Alterations in a unique class of cortical chandelier cell axon cartridges in schizophrenia

摘要

BackgroundThe axons of chandelier cells (ChCs) target the axon initial segment (AIS) of pyramidal neurons, forming an array of boutons termed a cartridge. In schizophrenia, the density of cartridges detectable by GABA membrane transporter-1 (GAT1) immunoreactivity is lower, whereas the density of AISs detectable by immunoreactivity for the α2 subunit of the GABA-A receptor is higher in layers 2-superficial 3 of the prefrontal cortex (PFC). These findings were interpreted as compensatory responses to lower GABA levels in ChCs. However, we recently found that in schizophrenia ChC cartridge boutons contain normal levels of the 67 kDa isoform of glutamic acid decarboxylase (GAD67) protein, the enzyme responsible for GABA synthesis in these boutons. To understand these findings we quantified the densities of ChC cartridges immunoreactive for vesicular GABA transporter (vGAT+), which is present in all cartridge boutons, and the subset of cartridges that contain calbindin (CB+).