Premium
Anti‐homeostatic synaptic plasticity of glycine receptor function after chronic strychnine in developing cultured mouse spinal neurons
Author(s) -
Carrasco M. A.,
Castro P. A.,
Sepulveda F. J.,
Cuevas M.,
Tapia J. C.,
Izaurieta P.,
Zundert B. van,
Aguayo L. G.
Publication year - 2007
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.2006.04306.x
Subject(s) - strychnine , cnqx , glycine receptor , bicuculline , neuroscience , neurotransmission , inhibitory postsynaptic potential , ampa receptor , synaptic plasticity , chemistry , homeostatic plasticity , synaptic augmentation , metaplasticity , biology , excitatory postsynaptic potential , nmda receptor , gabaa receptor , receptor , glycine , biochemistry , amino acid
In this study, we describe a novel form of anti‐homeostatic plasticity produced after culturing spinal neurons with strychnine, but not bicuculline or 6‐cyano‐7‐nitroquinoxaline‐2,3‐dione (CNQX). Strychnine caused a large increase in network excitability, detected as spontaneous synaptic currents and calcium transients. The calcium transients were associated with action potential firing and activation of γ‐aminobutyric acid (GABA A ) and alpha‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazolepropionic acid (AMPA) receptors as they were blocked by tetrodotoxin (TTX), bicuculline, and CNQX. After chronic blockade of glycine receptors (GlyRs), the frequency of synaptic transmission showed a significant enhancement demonstrating the phenomenon of anti‐homeostatic plasticity. Spontaneous inhibitory glycinergic currents in treated cells showed a fourfold increase in frequency (from 0.55 to 2.4 Hz) and a 184% increase in average peak amplitude compared with control. Furthermore, the augmentation in excitability accelerated the decay time constant of miniature inhibitory post‐synaptic currents. Strychnine caused an increase in GlyR current density, without changes in the apparent affinity. These findings support the idea of a post‐synaptic action that partly explains the increase in synaptic transmission. This phenomenon of synaptic plasticity was blocked by TTX, an antibody against brain‐derived neurotrophic factor (BDNF) and K252a suggesting the involvement of the neuronal activity‐dependent BDNF‐TrkB signaling pathway. These results show that the properties of GlyRs are regulated by the degree of neuronal activity in the developing network.