Research on the effect of Dipsaci Radix before and after salt-processed on kidney yang deficiency syndrome rats and the preliminary mechanism study through the BMP-Smad signaling pathway

Dipsaci Radix (DR) is the dry root of Dipsacus asper Wall. ex DC.The purpose of this study was to compare the effects of DR on rats before and after salt-processed with kidney yang deficiency syndrome (KYDS), and we selected the BMP-Smad signaling pathway to explore the mechanism of DR.The model of KYDS was established by subcutaneous injection of hydrocortisone, the crude DR (CDR) and salt-processed DR (SDR) were given the corresponding dose (2 g/kg, 4 g/kg, and 6 g/kg). The organ index and the contents of adrenocorticotropic hormone (ACTH), cortistatin (CORT), thyroid hormone (T4), tumor necrosis factor-alpha (TNF-α), testosterone (T), estradiol (E2), cyclic adenosine monophosphate (cAMP), cyclic guanosine monophosphate (cGMP), Na+-K+-ATPase, and growth hormone (GH) in serum were measured to evaluate the intervention effect of DR on KYDS rats. The expression of Smad 1, Smad 4, Smad 5, Smad 8, and BMP 7 protein in kidney was determined by immunohistochemistry, quantitative PCR (qPCR) and Western blot analysis. The effects of DR on 5 expression factors in the BMP-Smad signaling pathway were studied. Constituents absorbed into blood were identified by UPLC-Q-TOF/MS.The results showed that compared with the model group, the thymus and kidney index, as well as the contents of ACTH, CORT, cAMP, GH, Na+-K+-ATPase, T, T4, and E2 were significantly increased in the CDR and SDR groups, and the contents of cGMP and TNF-α were significantly decreased. Compared with the CDR high dose group, ACTH, Na+-K+-ATPase, T, and T4 were significantly increased in the SDR high dose group. The results of immunohistochemistry, qPCR, and Western blot analysis showed that compared with the model group, the expression levels of Smad 1, Smad 4, Smad 5, Smad 8 and BMP 7 proteins in the kidney of DR groups were significantly increased. And SDR groups tended to be better than CDR groups. 8 constituents migrating to blood were identified.This study showed that both CDR and SDR could have a good therapeutic effect on KYDS, and SDR was better than CDR. This study chose the BMP-Smad signaling pathway to study the mechanism of DR in the treatment of KYDS and provided a scientific basis for the processing mechanism of salt-processed.