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Intramuscular streptomycin effect on dark cells of utricle in guinea pigs
Abstract:
Streptomycin has been used in the treatment of Meniere's disease for almost half a century. Clinical studies showed that streptomycin may eliminate vertigo attacks and stabilize or improve hearing in the majority of patients. Animal experiments have demonstrated severe damage to the vestibular hair cells after streptomycin treatment. This study is to observe the effect of intramuscular streptomycin on dark cells of utricle. Guinea pigs that had received intramuscular injections of streptomycin sulfate 400 mg/kg per day for 1 and 2 weeks were studied. The dark cells of utricle were observed under transmission electron microscope. The pinocytotic vesicles and rough endoplasmic reticula markedly decreased and the plasmalemma infoldings in the lower part of the cell reduced in the 1-week group. The luminal membrane of the cells bulged out on the surface. After the cell membrane ruptured, the cytoplasmic organelle moved into the endolymphatic space and the cell dissolved. The morphologic changes indicated that streptomycin damaged the cytoplasmic granules and the plasma membrane infoldings of the dark cells. These cytologic characteristics are engaged in fluid secretion. The damage of secretory function of the dark cells may reduce the volume of endolymph.
Insights
Streptomycin treatment for Meniere
Area of Science:
- Ototoxicology
- Inner ear physiology
- Cell biology
Background:
- Streptomycin has been a long-standing treatment for Meniere's disease, aiming to control vertigo and preserve hearing.
- Previous research indicates streptomycin can cause significant damage to vestibular hair cells.
- The specific impact of streptomycin on the utricle's dark cells, crucial for endolymph homeostasis, remains less understood.
Purpose of the Study:
- To investigate the ultrastructural effects of intramuscular streptomycin on the dark cells of the guinea pig utricle.
- To elucidate the cellular mechanisms by which streptomycin may influence endolymph production.
Main Methods:
- Guinea pigs received daily intramuscular injections of streptomycin sulfate (400 mg/kg) for one or two weeks.
- Transmission electron microscopy was employed to examine the morphology of utricular dark cells.
- Quantitative and qualitative assessments of cellular organelles and membrane structures were performed.
Main Results:
- Streptomycin administration led to a marked decrease in pinocytotic vesicles and rough endoplasmic reticulum in dark cells.
- Reduction in plasmalemma infoldings and bulging of the luminal membrane were observed, preceding cell rupture.
- Cellular dissolution and release of cytoplasmic organelles into the endolymphatic space were evident, indicating severe damage.
Conclusions:
- Intramuscular streptomycin induces significant morphological damage to utricular dark cells, affecting key secretory structures.
- The observed damage to dark cells suggests a compromised fluid secretion capacity, potentially reducing endolymph volume.
- These findings provide cellular insights into the ototoxic mechanisms of streptomycin and its potential impact on Meniere's disease pathophysiology.