Salidiuretic action by genistein in the isolated, perfused rat kidney

Effects of Genistein on Common Kidney Diseases

Genistein is a naturally occurring phytoestrogen (soy or soybean products) that is classified as an isoflavone, and its structure is similar to that of endogenous estrogens; therefore, genistein can exert an estrogen-like effect via estrogen receptors. Additionally, genistein is a tyrosine kinase inhibitor, which enables it to block abnormal cell growth and proliferation signals through the inhibition of tyrosine kinase. Genistein is also an angiogenesis inhibitor and an antioxidant. Genistein has effects on kidney cells, some of the kidney’s physiological functions, and a variety of kidney diseases. First, genistein exerts a protective effect on normal cells by reducing the inflammatory response, inhibiting apoptosis, inhibiting oxidative stress, inhibiting remodeling, etc., but after cell injury, the protective effect of genistein decreases or even has the opposite effect. Second, genistein can regulate renin intake to maintain blood pressure balance, regulate calcium uptake to regulate Ca²⁺ and Pi balances, and reduce vasodilation to promote diuresis. Third, genistein has beneficial effects on a variety of kidney diseases (including acute kidney disease, kidney cancer, and different chronic kidney diseases), such as reducing symptoms, delaying disease progression, and improving prognosis. Therefore, this paper reviews animal and human studies on the protective effects of genistein on the kidney in vivo and in vitro to provide a reference for clinical research in the future.

Soy diet for nonalcoholic fatty liver disease: A meta-analysis of randomized controlled trials

INTRODUCTION

The efficacy of soy diet for nonalcoholic fatty liver disease remains controversial. We conduct a systematic review and meta-analysis to explore the influence of soy diet vs placebo on the treatment of non-alcoholic fatty liver disease.

METHODS

We search PubMed, EMbase, Web of science, EBSCO, and Cochrane library databases through October 2020 for randomized controlled trials assessing the efficacy of soy diet vs placebo for nonalcoholic fatty liver disease. This meta-analysis is performed using the random-effect model.

RESULTS

Five randomized controlled trials are included in the meta-analysis. Overall, compared with control group for nonalcoholic fatty liver disease, soy diet is associated with significantly reduced HOMA-IR (standard mean difference [SMD] = -0.42; 95% confidence interval [CI] = -0.76 to -0.08; P = .01), increased insulin (SMD = -0.64; 95% CI = -0.98 to -0.30; P = .0002) and decreased malondialdehyde (SMD = -0.43; 95% CI = -0.74 to -0.13; P = .005), but demonstrated no substantial impact on body mass index (SMD = 0.17; 95% CI = -0.20 to 0.53; P = .37), alanine aminotransferase (SMD = -0.01; 95% CI = -0.61 to 0.60; P = .98), aspartate-aminotransferase (SMD = 0.01; 95% CI = -0.47 to 0.49; P = .97), total cholesterol (SMD = 0.05; 95% CI = -0.25 to 0.35; P = .73) or low density lipoprotein (SMD = 0; 95% CI = -0.30 to 0.30; P = .99).

CONCLUSIONS

Soy diet may benefit to alleviate insulin resistance for nonalcoholic fatty liver disease.

Genistein inhibits high fat diet-induced obesity through miR-222 by targeting BTG2 and adipor1

Obesity and diabetes mellitus have become major health problems worldwide. In recent years, genistein has been found to be capable of inhibiting obesity and alleviating insulin resistance. However, the molecular mechanism of genistein against obesity is still not fully understood. In this study, we used 3T3-L1 preadipocytes and obese mice as models to explore the molecular mechanism of genistein against obesity. We found that genistein can inhibit obesity and downregulate the expression of miR-222 in mouse adipose tissue. In 3T3-L1 preadipocytes, treatment with miR-222 inhibitor or genistein reduced the expression of miR-222 and promoted lipid decomposition, while miR-222 treatment increased the expression of miR-222 and inhibited lipolysis. Moreover, the dual-luciferase reporter assay system confirmed that BTG2 and adipor1 are the target genes of miR-222. Experiments conducted in vitro and in vivo suggest that genistein may regulate lipid metabolism in the adipose tissue of obese mice by regulating the expression of miR-222 and its target genes, BTG2 and adipor1. Our findings provide a new epigenetic mechanism underpinning the ability of genistein to resist obesity. These results may provide a reference point for the dietary treatment of obesity and type 2 diabetes mellitus.

