Purchase this article with an account.
B. Li, W. Shen; Developmental Expression of Chloride Transporters in Mouse Retina . Invest. Ophthalmol. Vis. Sci. 2006;47(13):5392.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Intracellular chloride plays a key role in controlling polarity of an inhibitory response. NKCC1 and KCC2, chloride transporters, are responsible for uptake and extrusion of chloride ions from local neurons, respectively. Expression of NKCC1 in the neurons results in an excitatory response to GABA and glycine input, often seen in developing neurons in the central brain. The expression of NKCC1 in retinal development and maturation is largely unknown. We investigated the expression of NKCC1 in developmental and adult mouse retinas.
Immunofluorescence antibody–labeling and Western blotting techniques were performed on postnatal (P1–P14) to adult mouse retinas. The localizations and expressions of two modification forms of NKCC1, KCC2 and SV2 were monitored on the retinal slices from the different stages.
During the development, NKCC1 gradually disappeared and replaced by KCC2 in the IPL in new born mice (P1–P5). Meanwhile, NKCC1 increasingly expressed in the OPL from P5 to P14, and stabilized after P21. NKCC1 was strongly, but mixed with KCC2, presented in the second–order neurons in the OPL in the adult retina. In contrast, KCC2 was a major chloride transporter in the IPL in the adult retina. During an early development (P1–P5), SV2, a synaptic vesicle protein 2, slowly moved down from photoreceptor outer nucleus layer to the axon terminals, followed with the formation of synapses in photoreceptors. An active form of NKCC1 strongly expressed in photoreceptor terminals, overlap with SV2, after the synaptic transmission formed. NKCC1, rather than KCC2, exclusively expressed in the terminals of developing and matured photoreceptors.
Expression of NKCC1 is concomitant with synaptic formation in the OPL during the early stage of retinal development. After forming a synaptic connection, a high intracellular chloride is required by photoreceptor synapse. A strong expression of NKCC1 in the pre–mature and adult OPL means that less inhibition is necessary at the first place of synapse in the retina. Possibly, GABA and glycine may produce depolarizing responses on photoreceptors and the second–order neurons in the pre–mature and adult retina.
This PDF is available to Subscribers Only