| Nonylphenol(NP), which belong to the alkylphenol endocrine disrupting chemicals, hasestrogenic-like activity. It widely exists in the environment and can enter the human body through various ways such as water, food chain, plastic utensils and so on, to cause serious influence to human health. At present, the toxicity research of NP focused on reproductive toxicity and immune toxicity, few on neurotoxicity, while related research has indicated that the active substances in mulberry have detoxification. Therefore, this paper carry out a further research on the detoxification mechanism of mulberry based on neurobehavioral toxicity of NP. By 28 days repeated oral toxicity test, the rat models of exposure NP were established [Control group: corn oil,NP group:30,90,270 mg/(kg·bw)].The open field test(OFT)and elevated plus maze(EPM)were used to observe the neurobehavioral toxicity of NP and discussed the neurotoxicity mechanism through analysis the effect of thyroid and monoamine neurotransmitter in rat exposed to NP. Then mulberry intervention trial was done with the dose that had obvious toxic effect as NP administration group. Vacuum freeze-drying machine was usedfor drying processing of fresh mulberry. Extracting conditions of active substances from mulberry were 80% ethanol, liquid-to-solid ratio 15, and ultrasonic-assisted extracted 90 min. The extract was concentrated by a rotary evaporator and analyzed by HPLC-Q-TOF-MS. The rat models of NP exposure were intervened with mulberry extract [Control group: corn oil, Mulberry extract group: 120 mg/(kg·bw),NP group:270 mg/(kg·bw), Mulberry extract intervention group:30,60,120 mg/(kg·bw)]. The OFT and EPM were used to observe the intervention effect of mulberry extract on NP neurobehavioral toxicity. To explore the intervention mechanismof mulberry extracton NP exposure,Nuclear Erythroid-2-related Factor 2(Nrf2) pathway combined with thyroid and monoamine neurotransmitterwere detected in rats of different groups.SPSS19.0 was used for the statistical analysis.The main results are showed as follows:(1)The general toxicity of NP on rat: Compared with control group, high dose NP exposure caused the weight gaining slow(P<0.01), and food utilization rates declining(P<0.01),each different doses of NP exposure caused the liver and kidney coefficients increased(P<0.01).(2)The neurobehavioral toxicity of NP on rat: No significant differences were found in the OFT and EPM among the groups before NP exposure(P>0.05). The distance traveled in the center and entrance frequency to the center of high dose NP group were significantly lower than control group(P<0.05).The OT, OT%, OE, and OE% of high dose NP group were significantly lower than control group(P<0.05 or P<0.01).(3)The effect of thyroid and monoamine neurotransmitter in rat exposed to NP: High dose NP exposure caused serum FT3 and FT4 levels significantly decreased(P<0.05), and the serum r T3 level significantly increased(P<0.05). The serum TSH level significantly increased in each does NP groups(P<0.05). High dose NP exposure caused liver DIO? and DIO ? activities significantly increased( P<0.05), and the liver DIO ? activities significantly increase in each does NP groups(P<0.01). The hypothalamic 5-HT, NE, DAlevels significantly increased in each NP exposure groups(P<0.05 or P<0.01).High dose NP exposure causedhypothalamic MAOactivities significantly decreased(P<0.05).(4)Composition analysis and structure identification of extract in mulberry: There were protein(0.38%), total sugar(4.96%),including 2.36% of the reducing sugar, water(90.18%), polyphenol(3.49%) and flavonoid(0.74%) in mulberry extract. By HPLC-Q-TOF-MS, some active substances were identified in mulberry extract, such as cyaniding-3-glucoside, rutin, resveratrol, quercetin and so on.(5)The intervention effect of mulberry extract on NP general toxicity: The total food utilization rate of medium and high dose intervention group were higher than NP group(P<0.05 ? P<0.01).The liver coefficients of medium and high dose intervention groups were lower than NP group(P<0.05).(6)The intervention effect of mulberry extract on NP neurobehavioral toxicity:No significant differences were found in the OFT and EPM among the groups before NP exposure(P>0.05).The distance traveled in the center and entrance frequency to the center of High dose intervention group were significantly higher than NP group(P<0.05).The OT, OT%, OE, and OE% of High dose intervention group were significantly higher than NP group(P<0.05 or P<0.01).(7) The intervention effect of mulberry extract on thyroid and monoamine neurotransmitter: The serum FT3 level of high dose intervention group was significantly higher than NP group(P<0.05). The serum FT4 level of each different dose groups was significantly higher than NP group(P<0.05 or P<0.01).The serum r T3, TSH level, and the liver DIO?activities of high dose intervention group was significantly lower than NP group( P<0.05).The hypothalamic 5-HT level ofhigh dose intervention group was significantly lower than NP group(P<0.05).The same changes were happened on hypothalamic DA level of medium and high dose intervention groups( P<0.05).Thehypothalamic MAOactivities of High dose intervention group was significantly higher than NP group(P<0.05).(8)The intervention effect of mulberry extract on NP Nrf2 and its downstream phase II detoxifying enzymes: The liver GST and UGT2b1 activities of High dose intervention group were significantly higher than NP group(P<0.05).Compared with NP group, high dose mulberry extract significantly induced up-regulation of the m RNA expression of Nrf2, GST and UGT2b1(P<0.01)in liver. Also, medium dose mulberry extract significantly induced up-regulation ofthe m RNA expression of GST, too(P<0.05).Those results showed that NP might cause anxiety by inducing hypothyroidism and changing the levels of monoamine neurotransmitter. While mulberry extract might induce phase II detoxifying enzymes activities by Nrf2 pathway, and improve the effects of thyroid and monoamine neurotransmitter in the rats of NP exposure to achieve the purpose of detoxification. |
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