Diet and Diabetic Kidney Disease: Plant Versus Animal Protein

PURPOSE OF REVIEW

The goal of this review is to present an overview of the evidence on the effectiveness of plant-based diets in delaying progression of diabetic kidney disease (DKD).

RECENT FINDINGS

The ideal quantity of dietary protein has been a controversial topic for patients with DKD. Smaller studies have focused on protein source, plant versus animal, for preventing progression. Limited evidence suggests that dietary patterns that focus on plant-based foods, those that are lower in processed foods, or those that are lower in advanced glycation end products (AGE) may be useful in prevention of DKD progression. Increasing plant-based foods, incorporating diet patterns that limit processed foods, or potentially lowering AGE contents in diets may be beneficial for dietary management of DKD. However, dietary studies specifically targeted at DKD treatment are sparse. Further, large trials powered to assess outcomes including changes in kidney function, end-stage kidney disease, and mortality are needed to provide more substantial evidence for these diets.

Natriuretic effect of equol

A furosemide-sensitive Na-K-Cl cotransporter (NKCC2 isoform) accounts for almost all luminal NaCl reabsorption in the thick ascending limb of Henle's loop (TALH). The activity of this transport protein is regulated by humoral factors known as cotransport inhibitory factors. One family of these compounds is represented by the urinary phytoestrogens equol and genistein, which inhibit cotransport fluxes at concentrations similar to furosemide. Moreover, they possess salidiuretic potency similar to furosemide in the isolated perfused rat kidney, but are less potent than furosemide (in vivo). Thus, dietary phytoestrogens can be responsible, at least in part, for the low blood pressure of vegetarians.

Nitric oxide enhancement and blood pressure decrease in patients with metabolic syndrome using soy protein or fish oil

OBJECTIVE: To verify the effects of fish oil and soy on nitric oxide (NO) and blood pressure in patients with metabolic syndrome (MS). SUBJECTS AND METHODS: Sixty women with MS were investigated in a parallel randomized design study. The first group maintained their usual diet; the second group received 25 g/day of soy; the third group received 3 g/day of n-3 fatty acids, and the fourth group the same amount previously cited of n-3 fatty acids and soy. RESULTS: Serum nitric oxide metabolites showed significant increase after 90 days in the fish oil and soy groups. Systolic pressure reduced after 45 days of treatment with fish oil, whereas diastolic pressure decreased significantly throughout the study in the soy group. CONCLUSIONS: NO increase and blood pressure reduction with fish oil or soy protein reinforce the importance of the influence of NO on blood pressure in patients with MS.

Comparison of hypertension and its risk factors between the Guangxi Bai Ku Yao and Han populations

OBJECTIVE

Little is known about the prevalence of hypertension in Bai Ku Yao, an isolated subgroup of the Yao minority in China. The aim of this study was to compare the difference in the prevalence of hypertension and its risk factors between the Guangxi Bai Ku Yao and Han populations.

METHODS

A cross-sectional study of hypertension in 1170 subjects of Bai Ku Yao and 1173 participants of Han Chinese aged 15-89 was conducted by a stratified randomized cluster sampling. Information on diet and lifestyle was collected with standardized questionnaires. Blood pressure, serum lipids and several anthropometric parameters were obtained in all subjects.

RESULTS

Systolic, diastolic and pulse pressure levels and hypertension prevalence (10.85% vs 16.45%, p<0.001) were lower in Bai Ku Yao than in Han. Hypertension was positively correlated with male, age, physical activity, body mass index, waist circumference, total energy, total fat and sodium intakes, and negatively associated with education level and total dietary fibre intake in both ethnic groups (p<0.05-0.001). Hypertension was also positively associated with alcohol consumption in Han. The rates of awareness, treatment and control were lower in Bai Ku Yao than in Han (p<0.05 for all).

