Serum nitric oxide and glutathione levels in preeclamptic and normotensive women during labor

Serum levels of asymmetric dimethylarginine, vascular endothelial growth factor, and nitric oxide metabolite levels in preeclampsia patients

Background. Hypertensive disorder generally complicates 5-10 percent of all pregnancies. Angiogenic growth factors may be helpful for the diagnosis and prediction of preeclampsia. Therefore, in this study we attempted to determine the serum levels of asymmetric dimethylarginine (ADMA), vascular endothelial growth factor (VEGF), and nitric oxide (NO) metabolite (nitrite) in preeclampsia patients and compared the levels with those obtained from normal pregnant women. Methods. Ninety pregnant women (19-33 years old) in two groups of preeclampsia and normal were considered during 2012. The levels of ADMA, VEGF, and nitrite were measured in maternal serum samples using ELISA kits. Results. Significant increase of VEGF and nitrite levels was observed in preeclampsia patients when compared with other groups (P < 0.05). The serum level of ADMA demonstrated a similar increased trend in preeclampsia patients; however, the increase was not statistically significant (P = 0.08). Conclusion. The findings reveal that the elevation of serum levels of VEGF and nitrite and possibly ADMA may be involved in the pathogenesis of preeclampsia.

Differential expression of HSP90α and heme oxygenase in cord blood RBC during preeclampsia

Preeclampsia is a multisystem disorder with profound implications on both mother and fetus. Analysis of umbilical cord blood red blood cell (RBC) changes shall depict the fetal response to pregnancy-specific complications like preeclampsia. This study aims to analyze the regulation relationship between HSP90α and heme oxygenase-2 (HO-2) in cord blood RBC during preeclampsia. The lipid hydroperoxide (LHP) and 3-nitrotyrosine (3-NT) levels were measured as stress markers in cord blood RBC of both subjects. The impact of stress on RBC was assessed by measuring the level of membrane bound enzymes and assessing the changes in cord blood RBC. The expression of HSP90α and HO-2 were analyzed by enzyme-linked immunosorbent assay (ELISA) and immunohistochemistry analysis, respectively. There was significant increase in the level of LHP (p < 0.01), 3-NT (p < 0.05), HSP90α (p < 0.01) with decrease in the expression of HO-2 (p < 0.05) in cord blood RBC of preeclamptic subjects compared to normotensive subjects. Similarly, the membrane damage in preeclamptic RBC was assessed by spectrophotometrically and found to be increased by 41.7%, along with increase in number of nucleated RBC. The antiproliferative effect of carbon monoxide under stress might decrease the expression of HO-2 under conditions when there is an increasing need for RBC. The role of HSP90α level in cord blood RBC is discussed with reference to nitrative stress in preeclampsia. This study concludes the increased expression of nucleated RBC, HSP90α and corresponding decreased expression of HO-2 in such hypoxic condition may play a protective role; to prevent cord blood RBC against stress induced damage during preeclampsia.

The role of the L-arginine-nitric oxide pathway in preeclampsia

Preeclampsia (PE) is a major cause of maternal and perinatal mortality, especially in developing countries. Its etiology involves multiple factors, but no specific cause has been identified. Evidence suggests that clinical manifestations are caused by endothelial dysfunction. Nitric oxide (NO), which is synthesized from L-arginine in endothelial cells by the endothelial nitric oxide synthase (eNOS), provides a tonic dilator tone and regulates the adhesion of white blood cells and platelet aggregation. Alterations in the L-arginine-NO pathway have been associated with the development of PE. Various studies, reporting decreased, elevated or unchanged levels of nitrite (NO(2)) and nitrate (NO(3)), two end products of NO metabolism, have been published. Our group contributed to those contradictory reports describing cases of PE with both elevated and decreased levels of NO(2) and NO(3). Apparently, diminished levels of NO could be related to deficiencies in the ingestion of dietary calcium associated to low levels of plasma ionic calcium, which is crucial to the eNOS' activity. Also, low levels of NO could be associated with the presence of eNOS polymorphisms or the presence of increased levels of ADMA, the endogenous inhibitor of NO. High levels of NO associated to low levels of cGMP suggest a decreased bioactivity of NO, which is probably related to an increased degradation of NO caused by a high production of superoxide in states of infection and inflammation. The present article analyses and reviews the reported paradoxical roles of the L-arginine-NO pathway in PE and gives a possible explanation for these results.

Nitric oxide metabolites in preterm and induced labor

BACKGROUND

Nitric oxide has potent relaxant effects on the pregnant uterus and has been associated with a quiescent uterus in animal and human studies. Nitric oxide donors have been used to arrest preterm labor and a reduction in nitric oxide production has been reported before the onset of labor.

OBJECTIVE

The aim of the study was to estimate the serum levels of nitrate and nitrite in women undergoing spontaneous preterm labor and induced labor.

