Expression of GABAB1 and GABAB2 mRNA in the human brain

GABA(B) receptors are widely expressed in the CNS. The distribution of the recently cloned GABA(B1) receptor is highly concordant with GABA(B) ligand binding sites, but experiments with transfected cell lines indicate that GABA(B1) has to heterodimerize with GABA(B2) to gain the functionality of a native GABA(B) receptor. Using in situ hybridization we investigated the expression of GABA(B1) and GABAB2 mRNAs in the human brain. Both transcripts were detectable in prefrontal-cortex, hippocampus and cerebellum with no apparent mismatch. A distinct expression of GABA(B1) was detected in putative Bergmann glia. In the human striatum GABA(B1) mRNA was expressed in moderate amounts, whereas the GABAB2 mRNA signal was not clearly above background. According to our data, the current concept on GABA(B) receptor composition needs re-evaluation, at least for certain brain structures. NeuroReport 12:3269-3275 (C) 2001 Lippincott Williams & Wilkins.