Experimental Study On Intervention Of Peripheral Neurotoxicity Of Oxaliplatin In Wenjing Tongluo Powder

Oxaliplatin is an important drug used in the treatment of colorectal cancer. However, it frequently causes severe acute and chronic peripheral neuropathies. We recently reported that repeated external administration of Wenjing Tongluo(WJTL) ameliorated the oxaliplatin-induced peripheral neuropathy in clinical studies. Wenjing Tongluo (WJTL), prepared from five herbs, Laoguancao (Erodium stephanianum, Wild., defatted gum resin), Chuanwu (Aconitum carmichaeli Debx, rhizome),Guizhi(Cinnamomum cassia Presl, stem),Honghua(Carthamus tinctorius L.,coronal).Objective1. To discuss whether Wenjing Tongluo(WJTL) affects the anti-tumor effect of oxaliplatin in the tumour cells-implanted mice.2. To discuss the effects of Wenjing Tongluo Formula on oxaliplatin-induced neurotoxicity of rats. To determine the possible mechanisms,including the effects on the neurons of Dorsal Root Ganglion (DRG) of rats, neuropathic pain due to the change of spinal and DRG of rats.Methods1. Tumor cells-implanted mice modelMale BALB/c mice were divided into control group, model group, and TCM group.CT-26 (2×106 cells per mouse) were implanted subcutaneously in the right paw of BALB/c mice. Oxaliplatin (6 mg/kg, i.p.) was injected twice a week and TCM group was given Wenjing Tongluo Formula to soak rats’limbs and tails for 20min, twice a day. Behavioural tests including mechanical allodynia and cold hyperalgesia were detected.The tumour volumes, weigh,and tumor inhibition rate were calculated.2. The rat model of oxaliplatin-induced neuropathyFemale Wistar rats were randomly divided into control group, model group, and TCM group. Intraperitoneal injection was used to inject oxaliplatin 4 mg/kg, twice a week for 4 weeks(days 1,2,8,9,15,16,22 and 23) to establish oxaliplatin-induced peripheral nerve rat models. Rats in the normal group received intraperitoneal injection with 5% glucose. TCM group was given Wenjing Tongluo Formula to soak rats’limbs and tails for 20min, twice a day. Rats in the model group were soaked with deionized water for comparison (1)Behavioural tests including mechanical allodynia and cold hyperalgesia were detected under the mechanical and cold temperature stimulation.(2) Neurophysiological assessment:Tail’s sensory nerve conduction velocities of rats were detected by the MedLab-U/4CS system(3)NGF level were detected by ELISA kit. (4) Morphologic determinations were performed under the light microscope after HE stain. The L4-L6 DRG neuron aptosis, the expression of GFAP in L4-L6 spinal dorsal horn of rats, were studied respectively.(5) RT-PCR method was used to find out th change of mRNA level of GLT-1,GLAST, TRPA1 in rat DRGs.ResultsOxaliplatin significantly inhibited the increase of tumor volumes and weigh compared with vehicle on days 11 and 15 in tumor cells-implanted mice(P<0.05, P<0.01). Wenjing Tongluo(WJTL) had no effect on the oxaliplatin induced inhibition of tumor growth.Rats in model group showed obvious behavioral changes compared with control group (P<0.05); Rats in the TCM group improved in behavioristics compared with model group (P <0.01); Inaddithion, WJTL rised NGF and SNCV of rats (P<0.05); level of DRG neurons apotosis and number of GFAP positive cells of rats in the model group increased compared with control group (P<0.05),while the increase in the TCM group was not obvious. In addition, compared with control group, astrocytes in spinal dorsal horn of model group were enlarged;protuberances increased and became coarse. Compared with model group, active cells and protuberances in the TCM group decreased. RT-PCR assays showed that treating with oxaliplatin (4mg/kg, i.p.)twice a week greatly decreased the mRNA level of GLT-1 and GLAST(P<0.05),while increased the level of TRPA1 of rats. WJTL were able to increase GLT-1 and GLAST mRNA levels(P<0.01), while decreased the TRPA1 mRNA level(P< 0.05).Conclusion1. These results suggest that Wenjing Tongluo Formula can improve behavioral changes of model rats under mechanical and temperature stimulation, probably related to the function that fistly preventing the decrease of NGF level, SNCV, neuron cell aptosis, secondly inhibiting the harmful neuronal signal transmission induced by astrocyte in spinal dorsal horn, thirdly making the mRNA level of GLT-1,GLAST, TRPA1 stable in rat DRGs.2. Wenjing Tongluo Formula ameliorates the oxaliplatin-induced neuropathy in the rat model without affecting the anti-tumour activity of oxaliplatin.