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Cochlear Implantation in the Guinea Pig
Published on: June 15, 2018
Initial changes in the sensory hair-cell membrane following aminoglycoside administration in a guinea pig model
M Takumida1, J Wersäll, D Bagger-Sjöbäck
1Department of Otolaryngology, Karolinsk Institutet, Karolinska Sjukhuset, Stockholm, Sweden.
Abstract:
This study demonstrates the initial changes affecting the sensory hair-cell plasma membranes in the vestibular end organs of gentamicin-treated guinea pigs by using a ruthenium red staining technique. First, 0.1 ml of a solution containing 5 mg gentamicin sulfate was injected into the middle ear. After 7 days, the sensory hair cell cilia were observed to be degenerating. The various stages of this degeneration process were classified into two types: the decrease in glycocalyx was designated type I fusion, while type II fusion was characterized by a bleb formation of the plasma membrane of the sensory hair cells, followed by a decrease in glycocalyx. The latter mechanism allowed plasma membrane contact, with subsequent fusion of the plasma membrane of neighboring sensory hair-cell cilia. The material also illustrates the degeneration of ciliary actin filaments. These findings suggest that the aminoglycoside affects both the glycocalyx and the plasma membrane, and that the decrease in glycocalyx may be the first sign of sensory hair-cell fusion.
Insights
Gentamicin causes sensory hair cell fusion in guinea pigs. This degeneration involves plasma membrane blebbing and actin filament breakdown, with reduced glycocalyx appearing as an initial sign.
Area of Science:
- Ototoxicity research
- Cell biology
- Vestibular system science
Background:
- Gentamicin is an aminoglycoside antibiotic.
- Aminoglycosides are known to cause ototoxicity.
- The precise initial cellular changes leading to hair cell death are not fully understood.
Purpose of the Study:
- To investigate the initial structural changes in vestibular sensory hair cell plasma membranes following gentamicin exposure.
- To classify the stages of sensory hair cell cilia degeneration induced by gentamicin.
- To elucidate the role of the glycocalyx and plasma membrane in gentamicin-induced hair cell fusion.
Main Methods:
- Guinea pigs were treated with gentamicin sulfate via middle ear injection.
- Ruthenium red staining was employed to visualize sensory hair cell plasma membranes.
- Degeneration stages were observed and classified using microscopy.
Main Results:
- Gentamicin treatment led to degeneration of sensory hair cell cilia after 7 days.
- Two types of fusion were identified: Type I (glycocalyx decrease) and Type II (bleb formation, glycocalyx decrease, and plasma membrane fusion).
- Degeneration of ciliary actin filaments was also observed.
Conclusions:
- Gentamicin impacts both the glycocalyx and plasma membrane of sensory hair cells.
- A decrease in the glycocalyx may represent the earliest indicator of sensory hair cell fusion.
- These findings provide insight into the mechanisms of aminoglycoside-induced ototoxicity.
