The role of apoptosis in cisplatin-induced ototoxicity in rats

Curcumin Prevents Ototoxicity Induced by Cisplatin as Evaluated with OAE

Introduction

This study, assess the efficacy of curcumin therapy in preventing/improving cochlear damage in Rattus norvegicus ototoxic model as evaluated with OAE examination.

Materials and Methods

This study utilized 27 rats which had been injected with single dose 8mg/KgBB of cisplatin, and then divided into 3 groups. The first group was not given curcumin. The second group received curcumin at a dose of 150 mg/KgBB. The third group received curcumin at a dose of 300 mg/KgBB. Curcumin was given from the time of single dose cisplatin injection (day 0) to day 7. OAE examination was performed on the day before the single dose of cisplatin (day 0), day 3, 4 and 7 after curcumin administration.

Results

There was a decline in the average value of SNR in all groups starting from high frequency. However, in the rat groups receiving curcumin there was a slow decrease in the SNR value, which also obtained statistically significant differences in the SNR values of all groups.

Conclusion

Administration of certain doses of curcumin may reduce the modest and statistically insignificant decrease in mean SNR values indicating a reduction in ototoxicity from cisplatin.

Schisandra B, a representative lignan from Schisandra chinensis, improves cisplatin-induced toxicity: An in vitro study

Schisandrin B (Scheme B) is the most abundant and active lignan monomer isolated from Schisandra chinensis. At present, most reports focus on its cardioprotective and hepatoprotective effects, however, the related reports on gastrointestinal protective effects are still limited. The study aims to evaluate the protective effect of Scheme B on cisplatin-induced rat intestinal crypt epithelial (IEC-6) cell injury and the possible molecular mechanisms. The results showed that Scheme B at 2.5, 5 and 10 μM could inhibit dose-dependently the reduction of cell activity induced by cisplatin exposure at 1 μM, decrease the levels of reactive oxygen species (ROS) and malondialdehyde (MDA), while increasing glutathione (GSH), superoxide dismutase (SOD) and catalase (CAT) to alleviate oxidative stress injury in IEC-6 cell lines. Meanwhile, Scheme B could relieve cisplatin-induced apoptosis by regulating PI3K/AKT and the downstream caspase signaling pathway. The results from flow cytometry analysis and mitochondrial membrane potential (MMP) staining also demonstrated the anti-apoptosis effect of Scheme B. Furthermore, Scheme B was found to reduce the inflammation associated with cell damage by evaluating the protein expressions of the nuclear factor-kappa B (NF-κB) signaling pathway. Importantly, Wnt/β-catenin, as a functional signaling pathway that drives intestinal self-recovery, was also in part regulated by Scheme B. In conclusion, Scheme B might alleviate cisplatin-induced IEC-6 cell damage by inhibiting oxidative stress, apoptosis, inflammation, and repairing intestinal barrier function. The present research provides a strong evidence that Scheme B may be a useful modulator in cisplatin-induced intestinal toxicity.

The effects of ethyl pyruvate against experimentally induced cisplatin ototoxicity in rats

INTRODUCTION

Cisplatin (CDDP) is a widely used antineoplastic drug. However, its use is limited due to the ototoxic side effects. In this study, the effects of ethyl pyruvate (EP), known for its antioxidant and anti-inflammatory effects, against CDDP ototoxicity were investigated.

METHODS

Thirty-two Wistar albino rats (n:8) were used in this study. CDDP was administered i.p. as a single dose of 15 mg/kg/day in order to cause ototoxicity. EP was applied i.p. at a dose of 50 mg/kg/day for 7 days.

RESULTS

When the Auditory Brainstem Responses (ABR) and Distortion Product Otoacoustic Emissions (DPOAE) tests carried out in the pre-treatment and post-treatment periods were examined, it was observed that the hearing functions were significantly impaired with the CDDP application, while a significant improvement was observed in the CDDP + EP group. Compared to the control group, the CDDP group had significantly higher malondialdehyde (MDA) levels and significantly lower glutathione peroxidase (GPx), superoxide dismutase (SOD) and catalase (CAT) levels. In the CDDP + EP group, there was no deterioration in MDA, SOD and CAT levels that was observed in the CDDP group. The increase in pro-inflammatory cytokine (IL-1β, IL-6 and TNF-α) levels caused by CDDP administration was observed to be significantly decreased in the CDDP + EP group.

