Postnatal changes of nicotinic acetylcholine receptor α2, α3, α4, α7 and β2 subunits genes expression in rat brain

Postnatal changes of nicotinic acetylcholine receptor (nAChR) alpha 2, alpha 3, alpha 4, alpha 7 and beta 2 subunits mRNAs were investigated in rat brain using ribonuclease protection assay. Multiple developmental patterns were observed. (1) transient expression during the first few postnatal weeks; alpha 2 in the hippocampus and rain stem, alpha 3 in the striatum, cerebellum and cortex, alpha 4 in the hippocampus, striatum and cerebellum, alpha 7 in the cerebellum and beta 2 in the striatum. (2) Constant expression across development; alpha 2 and alpha 3 in the thalamus, alpha 4 in the Cortex thalamus and brain stem, alpha 7 in the thalamus and brain stem and beta 2 in all brain regions except striatum. (3) Non-detection across development; alpha 2 in the cortex; striatum and cerebellum. (4) Increase with age; alpha 7 in the cortex and hippocampus. (5) Bell-shaped development; alpha 7 in the striatum. Postnatal changes of nAChR isoforms in different brain regions of rat were investigated by receptor binding assays. The developmental patterns of [H-3]epibatidine and (-)-[H-3]nicotine binding sites were similar to each other in each brain region, but different from that of [H-3]alpha-bungarotoxin binding sites. No obvious correlation was observed between the developmental patterns of [H-3]alpha-bungarotoxin, [H-3]epibatidine and (-)-[H-3]nicotine binding sites and corresponding subunits mRNAs. These results indicate that multiple mechanisms are involved in changes of gene expression of nAChRs subunits in the brain of developing rats. (C) 1998 ISDN. Published by Elsevier Science Ltd.