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Origins of Glutamatergic Terminals in the Inferior Colliculus Identified by Retrograde Transport and Expression of VGLUT1 and VGLUT2 Genes.

Ito T, Oliver DL - Front Neuroanat (2010)

Bottom Line: In the superior olivary complex (SOC), the majority of FG-positive cells expressing VGLUT2 were in the lateral superior olive, medial superior olive, and some periolivary nuclei.Fewer FG-positive cells expressed VGLUT1&2.Our data suggest that (1) the most likely sources of VGLUT2 terminals in the IC are the intermediate nucleus of the lateral lemniscus, the dorsal cochlear nucleus, the medial and lateral superior olive, and the IC itself, (2) VGLUT1 terminals in the IC originate only in the ipsilateral auditory cortex, and (3) VGLUT1&2 terminals in IC originate mainly from the VCN with minor contributions from the SOC and the lateral lemniscal nuclei.

View Article: PubMed Central - PubMed

Affiliation: Department of Anatomy, Faculty of Medical Sciences, University of Fukui Fukui, Japan.

ABSTRACT
Terminals containing vesicular glutamate transporter (VGLUT) 2 make dense axosomatic synapses on tectothalamic GABAergic neurons. These are one of the three types of glutamatergic synapses in the inferior colliculus (IC) identified by one of three combinations of transporter protein: VGLUT1 only, VGLUT2 only, or both VGLUT1 and 2. To identify the source(s) of these three classes of glutamatergic terminals, we employed the injection of Fluorogold (FG) into the IC and retrograde transport in combination with in situ hybridization for VGLUT1 and VGLUT2 mRNA. The distribution of FG-positive soma was consistent with previous reports. In the auditory cortex, all FG-positive cells expressed only VGLUT1. In the IC, the majority of FG-positive cells expressed only VGLUT2. In the intermediate nucleus of the lateral lemniscus, most FG-positive cells expressed VGLUT2, and a few FG-positive cells expressed both VGLUT1 and 2. In the superior olivary complex (SOC), the majority of FG-positive cells expressing VGLUT2 were in the lateral superior olive, medial superior olive, and some periolivary nuclei. Fewer FG-positive cells expressed VGLUT1&2. In the ventral cochlear nucleus, almost all FG-positive cells expressed VGLUT1&2. On the other hand in the dorsal cochlear nucleus, the vast majority of FG-positive cells expressed only VGLUT2. Our data suggest that (1) the most likely sources of VGLUT2 terminals in the IC are the intermediate nucleus of the lateral lemniscus, the dorsal cochlear nucleus, the medial and lateral superior olive, and the IC itself, (2) VGLUT1 terminals in the IC originate only in the ipsilateral auditory cortex, and (3) VGLUT1&2 terminals in IC originate mainly from the VCN with minor contributions from the SOC and the lateral lemniscal nuclei.

No MeSH data available.


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Fluorescent micrographs of retrogradely labeled cells in the IC (A), NLL (B–D), CNC (E–G), and SOC (H–Q). Some retrogradely labeled cells expressed only VGLUT2 (white arrows) or both VGLUT1 and VGLUT2 (black arrows). The “c” and “i” after the abbreviation of the nuclei mean contralateral and ipsilateral to the injection site. Green: VGLUT2; red: VGLUT1; blue: FG. Scale bar: 50 μm.
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Figure 3: Fluorescent micrographs of retrogradely labeled cells in the IC (A), NLL (B–D), CNC (E–G), and SOC (H–Q). Some retrogradely labeled cells expressed only VGLUT2 (white arrows) or both VGLUT1 and VGLUT2 (black arrows). The “c” and “i” after the abbreviation of the nuclei mean contralateral and ipsilateral to the injection site. Green: VGLUT2; red: VGLUT1; blue: FG. Scale bar: 50 μm.

Mentions: The main source of VGLUT2 inputs to the IC from the midbrain was the contralateral IC and the ipsilateral INLL. The majority of the retrogradely labeled cells in the IC were located in the contralateral central nucleus (Figure 2A). We found numerous neurons expressing VGLUT2 but none that expressed VGLUT1. VGLUT2 was expressed in around 90% of FG-positive cells in the central nucleus and lateral cortex (Table 2) and in over 70% of FG-positive neurons in dorsal cortex (Table 2). No neurons expressed VGLUT1 or VGLUT1&2 (Figures 2B,3A1–4; Tables 1,2). The FG-labeled cells without VGLUT expression are likely the GABAergic neurons. So, both glutamatergic and GABAergic neurons have projections through the commissure of the IC.


