Da. Bereiter, MICROINJECTIONS OF GLUTAMATE WITHIN TRIGEMINAL SUBNUCLEUS INTERPOLARIS ALTERS ADRENAL AND AUTONOMIC FUNCTION IN THE CAT, Brain research, 622(1-2), 1993, pp. 155-162
The influence of rostral portions of the trigeminal sensory complex on
adrenal and autonomic function was assessed by microinjections of L-g
lutamate (500 or 5 mM, 100 nl) directed at subnucleus interpolaris (Vi
) or at the nucleus principalis/subnucleus oralis level (Vp/Vo) in chl
oralose-anesthetized cats. Microinjections of glutamate (500 mM) withi
n Vi evoked prompt (by + 1 min) dose-related increases in the adrenal
secretion of epinephrine (+11.4+/-2.5 ng/min, P < 0.001), adrenal bloo
d flow (+0.19+/-0.06 ml/min, P < 0.05), mean arterial pressure (+6.6+/
-3.O mmHg, P < 0.025) and heart rate (+8.0+/-2.7 beats/min, P < 0.01,
n = 16). Microinjections of lower doses of L-glutamate (5 mM, n = 7) w
ithin Vi had no effect. Microinjections of 500 mM glutamate within Vp/
Vo (n = 15) or within the spinal trigeminal tract (n = 13) had no cons
istent effect on adrenal or autonomic function. Plasma concentrations
of ACTH were not altered significantly by glutamate regardless of dose
or of the site of injection. The results suggest that local release o
f glutamate within Vi, but not within Vp/Vo, influences adrenal and au
tonomic function. Together with previous results obtained after inject
ions of glutamate within subnucleus caudalis, these data indicate that
glutaminergic input to both Vi and to more caudal portions of the spi
nal trigeminal nucleus contribute to the control of autonomic function
such as that which often accompanies trigeminal nociception.