CONCLUSIONS

The difference in the hypertension prevalence between the two ethnic groups might result from different diet, lifestyle, physical activity level, sodium intake and genetic factors.

Cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel and Na-K-Cl cotransporter NKCC1 isoform mediate the vasorelaxant action of genistein in isolated rat aorta

The soy phytoestrogen genistein is a potent vasorelaxant, but its mechanism of action is poorly understood. Here, we used endothelium-denuded rat aorta to investigate the role of the cyclic AMP(cAMP)-activated, cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel, and its associated Na-K-Cl cotransporter NKCC1. Isolated, endothelium-denuded rat aorta was contracted with phenylephrine 1 microM, and the vasorelaxant responses to genistein were investigated under conditions where CFTR was inhibited by DPC (diphenylamine-2-carboxylic acid) or glibenclamide (n=6 for compound). Both compounds fully antagonized the vasorelaxant responses to genistein, with IC50=57+/-18 microM and 42+/-11 microM for DPC and glibenclamide respectively. H-89, a selective protein kinase A (PKA) inhibitor, blocked the vasorelaxant responses to genistein. Finally, the NKCC1 inhibitor, bumetanide fully antagonized the vasorelaxant responses to genistein against phenylephrine- or KCl-induced contractions, with IC50=2.0+/-0.2 microM and 1.6+/-0.5 microM, respectively (n=6 for condition). These results strongly suggest that CFTR opening is involved in the vasorelaxant action of genistein, and that cAMP-dependent CFTR phosphorylation and chloride entry via the NKCC1 cotransporter are required for genistein action.

Effects of dual-action genistein derivatives on relaxation in rat aorta

Protein tyrosine kinases and nitric oxide (NO) play important roles in several cardiovascular diseases. In this study, we examined the actions of two compounds, each has structure of genistein (a tyrosine kinase inhibitor) and an NO donor, on endothelium-independent relaxation responses in the isolated rat aorta. By rational drug design, genistein was modified to acquire an NO donor, and we synthesized two such compounds (G-II, G-VI). These compounds and genistein induced dose-dependent relaxation responses in endothelium-denuded aortic strips, the rank order of potencies being G-VI > G-II > genistein. Incubation of endothelium-denuded strips with 1H-[1,2,4] oxadiazolo[4,3-a]-quinoxalin-1-one (ODQ, 10 microM), a guanylyl cyclase inhibitor, inhibited both the G-II- and G-VI-induced relaxations, but not the genistein-induced relaxation. The residual relaxations induced by these two compounds were similar to the genistein-induced relaxation. Incubation of endothelium-denuded strips with lysophosphatidylcholine (LPC, 20 microM)-which is a major atherogenic lysophospholipid component of oxidized low-density lipoprotein and is known to activate tyrosine kinase-caused a significant rightward shift in the dose-response curve for genistein. LPC also shifted the G-II- and G-VI-induced relaxation curves to the right; however, these relaxations in the presence of LPC were greater than that induced by genistein. The sodium nitroprusside-induced relaxation in endothelium-denuded strips was similar between in the absence and presence of LPC. These results suggest that each of our newly developed G-II and G-VI compounds has a dual action, as an NO donor and a tyrosine kinase inhibitor. These compounds may be useful against certain cardiovascular diseases.

Longitudinal study of soy food intake and blood pressure among middle-aged and elderly Chinese women

BACKGROUND

Several small-scale clinical trials have suggested a potential beneficial effect of short-term soy consumption on blood pressure (BP). Data are scanty on long-term effects of the usual intake of soy foods on BP in general populations.

OBJECTIVE

Our aim was to examine the association between usual intake of soy foods and BP.

DESIGN

The usual intake of soy foods was assessed at baseline, and BP was measured 2-3 y after the baseline survey among 45 694 participants of the Shanghai Women's Health Study aged 40-70 y who had no history of hypertension, diabetes, or cardiovascular disease at recruitment. Multiple regression models were used to estimate mean differences in BP associated with various intakes of soy foods.

