For glutamate and the developing optic pathway, glutamate and its ionotropic receptor subunits are expressed widely in retina and ventral diencephalon, and in cells that are related to the chiasm formation. These studies indicate that glutamate may act as a communicator or attractor to coordinate with other factors to affect the retinal axon pathfinding in the prenatal optic pathway. / Furthermore, for the function of glutamate, AMPARs and KARs in the optic chiasm formation, we did retinal explant culture experiment at E14 in vitro, with application of different concentration of L-glutamate (500muM -1mM), AMPAR antagonists: CP465022 hydrochloride (2-20muM) and GYK15466 dihydrochloride (25-150muM), and KAR antagonists: CNQX (50-500muM) and UBP301 (5-25muM). The results show that L-glutamate promotes retinal axon outgrowth; AMPA receptor antagonists inhibit that; and KAR antagonists have no effect on that. In the presence of different combinations of ionotropic receptor antagonists (including NMDAR antagonist), they suggest that the blockage of glutamate iontroptic receptors displays an obvious effect of inhibiting neurite outgrowth in E14 retinal explants. However, inhibiting kainate receptors show little effect on retinal neurite outgrowth which is different from that of blocking AMPARs. We also did E13 and E15 brain slice culture experiments, and found that blocking of glutamate ionotropic receptors affects crossed axon projection in the midline at early stage, but has no effect to the uncrossed one. / Glutamate is the dominant amino acid neurotransmitter in the central nervous system naturally occurring in the L-form. Glutamate ionotropic receptors can be further a-amino-3-hydroxy-5-methy1-4-isoxazole-propionate divided into three types by their ligand (AMPA, specificities: GluR1-4), N-methyl-D-aspartate (NMDA, NR1-3) and kainate (KA, GluR5-7 and KA1-2) receptors, which function as ligand-gated ion channels. In this study, we focus on the AMPARs and KARs which are expressed in the developing brain. / Here, we used semi-quantitative RT-PCR to analyze mRNA expression levels of AMPAR and KAR subunits in the mouse retina and ventral diencephalons at different developmental stages, and in adult retina. The results show that both AMPAR and KAR subunits can be detected in retina and ventral diencephalon at as early as E13. We also used specific antibodies to investigate glutamate, AMPAR and KAR subunit expression in the mouse retinofugal pathway. We found that: 1) Glutamate is expressed at as early as E13. In retina, it tends to localize in retinal ganglion cells (RGCs) and their axons; in ventral diencephalon, it is most intense in optic stalk, optic chiasm and optic tract. It is also localized with chiasmatic neurons, which are related to the formation of optic chiasm. 2) For the individual AMPAR and KAR subunits, all of them are expressed at as early as E13. The immunoreactive GluRl and GluR5/6/7 are distributed preferentially in the RGCs and their axons; the staining of GluR2/3 and GluR4 are largely found in RGCs and the supporting cells around the pathway, but for GluR4, its staining is weakly detected in optic fibers and strongly in the midline of chiasm. Although the staining patterns of these specific subunits are different, they are all localized in chiasmatic neurons in diencephalon. / Cheng, Xiaojing. / "November 2010." / Adviser: Sun On Chan. / Source: Dissertation Abstracts International, Volume: 73-04, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 137-152). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.
| Identifer | oai:union.ndltd.org:cuhk.edu.hk/oai:cuhk-dr:cuhk_344766 |
| Date | January 2011 |
| Contributors | Cheng, Xiaojing., Chinese University of Hong Kong Graduate School. Division of Anatomy. |
| Source Sets | The Chinese University of Hong Kong |
| Language | English, Chinese |
| Detected Language | English |
| Type | Text, theses |
| Format | electronic resource, microform, microfiche, 1 online resource (ix, 152 leaves : ill. (some col.)) |
| Rights | Use of this resource is governed by the terms and conditions of the Creative Commons “Attribution-NonCommercial-NoDerivatives 4.0 International” License (http://creativecommons.org/licenses/by-nc-nd/4.0/) |
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