Molecular characterization of muscarinic receptors in the human vestibular periphery. Implications for pharmacotherapy.
OBJECTIVE
Muscarinic acetylcholine receptor subtypes are expressed in the human vestibular periphery to receive efferent innervation on the type II vestibular hair cells and primary afferent dendrites.


BACKGROUND
Previous immunohistochemical and electrophysiologic studies have shown that acetylcholine (ACh) is likely the primary neurotransmitter of the efferent vestibular periphery. The structural distribution of nicotinic receptors (nAChR) and muscarinic receptors (mAChR) are not well established in the human vestibular periphery.


METHODS
Reverse transcription polymerase chain reaction (RT-PCR) was used to study the expression of all five mAChR subtypes in Scarpa's ganglia and the vestibular end-organs of the rat and human.


RESULTS
The authors found m1 through m5 expression in rats, and m1, m2, and m5 expression in humans.


CONCLUSIONS
These studies show evidence that both muscarinic acetylcholine receptors are present in the human vestibular periphery in addition to the nicotinic receptors reported previously. The pharmacologic implications of these data are discussed.
Ishiyama
A
A
Otology Group, EAR Foundation, Nashville, Tennessee, USA.
López
I
I
Wackym
P A
PA
D000818:Animals; D046508:Culture Techniques; D017931:DNA Primers; D018076:DNA, Complementary; D004587:Electrophoresis, Agar Gel; D005784:Gene Amplification; D006801:Humans; D009475:Neurons, Afferent / Q000502:physiology; D009476:Neurons, Efferent / Q000502:physiology; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger; D051381:Rats; D011976:Receptors, Muscarinic / Q000235:genetics*; D014158:Transcription, Genetic; D014725:Vestibular Nerve
D017931:DNA Primers; D018076:DNA, Complementary; D012333:RNA, Messenger; D011976:Receptors, Muscarinic