Synaptic interaction between GABAergic terminals and substance P receptor-positive neurons in rat spinal superficial laminae.
OBJECTIVE
To identify synaptic relationship between gamma-aminobutyric acid (GABA)-containing terminals and substance P receptor-positive neurons in the superficial dorsal horn of rat spinal cord.


METHODS
A combination of preembedding immunoperoxidase staining for substance P receptor with postembedding immunogold staining for GABA was employed.


RESULTS
Intense substance P receptor-expressing neurons were concentrated in medial half of the lamina I and the outer lamina II of the spinal cord. Under electron microscopy, substance P receptor immunoreactivity was found mainly in perikarya and dendrites, and deposited along neuronal membranes, in Golgi complex, in rough endoplasmic reticulum and on the surface of mitochondria with patch- or granular-like staining. The double-labeling studies revealed that substance P receptor-expressing dendrites received symmetric synaptic contacts from axonal terminals labeled with immunogold particles indicating GABA. GABA also co-localized with substance P receptors in the dendrites.


CONCLUSIONS
The synaptic contact between GABA-containing terminal and substance P receptor-expressing neuron provided important morphological evidence for previous pharmacological studies concerning antinociceptive function of GABA in the spinal cord.
Tao
Y X
YX
Shanghai Institute of Physiology, Chinese Academy of Sciences, Shanghai 200031, China.
Li
Y Q
YQ
Zhao
Z Q
ZQ
D000818:Animals; D008297:Male; D020671:Posterior Horn Cells / Q000737:chemistry*; D051381:Rats; D017207:Rats, Sprague-Dawley; D018040:Receptors, Neurokinin-1 / Q000032:analysis*; D013116:Spinal Cord / Q000737:chemistry*; D009435:Synaptic Transmission; D005680:gamma-Aminobutyric Acid / Q000032:analysis*
D018040:Receptors, Neurokinin-1; D005680:gamma-Aminobutyric Acid