Abstract
Biochemical, histochemical and pharmacologic evidence suggest a functional role for acetylcholine (ACh), norepinephrine (NE) and serotonin (5-HT) in the spinal cord, possibly as synaptic transmitters. However, except for ACh sensitivity of Renshaw cells, Curtis, Phillis and Watkins (1961) did not find other neurons in the spinal cord responsive to ACh, NE or 5-HT. We reinvestigated this problem in the lumbosacral segments of decerebrated and ether-anesthetized cats using 5-barrel glass micropipette electrodes to administer ACh, NE and 5-HT electrophoretically to single neurons at the site of extracellular action potential recording. We found that a number of interneurons in the spinal cordresponded to the electrophoretic administration of ACh, NE and 5-HT with either facilitation or depression of firing. Some neurons responded to one, others to two and some to all three compounds with no correlation in the direction of their responses. The finding of neurons in the spinal cord responsive to the electrophoretic administration of ACh, NE and 5-HT providesa basis for studying the possible involvement of these substances in synaptic transmission.
Footnotes
- Received January 14, 1966.
- Accepted March 25, 1966.
- © 1966 by The Williams & Wilkins Co.
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