ABSTRACT
Objective:To explore the effect and mechanism of Guizhitang with different proportions of Cinnamomi Ramulus and Paeoniae Alba Radix on overactive cardiac sympathetic nerves in salt-sensitive hypertensive rats. Method:Randomly divide the forty male 6-week-old salt-sensitive hypertensive rats into five groups： the normal control group， the model group， the Cinnamomi Ramulus and Paeoniae Alba Radix 1∶1 group， the Cinnamomi Ramulus and Paeoniae Alba Radix 1∶2 group，and the Cinnamomi Ramulus and Paeoniae Alba Radix 2∶1 group， each group has 8 animals， the normal control group was fed with low-salt feed， and the remaining four groups were fed with 8% high-salt feed. After 4 weeks of feeding， gastric feeding was started. Give both the normal control group and model group saline and the Cinnamomi Ramulus and Paeoniae Alba Radix 1∶1 group， the 1∶2 group，and the 2∶1 group， were given Guizhitang aqueous solution at 4.0， 5.5 and 5.5 g·kg-1， respectively. Continuous gavage intervention was held for 4 weeks. IITC multi-channel non-invasive sphygmomanometer was used to detect changes of systolic blood pressure before and after treatment in rats. Left ventricular anterior wall end-diastolic thickness （LVAWd） and interventricular septal diastolic thickness （IVSd） were detected by echocardiography. Hematoxylin-eosin（HE）staining and Masson staining were used to observe the myocardial morphological changes of rats in each group， Western blot was used to detect the expression of nerve growth factor （NGF）， growth-associated protein 43 （GAP43） and tyrosine hydroxylase （TH） protein. Result:After 4 weeks of intervention with Guizhitang， compared with the normal control group， the blood pressure， LVAWd and IVSd of the model group were significantly increased， and the expressions of NGF， TH and GAP43 protein were significantly increased （P<0.01）. HE and Masson staining results showed that the model group had myocardial cell edema， a large number of inflammatory cell infiltration， myocardial fiber hyperplasia and disordered arrangement， and a large amount of collagen deposition could be seen in the intercellular substance. Compared with model group， the systolic blood pressure of rats in each Guizhitang group increased slowly， and the expression of NGF， TH and GAP43 protein decreased （P<0.05，P<0.01），the Cinnamomi Ramulus and Paeoniae Alba Radix 1∶1 group has the best effect. The results of echocardiography shows that the 1∶1 Guishao group could reduce LVAWd and IVSd levels （P<0.05，P<0.01）， the Cinnamomi Ramulus and Paeoniae Alba Radix 1∶2 group could reduce IVSd level （P<0.05）， there was no statistical difference in LVAWd， there was no statistical difference in LVAWd and IVSd in 2∶1 group. In terms of myocardial morphology， each group of Guizhitang can reduce cell edema and inflammatory cell infiltration， reduce myocardial fiber hyperplasia and collagen deposition， and improve the disorder of myocardial fiber arrangement. Among them， the 1∶1 group has the best effect. Conclusion:Guizhitang can inhibit the overactive activation of cardiac sympathetic nervous system，reduce the extent of myocardial fibrosis， inflammatory infiltration and myocardial hypertrophy， and protect salt-sensitive hypertension rats， whose mechanism may be related to regulating the expression of heart NGF.Among them， the Cinnamomi Ramulus and Paeoniae Alba Radix 1∶1 group is better than the 1∶2 and 2∶1 group in reducing myocardial fibrosis， inflammatory infiltration and myocardial hypertrophy.