ABSTRACT
Objective To determine whether or not capsazepine(CPZ),a transient receptor po-tential vanilloid-1(TRPV1)antagonist,attenuates lidocaine-induced cytotoxicity on rat dorsal root ganglion (DRG)neurons in vitro.Methods Adequate DRG neurons from 3-day neonatal Wistar rats were obtained,cultured and purified in vitro.To achieve higher cell viability,we reduced the concen-tration of trypsin to 0.125% compared with others.The purified DRG neurons were incubated with 0,2.5,5,10,20 and 40 mmol/L lidocaine for 10 min,respectively,their viabilities were examined using Cell Counting Kit(CCK-8)assay,and the lethal concentration 50(LC50 )of lidocaine on DRG neurons was calculated.Then,the variation of lidocaine-induced cell viability at LC50 ,when 0,1,10 and 100 μmol/L CPZ were respectively added to the incubations,was examined with CCK-8 assay. Results The purified percentage of DRG neurons was as high as 91% after digesting by 0.125%trypsin and purifying in vitro.Cell viability of DRG neurons in group L1,L2,L3,L4,L5 was signifi-cantly down regulated compared with the control group,to be specific,that of L3,L4,L5 being re-markably lower than that of L1,that of L4,L5 lower than that of L2 and that of L5 lower than that L3 and L4.After lidocaine induced DRG neurons for 10 min,LC50 was 30 mmol/L;10 μmol/L and 100 μmol/L CPZ significantly reduced LC50 DRG neuron toxicity induced by lidocaine (P <0.05). The effect of 10 μmol/L CPZ had reached the maximal effect,decreasing the cell viability decrease from 50% to 35%.Conclusion The novel method in this experiment is effective to obtain good DRG neurons,the LC50 of lidocaine on rat DRG neurons is 30 mmol/L,and CPZ attenuates the cytotoxicity induced by lidocaine on rat DRG neurons.
ABSTRACT
OBJECTIVES: There is limited data regarding the toxicity of methylcyclohexane, despite its wide use in rubber adhesives, paint diluents, and cleansing agents. This study aimed to verify the toxicity and influence on the reproductive system of methylcyclohexane after its repeated injection in Sprague Dawley (SD) rats. METHODS: Methylcyclohexane was injected subcutaneously into male and female SD rats once a day, five times a week, for 13 weeks at different doses (0, 10, 100, and 1,000 mg/kg/day) for each group. The toxicity of testing material was verified by observing the change in body and organ weight, hematological change, pathological findings, and effect on the reproductive system at each different concentration. RESULTS: In the 1,000 mg/kg/day group, there were cases of animal deaths. In animals that survived, hematological changes, including a decrease in the red blood cell count, were observed. A considerable weight gain or loss and pathological abnormalities in the liver, kidney, and other organs were found. However, the 10 and 100 mg/kg/day groups did not cause deaths or other specific abnormalities. In terms of reproductive toxicity, there were changes in hormone levels, including a significant decrease in hormones such as estradiol and progesterone (p < 0.001) in male animals. Menstrual cycle change for female animals did not show concentration dependency. CONCLUSION: When injected repeatedly for 13 weeks, methylcyclohexane proved to be toxic for the liver, heart, and kidney at a high dose. The absolute toxic dose was 1,000 mg/kg/day, while the no observed adverse effect level was less than 100 mg/kg/day. The substance exerted little influence on the reproductive system.