Inhibition of cerebral cortical neurones by a 5-hydroxytryptaminergic pathway from median raphé nucleus.
Recent observations made in our laboratory have shown that metergoline is a selective 5-hydroxytryptamine (5-HT) antagonist in the cerebral cortex. Fluoxetine is a reportedly selective 5-HT neuronal uptake blocker. In the present investigation these drugs have been used to examine the existence of a putative 5-HT input to the cerebral cortex. In rats anaesthetized with a mixture of methoxyflurane, nitrous oxide, and oxygen, stimulation of the median raphé nucleus or of the ipsilateral cortical surface and iontophoretically applied 5-HT decreased the firing of the deep cerebral cortical neurones. Metergoline antagonized the 5-HT-induced depression and reduced the duration of inhibition produced by raphé nucleus stimulation. These results suggest that the cerebral cortical neurones are inhibited by an ascending 5-HT-containing pathway.
D000818:Animals; D001933:Brain Stem / Q000502:physiology*; D002540:Cerebral Cortex / Q000166:cytology* / Q000187:drug effects; D004558:Electric Stimulation; D008297:Male; D008711:Metergoline / Q000494:pharmacology; D009433:Neural Inhibition / Q000187:drug effects; D009434:Neural Pathways / Q000502:physiology*; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D010647:Phenyl Ethers / Q000494:pharmacology; D011437:Propylamines / Q000494:pharmacology; D051381:Rats; D012701:Serotonin / Q000494:pharmacology / Q000502:physiology*
D010647:Phenyl Ethers; D011437:Propylamines; D008711:Metergoline; D012701:Serotonin