MATERIALS AND METHOD

Venous blood was drawn from 39 patients before the onset of labor (control) and also from 17 patients undergoing induction of labor who were in active labor (study group A), and 24 patients in spontaneous preterm labor (study group B). Serum concentrations of nitrate and nitrite were estimated in the samples using the HPLC method.

RESULTS

The maternal age of the patients was similar in all the groups. There was no significant difference in the mean gestational age at delivery between the control and group-A patients (38.86 vs. 38.29 weeks); however, there was a significant difference between the control and group-B patients (38.86 vs. 30.92; p < 0.0001), and between study groups A and B (38.29 vs. 30.92 weeks; p < 0.0001). The mean serum levels of nitrite in groups A and B (0.563 +/- 0.15 and 0.512 +/- 0.13, respectively) were significantly lower than the level in the control group (0.915 +/- 0.13; p < 0.0001). Although the serum nitrate levels in study groups A and B were lower than in the control group, this difference was not significant. The maternal outcome was satisfactory but, as expected, the mean birth weight of the babies in group B (1,665.73 +/- 863.84 g) was significantly lower than the birth weights in the control and group-A patients (p < 0.0001).

CONCLUSION

There is a drop in nitric oxide production in active preterm labor and induced labor. These findings need to be confirmed in larger studies to establish the role of nitric oxide in the initiation of labor.

The pharmacology of nitric oxide in the peripheral nervous system of blood vessels

Unanticipated, novel hypothesis on nitric oxide (NO) radical, an inorganic, labile, gaseous molecule, as a neurotransmitter first appeared in late 1989 and into the early 1990s, and solid evidences supporting this idea have been accumulated during the last decade of the 20th century. The discovery of nitrergic innervation of vascular smooth muscle has led to a new understanding of the neurogenic control of vascular function. Physiological roles of the nitrergic nerve in vascular smooth muscle include the dominant vasodilator control of cerebral and ocular arteries, the reciprocal regulation with the adrenergic vasoconstrictor nerve in other arteries and veins, and in the initiation and maintenance of penile erection in association with smooth muscle relaxation of the corpus cavernosum. The discovery of autonomic efferent nerves in which NO plays key roles as a neurotransmitter in blood vessels, the physiological roles of this nerve in the control of smooth muscle tone of the artery, vein, and corpus cavernosum, and pharmacological and pathological implications of neurogenic NO have been reviewed. This nerve is a postganglionic parasympathetic nerve. Mechanical responses to stimulation of the nerve, mainly mediated by NO, clearly differ from those to cholinergic nerve stimulation. The naming "nitrergic or nitroxidergic" is therefore proposed to avoid confusion of the term "cholinergic nerve", from which acetylcholine is released as a major neurotransmitter. By establishing functional roles of nitrergic, cholinergic, adrenergic, and other autonomic efferent nerves in the regulation of vascular tone and the interactions of these nerves in vivo, especially in humans, progress in the understanding of cardiovascular dysfunctions and the development of pharmacotherapeutic strategies would be expected in the future.

Effect of palm oil on oxidative stress-induced hypertension in Sprague-Dawley rats

BACKGROUND

Oxidative stress, associated with increased plasma isoprostane (ISO) and reductions in plasma glutathione (GSH), has been shown to cause severe hypertension in normal rats. Palm oil (PO), with an unsaturated-to-saturated fatty acid ratio close to one and rich in antioxidant vitamins, has been investigated for its beneficial effects on arterial thrombosis and atherosclerosis. In this study, the effect of PO on oxidative stress induced by inhibition of GSH synthesis (using buthionine sulfoximine [BSO]) was examined.

METHODS

Sprague-Dawley rats were separated into two groups and received either natural vitamin-rich PO (Carotino, 5 g/kg daily) or water by gavage. After 4 weeks, they were further divided between receiving either BSO (30 mmol/L/day in the drinking water) or drug-free water for an additional week. Mean arterial pressure (MAP), heart rate (HR), and body weight (BW) were measured before and weekly during the experiment. The levels of plasma ISO, nitric oxide (NO), prostacyclin (PGI2), and thromboxane A2 (TXA2) were determined by enzyme immunoassay, and plasma, heart, and kidney GSH by high-performance liquid chromatography.

RESULTS

The PO reduced the age-dependent increase in MAP, and the pressor response to BSO, without changing the HR or BW compared to the BSO and control groups. It also elevated PGI2, NO, and aortic cGMP, but decreased TXA2 and aortic cAMP. In addition, the BSO-induced increase in ISO and TXA2, and the reduction in kidney GSH were attenuated by PO. However, the PO effect on NO, PGI2, cGMP, and TXA2 was partly counteracted by BSO.

CONCLUSIONS

Palm oil reduces BSO-induced oxidative stress and attenuates hypertension by mechanisms involving changes in endothelium-derived factors.