Expression Of M2 Muscarinic Acetylcholine Receptor Of Guinea Pig Vestibular Hair Cell

[Object] Recent experimental work has demonstrated that five muscarinic acetylcholine receptor (mAChR) subtypes (m1–m5) are expressed in the vestibular periphery. However, the cellular location of the mAChRs were unclear. In this study, we investigate whether there is the expression of m2 muscarinic receptor mRNA in vestibular end-organ and isolated typeⅡvestibular hair cells of guinea pig.[Methods] Using reverse transcription polymerase chain reaction (RT-PCR) and single cell RT-PCR technique respectively to detect the expression of m2 muscarinic receptor mRNA in vestibular end-organ and isolated typeⅡvestibular hair cells of guinea pig.[Results] In vestibular end-organ, a cDNA of the expected size was obtained by RT-PCR. Further, m2 mRNA was identified by RT-PCR from individually isolated type II vestibular hair cells (single-cell RT-PCR). The products were confirmed to be m2 by sequence analysis.[Conclusion] These results demonstrate the expression of m2 mAChR in the typeⅡvestibular hair cells of the guinea pig, and lend further support for the role of m2 may be one of the mediators of efferent cholinergic signaling in vestibular hair cells as well.