Ha. Lekan et Sm. Carlton, GLUTAMATERGIC AND GABAERGIC INPUT TO RAT SPINOTHALAMIC TRACT CELLS INTHE SUPERFICIAL DORSAL HORN, Journal of comparative neurology, 361(3), 1995, pp. 417-428
The distribution of synaptic terminals onto spinothalamic tract cells
(types I and II) of the superficial dorsal horn was determined with sp
ecial reference to the amino acid transmitters glutamate and gamma-ami
nobutyric acid. Fifteen spinothalamic cells retrogradely labeled from
the thalamus with the neuroanatomical tracer wheatgerm agglutinin conj
ugated to horseradish peroxidase were sectioned for electron microscop
y. Serial sections from several levels through each cell were immunost
ained for glutamate and gamma-aminobutyric acid using a postembedding
immunogold technique. Perimeter measurements of spinothalamic cell som
ata and dendrites and the lengths of apposition for all terminal profi
les in contact with the spinothalamic cells were obtained from electro
n micrographs using a digitizing tablet. These data were used to deter
mine the density of terminals on the soma and dendrites. In addition,
the terminal population on these cells was categorized by transmitter
content (glutamate, gamma-aminobutyric acid, or unlabeled). The result
s demonstrate that terminal density increased on dendrites relative to
their distance from the soma. Glutamatergic and GABAergic input compo
sed 37% and 20% of the terminal population, respectively, and these pe
rcentages remained uniform for the soma and dendrites. There were no s
ignificant differences among the 15 cells analyzed for this study. The
results, therefore, suggest that both type I and type II STT cells of
the superficial DH have similar synaptic organizations. (C) 1995 Wile
y-Liss, Inc.