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Structural and physiological change of the bullfrog semicircular canal due to gentamicin intoxication
Abstract:
The effect of Gentamicin (GM) on the vestibular organ was studied using bullfrogs. The ototoxicity was compared among 3 different ways of administration, i.e., intraperitoneal (IP), intramuscular (IM) and intralabyrinthine (IL) injections. Morphological change of the posterior canal crista was observed by SEM. The posterior canal ampullary nerve action potentials (AP) were recorded, and were compared with SEM findings of the sensory epithelia. Morphological and physiological changes were severe in the order of IL greater than IM greater than IP. Morphological and physiological changes developed as the postinjection time elapsed. Morphological damage started at the narrow portion of the crista and developed towards the center and finally towards the periphery. Physiological change was already observed before the morphological damage. Physiological change tended to correlate with the morphological damage.
Insights
This study compared Gentamicin (GM) ototoxicity in bullfrogs across intraperitoneal, intramuscular, and intralabyrinthine injections. Intralabyrinthine administration caused the most severe vestibular damage.
Area of Science:
- Ototoxicity research
- Vestibular system physiology
- Pharmacology
Background:
- Gentamicin (GM) is an aminoglycoside antibiotic with known ototoxic potential.
- Understanding the dose-response and administration route is crucial for minimizing vestibular damage.
Purpose of the Study:
- To compare the ototoxicity of Gentamicin (GM) via different administration routes (intraperitoneal, intramuscular, intralabyrinthine).
- To correlate morphological and physiological changes in the bullfrog vestibular organ following GM exposure.
Main Methods:
- Bullfrogs were administered GM via intraperitoneal (IP), intramuscular (IM), or intralabyrinthine (IL) injections.
- Scanning Electron Microscopy (SEM) was used to assess morphological changes in the posterior canal crista.
- Posterior canal ampullary nerve action potentials (AP) were recorded to evaluate physiological function.
Main Results:
- Ototoxicity severity followed the order: IL > IM > IP.
- Both morphological and physiological changes progressed over time post-injection.
- Morphological damage initiated at the crista's narrow portion, spreading centrally and peripherally.
- Physiological changes preceded observable morphological damage and correlated with its extent.
Conclusions:
- The route of administration significantly impacts Gentamicin-induced ototoxicity.
- Intralabyrinthine administration poses the highest risk to vestibular function.
- Early physiological alterations may precede detectable structural damage, highlighting the sensitivity of electrophysiological measures.