Related Experiment Video
Updated: Aug 20, 2025
Cochlear Implant Surgery and Electrically-evoked Auditory Brainstem Response Recordings in C57BL/6 Mice
Published on: January 9, 2019
mTOR Signaling in BDNF-Treated Guinea Pigs after Ototoxic Deafening
Annamaria Tisi1, Dyan Ramekers2,3, Vincenzo Flati1
1Department of Biotechnological and Applied Clinical Sciences, University of L'Aquila, 67100 L'Aquila, Italy.
Abstract:
The mammalian target of rapamycin (mTOR) signaling plays a critical role in cell homeostasis, growth and survival. Here, we investigated the localization of the main mTOR signaling proteins in the organ of Corti of normal-hearing and deafened guinea pigs, as well as their possible modulation by exogenously administered brain-derived neurotrophic factor (BDNF) in deafened guinea pigs. Animals were ototoxically deafened by systemic administration of kanamycin and furosemide, and one week later, the right cochleas were treated with gelatin sponge soaked in rhBDNF, while the left cochleas were used as negative controls. Twenty-four hours after treatment, animals were euthanized, and the cochleas were processed for subsequent analysis. Through immunofluorescence, we demonstrated the localization of AKT, pAKT, mTOR, pmTOR and PTEN proteins throughout the cochlea of guinea pigs for the first time, with a higher expression in supporting cells. Moreover, an increase in mTOR immunostaining was observed in BDNF-treated cochleas by means of fluorescence intensity compared to the other groups. Conversely, Western blot analysis showed no significant differences in the protein levels between groups, probably due to dilution of proteins in the neighboring tissues of the organ of Corti. Altogether, our data indicate that mTOR signaling proteins are expressed by the organ of Corti (with a major role for supporting cells) and that the modulation of mTOR may be a protective mechanism triggered by BDNF in the degenerating organ of Corti.
Insights
Mammalian target of rapamycin (mTOR) signaling proteins are present in the guinea pig cochlea, particularly in supporting cells. Brain-derived neurotrophic factor (BDNF) may modulate mTOR signaling, potentially offering a protective mechanism in the degenerating organ of Corti.
Area of Science:
- Oto-neuroscience
- Cellular signaling
- Molecular biology
Background:
- The mammalian target of rapamycin (mTOR) pathway is crucial for cellular functions like homeostasis, growth, and survival.
- Understanding mTOR signaling in the auditory system is vital for addressing hearing loss.
- The role of mTOR and its modulation by neurotrophic factors in the cochlea remains underexplored.
Purpose of the Study:
- To investigate the localization of key mTOR signaling proteins (AKT, pAKT, mTOR, pmTOR, PTEN) in the guinea pig organ of Corti.
- To examine the potential modulation of these proteins by brain-derived neurotrophic factor (BDNF) in an ototoxically deafened model.
- To explore the protective mechanisms involving mTOR signaling in the degenerating cochlea.
Main Methods:
- Ototoxic deafness induced in guinea pigs using kanamycin and furosemide.
- Localized treatment of cochleas with recombinant human BDNF (rhBDNF) via gelatin sponge.
- Immunofluorescence microscopy to determine protein localization and expression.
- Western blot analysis to quantify protein levels.
Main Results:
- mTOR signaling proteins (AKT, pAKT, mTOR, pmTOR, PTEN) were successfully localized in the guinea pig cochlea for the first time, with higher expression in supporting cells.
- BDNF treatment led to increased mTOR immunostaining intensity in the cochlea compared to controls.
- Western blot analysis did not reveal significant differences in overall protein levels, possibly due to tissue dilution.
Conclusions:
- mTOR signaling proteins are expressed in the organ of Corti, with supporting cells playing a significant role.
- BDNF may modulate mTOR signaling in the degenerating organ of Corti.
- Modulation of mTOR signaling by BDNF could represent a protective mechanism against cochlear degeneration.