Origins of Glutamatergic Terminals in the Inferior Colliculus Identified by Retrograde Transport and Expression of VGLUT1 and VGLUT2 Genes.

Ito T, Oliver DL - Front Neuroanat (2010)

Fluorescent micrographs of retrogradely labeled cells in the IC (A), NLL (B–D), CNC (E–G), and SOC (H–Q). Some retrogradely labeled cells expressed only VGLUT2 (white arrows) or both VGLUT1 and VGLUT2 (black arrows). The “c” and “i” after the abbreviation of the nuclei mean contralateral and ipsilateral to the injection site. Green: VGLUT2; red: VGLUT1; blue: FG. Scale bar: 50 μm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2967334&req=5

Figure 3: Fluorescent micrographs of retrogradely labeled cells in the IC (A), NLL (B–D), CNC (E–G), and SOC (H–Q). Some retrogradely labeled cells expressed only VGLUT2 (white arrows) or both VGLUT1 and VGLUT2 (black arrows). The “c” and “i” after the abbreviation of the nuclei mean contralateral and ipsilateral to the injection site. Green: VGLUT2; red: VGLUT1; blue: FG. Scale bar: 50 μm.
Mentions: The main source of VGLUT2 inputs to the IC from the midbrain was the contralateral IC and the ipsilateral INLL. The majority of the retrogradely labeled cells in the IC were located in the contralateral central nucleus (Figure 2A). We found numerous neurons expressing VGLUT2 but none that expressed VGLUT1. VGLUT2 was expressed in around 90% of FG-positive cells in the central nucleus and lateral cortex (Table 2) and in over 70% of FG-positive neurons in dorsal cortex (Table 2). No neurons expressed VGLUT1 or VGLUT1&2 (Figures 2B,3A1–4; Tables 1,2). The FG-labeled cells without VGLUT expression are likely the GABAergic neurons. So, both glutamatergic and GABAergic neurons have projections through the commissure of the IC.

Bottom Line: In the superior olivary complex (SOC), the majority of FG-positive cells expressing VGLUT2 were in the lateral superior olive, medial superior olive, and some periolivary nuclei.Fewer FG-positive cells expressed VGLUT1&2.Our data suggest that (1) the most likely sources of VGLUT2 terminals in the IC are the intermediate nucleus of the lateral lemniscus, the dorsal cochlear nucleus, the medial and lateral superior olive, and the IC itself, (2) VGLUT1 terminals in the IC originate only in the ipsilateral auditory cortex, and (3) VGLUT1&2 terminals in IC originate mainly from the VCN with minor contributions from the SOC and the lateral lemniscal nuclei.

View Article: PubMed Central - PubMed

Affiliation: Department of Anatomy, Faculty of Medical Sciences, University of Fukui Fukui, Japan.

ABSTRACT
Terminals containing vesicular glutamate transporter (VGLUT) 2 make dense axosomatic synapses on tectothalamic GABAergic neurons. These are one of the three types of glutamatergic synapses in the inferior colliculus (IC) identified by one of three combinations of transporter protein: VGLUT1 only, VGLUT2 only, or both VGLUT1 and 2. To identify the source(s) of these three classes of glutamatergic terminals, we employed the injection of Fluorogold (FG) into the IC and retrograde transport in combination with in situ hybridization for VGLUT1 and VGLUT2 mRNA. The distribution of FG-positive soma was consistent with previous reports. In the auditory cortex, all FG-positive cells expressed only VGLUT1. In the IC, the majority of FG-positive cells expressed only VGLUT2. In the intermediate nucleus of the lateral lemniscus, most FG-positive cells expressed VGLUT2, and a few FG-positive cells expressed both VGLUT1 and 2. In the superior olivary complex (SOC), the majority of FG-positive cells expressing VGLUT2 were in the lateral superior olive, medial superior olive, and some periolivary nuclei. Fewer FG-positive cells expressed VGLUT1&2. In the ventral cochlear nucleus, almost all FG-positive cells expressed VGLUT1&2. On the other hand in the dorsal cochlear nucleus, the vast majority of FG-positive cells expressed only VGLUT2. Our data suggest that (1) the most likely sources of VGLUT2 terminals in the IC are the intermediate nucleus of the lateral lemniscus, the dorsal cochlear nucleus, the medial and lateral superior olive, and the IC itself, (2) VGLUT1 terminals in the IC originate only in the ipsilateral auditory cortex, and (3) VGLUT1&2 terminals in IC originate mainly from the VCN with minor contributions from the SOC and the lateral lemniscal nuclei.

No MeSH data available.


Related in: MedlinePlus