RESULTS

Soy protein intake was inversely associated with both systolic BP (P for trend = 0.01) and diastolic BP (P for trend = 0.009) after adjustment for age, body mass index, and lifestyle and other dietary factors. The adjusted mean systolic BP was 1.9 mm Hg lower (95% CI: -3.0, -0.8 mm Hg) and the diastolic BP was 0.9 mm Hg lower (-1.6, -0.2 mm Hg) in women who consumed > or =25 g soy protein/d than in women consuming <2.5 g/d. The inverse associations became stronger with increasing age (P for interaction < 0.05 for both BPs). Among women >60 y old, the corresponding differences were -4.9 mm Hg (95% CI: -8.0, -1.9 mm Hg) for systolic BP and -2.2 mm Hg (95% CI: -3.8, -0.6 mm Hg) for diastolic BP.

CONCLUSION

Usual intake of soy foods was inversely associated with both systolic and diastolic BPs, particularly among elderly women.

The Multidrug Resistance ofIn VitroTumor Cell Lines Derived from Human Breast Carcinoma MCF-7 Does Not Influence Pentavalent Technetium-99m-Dimercaptosuccinic Acid Uptake

The main causes of multidrug resistance (MDR) are overexpression of P-glycoprotein (P-gp) and multidrug resistance-associated protein isoform 1 (MRP1) often associated with high levels of glutathione (GSH). We investigated whether MDR phenotype can influence Tc-99m-(V)-DMSA [pentavalent technetium-99m-dimercaptosuccinic acid] entry by comparing its uptake with that of Tc-99m-sestamibi (MIBI) on an in vitro model of sensitive (MCF-7) and variant resistant cell lines. Drug resistance was assessed by immunoblotting, GSH measurement, and 3-[4,5-dimethylthiazol-2-yl]-2,5,diphenyl tetrazolium bromide (MTT) assay. To correlate MDR phenotype with tracer accumulation, uptakes were performed with and without P-gp and MRP1 inhibitors and after GSH modulation. Similar accumulation of Tc-99m-(V)-DMSA was observed in all cell lines and the use of MDR reversals did not enhance its uptake. Our results demonstrate clearly that Tc-99m-(V)-DMSA uptake is not related to either P-gp and MRP1 expression, or GSH levels. In contrast, Tc-99m-MIBI accumulation is inversely proportional to the cell MDR phenotype. The combination of Tc-99m-(V)-DMSA and Tc-99m-MIBI may be a useful tool for noninvasive detection of malignant sites and their chemoresistance status.

Genistein treatment reduces arterial contractions by inhibiting tyrosine kinases in ovariectomized hypertensive rats

The aim of the present study was to evaluate the vascular effects of genistein in a short-term study. The ovariectomized spontaneously hypertensive rats (SHR) were divided into four groups (n = 8 in each), which received the following subcutaneous treatments either for 2 days or for 2 weeks: (1) solvent control (96% dimethylsulphoxide (DMSO) 1 ml/kg), (2) estradiol-17beta (25 microg/kg), (3) genistein (2.5 mg/kg; low-dose), and (4) genistein (25 mg/kg; high-dose). The renal arterial rings were studied using organ bath system. The renal artery contractions were attenuated by the 2-day low-dose genistein treatment as follows: angiotensin II (46%), noradrenaline (42%) KCl (36%), and endothelin-1 (34%). Only the angiotensin II-induced contractions were reduced by the 2-week treatment with estradiol-17beta (38%) and with the low-dose of genistein (31%). The 2-day genistein treatment reduced tyrosine phosphorylation, while the other treatments or treatment times had no effect. The 2-day low-dose genistein treatment had no estrogenic effect on the uterine morphology. The mechanism for attenuated contractility in the renal arteries after the 2-day low-dose genistein treatment is independent of the estrogenic effect of genistein, but is due to the tyrosine kinase inhibitory property of genistein.

