Monosynaptic connections between primary afferents and giant neurons in the turtle spinal dorsal horn
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Monosynaptic connections between primary afferents and giant neurons in the turtle spinal dorsal horn. / Fernández, A; Radmilovich, M; Russo, R E; Hounsgaard, J; Trujillo-Cenóz, O.
In: Experimental Brain Research, Vol. 108, No. 3, 01.03.1996, p. 347-56.Research output: Contribution to journal › Journal article › Research › peer-review
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T1 - Monosynaptic connections between primary afferents and giant neurons in the turtle spinal dorsal horn
AU - Fernández, A
AU - Radmilovich, M
AU - Russo, R E
AU - Hounsgaard, J
AU - Trujillo-Cenóz, O
PY - 1996/3/1
Y1 - 1996/3/1
N2 - This paper reports the occurrence of monosynaptic connections between dorsal root afferents and a distinct cell type-the giant neuron-deep in the dorsal horn of the turtle spinal cord. Light microscope studies combining Nissl stain and transganglionic HRP-labeling of the primary afferents have revealed the occurrence of axosomatic and axodendritic contacts between labeled boutons and giant neurons. The synaptic nature of these contacts has been confirmed by use of electron microscope procedures involving the partial three-dimensional reconstruction of identified giant neurons. Intracellular recording in spinal cord slices provided functional evidence indicating the monosynaptic connections between dorsal root afferents and giant neurons. The recorded neurons were morphologically identified by means of biocytin injection and with avidin conjugates. Electrical stimulation of the ipsilateral dorsal roots evoked synaptic responses with short, fixed latencies (1.6-5.6 ms), which remained unchanged at high frequencies (10 Hz). Excitatory polysynaptic potentials were also observed. By means of pharmacological procedures the short-latency response was dissected in two components: one insensitive to tetrodotoxin, the other abolished by the drug. The toxin-resistant component was presumed to be sustained by small-diameter C fibers. The synaptic response was mainly mediated by the glutamate-AMPA receptor subtype; however, a small component mediated by NMDA receptor was also present.
AB - This paper reports the occurrence of monosynaptic connections between dorsal root afferents and a distinct cell type-the giant neuron-deep in the dorsal horn of the turtle spinal cord. Light microscope studies combining Nissl stain and transganglionic HRP-labeling of the primary afferents have revealed the occurrence of axosomatic and axodendritic contacts between labeled boutons and giant neurons. The synaptic nature of these contacts has been confirmed by use of electron microscope procedures involving the partial three-dimensional reconstruction of identified giant neurons. Intracellular recording in spinal cord slices provided functional evidence indicating the monosynaptic connections between dorsal root afferents and giant neurons. The recorded neurons were morphologically identified by means of biocytin injection and with avidin conjugates. Electrical stimulation of the ipsilateral dorsal roots evoked synaptic responses with short, fixed latencies (1.6-5.6 ms), which remained unchanged at high frequencies (10 Hz). Excitatory polysynaptic potentials were also observed. By means of pharmacological procedures the short-latency response was dissected in two components: one insensitive to tetrodotoxin, the other abolished by the drug. The toxin-resistant component was presumed to be sustained by small-diameter C fibers. The synaptic response was mainly mediated by the glutamate-AMPA receptor subtype; however, a small component mediated by NMDA receptor was also present.
KW - 6-Cyano-7-nitroquinoxaline-2,3-dione
KW - Afferent Pathways
KW - Animals
KW - Cell Size
KW - Evoked Potentials
KW - Excitatory Amino Acid Antagonists
KW - Horseradish Peroxidase
KW - Microscopy, Electron
KW - Neurons, Afferent
KW - Nissl Bodies
KW - Receptors, N-Methyl-D-Aspartate
KW - Spinal Cord
KW - Spinal Nerve Roots
KW - Tetrodotoxin
KW - Turtles
M3 - Journal article
C2 - 8801115
VL - 108
SP - 347
EP - 356
JO - Experimental Brain Research
JF - Experimental Brain Research
SN - 0014-4819
IS - 3
ER -
ID: 33729609