CONCLUSIONS

Hearing tests and biochemical results show that ethyl pyruvate is protective against cisplatin ototoxicity with its antioxidant and anti-inflammatory effects.

Intraperitoneal curcumin and vitamin E combination for the treatment of cisplatin-induced ototoxicity in rats

INTRODUCTION

Cisplatin ototoxicity is characterized by irreversible, progressive, bilateral sensorineural hearing loss at high frequencies, accompanied by tinnitus. The aim of this study is to demonstrate the protective action of curcumin alone or in combination with vitamin E against cisplatin-induced ototoxicity in animal models.

MATERIAL AND METHODS

The study included 42 rats. Experimental animals were randomized into 6 groups. In the first group, intra-peritoneal cisplatin was administered alone. In the second group, intra-peritoneal cisplatin and curcumin were administered together. In the third group, intra-peritoneal cisplatin and vitamin E were administered together. In the fourth group, intra-peritoneal cisplatin was administered together with curcumin in combination with vitamin E. In the fifth group, intra-peritoneal curcumin was administered alone. The sixth group was sacrificed directly without administration of any drugs. A distortion product otoacoustic emission (DPOAE) test was applied to both ears of all experimental animals. Curcumin was administered 1 h before cisplatin treatment continued for three successive days. Vitamin E was administered only as a single dose 30 min prior to cisplatin. All animals were sacrificed following DPOAE testing on the 5th day of cisplatin administration. Histopathological findings included a TUNEL (TdT-mediated deoxyuridine triphosphate nick end-labeling) assay, and the percentage of apoptotic cells was calculated. DPOAE values and the percentage of apoptotic cells were compared before and after treatment and between experimental groups.

RESULTS

In Group 1, DPOAE values were significantly decreased at all frequencies (3000 Hz, 4000 Hz and 6000 Hz; P < 0.05). In Groups 2, 3, 4 and 5 there was no significant difference between the pre- and post-treatment DPOAE results (p > 0.05). Apoptotic index values were lower in all treatment groups compared to the cisplatin group, however the difference was only statistically significant in group 3 (p = 0.009).

CONCLUSION

In rats, cisplatin ototoxicity can be prevented with curcumin or curcumin-vitamin E combination.

The effects of the antioxidant α-tocopherol succinate on cisplatin-induced ototoxicity in HEI-OC1 auditory cells

CONCLUSION

D-α-tocopherol succinate significantly reduced a cisplatin-induced hair cell loss in HEI-OC1 cell lines. These effects were mediated by its scavenging activity against reactive oxygen species (ROS) and inhibition of apoptosis.

OBJECTIVES

Alpha-tocopherol is a class of methylated phenols, known as fat-soluble antioxidants, and is a different form of vitamin E, which reduces free radicals and acts as an antioxidant. We hypothesized that the antioxidative effect of α-tocopherol could protect against cisplastin-induced cytotoxicity, and thus evaluated its effects on cisplatin-induced ototoxicity in HEI-OC1 auditory cells.

METHODS

HEI-OC1 cells were pretreated with D-α-tocopherol succinate at a concentration of 10 µM for 24 h, and then exposed to 15 µM cisplatin for 48 h. The cellular viability was measured by using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method. The intracellular ROS level was measured by using a fluorescent dye, 2',7'-dichlorofluorescein diacetate (DCFH-DA). Both Annexin V-FITC and propidium iodide (PI) staining were performed to analyze the pattern of apoptosis. The enzymatic activity of caspase-3 was assayed with caspase3/CPP32 fluorometric assay kit. Also, it was assessed by immunoblotting technique of poly-ADP-ribose polymerase (PARP).

RESULTS

Pretreatment with 10 µM D-α-tocopherol succinate protected HEI-OC1 auditory cells against cisplatin-induced cytotoxicity. D-α-tocopherol succinate significantly reduced the cisplatin-induced increase in ROS. D-α-tocopherol succinate treatment induced a 15% reduction of ROS and 50% decrease in necrosis and late apoptosis as compared to cisplatin treatment. D-α-tocopherol succinate also decreased the activation of caspase-3 and reduced levels of cleaved poly-ADP-ribose polymerase (PARP).