Learning‐dependent regulation of beta2 and gamma2 subunits of GABAAR mRNA in sensory cortex of mice

Abstract

GABAA receptors are heteromeric, ligand‐gated ion channels, built up with 19 different subunits. In the somatosensory cortex the most prevalent subunits are: alpha1, beta2 and gamma2. We showed that classical conditioning, in which stimulation of a row of vibrissae (CS) was paired with a tail shock (UCS), results in changes in cortical inhibitory system. Among others, GABAAalpha1 mRNA is up‐regulated in layer IV of cortical representation of trained row of vibrissae. We examined the mRNA expression level of beta2 and gamma2 subunits of GABAAR. For in situ hybridization, 35S‐labeled oligonucleotides were used as antisense probes. The effects were examined 1 h, 24 h and 5 days after the training lasting 3 days. There are no changes observed in beta2 subunits mRNA level. Expression of mRNA of gamma2 subunits increased 5 days after the training, but in contrast to other elements of gabaergic system we investigated, the change was observed in layers II/III. This indicates that learning‐dependent regulation of GABAA receptor phenotype is specific for given neuronal subtype.