Establishment Of Mouse Model With Colistin Neurotoxicity, Mechanism Investigation And The Protective Effect Of NGF

In recent ten years, colistin is clinically being used increasingly as a last-line therapeuticoption and the one of the most effective drug for infections of multidrug resistant gram-negativebacteria, especially for patients with severe clinical. One of the major adverse effects in clinicalusage of colistin is neurotoxicity, limiting its optimal therapeutic effect which has attracted theattention of clinicians and scientists. Unfortunately, the proper mechanism of colistin neurotoxicityis unknown. On the other hand, certifying the mechanism of colistin neurotoxicity play animportant role in exploring new method attenuating its toxicity, which concerned at home andabroad. In this paper, we built the mice model of neurotoxicity by mimicing clinical administrationof intravenous colistin sulfate and using multiple evaluation methods, to investigate themitochondrial oxidative stress-mediated neurotoxicity mechanisms and the protective effect ofexogenous nerve growth factor （NGF） on colistin induced neurotoxicity.Kunming strain female mice received colistin sulfate （15,7.5,5.0and0mg/kg） intravenouslyfor7days successively. General toxicity evaluation, neurological behavior in combination test（spontaneous locomotor activity, sensory function and motor function）, neurophysiological test （Mwave parameters, F wave parameters and EMG test）, nerve morphology evaluation （opticalHistopathological and ultrastructural observation）, the oxidation-antioxidation system biochemicalindexes tests, the expression of apoptosis-related factors and content （caspase-3and9）, NGFcontent and related receptor expression (the TrkA and p75^NTR) were examined on days1,3,7and15（the administration of the day of the first0d）, respectively; Further, the mice were randomlydivided into the control group （0.9%saline）, colistin model group （colistin15mg/kg）, NGFprotection group （colistin sulfate15mg/kg+36μg/kg）, the neurological behavior, nerveelectrophysiology, NGF content and related receptor expression (TrkA and p75^NTR) were examinedafter7days for continuous administration. The results showed as follows:（1） By the analysis of the dose-dependent and time-dependent manners, the mouse model ofcolistin neurotoxicity can be successfully established when female mice were daily intravenousinjection of colistin sulfate15mg/kg for7d. （2） The results of nerve electrophysiology tests and neurological behavior tests showed thatcolisitn can injury the sensory and motor functions of mice, and the more sensitive indexes areheat pain threshold, SNCV and F-wave latency. It indicated that F-wave latency and SNVC can beused as the clinical indicative indexes of colistin induced-neurotoxicity.（3） Colistin can induce the imbalance oxidation-antioxidant system of nervous system in mice,which further lead to mitochondrial degeneration, and the significant increase of caspase-9and3.It indicated that mitochondrial oxidative stress pathway was one of the important mechanisms ofcolistin induced-neurotoxicity in mice.（4） Colistin can significantly increase the expressions of NGF and its receptor protein (TrkAand p75^NTR) of nerve tissues in mice and exogenous NGF can reduce the expression of theseproteins, which revealed that colistin neurotoxicity was related with the NGF ligand-receptorbinding in the nerve cells.（5） The exogenous NGF protective against colistin induced neurotoxicity by theneurophysiological and neurobehavioral tests.