Functional expression of muscarinic acetylcholine receptors in mouse taste buds

Taste buds, biological chemical sensors, consist of ∼ 40 cells each on mouse tongues. It is suggested that this taste bud cells (TBCs) form cell network with neurotransmitter receptors as neurons form them in the brain. Here we show that TBCs exclusively express M3 subtypes of muscarinic acetylcholine receptors (mAChRs) on the frontal part of the tongue by Ca2+-imaging, RT-PCR, and immunohistochemical studies, and those on the proximal part of the tongue express both M1 and M3 subtypes of mAChRs. We show the effects of innervation or the location on the tongue on the expression of mAChR subtypes, and discuss the physiological role of mAChRs on TBCs and its application on chemical sensors.