Postnatal developmental regulation of neuronal nicotinic receptor subunit alpha 7 and multiple alpha 4 and beta 2 mRNA species in the rat.
This study examined the postnatal development of neuronal nicotinic receptor (nAChR) alpha 7, alpha 4 and beta 2 subunit mRNA in the Sprague Dawley rat brain. The hippocampus, septum and cortex were removed on postnatal day 1 (P1), P7, P14, or P28 and analyzed by sex. Northern analysis of cortical and pooled hippocampal and septal total RNA with 32P-alpha-dCTP-labeled alpha 7, alpha 4 (recognizing alpha 4.1 and alpha 4.2 mRNA), and beta 2 nAChR cDNA probes identified three (2.4, 3.8 and 8.0 kb) alpha 4, four (3.5, 5.0, 7.5 and 10.0 kb) beta 2 and a single 5.7 kb alpha 7 mRNA species. Cortical alpha 4 mRNA peaked on P14 and remained high on P28, whereas hippocampal/septal alpha 4 mRNA was higher on P7 and P14 than on P1 and P28. Expression of cortical and hippocampal/septal beta 2 mRNAs decreased on P7, followed by a dramatic peak on P14. alpha 7 mRNA peaked on P7. Throughout development, 2.4 kb alpha 4 mRNA was more intense than 3.8 kb alpha 4 mRNA, whereas 5.0 kb beta 2 mRNA was the most intense cortical and hippocampal/septal beta 2 mRNA species. The alpha 4.1-specific cDNA probe detected similar-sized alpha 4 bands as the pan-specific alpha 4 cDNA probe, therefore precluding the identification of any band as alpha 4.2-specific. These results suggest that postnatal expression of alpha 4 and alpha 7 but not beta 2 mRNAs is brain region-specific, and that the contribution of multiple nAChR subunit mRNA species in development may vary.
Department of Pharmacology and Toxicology, Medical College of Virginia, Virginia Commonwealth University, Richmond 23298-0613, USA.
J J
JJ
Shacka
S E
SE
Robinson
D000375:Aging / Q000502:physiology; D000818:Animals; D000831:Animals, Newborn; D015152:Blotting, Northern; D001921:Brain / Q000254:growth & development / Q000378:metabolism*; D015342:DNA Probes; D017403:In Situ Hybridization; D012333:RNA, Messenger / Q000096:biosynthesis* / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D011978:Receptors, Nicotinic / Q000096:biosynthesis* / Q000235:genetics
D015342:DNA Probes; D012333:RNA, Messenger; D011978:Receptors, Nicotinic