THE EFFECTS OF SEROTONIN ANTAGONISTS ON THE INHIBITION OF PRIMATE SPINOTHALAMIC TRACT CELLS PRODUCED BY STIMULATION IN NUCLEUS RAPHE MAGNUS OR PERIAQUEDUCTAL GRAY
- 1 January 1982
- journal article
- research article
- Vol. 220 (2) , 266-277
Abstract
The effects of serotonin antagonists were examined on the inhibition and excitation of nociceptive spinothalamic tract cells from Macaca fascicularis produced by brainstem stimulation with short (200 ms) or long (2 s) stimulus trains. The inhibitory effects resulting from stimulation in either nucleus raphe magnus (NRM) or in the periaqueductal gray with short stimulus trains were significantly reduced after the administration of serotonin receptor blockers. Reductions in periaqueductal gray inhibition were also observed on inhibition produced by long duration trains; the effects on NRM inhibition were dependent on stimulus duration, current strength and dose of antagonist. The rare excitatory effect of NRM stimulation was also found to be reduced after the administration of a serotonin antagonist. The relatively weak effects of serotonin antagonists on NRM inhibition are discussed in relation to 3 hypotheses: parallel pathways, multiple receptors or corelease of serotonin and another transmitter from raphe-spinal neurons. [The serotonin antagonists included in this study were methysergide, metergoline, cinanserin and cyproheptadine.].This publication has 13 references indexed in Scilit:
- The origin of descending pathways in the dorsolateral funiculus of the spinal cord of the cat and rat: Further studies on the anatomy of pain modulationJournal of Comparative Neurology, 1979
- Excitation of primate spinothalamic neurons by cutaneous C-fiber volleysJournal of Neurophysiology, 1979
- Effects of stimulating in raphe nuclei and in reticular formation on response of spinothalamic neurons to mechanical stimuliJournal of Neurophysiology, 1979
- Immunohistochemical localization of enkephalin in rat brain and spinal cordJournal of Comparative Neurology, 1978
- Immunohistochemical evidence of substance P-like immunoreactivity in some 5-hydroxytryptamine-containing neurons in the rat central nervous systemNeuroscience, 1978
- A study of the origin of brain stem projections to monkey spinal cord using the retrograde transport methodExperimental Neurology, 1978
- Three bulbospinal pathways from the rostral medulla of the cat: An autoradiographic study of pain modulating systemsJournal of Comparative Neurology, 1978
- Spinal cord potentials evoked by cutaneous afferents in the monkeyJournal of Neurophysiology, 1977
- Excitatory responses of neurones in rat bulbar reticular formation to bulbar raphe stimulation and to iontophoretically applied 5‐hydroxytryptamine, and their blockade by LSD 25.The Journal of Physiology, 1977
- Responses of midbrain neurones to micro-iontophoretically applied 5-hydroxytryptamine: Comparison with the response to intravenously administered lysergic acid diethylamideNeuropharmacology, 1976