Immunohistochemical localization of α2-adrenergic receptors in the neonatal rat cochlea and the vestibular labyrinth

J Mol Neurosci. 2013 Nov;51(3):1010-20. doi: 10.1007/s12031-013-0089-2. Epub 2013 Aug 22.

Abstract

The α2-adrenergic receptors (α2-ARs), which mediate physiological responses to noradrenaline and adrenaline, are encoded by three different genes but all are coupled to the Gi/Go subfamily of G proteins. The present study investigated the localization of three subtypes, i.e., α2a-, α2b-, and α2c-ARs, in cochlea and vestibular labyrinth in rat in the early postnatal period by immunohistochemistry. The results showed that α2-ARs were widely distributed in regions, including the organ of Corti, spiral ganglion neurons, stria vascularis, crista ampullaris, Scarpa's ganglion, utricle, and Reissner's membrane. Furthermore, the cellular locations of α2-ARs between different cell subtypes as well as receptor subtypes and different observed time points also had diversity. α2a-AR mainly targeted to nuclei at postnatal ages (P)3. While at P(8), only ganglion neurons maintained this character whereas other cell types expressed α2a-AR mainly in plasma membrane. The α2b- and α2c-ARs exhibited predominantly in plasma membrane. Compared with P(8), α2c-AR was not present at stria vascularis at P(3). Overall, our observations indicated that there was region-specific regulation of α2-ARs development in cochlea and vestibular labyrinth. In addition, the extensive expressions of α2-ARs established a significant foundation for the exploration of the function of α2-ARs in cochlea and vestibular labyrinth.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Membrane / metabolism
  • Cochlea / cytology
  • Cochlea / metabolism*
  • Neurons / classification
  • Neurons / metabolism
  • Organ Specificity
  • Rats
  • Receptors, Adrenergic, alpha-2 / genetics
  • Receptors, Adrenergic, alpha-2 / metabolism*
  • Vestibular Nerve / cytology
  • Vestibular Nerve / metabolism
  • Vestibule, Labyrinth / cytology
  • Vestibule, Labyrinth / metabolism*

Substances

  • Receptors, Adrenergic, alpha-2