Diuretic activities of fayiren and coix seed in normal rats

Background Coix seed is a traditional Chinese medicine with pharmacological effects and food efficacy. It is well-know and widely used in China and other Asian countries. Fayiren is a new artillery material processed from Coix Seed. This is the first study of the diuretic activities of Fayiren and coix seed in normal rats. Methods Forty-eight rats were randomly divided into 6 groups (8 rats/group) according to body mass and urine volume stratification, namely model (physiological saline) group, positive control (furosemide 20 mg/kg) group, coix seed (1666 mg/kg) group, low-dose of Fayiren group (166 mg/kg) and high-dose Fayiren group (1666 mg/kg). Rats were fasted for 16 h before the experiment, with normal water supply. Immediately after administration, each group of rat was placed in a metabolic cage, and urine was collected once after every hour for a total of 6 times. The urine volume at each time point for collection was measured, and then totaled. After the 6 h recording procedure, the treatments were administered once a day and the urine was collected at the 24th, 48th, 72th, 96th, 110th, 134th, and 158th hours from the start respectively. The urine pH and Na +, K +, Ca 2+, Cl - concentrations at each time point of each group of rats were measured. The contents of ALD, ANP, ADH, Na+-K+-ATPase, the gene expression and protein levels of AQP1, AQP2 and AQP3 in urine of rats in each group were determined. SPSS22.0 statistical software was used to analyze the experimental data. One way ANOVA and multiple comparisons between LSD groups were performed. The difference is considered significant When p < 0.05 or p < 0.01. Results After the administration of Fayiren and coix seed, compared with normal rats, the total output of urine in the high-dose coix seed & Fayiren group and the positive control group both increased; In addition, the contents of Na+ and Cl-in urine in these groups increased as well. However, the content of K+ did not increase in all groups. Contents of ALD and ADH was decreased and increased contents of ANP observed in urine in both high-dose and low-dose Fayiren groups with significant differences from model group (P < 0.05). Coix seed significantly reduced ADH and increased ANP levels compared with model group (P < 0.05). There was no obvious change in the urine pH content in urine of all rats. All the aquaporin (AQP1, AQP2, and AQP3) contents were decreased comparing to the model group, the coix seed group, as well as the Fayiren group. The effect of coix seed was particularly notable on AQP2, and the difference was significant against the Furosemide group (P < 0.05). By contrast, Fayiren showed greater effects on AQP1 and AQP3, with statistically significant difference comparing to the model group (P༜0.05). Conclusions This study will provide experimental evidence for explaining the different mechanisms of diuretic effects in natural medicine use of coix seed and artillery material processed from Coix Seed. The Fayiren may affect the reabsorption of water in the kidney through mechanisms related to increased ANP secretion,decreased ALD and ADH secretion in urine, and it significantly affect the expression of aquaporin 1 and aquaporin 3. However, coix seed may increase ANP but decreased ADH secretion, further affecting the expression of aquaporin2 and exert diuretic effect.