• 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: