Review Article on Molecular Mechanism of Regulation of Hypertension by Macro-elements (Na, K, Ca and Mg), Micro-elements/Trace Metals (Zn and Cu) and Toxic Elements (Pb and As).

Hypertension (HT) is a medical condition arising due to increase in blood pressure (BP) prevalent worldwide. The balanced dietary intakes of macro-elements and micro-elements including Na, K, Ca, Mg, Zn, and Cu have been described to maintain BP in humans by regulating the osmolarity of blood, cells/tissues, prevention of generation of oxidative and nitrosative stress (OANS), and endothelial damage through their functioning as important components of renin-angiotensin-aldosterone system (RAAS), antioxidant enzyme defense system, and maintenance of blood vascular-endothelial and vascular smooth muscle cell (VSMC) functions. However, inadequate/excess dietary intakes of Na/K, Ca/Mg, and Zn/Cu along with higher Pb and As exposures recognized to induce HT through common mechanisms including the followings: endothelial dysfunctions due to impairment of vasodilatation, increased vasoconstriction and arterial stiffness, blood clotting, inflammation, modification of sympathetic activity and higher catecholamine release, increased peripheral vascular resistance, and cardiac output; increased OANS due to reduced and elevated activities of extracellular superoxide dismutase and NAD(P)H oxidase, less nitric oxide bioavailability, decrease in cGMP and guanylate cyclase activity, increase in intracellular Ca2+ ions in VSMCs, and higher pro-inflammatory cytokines; higher parathyroid and calcitriol hormones; activation/suppression of RAAS resulting imbalance in blood Na+, K+, and water regulated by renin, angiotensin II, and aldosterone through affecting natriuresis/kaliuresis/diuresis; elevation in serum cholesterol and LDL cholesterol, decrease in HDL cholesterol due to defect in lipoprotein metabolism. The present study recommends the need to review simple dietary mineral intervention studies/supplementation trials before keeping their individual dietary excess intakes/exposures in consideration because their interactions lead to elevation and fall of their concentrations in body affecting onset of HT.

Attenuation of Zn-induced hyperleptinemia/leptin resistance in Wistar rat after feeding modified poultry egg.

BACKGROUND: The prevalence of obesity is increasing exponentially world over. Leptin resistance/hyperleptinemia is attributed to its cause in majority of the obese humans where mutation in genetic component or ob gene has not been found operative. The generation of oxidative stress was suggested as its cause. In our previous study, we have reported that the inclusion of antioxidant enriched modified poultry egg (ME) in diet reversed the ionic imbalance and ameliorated the oxidative stress caused by excessive Zn in diet. In the present study, the efficacy of ME verses conventional egg (CE) was tested on Zn-induced leptin resistance in rat model to ascertain if the supplementation of antioxidants in the form of egg can reverse Zn-induced leptin resistance to leptin sensitive state. METHODS: Hyperleptinemia was induced in rats by feeding them Zn-supplemented hyperleptinemic diets-I and II (Zn-HL-Diet) for 2 months. Thereafter, half of them were fed either on CE or ME mixed Zn-HL-diets I and II for another two months. The data was analyzed applying one way Anova and Tukey's HSD post hoc test. RESULTS: The results revealed that food intake, gain in body weight, height and number/unit surface area of intestinal microvillus and serum leptin, glucose, insulin and cortisol were higher in CE and Zn-HL-Diet treated groups; serum Zn, Cu, Mg were higher and Cu and Mg in tissues were lower in them than the control group. In ME treated groups, these parameters were lower and were close to the control group. These changes resulted from the restoration of ionic balance of Zn, Cu and Mg in the blood serum and tissues including liver and hair in ME treated rats. CONCLUSION: The data suggest that Zn-induced leptin resistance can be attenuated through restoring the ionic balance of Zn, Cu and Mg through inclusion of antioxidants in diet such as these modified eggs. But further clinical studies are required before they are put to use for human consumption.

Excessive zinc in diet induces leptin resistance in Wistar rat through increased uptake of nutrients at intestinal level.

PROJECT: The ob gene has either been found to be mutant defective resulting in a deficiency of its product leptin or leptin has been found to be resistant to its receptors in obese human and rodents. The factors inducing leptin resistance have not been identified. Since excessive bioavailability of Zn has been implicated in obesity, we investigated if its excess in diet induces leptin resistance. PROCEDURE: For the investigations, three groups of Wistar rats were included in this study and they were fed on equicalories semi synthetic basal diet containing 20 mg, 40 mg or 80 mg Zn/kg diet for 120 days. There after they were sacrificed for hormonal status and intestinal investigations. RESULTS: The data of this study revealed that the food intake, gain in body weight, serum leptin, glucose, insulin, cortisol increased with increased Zn concentration in diet. TEM study showed a positive correlation between Zn concentration in diet and number of microvilli/unit surface area of the mucosal epithelial cells of the intestine. CONCLUSION: The results of this study suggest that excessive bioavailability of Zn induces leptin resistance through increased uptake of nutrients at intestinal level, leading to the growth of the fat cells which aggravated the leptin synthesis and its release in the blood stream. In spite of its higher circulating level, it was unable to reduce the food intake and gain in body weight in Zn treated rats equivalent to the control group.

