| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Spontaneous miniature inhibitory postsynaptic currents (mIPSCs) recorded in central neurons are usually highly variable in amplitude due to many factors such as intrinsic postsynaptic channel fluctuations at each release site, site-to-site variability between release sites, electrotonic attenuation due to variable dendritic locations of synapses, and the possibility of synchronous multivesicular release. A detailed knowledge of these factors is essential for the interpretation of mIPSC amplitude distributions and mean quantal size. We have studied glycinergic mIPSCs in two auditory brainstem nuclei, the rat anteroventral cochlear nucleus (AVCN) and the mouse medial nucleus of the trapezoid body (MNTB). Our previous results have demonstrated the location of glycinergic synapses on these neurons to be somatic, thus avoiding electrotonic complications. Spontaneous glycinergic mIPSCs were recorded from AVCN and MNTB neurons in brainstem slices, in the presence of TTX to block action potentials, and 6-cyano-7-nitroquinoxaline-2, 3-dione, (±)-2-amino-5-phosphonopentanoic acid and bicuculline to block glutamatergic and GABAergic synaptic currents. Ruthenium red (RuR), which was used to increase the frequency of mIPSCs, significantly changed the shape of most (90 %) mIPSC amplitude distributions by increasing the proportion of large-amplitude mIPSCs. The possibility was investigated (following previous evidence at GABAergic synapses) that large-amplitude glycinergic mIPSCs are due to synchronous multivesicular release initiated by presynaptic calcium sparks from ryanodine-sensitive calcium stores. Interval analysis of mIPSCs indicated that the number of potentially undetected (asynchrony < 0.5 ms) multivesicular mIPSCs was low in comparison with the number of large-amplitude mIPSCs. Ryanodine, thapsigargin and calcium-free perfusate did not reduce the frequency of large-amplitude mIPSCs (> 150 pA), arguing against a significant role for presynaptic calcium stores. Our results support previous evidence suggesting that RuR increases miniature postsynaptic current (mSC) frequency by a mechanism that does not involve presynaptic calcium stores. Our results also indicate that at glycinergic synapses in the AVCN and MNTB, site-to-site variability in mIPSC amplitude, rather than multivesicular release, is a major factor underlying the large range of amplitudes of glycinergic mIPSCs.
This article has been cited by other articles:
|
|
 |
|
  H. Shimizu, M. Fukaya, M. Yamasaki, M. Watanabe, T. Manabe, and H. Kamiya Use-dependent amplification of presynaptic Ca2+ signaling by axonal ryanodine receptors at the hippocampal mossy fiber synapse PNAS, August 19, 2008; 105(33): 11998 - 12003. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 I. Milenkovic, M. Witte, R. Turecek, M. Heinrich, T. Reinert, and R. Rubsamen Development of Chloride-Mediated Inhibition in Neurons of the Anteroventral Cochlear Nucleus of Gerbil (Meriones unguiculatus) J Neurophysiol, September 1, 2007; 98(3): 1634 - 1644. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. J. Camp, R. J. Callister, and A. M. Brichta Inhibitory Synaptic Transmission Differs in Mouse Type A and B Medial Vestibular Nucleus Neurons In Vitro J Neurophysiol, May 1, 2006; 95(5): 3208 - 3218. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 Q. Liu, B. Chen, M. Yankova, D. K. Morest, E. Maryon, A. R. Hand, M. L. Nonet, and Z.-W. Wang Presynaptic Ryanodine Receptors Are Required for Normal Quantal Size at the Caenorhabditis elegans Neuromuscular Junction J. Neurosci., July 20, 2005; 25(29): 6745 - 6754. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. Dahlhaus, R. Ruscheweyh, and J. Sandkuhler Synaptic input of rat spinal lamina I projection and unidentified neurones in vitro J. Physiol., July 15, 2005; 566(2): 355 - 368. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
G. B. Awatramani, R. Turecek, and L. O. Trussell Staggered Development of GABAergic and Glycinergic Transmission in the MNTB J Neurophysiol, February 1, 2005; 93(2): 819 - 828. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C.-Y. Chen and A. C. Bonham Glutamate suppresses GABA release via presynaptic metabotropic glutamate receptors at baroreceptor neurones in rats J. Physiol., January 15, 2005; 562(2): 535 - 551. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. Conti, Y. P. Tan, and I. Llano Action Potential-Evoked and Ryanodine-Sensitive Spontaneous Ca2+ Transients at the Presynaptic Terminal of a Developing CNS Inhibitory Synapse J. Neurosci., August 4, 2004; 24(31): 6946 - 6957. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
G. B. Awatramani, R. Turecek, and L. O. Trussell Inhibitory Control at a Synaptic Relay J. Neurosci., March 17, 2004; 24(11): 2643 - 2647. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. N. Leao, S. Oleskevich, H. Sun, M. Bautista, R. E.W. Fyffe, and B. Walmsley Differences in Glycinergic mIPSCs in the Auditory Brain Stem of Normal and Congenitally Deaf Neonatal Mice J Neurophysiol, February 1, 2004; 91(2): 1006 - 1012. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. Levi, S. M. Logan, K. R. Tovar, and A. M. Craig Gephyrin Is Critical for Glycine Receptor Clustering But Not for the Formation of Functional GABAergic Synapses in Hippocampal Neurons J. Neurosci., January 7, 2004; 24(1): 207 - 217. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
E. H. Chang, V. C. Kotak, and D. H. Sanes Long-Term Depression of Synaptic Inhibition Is Expressed Postsynaptically in the Developing Auditory System J Neurophysiol, September 1, 2003; 90(3): 1479 - 1488. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
