Electrophysiological Methods for Investigating Inhibitory Synaptic Plasticity
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This chapter provides a detailed electrophysiological protocol for investigating inhibitory synaptic plasticity using the gramicidin perforated patch clamp technique. Gramicidin is a polypeptide antibiotic that is used as a perforating agent because it forms pores in the neuronal membrane that are permeable to monovalent cations and small uncharged molecules, but not to Cl− . Preserving the neuronal Cl− gradient is essential for recording native inhibitory GABAA receptor (GABAA R) currents, which are largely carried by Cl− ions.
Inhibitory synaptic plasticity is a change in the strength of GABA- or glycine-mediated synaptic transmission. The mechanisms underlying inhibitory synaptic plasticity include changes in synaptic conductance (pre- or postsynaptically), as well as changes in the strength and polarity of the neuronal Cl− gradient. The gramicidin perforated patch clamp technique is preferable over the whole cell patch clamp technique, because it does not equilibrate the intracellular milieu with the artificial pipette solution, and thus permits the observation of changes in the native Cl− gradient following the induction of inhibitory synaptic plasticity. This methods chapter describes how to electrophysiologically record GABAA R inhibitory synaptic plasticity between mono-synaptically connected pairs of cultured hippocampal neurons.
