ANALYSIS OF NICOTINIC ACETYLCHOLINE-RECEPTOR SUBUNITS IN THE COCHLEA OF THE MOUSE

The present study was designed to catalogue and compare nicotinic rece ptor subunit messages in the mammalian cochlea, Fourteen nicotinic ace tylcholine receptor subunit messages were examined by polymerase chain reaction (PCR) analysis and nucleotide sequencing, Total RNA was extr acted from the auditory organs of 14- to 18-day-old CBA(J) mice, and m RNA was purified using oligo-dT cellulose. After reverse transcription , resulting cDNA was amplified by PCR with the use of primers specific for the nucleotide sequences representing the following nicotinic rec eptor subunits: muscle types alpha 1, beta 1, gamma, delta and epsilon neuronal types alpha 2,3,4,5,6,7 and beta 2,3,4. cDNA from cochlear t issue corresponding to the muscle-type receptor subunit pi and to neur onal-type receptor subunits alpha 2,4,5,6 and beta 2,3 was amplified, whereas cDNA for muscle types alpha 1, gamma, delta, and epsilon and n euronal types alpha 3,7 and beta 4 was not. All PCR products were homo logous in nucleotide sequence to the corresponding reference cDNAs fro m which the primers were designed, The current results indicate that n icotinic acetylcholine receptor (nAChR) subunits that are similar or i dentical to the stated muscle and neuronal types are expressed in the murine cochlea. The presence of messages corresponding to the muscle t ype pi and neuronal-type nAChR subunits may be correlated with the aty pical cholinergic response of cochlear hair cells to agonists and anta gonists.