Evidence for an Akt-kinase/NO/cGMP pathway in the cochlea of guinea pigs.
The protein kinase Akt (protein kinase B) can be activated by numerous growth factors via PI-3 kinase-generated phosphoinositides and is thought to have anti-apoptotic properties. Activated Akt/PKB boosts the activity of endothelial NO synthase (NOS III), which has been found in the key areas of the inner ear (e.g., hair cells and stria vascularis). In order to localize activated Akt/PKB (phospho-Akt) in the cochlea of guinea pigs, sections of ten temporal bones were observed immunohistochemically. The strongest immunoreactivity was found in and underneath inner hair cells (IHC). Within the organ of Corti, reactivity was found in supporting cells, while outer hair cells remained unstained. Spiral ganglion cells, the endothelium of the lateral wall and the vascular area of the modiolus showed moderate staining. The results give evidence that activated Akt/PKB influences the activity of the NO/cGMP pathway in the cochlea. Because of the antiapoptotic properties, activated Akt should now be examined under non-physiological conditions.
Hess
Alexander
A
Department of Otorhinolaryngology, University of Cologne, Kerpenerstrasse 62, 50924 Cologne, Germany.
Labbé
Daniel
D
Watanabe
Ken-Ichi
K
Bloch
Wilhelm
W
Michel
Olaf
O
D000818:Animals; D003051:Cochlea / Q000378:metabolism*; D006152:Cyclic GMP / Q000378:metabolism; D004789:Enzyme Activation; D005260:Female; D006168:Guinea Pigs; D006198:Hair Cells, Auditory / Q000378:metabolism; D007150:Immunohistochemistry; D009569:Nitric Oxide / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D009925:Organ of Corti / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D013136:Spiral Ganglion / Q000166:cytology / Q000378:metabolism
D009569:Nitric Oxide; D052250:Nitric Oxide Synthase Type III; D051057:Proto-Oncogene Proteins c-akt; D006152:Cyclic GMP