Effect Of Tannic Acid On The Expression Of Vglut3 And Vgat In Gustatory-related Brain Regions Of Brandt's Voles(Lasiopodomys Brandtii)

As an important plant polyphenols secondary metabolites,tannic acid(TA)changes herbivores' feeding behavior by influencing their feeding center and reward system.Whether the taste information of TA is transmitted from the traditional gustatory pathway to the feeding center and reward system,and whether TA influence the expression of taste-transmission-related genes in the gustatory pathway are still unclear.Glutamate(Glu)and ?-aminobutyric acid(GABA)are important excitatory and inhibitory neurotransmitters respectively in central nervous system,which also play a vital role in gustatory transmission.fosB/?fo.sB belongs to immediate early genes(IEGs),and the expression of the IEGs indicates activation of corresponding neurons.The subjects of this research were Brandti's voles,which were captured from Inner Mongolia grassland,then they were matched and bred indoor until fully grown up.We gave 500 ?L tannic acid solution on the surface of the tongue of Brandt's voles with different concentrations(0 mg·mL-1,30 mg·mL-1 and 60 mg·mL-1 as control,low dose and high dose group,respectively)for different time(1 d,5 d,10 d and 20 d).The real-time quantitative PCR(RT-qPCR)was used to assay the mRNA expression of vesicular glutamate transporter 3(Vglut3),vesicular GABA transporter(Vgat)and fosB/?fosB in nucleus of the solitary tract(NTS),the parabrachial nucleus(PBN)and the central amygdala(CeA).Immunohistochemistry(IHC)was used to measure the contents of VGLUT3,VGAT and FosB/AFosB.The body weights of animals were recorded every other day during the 20 days.So,the influence of tannic acid on the expression of taste-transmission-related genes in ventral gustatory pathways in Brandt's voles could be explored and the neural mechanisms of the affect of TA on the feeding behavior of herbivores could be elucidated.Besides,this results would provide theoretical basis for astrigency taste information pathway.The results were as follows.1.The results of RT-qPCR detection in NTS,PBN and CeA showed that after 1 d,5 d and 10 d treatment of TA,the expressions of fosB/?fosB mRNA in low and high dose group were significantly higher than those of control group while there was no significant differences in both low and high dose group after treated with TA for 20 d.The results of IHC detection in those three brain regions indicated that after 5 d and 10 d treatment of TA,the contents of FosB/?FosB in high dose group were significantly higher than those of control group.But this protein was not affected by low and high dose TA when treated for 1 d or 20 d.Therefore,it was suggested that TA could activate certain neurons in related brain regions of the ventral gustatory pathway,and animals would adapt to this stimulation after long-term treatment.2.In NTS,PBN and CeA,the expressions of Vglut3 in high dose group were also significantly higher than those of control group after the animals treated with TA for 1 d,5 d and 10 d,while there was no significant difference among all of the groups after 20 d treatment of TA.The results of IHC detection in those three brain regions indicated that after 5 d and 10 d treatment of TA,the expressions of VGLUT3 in low dose and high dose group were significantly higher than those of control group while there was no significant difference among low dose group,high dose group and control group after 1d and 20 d treatment of TA.The above results indicated that a certain dose of TA solution within a certain time could promote the mRNA and protein expression of Vglut3 in taste related brain regions of Brandt's voles.3.In contrast to the expression of Vglut3,the results of RT-qPCR detection in NTS,PBN and CeA showed that after 1 d,5 d and 10 d treatment of TA,the expressions of Vgat in high dose group were significantly lower than those of control group while there was no significant difference among low dose group,high dose group and control group after 20 d treatment of TA.The results of IHC detection in those three brain regions indicated that after 5 d and 10 d treatment of TA,the expressions of VGAT in high dose group were significantly lower than those of control group while there was no significant difference among low dose group,high dose group and control group after 1 d and 20 d treatment of TA.Those results meant that a certain dose of TA solution within a certain time could inhibit the mRNA and protein expression of Vgat in taste related brain regions of Brandt's voles.4.During the process of oral infusing different doses of TA solution to Brandt's voles in 20 days,animals' body weights were recorded every other day for 11 times.No significant difference of body weight was found among low dose group,high dose group and control group at each time point.Those results indicated that oral infusion of certain dose of TA solution could not influence the body weight of Brandt's voles.It could be concluded that a certain dose of TA solution could activate taste neurons in related brain regions of the ventral gustatory pathways,regulate gustatory information transmission of astringency,and influence the feeding behavior of herbivores by promoting the expression of Vglut3 while inhibiting the expression of Vgat in taste related brain regions of Brandt's voles.