title: Functional expression of P2 receptors in the inner ear of chicken embryo.
abstract: The purpose of the present study was to investigate the modulation of spontaneous afferent activity by ATP during embryonic development in a preparation isolated chicken inner ear. This work was performed using multiunit and single-unit extracellular recordings from the posterior semicircular canal nerve and the basilar papilla nerve. α,β-meATP, a P2X receptor agonist, notably increased the discharge frequency of the vestibular afferents between E15 and E18, but not in the basilar papilla. In contrast, the P2Y receptor agonist UTP produced a slight increase in the discharge frequency of basilar papilla afferents, without apparent changes in the vestibular afferent activity. 2-MeSATP, a P2Y agonist, increased the basal discharge of the primary afferents in a dose-age dependent way, but when we applied the antagonist of P2Y receptor, Reactive Blue 2 (10(-4)M), the effect of 2-MeSATP decreased significantly. This was observed both in vestibule and basilar papilla. Using RT-PCR the presence of P2X₃, P2Y₁, P2Y₂ and P2Y₆ mRNA was documented in the vestibular system with more important presence during the early stage (E15) than the later stage (E21), however in the basilar papilla we found only the P2Y₁, P2Y₂ and P2Y₆ mRNA with the same temporal course as in the vestibule. These results confirm our pharmacological findings. Together this data suggests a role for P2X receptors-mediated purinergic signaling in vestibular synaptic organization. Temporal changes in P2Y receptors during development might be involved in the establishment of the endolymphatic ion composition needed for normal vestibular and auditory transduction and/or specific cellular differentiation.
authors: Instituto de Fisiología, Benemérita Universidad Autónoma de Puebla, Av. 14 Sur 6301 Colonia Jardines de San Manuel CP 72570, Puebla, Pue., Mexico.
authors: Fabian
authors: F
authors: Galindo
authors: Eduardo
authors: E
authors: Monjaraz
authors: Salvador
authors: S
authors: Galicia
authors: Jorge
authors: J
authors: Cebada
authors: Celso
authors: C
authors: Cortés
authors: Amira
authors: A
authors: Flores
mesh_terms: D000200:Action Potentials; D000344:Afferent Pathways / Q000502:physiology; D000818:Animals; D002642:Chick Embryo; D007758:Ear, Inner / Q000294:innervation / Q000378:metabolism*; D009412:Nerve Fibers / Q000502:physiology; D009925:Organ of Corti / Q000378:metabolism; D058911:Purinergic P2X Receptor Agonists / Q000494:pharmacology; D058912:Purinergic P2Y Receptor Agonists / Q000494:pharmacology; D058469:Receptors, Purinergic P2X / Q000378:metabolism*; D058470:Receptors, Purinergic P2Y / Q000378:metabolism*; D014722:Vestibule, Labyrinth / Q000294:innervation / Q000378:metabolism
chemical_list: D058911:Purinergic P2X Receptor Agonists; D058912:Purinergic P2Y Receptor Agonists; D058469:Receptors, Purinergic P2X; D058470:Receptors, Purinergic P2Y
keywords: ATP; Chicken; Development; Inner ear; P2X receptor; P2Y receptor