The alpha 7 nicotinic receptors in human fetal brain and spinal cord

The alpha 7 nicotinic acetylcholine receptor subtype is believed to be involved in the regulation of neuronal growth, differentiation and synapse formation during the development of the human brain. In this study the expression of the alpha 7 nicotinic acetylcholine receptor was investigated in human fetal brain and spinal cord of 5-11 weeks gestational age. Both the specific binding of [ super(125)I] alpha -bungarotoxin to prenatal brain membranes and the expression of alpha 7 mRNA were significantly higher in the pons, medulla oblongata, mesencephalon and spinal cord of 9-11 weeks gestational age compared with cerebellum, cortex and subcortical forebrain. A significant positive correlation between gestational age and the expression of alpha 7 mRNA was observed in all brain regions except cortex. A positive correlation was also observed between the gestational age and the [ super(125)I] alpha -bungarotoxin binding in the pons, medulla oblongata, mesencephalon, and cerebellum. Consequently, a significant relationship between the alpha 7 mRNA levels and the binding sites for [ super(125)I] alpha -bungarotoxin was found in the fetal brain. The increasing levels of the alpha 7 nicotinic acetylcholine receptor during the first trimester support the important role of nAChRs for the development of the central nervous system.