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Proliferative regeneration of zebrafish lateral line hair cells after different ototoxic insults.

Mackenzie SM, Raible DW - PLoS ONE (2012)

Bottom Line: Certain treatments, including cisplatin and higher concentrations of dissolved copper, significantly delayed regeneration by one or more days.However, cisplatin did not block all regeneration as observed previously in the chick basilar papilla.The particular ototoxin did not appear to affect the mechanism of regeneration, as we observed evidence of recent proliferation in the majority of new hair cells in all cases.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Structure, University of Washington, Seattle, Washington, United States of America.

ABSTRACT
Sensory hair cells in the zebrafish lateral line regenerate rapidly and completely after damage. Previous studies have used a variety of ototoxins to kill lateral line hair cells to study different phenomena including mechanisms of hair cell death and regeneration. We sought to directly compare these ototoxins to determine if they differentially affected the rate and amount of hair cell replacement. In addition, previous studies have found evidence of proliferative hair cell regeneration in zebrafish, but both proliferation and non-mitotic direct transdifferentiation have been observed during hair cell regeneration in the sensory epithelia of birds and amphibians. We sought to test whether a similar combination of regenerative mechanisms exist in the fish. We analyzed the time course of regeneration after treatment with different ototoxic compounds and also labeled dividing hair cell progenitors. Certain treatments, including cisplatin and higher concentrations of dissolved copper, significantly delayed regeneration by one or more days. However, cisplatin did not block all regeneration as observed previously in the chick basilar papilla. The particular ototoxin did not appear to affect the mechanism of regeneration, as we observed evidence of recent proliferation in the majority of new hair cells in all cases. Inhibiting proliferation with flubendazole blocked the production of new hair cells and prevented the accumulation of additional precursors, indicating that proliferation has a dominant role during regeneration of lateral line hair cells.

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Proliferation is required for regeneration after treatment with gentamycin.(A) Wild type larvae were treated at 5 dpf with 200 μM gentamicin for 30 min (acute) or 50 μM gentamycin for 6 h (chronic) and allowed to recover for 96 h from the beginning of treatment. Gentamicin-induced hair cell death was delayed compared to neomycin. There was no dose-dependent effect on regeneration, which was complete by 96 hpt. (B) When fish were incubated in flubendazole during recovery, minimal regeneration was observed, suggesting that proliferation was required. N = 8 fish per group. Error bars are +/− SD.
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pone-0047257-g007: Proliferation is required for regeneration after treatment with gentamycin.(A) Wild type larvae were treated at 5 dpf with 200 μM gentamicin for 30 min (acute) or 50 μM gentamycin for 6 h (chronic) and allowed to recover for 96 h from the beginning of treatment. Gentamicin-induced hair cell death was delayed compared to neomycin. There was no dose-dependent effect on regeneration, which was complete by 96 hpt. (B) When fish were incubated in flubendazole during recovery, minimal regeneration was observed, suggesting that proliferation was required. N = 8 fish per group. Error bars are +/− SD.

Mentions: To determine whether gentamicin treatment altered the rate of lateral line hair cell regeneration, we treated 5 dpf larvae with acute (200 μM, 30 min) or chronic (50 μM, 6 h) gentamicin and measured regeneration until 96 hpt. Approximately half of the hair cells remained at 6 h after the beginning of treatment and continued to decrease until 24 hpt (Figure 7A), consistent with previous results [33]. Complete regeneration was observed in both groups 72 h after this nadir. To determine if these two regimens differentially favored proliferation or direct transdifferentiation, we also incubated larvae in 5 μM flubendazole immediately after acute or chronic gentamicin treatments. Flubendazole significantly blocked regeneration in both groups when measured at 48 hpt (p<0.001; Figure 7B).


Proliferative regeneration of zebrafish lateral line hair cells after different ototoxic insults.

Mackenzie SM, Raible DW - PLoS ONE (2012)

Proliferation is required for regeneration after treatment with gentamycin.(A) Wild type larvae were treated at 5 dpf with 200 μM gentamicin for 30 min (acute) or 50 μM gentamycin for 6 h (chronic) and allowed to recover for 96 h from the beginning of treatment. Gentamicin-induced hair cell death was delayed compared to neomycin. There was no dose-dependent effect on regeneration, which was complete by 96 hpt. (B) When fish were incubated in flubendazole during recovery, minimal regeneration was observed, suggesting that proliferation was required. N = 8 fish per group. Error bars are +/− SD.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3475690&req=5

pone-0047257-g007: Proliferation is required for regeneration after treatment with gentamycin.(A) Wild type larvae were treated at 5 dpf with 200 μM gentamicin for 30 min (acute) or 50 μM gentamycin for 6 h (chronic) and allowed to recover for 96 h from the beginning of treatment. Gentamicin-induced hair cell death was delayed compared to neomycin. There was no dose-dependent effect on regeneration, which was complete by 96 hpt. (B) When fish were incubated in flubendazole during recovery, minimal regeneration was observed, suggesting that proliferation was required. N = 8 fish per group. Error bars are +/− SD.
Mentions: To determine whether gentamicin treatment altered the rate of lateral line hair cell regeneration, we treated 5 dpf larvae with acute (200 μM, 30 min) or chronic (50 μM, 6 h) gentamicin and measured regeneration until 96 hpt. Approximately half of the hair cells remained at 6 h after the beginning of treatment and continued to decrease until 24 hpt (Figure 7A), consistent with previous results [33]. Complete regeneration was observed in both groups 72 h after this nadir. To determine if these two regimens differentially favored proliferation or direct transdifferentiation, we also incubated larvae in 5 μM flubendazole immediately after acute or chronic gentamicin treatments. Flubendazole significantly blocked regeneration in both groups when measured at 48 hpt (p<0.001; Figure 7B).

Bottom Line: Certain treatments, including cisplatin and higher concentrations of dissolved copper, significantly delayed regeneration by one or more days.However, cisplatin did not block all regeneration as observed previously in the chick basilar papilla.The particular ototoxin did not appear to affect the mechanism of regeneration, as we observed evidence of recent proliferation in the majority of new hair cells in all cases.

View Article: PubMed Central - PubMed

Affiliation: Department of Biological Structure, University of Washington, Seattle, Washington, United States of America.

ABSTRACT
Sensory hair cells in the zebrafish lateral line regenerate rapidly and completely after damage. Previous studies have used a variety of ototoxins to kill lateral line hair cells to study different phenomena including mechanisms of hair cell death and regeneration. We sought to directly compare these ototoxins to determine if they differentially affected the rate and amount of hair cell replacement. In addition, previous studies have found evidence of proliferative hair cell regeneration in zebrafish, but both proliferation and non-mitotic direct transdifferentiation have been observed during hair cell regeneration in the sensory epithelia of birds and amphibians. We sought to test whether a similar combination of regenerative mechanisms exist in the fish. We analyzed the time course of regeneration after treatment with different ototoxic compounds and also labeled dividing hair cell progenitors. Certain treatments, including cisplatin and higher concentrations of dissolved copper, significantly delayed regeneration by one or more days. However, cisplatin did not block all regeneration as observed previously in the chick basilar papilla. The particular ototoxin did not appear to affect the mechanism of regeneration, as we observed evidence of recent proliferation in the majority of new hair cells in all cases. Inhibiting proliferation with flubendazole blocked the production of new hair cells and prevented the accumulation of additional precursors, indicating that proliferation has a dominant role during regeneration of lateral line hair cells.

Show MeSH
Related in: MedlinePlus