TY - JOUR
T1 - Single unit studies of identified bulbospinal serotonergic units
AU - Wessendorf, Martin W.
AU - Anderson, Edmund G.
PY - 1983/11/21
Y1 - 1983/11/21
N2 - Non-serotonergic bulbospinal neurons were identified by conduction velocities greater than 6 m/s. These units were found to fire at rates from 0 to 22 Hz, to respond to sensory stimuli with either excitation or inhibition, and to have unremarkable spike shapes. In iontophoretic experiments, both excitation and inhibition were observed in response to acetylcholine, norepinephrine and serotonin. Serotonergic bulbospinal neurons were identified by their conduction velocities below 6 m/s. These neurons, (which have been shown to be destroyed by 5,7-dihydroxytryptamine36), exist as two groups: a slower-conducting group with conduction velocities below 1.2 m/s, and a faster-conducting group with conduction velocities between 2 and 6 m/s. The neurons of the faster-conducting group were found to be similar to the non-serotonergic group in their firing, spike shapes and responses to sensory stimuli; while the units of the slower-conducting group were consistently found to fire between 0.03 and 6 Hz, to respond to sensory stimuli only with excitation, and to have distinctive spike shapes. Despite these differences, both groups of serotonergic units were found to be consistently inhibited by ACh, NE and 5-HT. In contrast to reports of serotonergic neurons in the midbrain, these units were not generally found to be inhibited by i.v. LSD. It is concluded that the serotonergic neurons of the medullary raphe are distinct both from the non-serotonergic neurons, and from serotonergic neurons in other parts of the brain.
AB - Non-serotonergic bulbospinal neurons were identified by conduction velocities greater than 6 m/s. These units were found to fire at rates from 0 to 22 Hz, to respond to sensory stimuli with either excitation or inhibition, and to have unremarkable spike shapes. In iontophoretic experiments, both excitation and inhibition were observed in response to acetylcholine, norepinephrine and serotonin. Serotonergic bulbospinal neurons were identified by their conduction velocities below 6 m/s. These neurons, (which have been shown to be destroyed by 5,7-dihydroxytryptamine36), exist as two groups: a slower-conducting group with conduction velocities below 1.2 m/s, and a faster-conducting group with conduction velocities between 2 and 6 m/s. The neurons of the faster-conducting group were found to be similar to the non-serotonergic group in their firing, spike shapes and responses to sensory stimuli; while the units of the slower-conducting group were consistently found to fire between 0.03 and 6 Hz, to respond to sensory stimuli only with excitation, and to have distinctive spike shapes. Despite these differences, both groups of serotonergic units were found to be consistently inhibited by ACh, NE and 5-HT. In contrast to reports of serotonergic neurons in the midbrain, these units were not generally found to be inhibited by i.v. LSD. It is concluded that the serotonergic neurons of the medullary raphe are distinct both from the non-serotonergic neurons, and from serotonergic neurons in other parts of the brain.
KW - analgesic pathways
KW - lysergic acid diethylamide
KW - raphe nuclei
KW - serotonergic neurons
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U2 - 10.1016/0006-8993(83)90166-X
DO - 10.1016/0006-8993(83)90166-X
M3 - Article
C2 - 6315185
AN - SCOPUS:0021067684
SN - 0006-8993
VL - 279
SP - 93
EP - 103
JO - Brain Research
JF - Brain Research
IS - 1-2
ER -