Soy milk lowers blood pressure in men and women with mild to moderate essential hypertension

Soy-based diets reduce blood pressure in spontaneously hypertensive rats, but apparently not in hypertensive humans. In the present study, the antihypertensive potential of soy milk (500 mL twice daily) compared with cow's milk was investigated in a 3-mo double-blind randomized study of 40 men and women with mild-to-moderate hypertension. Before initiation of the study, urinary isoflavonoids (measured by HPLC) were undetectable in most cases (for genistein, they were always <100 micromol/L). After 3 mo of soy milk consumption, systolic blood pressure decreased by 18.4 +/- 10.7 mmHg compared with 1.4 +/- 7.2 mmHg in the cow's milk group (P < 0.0001), diastolic blood pressure decreased by 15.9 +/- 9.8 mmHg vs. 3.7 +/- 5.0 mmHg in the cow's milk group (P < 0.0001) and mean blood pressure decreased by 16.7 +/- 9.0 mmHg compared with 3.0 +/- 4.6 mmHg in the cow's milk group (P < 0.0001). Urinary genistein was strongly (r = -0.588) and significantly (P = 0.002) correlated with the decrease in blood pressure, particularly for diastolic values. In conclusion, chronic soy milk consumption had modest, but significant hypotensive action in essential hypertensive subjects. This hypotensive action was correlated with the urinary excretion of the isoflavonoid genistein.

Dietary soy exerts an antihypertensive effect in spontaneously hypertensive female rats

This study tested the hypothesis that dietary soy would attenuate the development of hypertension in female spontaneously hypertensive rats (SHR). Female SHR and control Wistar-Kyoto rats were obtained at 4 wk of age, randomly assigned to either an ovariectomized (OVX) group or a sham-operated group, and placed on a soy diet or control casein diet. After a minimum of 8 wk on their respective diets, mean arterial pressure (MAP) and heart rate (HR) were recorded before and after inhibition of nitric oxide synthase, air-jet stress, or ganglionic blockade. The major finding of this study is that MAP was reduced in the OVX SHR consuming soy diet compared with the casein-fed controls (150 +/- 4 vs. 164 +/- 3 mmHg). Plasma genistein concentrations were increased in the soy-fed OVX SHR (1.23 +/- 0.31 microM) compared with the casein-fed OVX SHR (nondetectable). However, there was no difference in plasma genistein concentrations between sham-operated and OVX SHR (1.37 +/- 0.42 vs. 1.23 +/- 0.31 microM). Inhibition of nitric oxide synthase increased MAP and decreased HR in all groups; diet did not affect this response. Air-jet stress increased MAP and HR in all groups. However, these responses were exaggerated in the soy-fed SHR. Finally, ganglionic blockade abolished the antihypertensive effect of soy diet in the OVX SHR. These findings indicate that dietary soy exerts an antihypertensive effect in OVX SHR. This effect does not involve the nitric oxide system but may be related to an as yet undefined interaction with the autonomic nervous system.

Soy based diet attenuates the development of hypertension when compared to casein based diet in spontaneously hypertensive rat

The purpose of this study was to compare the effects of soy and casein based diets on blood pressure and cardiovascular functions in male and female spontaneously hypertensive rats (SHR). The systolic blood pressure was measured at the beginning and at the end of study. After a five week supplementation period with three different diets, the rats were decapitated and arterial responses and the weight-to-body weight-ratios of the organs were studied. The development of hypertension was attenuated in both female and male rats on soy protein diet when compared to the casein diet. Soy based diet lowered serum total cholesterol level when compared to the control diet. Both casein and soy protein supplementation in diet induced a significant renal hypertrophy in both female and male SHR rats when compared to SHR rats on the control diet. Soy protein supplementation reduced significantly serum estradiol-17beta concentration when compared to the control diet. There were no differences in the serum testosterone concentrations between the diet groups. When compared to the casein based diet the soy based diet attenuated the development of hypertension and decreased serum total cholesterol level in SHRs. These effects were independent of gender. The mechanisms and clinical importance of these findings remain to be clarified.