Shakuyakukanzoto attenuates oxaliplatin-induced cold dysesthesia by inhibiting the expression of transient receptor potential melastatin 8 in mice

Oxaliplatin-induced peripheral neuropathy characterized especially as cold dysesthesia is a major dose-limiting side effect of the drug and is very difficult to control. In the present study, we examined whether the traditional herbal formulation Shakuyakukanzoto (SKT: 芍藥甘草湯Sháo Yào Gān Cǎo Tāng) could relieve oxaliplatin-induced cold dysesthesia in mice. The inhibitory mechanisms were also investigated. Repetitive administration of SKT (0.1–1.0 g/kg) starting from the day after oxaliplatin injection inhibited cold dysesthesia in a dose-dependent manner. Our previous report has shown that the mRNA expression of transient receptor potential melastatin 8 (TRPM8), characterized as a cold-sensing cation channel, is increased in the dorsal root ganglia of mice treated with oxaliplatin. In addition, TRPM8 antagonist TC-I 2014 (10 and 30 mg/kg) also attenuated cold dysesthesia in oxaliplatin-treated mice. Taken together, it is suggested that TRPM8 is involved in the cold dysesthesia induced by oxaliplatin. Repetitive administration of SKT inhibited the mRNA expression of TRPM8 induced by oxaliplatin in the dorsal root ganglia. These results suggested that prophylactic repetitive administration of SKT is effective in preventing the exacerbation of oxaliplatin-induced cold dysesthesia by inhibiting the mRNA expression of TRPM8 in the dorsal root ganglia.