Targeted Metabonomics Combined with 16SrRNA Gene Sequencing to Analyze the Effect of Rehmanniae Radix on Intestinal Flora in Rats with Kidney Yin Deficiency Syndrome Before and After Processing / 中药新药与临床药理

ABSTRACT

Objective To investigate the effects of Rehmanniae Radix before and after processing on the intestinal flora of rats with kidney yin deficiency syndrome.Methods SD rats were randomly divided into blank group,model group,probiotic group(0.35 g·kg-1),high-/medium-/low-dose groups of Rehmanniae Radix Praeparata(3.5,1.75,0.875 g·kg-1),and high-/medium-/low-dose groups of Rehmanniae Radix(3.5,1.75,0.875 g·kg-1),with 9 rats in each group.Except for the blank group,rats in each group were injected intramuscularly with Dexamethasone Sodium Phosphate Injection(0.35 mg·kg-1)once a day for 21 days.The drug was administered by gavage once a day on the seventh day of modelling for 14 days.The adrenal histopathological changes were observed by using HE staining;the levels of serum cyclic adenosine monophosphate(cAMP),cyclic guanosine monophosphate(cGMP),corticotropin-releasing hormone(CRH),adrenocorticotropic hormone(ACTH),and corticosterone(CORT)were detected by ELISA;and the levels of short-chain fatty acids in the feces and changes in the diversity of intestinal flora were detected by a targeted metabolomic approach in conjunction with 16SrRNA sequencing in the rats in each group.Results(1)Compared with the blank group,the body mass of rats in the model group was significantly decreased on days 7,14 and 21(P＜0.05,P＜0.01);serum levels of cAMP,CRH,ACTH,CORT and the cAMP/cGMP ratio were all significantly increased(P＜0.01),and the cGMP content was significantly decreased(P＜0.01);and the adrenal cortex was thinned,with the boundaries of various layers of the cortex unclear.Compared with the model group,the body mass of rats in the Rehmanniae Radix Praeparata administration group on day 21 were all significantly increased(P＜0.05,P＜0.01),and the serum content of cAMP,CRH,ACTH,CORT and the cAMP/cGMP ratio were all significantly decreased(P＜0.05,P＜0.01),and the content of cGMP was significantly increased(P＜0.05,P＜0.01)in the rats;body mass of rats in the Rehmanniae Radix administration group did not change significantly(P＞0.05),CRH and CORT contents in serum of rats in the high-dose group of Rehmanniae Radix were significantly reduced(P＜0.01),and ACTH contents in serum of rats in the medium-dose group of Rehmanniae Radix were significantly reduced(P＜0.05);the adrenal cortex of rats in all the administration groups were improved,in particular,the thickening of the adrenal cortex layers was obvious in the Rehmanniae Radix Praeparata group,and the improvement effect was superior to that in the Rehmanniae Radix group.(2)Compared with the blank group,the difference of Coverage index was not statistically significant(P＞0.05),and the coverage of each group was good;the abundance index(Sobs,Ace,Chao)and diversity index(Shannon)of the model group were significantly increased(P＜0.01),and the Simpson index was significantly decreased(P＜0.01).Compared with the model group,Sobs index was significantly decreased in the medium-and high-dose groups of Rehmanniae Radix Praeparata(P＜0.05),Chao index was significantly decreased in the administered groups of Rehmanniae Radix Praeparata and high-dose group of Rehmanniae Radix(P＜0.05,P＜0.01),and Simpson index was significantly increased in the high-dose group of Rehmanniae Radix Praeparata(P＜0.05).The changes of Rehmanniae Radix on the richness and diversity of intestinal microbial community in kidney yin-deficient rats were small,while Rehmanniae Radix Praeparata could better maintain the stability of the richness and diversity of intestinal microbial community in kidney yin-deficient rats.(3)Compared with the blank group,the abundance of phylum firmicutes in the feces of the model group was significantly decreased,while the abundance of bacteroides and actinomycetes was significantly increased.The abundance of Lactobacillus was significantly decreased(P＜0.01),while the abundance of norank_f__Muribaculaceae and Bifidobacterium was significantly increased(P＜0.01).Compared with the model group,the trend of recovery of bacterial abundance in the probiotic group and the high-dose group of Rehmanniae Radix Praeparata was more similar to that of the blank group,which showed that it had the best regulating effect on the ratio of bacterial flora;the abundance of lactobacillus in all administered groups was increased,with that of the probiotic group was significantly increased(P＜0.01);the abundance of norank__f__Muribaculaceae and Bifidobacterium were all decreased,among which the probiotic group and the medium-and high-dose groups of Rehmanniae Radix Praeparata were significantly decreased(P＜0.01),and the effect was significantly superior to that of Rehmanniae Radix.The COG functions of the samples in each group were mainly focused on amino acid transport and metabolism,carbohydrate transport and metabolism,translation,ribosomal structure and biogenesis,replication,recombination and repair,but the abundance information of each function was different between groups,which may be due to the differences caused by dysbiosis of intestinal flora.(4)Compared with the blank group,the levels of acetic acid,butyric acid and propionic acid in the faeces of rats in the model group were significantly decreased(P＜0.05,P＜0.01),and the level of isobutyric acid was significantly increased(P＜0.01).Compared with the model group,the levels of acetic acid,butyric acid and propionic acid in the faeces of rats in the probiotic group and the low-,medium-and high-dose groups of Rehmanniae Radix Praeparata were significantly increased(P＜0.05,P＜0.01)and the levels of isobutyric acid were significantly decreased(P＜0.05,P＜0.01);although the above indexes in the Rehmanniae Radix group were improved,the difference was not statistically significant(P＞0.05).Conclusion The enhanced therapeutic effect of Rehmanniae Radix after processing on rats with kidney yin deficiency syndrome may be related to its adjusting effect on intestinal flora.