The Protective Effects Of Huangqiguizhiwuwu Decoction On Oxaliplatin-induced Peripheral Neuropathy Based On The Mechanism Of Platinum-accumulation

Purpose By reading the general condition, degree of sensitivity to mechanical irritation and morphological changes of dorsal root ganglia(DRG) neurons of oxaliplatin-induced peripheral neuropathy(O-IPN) model rats, to evaluate the effects of Huangqiguizhiwuwu decoction on O-IPN. To further explore the mechanism, platinum content as well as Pt-transporters OCT2 and ATP7A expressions in DRG was detected.Methods 42 Wistar rats were devided into 4 groups, including blank group, model group, cimetidine(CIM) group and Huangqiguizhiwuwu decoction(Herb) group. After a week of adaptive feeding, all groups(n=12) were intraperitoneally injected of oxaliplatin 5mg/kg(at a volume of 2 ml/kg) twice a week for four weeks except blank group(n=6), which was injected of 5% glucose. Meanwhile, blank group and model group rats were given by gavage with 1ml 0.9% NS, Herb group was given with Huangqiguizhiwuwu decoction at the dosage of 5ml/kg body weight by gastric lavage and CIM group was intraperitoneally injected of cimetidine 30mg/kg(at a volume of 3 ml/kg) once a day for four weeks. At the same day of injecting oxaliplatin, the decoction and cimetidine were given one hour before injection. In the period, rats were weighed twice a week, as well as mechanical pain threshold. Observe the reaction, diet and excrement of rats after administration. On day 28, dissecting all the rats to gain lumbar 4-5 DRG. Nissl staining followed by observing the structure and size of neuron and nucleolus. Subsequently, Pt levels in DRG were measured by Inductively Coupled Plasma Mass Spectrometry(ICP-MS). Then the expression of Pt-transporters OCT2 and ATP7A in DRG was determined by RT-PCR and qPCR.Results O-IPN rats model was proved successful by the synthesis of behavior observing, mechanical irritation tests and cell morphology survey. It was obvious that degree of sensitivity to mechanical irritation increased after oxaliplatin administration (P<0.01). Huangqiguizhiwuwu decoction or cimetidine could prevent this trend more or less after the third period of administration, neither was distinct in the short term. Cytomorphology observation demonstrated that size of cell body and nucleolus were apt to decrease accompanied with multiple nucleoli and understain nissl bodies after injection of oxaliplatin, which could also be relieved by administration of Huangqiguizhiwuwu decoction or cimetidine. The results of Pt content detection indicated that oxaliplatin apparently increased Pt levels in DRG, while could be decreased by Huangqiguizhiwuwu decoction or cimetidine (P<0.05). PCR showed that application of oxaliplatin up-regulated the expression of Oct2 mRNA while down-regulated Atp7a mRNA expression slightly. In contrast, Huangqiguizhiwuwu decoction could down-regulate Oct2 mRNA expression and apparently up-regulate Atp7a mRNA expression. Interestingly, using cimetidine influenced little, only Oct2 mRNA expressed a little more.Conclusions Huangqiguizhiwuwu decoction could alleviate chronic neurotoxicity of oxaliplatin, but is not so apparent to acute O-IPN. The possible mechanism is that Huangqiguizhiwuwu decoction could slightly down-regulate Oct2 mRNA expression to prevent Pt influx and significantly up-regulate Atp7a mRNA expression to promote Pt efflux, which can play a role against Pt accumulation in DRG so as to relieve chronic O-IPN.