Antihypertensive effect of Cu and Mg enriched modified poultry eggPsi on Zn-induced hypertension in Wistar rat.

PROJECT: Excessive bioavailability of Zn either due to genetic predisposition or its high concentration in diet has been linked to increase in the prevalence of hypertension (HT) implicating the resultant deficiencies of Cu and Mg as its cause in some populations. To combat their nutritional deficiencies, a modified poultry egg (ME(Psi)) was designed containing higher amounts of Cu, Mg and other antioxidants (vitamin E and linolenic acid) in their optimized concentrations. Prior to its human clinical trials, its efficacy was tested in Zn induced HT Wistar rat model in the present study. PROCEDURE: In one set, the rats were fed on equicaloric semi-synthetic basal diet containing 20 mg Zn/kg diet (control diet-I, control group-I), Zn-induced-hypertensive-diets-II and III (Zn-HT-diet-II and Zn-HT-diet-III) containing 40 and 80 mg Zn/kg diet (groups-II and III) for 180 days. In another set, the rats were initially fed Zn-HT-diet-II and Zn-HT-diet-III for 90 days and then shifted to ME(Psi) mixed Zn-HT-diet-II and III designated as groups-IIME and IIIME fed for another 90 days completing 180 days of feeding. RESULTS: The results revealed that increase in systolic pressure (SP) and heart rates (HR) were Zn concentration dependent and coincided well with higher serum Zn, Cu, Mg, aldosterone, cortisol, dyslipidemia and higher Zn, and low Cu and Mg concentrations in liver of groups-II and III rats. On feeding ME(Psi) mixed diets, a significant reduction in SP and HR were linked with decrease in serum Zn, Cu, Mg, aldosterone, cortisol and blood lipid profile along with fall in Zn and rise in Cu and Mg concentrations in liver of groups-IIME and IIIME approaching closer to control group-I. CONCLUSION: This study makes the basis for human clinical trials of ME(Psi) on HT patients who exhibit high Zn, Cu and Mg in their blood serum.

Modulation of Zn-induced hyperinsulinemia/insulin resistance in Wistar rat fed modified poultry egg(psi).

Excessive bioavailability of Zn causes Cu and Mg deficiencies resulting in hyperglycemia and hyperinsulinemia/insulin resistance. These defects may ameliorate if the ionic imbalance in them is corrected. In view of this, three groups of rats were included in this study. Initially, they were fed on semi-synthetic equicalories basal diet containing 20 mg Zn (control, group-I), on 40 mg Zn (group-II) and 80 mg Zn/kg diet (group-III) respectively for 3 months. Thereafter, half of the rats in group-II and III were shifted on Cu and Mg enriched modified poultry egg (ME(Psi)) mixed diets (groups-IIME and IIIME) while the remaining were continued to feed on their respective diets for another 3 months completing a total of 6 months. Hyperglycemia, hyperinsulinemia, hypercortisolemia, hyperzincemia, hypercupremia and hypermagnesaemia with corresponding increase of lipid droplets in the zona fasciculate of adrenal cortex and reduction in liver glycogen content in rats of groups-II and III were recorded. These changes were linked with a rise in Zn and fall in Cu and Mg in their liver. The addition of ME(Psi) in their diets led to fall of Zn and rise in liver Cu and Mg, and fall in serum Zn, Cu and Mg resulting in the improvement of glucose disposal, increase in insulin sensitivity, reduction in lipid droplets in zona fasciculate and increase in glycogen content in the liver approaching closer to the control group-I. The data suggest that these ME(Psi) can serve as non-pharmacological dietary supplement to prevent insulin resistance/hyperinsulinemia in populations who are at higher risk of diabetes mellitus either due to their genetic predisposition of excessive absorption and retention of Zn or due to higher Zn content in the food chain.

Beneficial effects of modified egg* on oxidative stress in F1- generation of metabolic syndrome-X induced Wistar rat.

