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Synaptic Targets (synaptic + target)
Selected AbstractsGABAB receptor expression and function in olfactory receptor neuron axon growthDEVELOPMENTAL NEUROBIOLOGY, Issue 2 2004Catherine A. Priest Abstract Neurotransmitters have been implicated in regulating growth cone motility and guidance in the developing nervous system. Anatomical and electrophysiological studies show the presence of functional GABAB receptors on adult olfactory receptor neuron (ORN) nerve terminals. Using antisera against the GABAB R1a/b receptor isoforms we show that developing mouse olfactory receptor neurons express GABAB receptors from embryonic day 14 through to adulthood. GABAB receptors are present on axon growth cones from both dissociated ORNs and olfactory epithelial explants. Neurons in the olfactory bulb begin to express glutamic acid decarboxylase (GAD), the synthetic enzyme for GABA, from E16 through to adulthood. When dissociated ORNs were cultured in the presence of the GABAB receptor agonists, baclofen or SKF97541, neurite outgrowth was significantly reduced. Concurrent treatment of the neurons with baclofen and the GABAB receptor antagonist CGP54626 prevented the inhibitory effects of baclofen on ORN neurite outgrowth. These results show that growing ORN axons express GABAB receptors and are sensitive to the effects of GABAB receptor activation. Thus, ORNs in vivo may detect GABA release from juxtaglomerular cells as they enter the glomerular layer and use this as a signal to limit their outgrowth and find synaptic targets in regeneration and development. © 2004 Wiley Periodicals, Inc. J Neurobiol 60:154,165, 2004 [source] Difference in organization of corticostriatal and thalamostriatal synapses between patch and matrix compartments of rat neostriatumEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 10 2006Fumino Fujiyama Abstract The neostriatum, which possesses a mosaic organization consisting of patch and matrix compartments, receives glutamatergic excitatory afferents from the cerebral cortex and thalamus. Differences in the synaptic organization of these striatopetal afferents between the patch and matrix compartments were examined in the rat using confocal laser scanning and electron microscopes. Thalamostriatal terminals immunopositive for vesicular glutamate transporter (VGluT) 2 were less dense in the patch than in the matrix compartment, although the density of VGluT1-immunopositive corticostriatal terminals was almost evenly distributed in both the compartments. Quantitative analysis of ultrastructural images revealed that 84% of VGluT2-positive synapses in the patch compartment were formed with dendritic spines, whereas 70% in the matrix compartment were made with dendritic shafts. By contrast, VGluT1-positive terminals display a similar preference for specific synaptic targets in both compartments: about 80% made synapses with dendritic spines. In addition, VGluT2-positive axospinous synapses in the patch compartment were larger than the VGluT1-positive axospinous synapses in both compartments. As axospinous synapses are generally found in neuronal connections showing high synaptic plasticity, the present findings suggest that the thalamostriatal connection requires higher synaptic plasticity in the patch compartment than in the matrix compartment. [source] Synaptic contacts between an identified type of ON cone bipolar cell and ganglion cells in the mouse retinaEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 5 2005Bin Lin Abstract We surveyed the potential contacts between an identified type of bipolar cell and retinal ganglion cells in the mouse. By crossing two existing mouse strains (line 357 and line GFP-M), we created a double transgenic strain in which GFP is expressed by all members of a single type of ON cone bipolar cell and a sparse, mixed population of retinal ganglion cells. The GFP-expressing bipolar cells appear to be those termed CB4a of Pignatelli & Strettoi [(2004) J. Comp. Neurol., 476, 254,266] and type 7 of Ghosh et al. [(2004) J. Comp. Neurol., 469, 70,82 and J. Comp. Neurol., 476, 202,203]. The labelled ganglion cells include examples of most or all types of ganglion cells present in the mouse. By studying the juxtaposition of their processes in three dimensions, we could learn which ganglion cell types are potential synaptic targets of the line 357 bipolar cell. Of 12 ganglion cell types observed, 10 types could be definitively ruled out as major synaptic targets of the line 357 bipolar cells. One type of monostratified ganglion cell and one bistratified cell tightly cofasciculate with axon terminals of the line 357 bipolar cells. Double labelling for kinesin II demonstrates colocalization of bipolar cell ribbons at the sites of contact between these two types of ganglion cell and the line 357 bipolar cells. [source] Comparison of the ultrastructure of cortical and retinal terminals in the rat superior colliculusTHE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 8 2006Kamran Boka Abstract We compared the ultrastructure and synaptic targets of terminals of cortical or retinal origin in the stratum griseum superficiale and stratum opticum of the rat superior colliculus. Following injections of biotinylated dextran amine into cortical area 17, corticotectal axons were labeled by anterograde transport. Corticotectal axons were of relatively small caliber with infrequent small varicosities. At the ultrastructural level, corticotectal terminals were observed to be small profiles (0.44 ± 0.27 ,m2) that contained densely packed round vesicles. In tissue stained for gamma amino butyric acid (GABA) using postembedding immunocytochemical techniques, corticotectal terminals were found to contact small (0.51 ± 0.69 ,m2) non-GABAergic dendrites and spines (93%) and a few small GABAergic dendrites (7%). In the same tissue, retinotectal terminals, identified by their distinctive pale mitochondria, were observed to be larger than corticotectal terminals (3.34 ± 1.79 ,m2). In comparison to corticotectal terminals, retinotectal terminals contacted larger (1.59 ± 1.70 ,m2) non-GABAergic dendrites and spines (73%) and a larger proportion of GABAergic profiles (27%) of relatively large size (2.17 ± 1.49 ,m2), most of which were vesicle-filled (71%). Our results suggest that cortical and retinal terminals target different dendritic compartments within the neuropil of the superficial layers of the superior colliculus. Anat Rec Part A, 288A:850,858, 2006. © 2006 Wiley-Liss, Inc. [source] | ||||||||||