NeuroanatomyStereological estimates of the basal forebrain cell population in the rat, including neurons containing choline acetyltransferase, glutamic acid decarboxylase or phosphate-activated glutaminase and colocalizing vesicular glutamate transporters
Section snippets
Animals and surgery
Results from six adult male Wistar rats (Charles River Canada, St. Constant, Quebec, Canada), weighing approximately 250 g, are reported in this study. All procedures were approved by the McGill University Animal Care Committee and conform to standards of the Canadian Council on Animal Care and the U.S. National Institutes of Health guidelines. Special effort was made to minimize the number of animals used and their suffering. For surgery or killing, the rats were anesthetized with sodium
Distribution and estimates of ChAT+, GAD+ and PAG+ neurons
As evident in the MCPO (Fig. 1), ChAT+, GAD+ and PAG+ neurons were codistributed through the nuclei of the BF cholinergic cell area. Darkly stained with DAB, ChAT+ cells were most commonly medium to large in size, fusiform to polygonal in shape and in some regions grouped in clusters (Fig. 1A). Also darkly stained with DAB, GAD+ cells were variable in size from small to large, oval to polygonal in shape and relatively densely distributed through all areas where cholinergic cells were present (
Discussion
The present stereological estimates reveal a very large cell population in the BF of the rat that is composed of only a small proportion of ACh-synthesizing neurons together with a significant proportion of GABA-synthesizing neurons and major proportion of Glu-synthesizing neurons. Given the overlapping numbers, a proportion of ACh- and GABA-synthesizing neurons could also synthesize Glu. The vast proportion of Glu-synthesizing neurons also appears to have the capacity to store and release Glu
Acknowledgments
The research was supported by grants to I.G. and M.M. from the University of Milan and to B.E.J. from the Canadian Institutes of Health Research (CIHR, 13458) and the National Institute of Mental Health (NIMH, RO1 MH60119-01A1). We are most grateful to Dr. Takeshi Kaneko (Kyoto, Japan) for generously supplying the antibody for PAG. We would also like to thank Dr. Gianluca Vago (Department of Clinical Science Luigi Sacco, University of Milan, Milan, Italy) for his consultation.
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