Congenital malformations of neonates are one of the adverse effects of diabetic pregnancy which can be prevented by supplementation of vitamin E and C. The survived neonates usually are at higher risk to diabetes, hypertension, dyslipidemia and cardiovascular diseases that may possibly be prevented through antioxidants administration. In view of this information, the efficacy of modified poultry egg enriched with optimum minerals, vitamin E and omega-3 fatty acids was studied on F1-generation, which were made to survive by feeding them this modified egg to diabetic mothers of Wistar rats. The survived F1-generation displayed hyperglycemia, dyslipidemia and hypertension like their parents, evaluated after three months of the experiment. Their mineral status revealed a higher Zn and lower Cu, Mg and Mn levels in liver and kidney. Their lipid peroxidation products were however higher and the enzyme activities of superoxide dismutase, catalase, glutathione-S-transferase, glutathione reductase, glutathione (reduced) and glucose -6 phosphate dehydrogenase were significantly lower. In the other group of F1-generation, fed modified egg mixed diet, a significant reduction in the blood pressure, serum glucose, serum lipid profile, and the lipid peroxidation products, and a significant increase in the activities of enzymes per se with reversal of Zn, Cu, Mg and Mn levels closer to the control group were recorded. The data suggest that the modified egg can ameliorate the oxidative stress in F1-generation of diabetic rats by improving the mineral status in their body.

Attenuation of Zn-induced acute pancreatitis in Wistar rat fed on Cu- and Mg- enriched modified poultry egg Psi.

Zinc (Zn) consumption has increased in many populations either due to the increased intake of Zn-fortified foods as in the USA or in agricultural food stuffs as in some Indian states during the last decade. Its excessive intake has been reported to induce acute pancreatitis (AP) in many studies due to increase in oxidative stress that was further reported to cause Cu and Mg deficiencies. This led us to design a modified poultry egg (ME(Psi)) enriched with Cu and Mg along with other antioxidants, and its efficacy on Zn-induced AP was studied in male Wistar rats. In one set, the rats were fed on equacaloric semi-synthetic basal diet containing 20 mg Zn/kg diet (control, group I), and Zn-induced AP-I diet and AP-II diet containing 40 and 80 mg Zn/kg diet (groups II and III) for 180 days, respectively. In another set, the rats were initially fed on Zn-induced AP-I and AP-II diets for 90 days and then shifted to ME(Psi)-mixed Zn-induced AP-I and AP-II diets in groups IIME and IIIME for another 90 days. At the end of the experiment, data displayed increased serum and urinary Zn, Cu, and Mg levels in groups II and III rats, which were reduced and approached closer to control group I after ME(Psi) feeding in groups IIME and IIIME rats. Transmission electron microscopic studies of acinar cells revealed progressive dilation, vesicularization, and degeneration of endoplasmic reticulum (ER), and decrease in zymogen granules (ZG) in groups II and III rats in contrast to their curvilinear or concentric long parallel running cisternal profile of ER in control group I. The treatment of ME(Psi) helped in the restoration of the ER profile and ZG number, approaching closer to the control group I. The degree of recovery was dependent upon the degree of toxicity caused by the amount of Zn given in the diet. The results of this study suggest that ME(Psi)-mixed diet can protect the acinar cells from the deleterious effects of Zn by decreasing the oxidative stress.

Normolipidemic effect of antioxidants in low cholesterol-modified poultry eggPsi on Zn-induced dyslipidemia and liver pathology in Wistar rats.

A low cholesterol (CH)-modified poultry egg (ME Psi) containing more vitamin E, lenolenic acid, and minerals Cu and Mg but low total lipid (TL) and Zn contents than the conventional egg evaluated to reduce the severity of dyslipidemia induced by excessive Zn in the diet. The experimental data was recorded on male rats fed on normolipidemic (NL) semi-synthetic basal diet containing 20 mg Zn/kg diet in control group I, Zn supplemented dyslipidemic diet-A (Zn-DL-A) and B (Zn-DL-B) containing 40 and 80 mg Zn/kg diet in groups II and III, and ME Psi-mixed Test diet-A (Zn-DL-A + 4 ME Psi) and Test diet-B (Zn-DL-B + 4 ME Psi) in groups IIEM and IIIEM, respectively, for 180 and 90 days. Data recorded on liver and blood lipid profiles showed reduction in the concentration of TL, CH, triglycerides, and glycogen (GG) in liver consequently leading to their rise in blood serum including rise in VLDL-c and LDL-c but fall in HDL-c in groups II and III rats that reversed after ME Psi treatment resulting in rise of their levels in the liver and fall in the blood of groups IIEM and IIIEM rats, respectively. Mineral status in the liver showed a rise in Zn but fall in Cu and Mg levels in groups II and III that was reversed after ME Psi treatment resulting in fall in Zn and rise in Cu and Mg concentration in the liver of groups IIEM and IIIEM rats. Hepatopathogical studies showed reduction in the dilatation of long citernal profile of endoplasmic reticulum and increase in GG and TL granules in the cytoplasm of hepatocytes of groups IIEM and IIIEM after ME Psi treatment than those of groups II and III rats. It was concluded that the inclusion of ME Psi would be helpful in reducing dyslipidemia by correcting the ionic imbalance generated by excessive Zn intake in rats or by drugs, even in chronic diseased conditions without aggravating risk factors for heart diseases in humans that need further studies.

