Glutamate decarboxylase-immunoreactive neurons and terminals in the periaqueductal gray of the rat.
The periaqueductal gray of 5 rats was processed for immunocytochemistry using an antiserum to glutamate decarboxylase. In both colchicine-pretreated (4 rats) and untreated (1 rat) animals, glutamate decarboxylase-positive cell bodies were present in all periaqueductal gray subdivisions, especially in the dorsal and ventrolateral subdivision. The perikaryal cross-sectional area of labelled neurons was smaller than that of periaqueductal gray projecting neurons retrogradely labelled with horseradish peroxidase in separate experiments. The morphology of glutamate decarboxylase-containing neurons resembled that of small polygonal, triangular and fusiform cells described in previous Golgi studies. Glutamate decarboxylase immunoreactivity was also observed in a large number of terminal-like structures, most of which were distributed close to the somata and dendrites of both glutamate decarboxylate-positive and -negative neurons. At all rostrocaudal levels the highest concentration of these elements was observed around the aqueduct. These results suggest that two sub-populations of neurons are present in the periaqueductal gray of rats, one consisting of small-sized glutamate decarboxylase-positive neurons (intrinsic neurons) and the other of large-sized glutamate decarboxylase-negative neurons (projecting neurons). Intrinsic circuits could be present between glutamate decarboxylase-positive and -negative neurons and between glutamate decarboxylase-positive neurons.
Barbaresi
P
P
Institute of Human Physiology, University of Ancona, Italy.
Manfrini
E
E
D000818:Animals; D003078:Colchicine; D005968:Glutamate Decarboxylase / Q000032:analysis*; D006735:Horseradish Peroxidase; D007150:Immunohistochemistry; D009411:Nerve Endings / Q000201:enzymology*; D010487:Periaqueductal Gray / Q000166:cytology / Q000201:enzymology*; D051381:Rats
D006735:Horseradish Peroxidase; D005968:Glutamate Decarboxylase; D003078:Colchicine