GABAergic basal forebrain afferents innervate selectively GABAergic targets in the main olfactory bulb
Autor: | Carlos Crespo, F.J. Martínez-Guijarro, Laura Rovira-Esteban, J.M. Blasco-Ibáñez, Emilio Varea, Juan Nacher, Francisco Javier Gracia-Llanes |
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Rok vydání: | 2010 |
Předmět: |
Male
Olfactory system Vesicular Inhibitory Amino Acid Transport Proteins Periglomerular cell Olfaction Biology Prosencephalon Neural Pathways medicine Animals Neurons Afferent Rats Wistar gamma-Aminobutyric Acid Basal forebrain General Neuroscience Olfactory tubercle Granule cell Olfactory Bulb Rats Olfactory bulb Neuroanatomical Tract-Tracing Techniques medicine.anatomical_structure nervous system GABAergic Female Neuroscience |
Zdroj: | Neuroscience. 170:913-922 |
ISSN: | 0306-4522 |
Popis: | In this work we have analyzed the targets of the GABAergic afferents to the main olfactory bulb originating in the basal forebrain of the rat. We combined anterograde tracing of 10 kD biotinylated dextran amine (BDA) injected in the region of the horizontal limb of the diagonal band of Broca that projects to the main olfactory bulb, with immunocytochemical detection of GABA under electron microscopy or vesicular GABA transporter (vGABAt) under confocal fluorescent microscopy. GABAergic afferents were identified as double labeled BDA-GABA boutons. Their targets were identified by their ultrastructure and GABA content. We found that GABAergic afferents from the basal forebrain were distributed all over the bulbar lamination, but were more abundant in the glomerular and inframitral layers (i.e. internal plexiform layer and granule cell layer). The fibers had thick varicosities with abundant mitochondria and large perforated synaptic specializations. They contacted exclusively GABAergic cells, corresponding to type 1 periglomerular cells in the glomerular layer, and to granule cells in inframitral layers. This innervation will synchronize the bulbar inhibition and consequently the response of the principal cells to the olfactory input. The effect of the activation of this pathway will produce a disinhibition of the bulbar principal cells. This facilitation might occur at two separate levels: first in the terminal tufts of mitral and tufted cells via inhibition of type 1 periglomerular cells; second at the level of the firing of the principal cells via inhibition of granule cells. The GABAergic projection from the basal forebrain ends selectively on interneurons, specifically on type 1 periglomerular cells and granule cells, and is likely to control the activity of the olfactory bulb via disinhibition of principal cells. Possible similarities of this pathway with the septo-hippocampal loop are discussed. |
Databáze: | OpenAIRE |
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