QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

HOME  |   SEARCH  |   ARCHIVE  |   SUBSCRIBE  |   CONTACT  |   HELP

The Journal of Neuroscience, March 1, 2006, 26(9):2555-2563; doi:10.1523/JNEUROSCI.3667-05.2006

This Article Full Text Full Text (PDF) Supplemental data Submit an eLetter Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (11) Citing Articles via Google Scholar Google Scholar Articles by Rabl, K. Articles by Thoreson, W. B. Search for Related Content PubMed PubMed Citation Articles by Rabl, K. Articles by Thoreson, W. B.

 Previous Article  |  Next Article 

Cellular/Molecular
Paired-Pulse Depression at Photoreceptor Synapses

Katalin Rabl,¹ Lucia Cadetti,¹ and Wallace B. Thoreson^1,2

¹Departments of Ophthalmology and Visual Sciences and ²Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, Nebraska 68198-5840

Correspondence should be addressed to Wallace B. Thoreson, Ophthalmology Department, University of Nebraska Medical Center, Durham Research Center, Room 4026, Omaha, NE 68198-5840. Email: wbthores{at}unmc.edu

Synaptic depression produced by repetitive stimulation is likely to be particularly important in shaping responses of second-order retinal neurons at the tonically active photoreceptor synapse. We analyzed the time course and mechanisms of synaptic depression at rod and cone synapses using paired-pulse protocols involving two complementary measurements of exocytosis: (1) paired whole-cell recordings of the postsynaptic current (PSC) in second-order retinal neurons and (2) capacitance measurements of vesicular membrane fusion in rods and cones. PSCs in ON bipolar, OFF bipolar, and horizontal cells evoked by stimulation of either rods or cones recovered from paired-pulse depression (PPD) at rates similar to the recovery of exocytotic capacitance changes in rods and cones. Correlation between presynaptic and postsynaptic measures of recovery from PPD suggests that 80–90% of the depression at these synapses is presynaptic in origin. Consistent with a predominantly presynaptic mechanism, inhibiting desensitization of postsynaptic glutamate receptors had little effect on PPD. The depression of exocytotic capacitance changes exceeded depression of the presynaptic calcium current, suggesting that it is primarily caused by a depletion of synaptic vesicles. In support of this idea, limiting Ca²⁺ influx by using weaker depolarizing stimuli promoted faster recovery from PPD. Although cones exhibit much faster exocytotic kinetics than rods, exocytotic capacitance changes recovered from PPD at similar rates in both cell types. Thus, depression of release is not likely to contribute to differences in the kinetics of transmission from rods and cones.

Key words: ribbon synapse; capacitance measurement; retina; tiger salamander; photoreceptor; postsynaptic current

---

Received Aug. 30, 2005; revised Jan. 12, 2006; accepted Jan. 13, 2006.

Correspondence should be addressed to Wallace B. Thoreson, Ophthalmology Department, University of Nebraska Medical Center, Durham Research Center, Room 4026, Omaha, NE 68198-5840. Email: wbthores{at}unmc.edu

This article has been cited by other articles:

				T. M. Bartoletti, N. Babai, and W. B. Thoreson Vesicle Pool Size at the Salamander Cone Ribbon Synapse J Neurophysiol, January 1, 2010; 103(1): 419 - 423. [Abstract] [Full Text] [PDF]

				Q. Liu, G. Hollopeter, and E. M. Jorgensen Graded synaptic transmission at the Caenorhabditis elegans neuromuscular junction PNAS, June 30, 2009; 106(26): 10823 - 10828. [Abstract] [Full Text] [PDF]

				J.-J. Pang, F. Gao, A. Barrow, R. A. Jacoby, and S. M. Wu How do tonic glutamatergic synapses evade receptor desensitization? J. Physiol., June 15, 2008; 586(12): 2889 - 2902. [Abstract] [Full Text] [PDF]

				B. Innocenti and R. Heidelberger Mechanisms Contributing to Tonic Release at the Cone Photoreceptor Ribbon Synapse J Neurophysiol, January 1, 2008; 99(1): 25 - 36. [Abstract] [Full Text] [PDF]

				R. Heidelberger Mechanisms of tonic, graded release: lessons from the vertebrate photoreceptor J. Physiol., December 15, 2007; 585(3): 663 - 667. [Abstract] [Full Text] [PDF]

				A. Molnar and F. Werblin Inhibitory Feedback Shapes Bipolar Cell Responses in the Rabbit Retina J Neurophysiol, December 1, 2007; 98(6): 3423 - 3435. [Abstract] [Full Text] [PDF]

				G.-L. Li, J. Vigh, and H. von Gersdorff Short-Term Depression at the Reciprocal Synapses between a Retinal Bipolar Cell Terminal and Amacrine Cells J. Neurosci., July 11, 2007; 27(28): 7377 - 7385. [Abstract] [Full Text] [PDF]

				J. L. Duncan, H. Yang, T. Doan, R. S. Silverstein, G. J. Murphy, G. Nune, X. Liu, D. Copenhagen, B. L. Tempel, F. Rieke, et al. Scotopic visual signaling in the mouse retina is modulated by high-affinity plasma membrane calcium extrusion. J. Neurosci., July 5, 2006; 26(27): 7201 - 7211. [Abstract] [Full Text] [PDF]

Home  |   Search  |   Archive  |   Subscribe  |   Contact  |   Help