%) of the units excited by ANG II were also excited by Are stimulat
ion. Additionally, four (19.0%) of the units excited by ANG II were in
hibited by Glu stimulation of Are. The remaining SFO units did not alt
er their discharge rate to activation of Are neurons. The response of
units to hyper tonic NaCl or to ANG II was attenuated during simultane
ous activation of Are. These data suggest that Are may be involved in
modulating the activity of SFO neurons that function in the detection
of blood-borne signals from the depletion of intra- and extracellular
fluid volumes.