Ultrastructural evidence for GABA-mediated disinhibitory circuits in the spinal cord of the cat.
The synaptic relationships between gamma-aminobutyric acid (GABA)-immunoreactive and enkephalin-immunoreactive profiles in the cat spinal cord were examined using combined pre-embedding immunoperoxidase and post-embedding immunogold electron microscopic immunocytochemistry. Although colchicine was not used, enkephalin-immunoreactive somata and dendrites were detected in regions associated with nociceptive transmission, including laminae I, II, V and X. In each of these laminae, many GABA-immunoreactive terminals were found presynaptic to enkephalin-immunoreactive cell bodies and dendrites. We propose that disinhibition of opioid-containing neurons may be a common feature of pain-related circuits in the cat spinal cord.
Liu
H
H
Department of Anatomy, University of California, San Francisco 94143.
Llewellyn-Smith
I J
IJ
Pilowsky
P
P
Basbaum
A I
AI
D000818:Animals; D002415:Cats; D003712:Dendrites / Q000502:physiology / Q000648:ultrastructure; D004745:Enkephalins / Q000032:analysis; D007124:Immunoenzyme Techniques; D016253:Microscopy, Immunoelectron; D009474:Neurons / Q000502:physiology* / Q000648:ultrastructure; D013116:Spinal Cord / Q000502:physiology* / Q000648:ultrastructure; D013569:Synapses / Q000502:physiology* / Q000648:ultrastructure; D005680:gamma-Aminobutyric Acid / Q000032:analysis / Q000502:physiology*
D004745:Enkephalins; D005680:gamma-Aminobutyric Acid