Postnatal changes of nicotinic acetylcholine receptor alpha 2, alpha 3, alpha 4, alpha 7 and beta 2 subunits genes expression in rat brain

Postnatal changes of nicotinic acetylcholine receptor (nAChR) alpha 2, alph a 3, alpha 4, alpha 7 and beta 2 subunits mRNAs were investigated in rat br ain using ribonuclease protection assay. Multiple developmental patterns we re observed. (1) transient expression during the first few postnatal weeks; alpha 2 in the hippocampus and rain stem, alpha 3 in the striatum, cerebel lum and cortex, alpha 4 in the hippocampus, striatum and cerebellum, alpha 7 in the cerebellum and beta 2 in the striatum. (2) Constant expression acr oss 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; al pha 7 in the cortex and hippocampus. (5) Bell-shaped development; alpha 7 i n the striatum. Postnatal changes of nAChR isoforms in different brain regi ons of rat were investigated by receptor binding assays. The developmental patterns of [H-3]epibatidine and (-)-[H-3]nicotine binding sites were simil ar to each other in each brain region, but different from that of [H-3]alph a-bungarotoxin binding sites. No obvious correlation was observed between t he developmental patterns of [H-3]alpha-bungarotoxin, [H-3]epibatidine and (-)-[H-3]nicotine binding sites and corresponding subunits mRNAs. These res ults indicate that multiple mechanisms are involved in changes of gene expr ession of nAChRs subunits in the brain of developing rats. (C) 1998 ISDN. P ublished by Elsevier Science Ltd.