Purinergic signaling in cochleovestibular hair cells and afferent neurons.

1. Purinergic Signal. 2010 Jun;6(2):201-9. doi: 10.1007/s11302-010-9183-x. Epub 2010
May 20.

Purinergic signaling in cochleovestibular hair cells and afferent neurons.

Ito K, Dulon D.

Purinergic signaling in the mammalian cochleovestibular hair cells and afferent
neurons is reviewed. The scope includes P2 and P1 receptors in the inner hair
cells (IHCs) of the cochlea, the type I spiral ganglion neurons (SGNs) that
convey auditory signals from IHCs, the vestibular hair cells (VHCs) in the
vestibular end organs (macula in the otolith organs and crista in the
semicircular canals), and the vestibular ganglion neurons (VGNs) that transmit
postural and rotatory information from VHCs. Various subtypes of P2X ionotropic
receptors are expressed in IHCs as well as P2Y metabotropic receptors that
mobilize intracellular calcium. Their functional roles still remain speculative,
but adenosine 5′-triphosphate (ATP) could regulate the spontaneous activity of
the hair cells during development and the receptor potentials of mature hair
cells during sound stimulation. In SGNs, P2Y metabotropic receptors activate a
nonspecific cation conductance that is permeable to large cations as NMDG(+) and
TEA(+). Remarkably, this depolarizing nonspecific conductance in SGNs can also be
activated by other metabotropic processes evoked by acetylcholine and tachykinin.
The molecular nature and the role of this depolarizing channel are unknown, but
its electrophysiological properties suggest that it could lie within the
transient receptor potential channel family and could regulate the firing
properties of the afferent neurons. Studies on the vestibular partition (VHC and
VGN) are sparse but have also shown the expression of P2X and P2Y receptors.
There is still little evidence of functional P1 (adenosine) receptors in the
afferent system of the inner ear.

DOI: 10.1007/s11302-010-9183-x
PMCID: PMC2912986
PMID: 20806012

Know more about