Pharmacology of the brachium conjunctivum: Red nucleus synaptic system in the baboon

Abstract

Acetylcholine, biogenic amines, and certain amino acids were applied by microiontophoresis to parvicellular and magnocellular red nucleus (RN) neurons of baboon while recording brachium conjunctivum (BC)-evoked and amino acid-evoked unit discharge from these neurons. Glycine, gamma-aminobutyric acid, and beta-alanine were potent depressants of BC-RN synaptic transmission, amino acid-evoked firing, and spontaneous activity of all RN neurons studied. Glycine was clearly more potent than the other 2 depressant amino acids. L-Glutamic and DL-homocysteic acid were strong excitants of all RN neurons tested. Dopamine, noradrenaline, and 5-hydroxytryptamine depressed the excitability of both parvicellular and magnocellular RN neurons; no excitatory effects were observed with these biogenic amines on RN neurons. Acetylcholine increased the rate of firing of spontaneously discharging parvicellular RN neurons and facilitated the amino acid-induced firing of these same neurons. Acetylcholine did not facilitate BC-RN synaptic transmission nor could this transmission be blocked by cholinergic antagonists. Unlike parvicellular RN neurons, the responsiveness of magnocellular neurons was either unaltered by acetylcholine or slightly decreased. These experiments demonstrate a difference in the pharmacologic responsiveness of parvicellular and magnocellular RN neurons to acetylcholine but do not provide evidence for a cholinergic input to RN via the brachium conjunctivum.

Transmitters in Motor Systems

“…This seems to be the more reasonable alternative, because none of the several other agents tested (monoamines and ACh) had the required excitatory effect. On the other hand, the excitation of small rubral cells by ACh (204) would be consistent with the existence of some kind of cholinergic facilitatory input.…”

Transmitters in Motor Systems

“…This seems to be the more reasonable alternative, because none of the several other agents tested (monoamines and ACh) had the required excitatory effect. On the other hand, the excitation of small rubral cells by ACh (204) would be consistent with the existence of some kind of cholinergic facilitatory input.…”

A red nucleus–VTA glutamate pathway underlies exercise reward and the therapeutic effect of exercise on cocaine use

“…This is supported by the finding that D2 and D3 receptors and the DA transporters are detected in RN neurons within human brain tissue ( 56 ). Further functional assays indicate that DA produces an inhibitory effect on the excitability of RN neurons in the baboon brain ( 57 ). Together, these findings challenge the long-held view that the descending rubrospinal tract simply travels through the VTA to regulate motor neurons in the spinal cord, without functional connections to VTA neurons.…”

Emotions Studied by Imaging of the Human Brain: The Somatic and Emotional Motor Systems

“…The red nucleus decides about limb movements, i.e., in which direction the animal is moving or when and how it reaches for food. The red nucleus receives afferent information from the cerebellum, motor and premotor cortex (Kuypers 1981;Holstege 1991), and from the serotonergic, noradrenergic, and dopaminergic level-setting systems (Huffman and Davis 1977;Bosler et al 1983;Domyancic and Morilak 1997), as well as from the deep layers of the superior colliculus, (personal observation), where visual, auditory, and somatosensory information is processed.…”

Transmitters in Motor Systems

“…This seems to be the more reasonable alternative, because none of the several other agents tested (monoamines and ACh) had the required excitatory effect. On the other hand, the excitation of small rubral cells by ACh (204) would be consistent with the existence of some kind of cholinergic facilitatory input.…”

A red nucleus–VTA glutamate pathway underlies exercise reward and the therapeutic effect of exercise on cocaine use

“…This is supported by the finding that D2 and D3 receptors and the DA transporters are detected in RN neurons within human brain tissue ( 56 ). Further functional assays indicate that DA produces an inhibitory effect on the excitability of RN neurons in the baboon brain ( 57 ). Together, these findings challenge the long-held view that the descending rubrospinal tract simply travels through the VTA to regulate motor neurons in the spinal cord, without functional connections to VTA neurons.…”

Emotions Studied by Imaging of the Human Brain: The Somatic and Emotional Motor Systems

“…The red nucleus decides about limb movements, i.e., in which direction the animal is moving or when and how it reaches for food. The red nucleus receives afferent information from the cerebellum, motor and premotor cortex (Kuypers 1981;Holstege 1991), and from the serotonergic, noradrenergic, and dopaminergic level-setting systems (Huffman and Davis 1977;Bosler et al 1983;Domyancic and Morilak 1997), as well as from the deep layers of the superior colliculus, (personal observation), where visual, auditory, and somatosensory information is processed.…”

Transmitters in Motor Systems

“…This seems to be the more reasonable alternative, because none of the several other agents tested (monoamines and ACh) had the required excitatory effect. On the other hand, the excitation of small rubral cells by ACh (204) would be consistent with the existence of some kind of cholinergic facilitatory input.…”

A red nucleus–VTA glutamate pathway underlies exercise reward and the therapeutic effect of exercise on cocaine use

“…This is supported by the finding that D2 and D3 receptors and the DA transporters are detected in RN neurons within human brain tissue ( 56 ). Further functional assays indicate that DA produces an inhibitory effect on the excitability of RN neurons in the baboon brain ( 57 ). Together, these findings challenge the long-held view that the descending rubrospinal tract simply travels through the VTA to regulate motor neurons in the spinal cord, without functional connections to VTA neurons.…”

Emotions Studied by Imaging of the Human Brain: The Somatic and Emotional Motor Systems

“…The red nucleus decides about limb movements, i.e., in which direction the animal is moving or when and how it reaches for food. The red nucleus receives afferent information from the cerebellum, motor and premotor cortex (Kuypers 1981;Holstege 1991), and from the serotonergic, noradrenergic, and dopaminergic level-setting systems (Huffman and Davis 1977;Bosler et al 1983;Domyancic and Morilak 1997), as well as from the deep layers of the superior colliculus, (personal observation), where visual, auditory, and somatosensory information is processed.…”