Dopamine modifies the balance of rod and cone inputs to horizontal cells of the Xenopus retina

Witkovsky, Paul; Stone, S.; Besharse, Joseph C.

doi:10.1016/0006-8993(88)91048-7

Cited by 121 publications

(91 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…With gramicidin-perforated patch-recording techniques, quinpirole stimulated a small depolarization of the dark membrane potential averaging 1.2 ± 0.46 mV (P = 0.03, n = 11). Similar to results of Witkovsky et al (1988), quinpirole caused little change in peak amplitude or waveform. As can be seen from the amplitude/intensity curves for 580-and 680-nm light flashes in Figure 3C and the difference in σ values for 580-and 680-nm lights plotted in Figure 3D, quinpirole did not significantly alter the relative sensitivity of rods to 580-versus 680-nm lights which was in both cases near 2.2 log units, consistent with the light-evoked current measurements of Makino and Dodd (1996).…”

Section: Effects Of Quinpirole On I Casupporting

confidence: 76%

“…The first is that quinpirole, an agonist at dopamine D 2 /D 4 receptors (Grandy et al, 1994;Van Tol, 1994), increases cone input to the second-order retinal neurons, horizontal and bipolar cells (Witkovsky et al, 1988;present report). The other is that quinpirole increases I Ca in rods (Stella & Thoreson, 2000), a result that would be predicted to increase transmitter release by rods and enhance rod input to second-order neurons.…”

Section: Discussion the Experimental Problem Posed By Prior Findingsmentioning

confidence: 88%

See 1 more Smart Citation

D₂-like dopamine receptors promote interactions between calcium and chloride channels that diminish rod synaptic transfer in the salamander retina

et al. 2002

Self Cite

View full text Add to dashboard Cite

show abstract

Section: Effects Of Quinpirole On I Casupporting

confidence: 76%

Section: Discussion the Experimental Problem Posed By Prior Findingsmentioning

confidence: 88%

D₂-like dopamine receptors promote interactions between calcium and chloride channels that diminish rod synaptic transfer in the salamander retina

et al. 2002

Self Cite

View full text Add to dashboard Cite

show abstract

“…Although circadian mechanisms increase dopamine release modestly during prolonged darkness at night (Weiler et al, 1997), dopamine release is substantially enhanced (up to 3-4-fold) by increasing illumination (Godley and Wurtman, 1988;Boatright et al, 1989;Witkovsky et al, 1993). Increasing dopamine levels in daylight illumination diminish the strength of rod signals and enhance cone signals in second-order neurons (Witkovsky et al, 1988(Witkovsky et al, , 1989. The effects of dopamine on photoreceptor output are mediated in part by D 2 -like (D 2 or D 4 ) dopamine receptors on rods and cones (Muresan and Besharse, 1993).…”

Section: Extrinsic Neuromodulatorsmentioning

confidence: 99%

Synaptic transmission at retinal ribbon synapses

Heidelberger

Thoreson

Witkovsky

2005

Progress in Retinal and Eye Research

Self Cite

209

231

View full text Add to dashboard Cite

The molecular organization of ribbon synapses in photoreceptors and ON bipolar cells is reviewed in relation to the process of neurotransmitter release. The interactions between ribbon synapseassociated proteins, synaptic vesicle fusion machinery and the voltage-gated calcium channels that gate transmitter release at ribbon synapses are discussed in relation to the process of synaptic vesicle exocytosis. We describe structural and mechanistic specializations that permit the ON bipolar cell to release transmitter at a much higher rate than the photoreceptor does, under in vivo conditions. We also consider the modulation of exocytosis at photoreceptor synapses, with an emphasis on the regulation of calcium channels.

show abstract

“…Xenopus HCs have a glycine-gated Cl conductance (Stone and Witkovsky, 1984) and may also have a small GABA-gated Cl conductance (Witkovsky and Stone, 1987). In the absence of any detailed information on the dependence of the HC Cl conductance on light level in this preparation, we begin by making the simplif ying assumption that the C l conductance is constant.…”

Section: A Model For Gain At the Rod Output Synapsementioning

confidence: 99%

Gain of Rod to Horizontal Cell Synaptic Transfer: Relation to Glutamate Release and a Dihydropyridine-Sensitive Calcium Current

