Expression of neuronal nicotinic acetylcholine receptor genes in the developing chick visual system

Expression of the neuronal non‐alpha nicotinic acetylcholine receptor (n alpha nAChR) gene is transiently stimulated in the chick optic tectum between embryonic days 7 and 16 with a peak value reached around embryonic day 12. This stimulation takes place at the time when optic nerve axons are invading this region of the brain and proceeds along a rostral to caudal gradient. Transcripts of the n alpha nAChR gene are localized in the superficial layers of the tectum at the time when cells in these layers are forming synapses with retina axons. The transient expression of n alpha nAChR gene does not take place in the optic tectum of ‘eyeless’ embryos. The results of our study suggest that the neuronal n alpha nAChR gene may play a role in neurogenesis of retino‐tectal connections.