Assessment of minerals in obesity-related diseases in the Chandigarh (India) population.

Excessive Zn but normal Cu and Mg in the staple food consumed by the people of Chandigarh (Union territory and capital of Punjab and Haryana States of India) has been considered to be the major risk factor for the prevalence of obesity (33.15%) and obesity-related diseases in this region. Therefore, in the present investigations, in obesity-related diseases, the status of these minerals was estimated in their tissues, including hair, nails, and blood serum and urine, and compared with those of normal subjects. They were grouped as: normal subjects in control Group A, middle-aged diabetics in Group D(M), older diabetics in Group D(O), and diabetics with osteoarthritis in Group D+ OA, osteoarthritis in Group OA and rheumatoid arthritis in Group RA, respectively. The results evaluated in the order as: hair Zn, group D+OA>D(M)>OA>A (control)>RA>D(O) (p < 0.001); hair Cu, group A (control)>D(M)>OA>D+OA>D(O)>RA (p < 0.001); hair Mg, group A (control)>D(M)>OA>D+OA>RA>D(O) (p < 0.001, 0.01); hair Mn, group A (control)>RA>OA>D-OA>D(M)>D(O) (p < 0.001); nail Zn, group D(M)>D+OA>OA>A (control)>RA>D(O) (p < 0.001, 0.05); nail Cu, group A (control)>OA>D(M)>D+OA>RA>D(O) (p < 0.001); nail Mg, group A (control)>OA>D(M)>D(O)>D+OA >RA (p < 0.001); nail Mn, group A (control) >RA>OA>D+OA>D(M)>D(O) (p < 0.01); urine Zn, group D(O)>D(M)>D+OA>A (control)>RA>OA (p < 0.01); urine Cu, group RA>D+OA>D(O)>OA> D(M)>A (control) (p<0.001); urine Mg, group RA>OA>D+OA>D(O)>D(M)>A (control; p < 0.001); urine Mn, group D(O)>D(M)>OA>D+OA>RA>A (control; p < 0.001), respectively. The analysis of the mineral status in serum of diabetics further showed their highly significant rise from lower mean age subgroup to higher mean age subgroup than their control counter parts (p < 0.001, 0.01, and 0.05) with coincident deficiencies of Cu, Mg, and Mn in their tissues. This study would be helpful considering the status of minerals in these obesity-related diseases depending on the choice of the food consumed to improve the quality of life and prognosis for the diseases.

Mineral factors controlling essential hypertension--a study in the Chandigarh, India population.

Essential hypertension (EH) is a major public health problem world over and in India. Recent data on EH in the population of Chandigarh (Union Territory and capital of Punjab and Haryana States of India) revealed that the prevalence of EH has become double in the last 30 years in the residents of Chandigarh (26.9 to 45.80% in the year 1968 and 2002). Zinc (Zn), copper (Cu), magnesium (Mg), and manganese (Mn) in the serum are considered important in maintaining the human hypertension. The high Zn intake was considered to increase the blood pressure (BP) and to affect the other mineral status in the body. Recent survey on the trace metal status of different vegetables in the State of Punjab around Chandigarh (India) revealed that Zn level is significantly higher (40 mg/kg or more in above ground vegetables and 120 mg/kg or above in underground vegetables) in underground water-irrigated vegetables, but the levels of Cu and Mg are within prescribed limit. The present study was conducted on Chandigarh population to evaluate the levels of Zn, Cu, Mg, and Mn in the blood and urine of normotensive (NT) control and hypertensive (HT) subjects matched with number, age and sex. Atomic absorption spectrophotometer studies reevaluated that the levels of serum Zn, Mg, and Mn were significantly higher (p < 0.001), but the level of Cu was low in the HT subjects (BP = 160/93) compared to NT control (BP = 140/83). Higher levels of urinary Zn, Cu, Mg, and Mn were observed in the HT subject vs NT control (p < 0.001). Positive correlations were evaluated between the levels of serum Zn, Mg, and Mn vs systolic and diastolic pressures (DP and SP), respectively (r = 0.928, 0.863, 0.876, 0.808, 0.404, 0.326, p < 0.01), but negative and positive nonsignificant correlations between the serum Cu with SP and DP were recorded (r = -0.032, r = 0.024). Positive correlations were also evaluated between urinary levels of Zn, Cu, Mg, and Mn vs SP and DP (r = 0.718, 0.657, 0.750, 0.681, 0.630, 0.578, 0.516, 0.461, p < 0.01). Prevalence of essential hypertension may be due to higher Zn level in the food chain that makes the individuals vulnerable to other diseases over the time related to essential hypertension.