Witkovsky

Schmitz²,

Akopian³

et al. 1997

J. Neurosci.

Self Cite

View full text Add to dashboard Cite

We related rod to horizontal cell synaptic transfer to glutamate release by rods. Simultaneous intracellular records were obtained from dark-adapted rod-horizontal cell pairs. Steadystate synaptic gain (defined as the ratio of horizontal cell voltage to rod voltage evoked by the same light stimulus) was 3.35 Ϯ 0.60 for dim flashes and 1.50 Ϯ 0.03 for bright flashes. Under conditions of maintained illumination, there was a measurable increment of horizontal cell hyperpolarization for each light-induced increment of rod hyperpolarization over the full range of rod voltages.In separate experiments we studied glutamate release from an intact, light-responsive photoreceptor layer, from which inner retinal layers were removed. Steady light reduced glutamate release as a monotonic function of intensity; spectral sensitivity measures indicated that we monitored glutamate release from rods. The dependence of glutamate release on rod voltage was well fit by the activation function for a high-voltage-activated, dihydropyridine-sensitive L-type calcium current, suggesting a linear dependence of glutamate release on [Ca] i in the synaptic terminal. A simple model incorporating this assumption accounts for the steady-state gain of the rod to horizontal cell synapse.Key words: Xenopus; photoreceptor; rod; synaptic gain; horizontal cell; glutamate release; calcium In vertebrate retinas, the photoreceptors (rods and cones) and the second-order retinal neurons (horizontal and bipolar cells) all are nonspiking neurons with light-evoked responses that are slow potentials of complex waveform, graded in amplitude with stimulus intensity. Glutamate, the transmitter used by both rods and cones (Copenhagen and Jahr, 1989;Marc et al., 1990) is released at a steady rate in darkness (Schmitz and Witkovsky, 1996). Light, by hyperpolarizing the photoreceptor membrane, decreases glutamate release (for review, see Wu, 1994).At synapses between spiking cells, types N and P calcium channels are most often implicated in the gating of neurotransmitter release (for review, see Olivera et al., 1994;Regehr and Mintz, 1994;Katz et al. 1995). In contrast, at a tonic retinal synapse for which a depolarizing bipolar cell is the presynaptic element, transmitter release is controlled by a dihydropyridinesensitive L -type calcium current (Heidelberger and Matthews, 1992;Tachibana et al., 1993). Rods and cones also possess an L-type C a current (Bader et al., 1982;Corey et al., 1984;Barnes and Hille, 1989;Lasater and Witkovsky, 1991;Wilkinson and Barnes, 1996), and there is evidence that it underlies exocytosis (Rieke and Schwartz, 1996) and glutamate release (Schmitz and Witkovsky, 1997). In contrast to the depolarizing bipolar cell, however, light hyperpolarizes the photoreceptor, bringing its membrane into a voltage range (ϽϪ45 mV) in which the L-type Ca current, as characterized by whole-cell patch-clamp recordings (Corey et al., 1984;Wilkinson and Barnes, 1996), becomes too small to measure. A main concern of the present study is whether the L-type Ca ...

show abstract

Dopamine modifies the balance of rod and cone inputs to horizontal cells of the Xenopus retina

Cited by 121 publications

References 9 publications

D₂-like dopamine receptors promote interactions between calcium and chloride channels that diminish rod synaptic transfer in the salamander retina

D₂-like dopamine receptors promote interactions between calcium and chloride channels that diminish rod synaptic transfer in the salamander retina

Synaptic transmission at retinal ribbon synapses

Gain of Rod to Horizontal Cell Synaptic Transfer: Relation to Glutamate Release and a Dihydropyridine-Sensitive Calcium Current

Contact Info

Product

Resources

About

Dopamine modifies the balance of rod and cone inputs to horizontal cells of the Xenopus retina

Cited by 121 publications

References 9 publications

D2-like dopamine receptors promote interactions between calcium and chloride channels that diminish rod synaptic transfer in the salamander retina

D2-like dopamine receptors promote interactions between calcium and chloride channels that diminish rod synaptic transfer in the salamander retina

Synaptic transmission at retinal ribbon synapses

Gain of Rod to Horizontal Cell Synaptic Transfer: Relation to Glutamate Release and a Dihydropyridine-Sensitive Calcium Current

Contact Info

Product

Resources

About

D₂-like dopamine receptors promote interactions between calcium and chloride channels that diminish rod synaptic transfer in the salamander retina

D₂-like dopamine receptors promote interactions between calcium and chloride channels that diminish rod synaptic transfer in the salamander retina