Differential expression of an inwardly rectifying chloride conductance in rat brain neurons: A potential mechanism for cell-specific modulation of postsynaptic inhibition

Abstract

A voltage-sensitive inwardly rectifying chloride (Cl-) conductance (G(Cl(v))) is present in hippocampal pyramidal but not dentate gyrus neurons and has a significant role in modulation of neuronal inhibition by GABA. G(Cl(v)) has the same activation properties as the cloned and expressed Cl channel CIC-2. In brain, CIC-2 was detected selectively in neurons, and in hippocampus was detected in the same populations of neurons that demonstrate G(Cl(v)). CIC-2 mRNA expression varied widely in different neuronal populations in brain but was greatest in pyramidal and other large neurons and least in interneurons. The observed differential expression of CIC-2 provides a potential molecular basis for the paradoxical excitation produced by GABA(A) receptor activation in selected neuronal populations.