| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Department of Anatomy, Hebrew University Medical School, Jerusalem, Israel.
1. Synaptic transmission between dorsal root afferents and alpha-motoneurones was studied in the in vitro hemisected spinal cord preparation isolated from neonatal rats. 2. Repetitive stimulation of the dorsal roots depressed the monosynaptic reflex recorded from the homologous ventral roots. The depression developed within the first five to six pulses in a stimulus train and stabilized at a plateau-like level for many seconds of stimulation. 3. The magnitude of the reflex depression depended on the stimulation interval and was capable of reducing the reflex to 17% of its undepressed control during 5 Hz stimulus trains. Complete recovery from depression was obtained at stimulation intervals greater than or equal to 30 s. 4. Monosynaptic excitatory postsynaptic potentials (EPSPs) were recorded intracellularly after reduction of the activity in polysynaptic pathways by addition of mephenesin to the bathing media. These EPSPs exhibited a prolonged, frequency-dependent synaptic depression. The depression reduced the amplitude of the EPSP to 25% of the undepressed control during 5 Hz stimulus trains, and was alleviated completely at stimulus interval greater than or equal to 60 s. 5. The prolonged EPSP depression was not altered by blockade of glycinergic and type-A gamma-aminobutyric acid (GABAA-ergic) receptors underlying postsynaptic inhibition in the spinal cord. Injection of current steps to motoneurones before and during the prolonged depression revealed similar values of the membrane time constant and input resistance. These excluded changes in the passive properties of the motoneurone membrane as an explanation for the observed synaptic depression. 6. Extracellular recordings of terminal potentials and their accompanying synaptic fields from motor nuclei in the ventrolateral cord revealed that the frequency-dependent depression in the synaptic fields was not preceded by any detectable changes in the amplitude or the shape of the terminal potential, suggesting that the depression cannot be attributed to impairment of action potential invasion to the afferent terminals. 7. Reduction of the basic level of transmitter release in the spinal cord by increasing the Mg2+/Ca2+ ratio of the bathing solution or by application of 2 microM of L(-)baclofen markedly diminished the synaptic potential depression at all the stimulation intervals tested in this study. Recovery from depression was evident for stimulation intervals greater than or equal to 5 s. Under these conditions, short tetanic trains (5 pulses at 25 Hz) revealed a substantial facilitation and potentiation of the EPSPs. 8. We suggest that prolonged depression of synaptic potentials in the neonatal rat reflects decreased transmitter output from the activated afferent terminals.(ABSTRACT TRUNCATED AT 400 WORDS)
This article has been cited by other articles:
|
|
 |
|
  J. Lundbye-Jensen and J. B. Nielsen Immobilization induces changes in presynaptic control of group Ia afferents in healthy humans J. Physiol., September 1, 2008; 586(17): 4121 - 4135. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
G. Barriere, M. Tartas, J.-R. Cazalets, and S. S. Bertrand Interplay between neuromodulator-induced switching of short-term plasticity at sensorimotor synapses in the neonatal rat spinal cord J. Physiol., April 1, 2008; 586(7): 1903 - 1920. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 K. E. Personius, Q. Chang, G. Z. Mentis, M. J. O'Donovan, and R. J. Balice-Gordon Reduced gap junctional coupling leads to uncorrelated motor neuron firing and precocious neuromuscular synapse elimination PNAS, July 10, 2007; 104(28): 11808 - 11813. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
E. Zaporozhets, K. C. Cowley, and B. J. Schmidt Propriospinal neurons contribute to bulbospinal transmission of the locomotor command signal in the neonatal rat spinal cord J. Physiol., April 15, 2006; 572(2): 443 - 458. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 C. Marchetti, J. Tabak, N. Chub, M. J. O'Donovan, and J. Rinzel Modeling Spontaneous Activity in the Developing Spinal Cord Using Activity-Dependent Variations of Intracellular Chloride J. Neurosci., April 6, 2005; 25(14): 3601 - 3612. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
