Introduction

Cruciferous vegetables are a rich source of sulforaphane (SFN), which acts as a natural HDAC inhibitor (HDACi). Our previous study found that HDACi could restore histone acetyltransferase/histone deacetylase (HAT/HDAC) balance in the cochlea and attenuate gentamicin-induced hearing loss in guinea pigs. Here, we investigated the protective effect of SFN on cisplatin-induced hearing loss (CIHL).

Methods

Thirty rats were randomly divided into 3 equal groups: the control group, cisplatin group, and SFN+cisplatin group. Rats were injected with SFN (30 mg/kg once a day) and cisplatin (7 mg/kg twice a day) for 7 days to investigate the protective role of SFN on CIHL. We observed auditory brainstem response (ABR) threshold shifts and immunostained cochlear basilar membranes of rats. For in vitro experiments, we treated HEI-OC1 cells and rat cochlear organotypic cultures with SFN (5, 10, and 15 μM) and cisplatin (10 μM). Immunofluorescence, cell viability, and protein analysis were performed to further analyze the protective mechanism of SFN on CIHL.

Results

SFN (30 mg/kg once a day) decreased cisplatin (7 mg/kg twice a day)-induced ABR threshold shifts and outer hair cell loss. CCK-8 assay showed that cisplatin (10 μM) reduced the viability of HEI-OC1 cells to 42%, and SFN had a dose-dependent protective effect. In cochlear organotypic cultures, we found that SFN (10 and 15 μM) increased cisplatin (10 μM)-induced myosin 7a⁺ cell count and restored ciliary morphology. SFN (5, 10, and 15 μM) reversed the cisplatin (10 μM)-induced increase in HDAC2, -4, and -5 and SFN (15 μM) reversed the cisplatin (10 μM)-induced decrease in H3-Ack9 [acetyl-histone H3 (Lys9)] protein expression in HEI-OC1 cells. Neither cisplatin nor cisplatin combined with SFN affected the expression of HDAC7, or HDAC9.

Conclusion

SFN prevented disruption of the HAT/HDAC balance, protecting against CIHL in rats.

中文翻译：

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萝卜硫素通过抑制组蛋白脱乙酰酶表达减轻顺铂引起的听力损失

介绍

十字花科蔬菜富含萝卜硫素 (SFN)，它是一种天然的 HDAC 抑制剂 (HDACi)。我们之前的研究发现，HDACi 可以恢复耳蜗中的组蛋白乙酰转移酶/组蛋白去乙酰化酶 (HAT/HDAC) 平衡，并减轻庆大霉素引起的豚鼠听力损失。在这里，我们研究了 SFN 对顺铂引起的听力损失 (CIHL) 的保护作用。

方法

30只大鼠随机分为3个相等的组：对照组、顺铂组和SFN+顺铂组。给大鼠注射 SFN（30 mg/kg，每天一次）和顺铂（7 mg/kg，每天两次），持续 7 天，以研究 SFN 对 CIHL 的保护作用。我们观察到大鼠的听觉脑干反应 (ABR) 阈值变化和免疫染色的耳蜗基底膜。对于体外实验，我们用 SFN（5、10 和 15 μM）和顺铂（10 μM）处理了 HEI-OC1 细胞和大鼠耳蜗器官培养物。进行免疫荧光、细胞活力和蛋白质分析以进一步分析SFN对CIHL的保护机制。

结果

SFN（30 mg/kg，每天一次）降低了顺铂（7 mg/kg，每天两次）诱导的 ABR 阈值变化和外毛细胞损失。CCK-8 测定显示顺铂（10 μM）将 HEI-OC1 细胞的活力降低至 42%，SFN 具有剂量依赖性保护作用。在耳蜗器官培养中，我们发现 SFN（10 和 15 μM）增加了顺铂（10 μM）诱导的肌球蛋白 7a ⁺细胞计数并恢复了睫状体形态。SFN（5、10 和 15 μM）逆转顺铂（10 μM）诱导的 HDAC2、-4 和 -5 增加，SFN（15 μM）逆转顺铂（10 μM）诱导的 H3-Ack9 减少 [ HEI-OC1 细胞中的乙酰组蛋白 H3 (Lys9)] 蛋白表达。顺铂和顺铂联合SFN均不影响HDAC7或HDAC9的表达。

结论

SFN 防止破坏 HAT/HDAC 平衡，保护大鼠免受 CIHL。