Neurons are able to maintain membrane potential and synaptic integrity by an
intricate equilibrium of membrane transporter proteins and ion channels. Two
membrane proteins of particular importance in the vertebrate retina are the
excitatory amino acid transporters (EAATs) which are responsible for the reuptake
of glutamate into both glial and neuronal cells and the sodium potassium
chloride cotransporters (NKCCs) that are responsible for the uptake of chloride
ions into the cell. NKCCs are electro-neutral with the uptake of 2 Cl- coupled to
an exchange of a potassium and Na+ ion into the cells. Therefore, there is little
change of cell membrane potential in the action of NKCCs. In this study the
localization and function of EAATs in the distal retina is investigated. Whole cell
patch clamp recordings in lower vertebrate retina have demonstrated that EAAT2
is the main synaptic EAATs in rod photoreceptors and it is localized to the axon terminals. Furthermore, the action of the transporter seems to be modified by
intracellular calcium concentration. There is also evidence that EAAT2 might be
regulated by feedback from the neuron network by glycinergic and GABAergic
mechanisms. The second half of this study investigates expression of NKCCs in
the retina by western blot analysis and quantitative polymerase chain reaction.
There are two forms of NKCCs, NKCC1 and NKCC2. NKCC1 is mostly
expressed in the central nervous system and NKCC2 was thought to only be
expressed in the kidneys. NKCC1 is responsible for the majority of chloride
uptake into neuronal and epithelial cells and NKCC1 is expressed in the distal
retina where photoreceptors synapse on second order horizontal and bipolar
cells. This study found the expression of NKCC1 in the distal retina to be
regulated by temporal light and dark adaptation. Light adaptation increased
phosphorylated NKCC1 expression (the active form of the cotransporter). The
increase in NKCC1 expression during light adaptation was modulated by
dopamine. Specifically, a D1 receptor agonist increased phosphorylated NKCC1
expression. Dopamine is an essential chemical and receptor known for initiating
light adaptation in retina. Finally, an NKCC1 knockout mouse model was
examined and it revealed that both forms of NKCC are expressed in the
vertebrate retina. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2014. / FAU Electronic Theses and Dissertations Collection
| Identifer | oai:union.ndltd.org:fau.edu/oai:fau.digital.flvc.org:fau_13694 |
| Contributors | Purpura, Lauren Angeline (author), Shen, Wen (Thesis advisor), Florida Atlantic University (Degree grantor), Charles E. Schmidt College of Science, Department of Biological Sciences |
| Publisher | Florida Atlantic University |
| Source Sets | Florida Atlantic University |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation, Text |
| Format | 65 p., application/pdf |
| Rights | Copyright © is held by the author, with permission granted to Florida Atlantic University to digitize, archive and distribute this item for non-profit research and educational purposes. Any reuse of this item in excess of fair use or other copyright exemptions requires permission of the copyright holder., http://rightsstatements.org/vocab/InC/1.0/ |
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