Strychnine-sensitive stabilization of postsynaptic glycine receptor clusters

Area of Science:

• Neuroscience
• Molecular Biology
• Cell Biology

Background:

• Postsynaptic ionotropic receptor aggregation mechanisms in the central nervous system are poorly understood.
• The glycine receptor (GlyR) and gephyrin form a model system for studying these aggregation processes.
• Glycine receptors are inhibited by strychnine.

Purpose of the Study:

• To investigate the effects of chronic strychnine treatment on gephyrin and glycine receptor expression and cellular distribution.
• To elucidate the roles of functional glycine receptors and electrical activity in postsynaptic receptor clustering.

Main Methods:

• Primary cultures of spinal cord neurons were treated with strychnine.
• Reverse transcriptase-polymerase chain reaction (RT-PCR) was used to analyze mRNA expression.
• Standard and confocal immunofluorescence microscopy assessed protein expression and subcellular distribution.

Main Results:

• Strychnine treatment did not alter gephyrin or glycine receptor mRNA levels or the proportion of immunoreactive cells.
• Chronic strychnine exposure significantly reduced glycine receptor clusters on the somato-dendritic membrane.
• Gephyrin cluster distribution and number remained unchanged, indicating differential regulation of GlyR and gephyrin aggregation.

Conclusions:

• Functional glycine receptors are essential for the formation of glycine receptor clusters at the postsynaptic membrane.
• Electrical synaptic activity is not required for glycine receptor cluster formation.
• Glycine receptor and gephyrin aggregation are regulated by distinct molecular mechanisms.