L. B. Silverman-Gavrila, P. M. R. Orth, and M. P. Charlton Phosphorylation-Dependent Low-Frequency Depression at Phasic Synapses of a Crayfish Motoneuron J. Neurosci., March 23, 2005; 25(12): 3168 - 3180. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 Y. Li and R. E. Burke Developmental Changes in Short-Term Synaptic Depression in the Neonatal Mouse Spinal Cord J Neurophysiol, December 1, 2002; 88(6): 3218 - 3231. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. Donato and A. Nistri Differential Short-Term Changes in GABAergic or Glycinergic Synaptic Efficacy on Rat Hypoglossal Motoneurons J Neurophysiol, August 1, 2001; 86(2): 565 - 574. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. Kilbride, A. M. Rush, M. J. Rowan, and R. Anwyl Presynaptic Group II mGluR Inhibition of Short-Term Depression in the Medial Perforant Path of the Dentate Gyrus In Vitro J Neurophysiol, June 1, 2001; 85(6): 2509 - 2515. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Y. Li and R. E. Burke Short-Term Synaptic Depression in the Neonatal Mouse Spinal Cord: Effects of Calcium and Temperature J Neurophysiol, May 1, 2001; 85(5): 2047 - 2062. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
I. Delvolve, H. Gabbay, and A. Lev-Tov The Motor Output and Behavior Produced by Rhythmogenic Sacrocaudal Networks in Spinal Cords of Neonatal Rats J Neurophysiol, May 1, 2001; 85(5): 2100 - 2110. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 F. J. Thompson, R. Parmer, P. J. Reier, D. C. Wang, and P. Bose Scientific Basis of Spasticity: Insights from a Laboratory Model J Child Neurol, January 1, 2001; 16(1): 2 - 9. [Abstract] [PDF]
|
|
|
|
 |
|
 C. Aymard, R. Katz, C. Lafitte, E. Lo, A. Penicaud, P. Pradat-Diehl, and S. Raoul Presynaptic inhibition and homosynaptic depression: A comparison between lower and upper limbs in normal human subjects and patients with hemiplegia Brain, August 1, 2000; 123(8): 1688 - 1702. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. C. Rekling, G. D. Funk, D. A. Bayliss, X.-W. Dong, and J. L. Feldman Synaptic Control of Motoneuronal Excitability Physiol Rev, April 1, 2000; 80(2): 767 - 852. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. Lev-Tov, I. Delvolve, and E. Kremer Sacrocaudal Afferents Induce Rhythmic Efferent Bursting in Isolated Spinal Cords of Neonatal Rats J Neurophysiol, February 1, 2000; 83(2): 888 - 894. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. L. Brody and D. T. Yue Relief of G-Protein Inhibition of Calcium Channels and Short-Term Synaptic Facilitation in Cultured Hippocampal Neurons J. Neurosci., February 1, 2000; 20(3): 889 - 898. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
E. Sernagor and N. M. Grzywacz Spontaneous Activity in Developing Turtle Retinal Ganglion Cells: Pharmacological Studies J. Neurosci., May 15, 1999; 19(10): 3874 - 3887. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. Ritter, P. Wenner, S. Ho, P. J. Whelan, and M. J. O'Donovan Activity Patterns and Synaptic Organization of Ventrally Located Interneurons in the Embryonic Chick Spinal Cord J. Neurosci., May 1, 1999; 19(9): 3457 - 3471. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B. Fedirchuk, P. Wenner, P. J. Whelan, S. Ho, J. Tabak, and M. J. O'Donovan Spontaneous Network Activity Transiently Depresses Synaptic Transmission in the Embryonic Chick Spinal Cord J. Neurosci., March 15, 1999; 19(6): 2102 - 2112. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
E. Kremer and A. Lev-Tov GABA-Receptor-Independent Dorsal Root Afferents Depolarization in the Neonatal Rat Spinal Cord J Neurophysiol, May 1, 1998; 79(5): 2581 - 2592. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
E. Bracci, M. Beato, and A. Nistri Afferent Inputs Modulate the Activity of a Rhythmic Burst Generator in the Rat Disinhibited Spinal Cord In Vitro J Neurophysiol, June 1, 1997; 77(6): 3157 - 3167. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. C. Mears and E. Frank Formation of Specific Monosynaptic Connections between Muscle Spindle Afferents and Motoneurons in the Mouse J. Neurosci., May 1, 1997; 17(9): 3128 - 3135. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
E. Bracci, L. Ballerini, and A. Nistri Localization of Rhythmogenic Networks Responsible for Spontaneous Bursts Induced by Strychnine and Bicuculline in the Rat Isolated Spinal Cord J. Neurosci., November 1, 1996; 16(21): 7063 - 7076. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
