Prostanoid production in the umbilicoplacental arterial tree relative to impaired glucose tolerance

Gestational diabetes mellitus is associated with in vivo platelet activation and platelet hyperreactivity

BACKGROUND

Gestational diabetes mellitus is associated with obstetrical and long-term cardiovascular complications. Although platelet hyperresponsiveness in type-2 diabetes mellitus has been well characterized and has been shown to play a crucial role in cardiovascular complications, this aspect has been little studied in gestational diabetes mellitus.

OBJECTIVE

We aimed to evaluate platelet reactivity, in vivo platelet activation, and endothelial function in gestational diabetes mellitus in comparison with normal pregnancy.

STUDY DESIGN

This was a prospective, case-control study of 23 women with gestational diabetes mellitus and 23 healthy pregnant women who were studied at 26 to 28 and 34 to 36 weeks of gestation and at 8 weeks postpartum. Platelet reactivity and in vivo platelet activation, including light transmission aggregometry, PFA-100, platelet activation antigen expression, platelet adhesion under flow, platelet nitric oxide and reactive oxygen species production, and endothelial dysfunction markers, were assessed.

RESULTS

The study of platelet function showed a condition of platelet hyperreactivity in cases with gestational diabetes mellitus when compared with healthy pregnant women at enrollment, which was further enhanced at the end of pregnancy and tended to decrease 2 months after delivery, although it still remained higher in gestational diabetes mellitus. In vivo platelet activation was also evident in gestational diabetes mellitus, especially at the end of pregnancy, in part persisting up to 8 weeks after delivery. Finally, women with gestational diabetes mellitus showed defective platelet nitric oxide production and endothelial dysfunction when compared with healthy pregnancies.

CONCLUSION

Our data showed that gestational diabetes mellitus generates a condition of platelet hyperreactivity that in part persists up to 2 months after delivery. Impaired platelet sensitivity to nitric oxide and reduced platelet and endothelial nitric oxide production may contribute to the platelet hyperreactivity condition. Platelet hyperreactivity may play a role in the long-term cardiovascular complications of gestational diabetes mellitus women.

COX2 and NOS3 gene polymorphisms in women with gestational diabetes

BACKGROUND

Gestational diabetes (GDM) is carbohydrate intolerance occurring in pregnancy. Low-grade inflammation plays an important role in the pathogenesis of this disorder. The present study aimed to examine the association between COX2 (rs6681231) and NOS3 (rs1799983 and rs2070744) gene polymorphisms and GDM.

METHODS

The study included 204 pregnant women with GDM and 207 pregnant women with normal glucose tolerance. The diagnosis of GDM was based on a 75-g oral glucose tolerance test at 24-28 weeks of gestation.

RESULTS

We observed an increased frequency of COX2 rs6681231 CC and GC genotype carriers among women with GDM (CC + GC versus GG, odds ratio = 1.55, 95% confidence interval = 1.01-2.36, p = 0.043; C versus G, odds ratio = 1.59, 95% confidence interval = 1.10-2.30, p = 0.013). There were no statistically significant differences in the distribution of NOS3 rs1799983 and rs2070744 between GDM and healthy women. Moreover, among women treated with insulin, we observed an increased frequency of COX2 rs6681231 CC and NOS3 rs1799983 TT genotype carriers.

CONCLUSIONS

The results of the present study suggest that the CC genotype of the COX2 rs6681231 polymorphism is associated with an increased risk of GDM and the need for insulin therapy, whereas the TT genotype of the NOS3 rs1799983 polymorphism may be associated with the need for insulin therapy in women with GDM.

Women and Omega-3 Fatty Acids

Omega-3 fatty acids (omega-3 FA) are constituents of the membranes of all cells in the body and are precursors of locally produced hormones, eicosanoids, which are important in the prevention and treatment of various diseases, especially in women. Omega-3 FA are of interest in some of the most common conditions affecting women. One mechanism underlying dysmenorrhea is a disturbed balance between antiinflammatory, vasodilator eicosanoids derived from omega-3 FA and proinflammatory, vasoconstrictor eicosanoids derived from omega-6 FA. Increased intake of omega-3 FA can reverse the symptoms in this condition by decreasing the amount of omega-6 FA in cell membranes. An increased prostacyclin/thromboxane ratio induced by omega-3 FA can facilitate pregnancy in women with infertility problems by increasing uterine blood flow. Supplementation with omega-3 FA during pregnancy lowers the risk of premature birth and can increase the length of pregnancy and birth weight by altering the balance of eicosanoids involved in labor and promote fetal growth by improving placental blood flow. Intake of omega-3 FA during pregnancy and breast feeding may facilitate the child's brain development. There is also some evidence that supplementation with omega-3 FA might help to prevent preeclampsia, postpartum depression, menopausal problems, postmenopausal osteoporosis, and breast cancer. Furthermore, because elevated triglyceride levels are associated with cardiovascular disease, especially in women; and because omega-3 FA have powerful effects on triglycerides, women in particular gain from an increased intake of these fatty acids. This is especially important in women receiving hormone therapy, which can increase triglyceride levels. The quality of the omega-3 FA preparation is important. It should have an appropriate antioxidant content not to induce lipid peroxidation, and its content of dioxin and polychlorinated biphenyls (PCBs) should be well below the established safe limit.

Structural, functional and circulatory placental changes associated with impaired glucose metabolism

OBJECTIVE

To investigate associations between structural, functional and circulatory placental changes in pregnancies complicated by impaired glucose metabolism.

DESIGN

Umbilical artery (UA) blood flow resistance was measured by Doppler velocimetry in 21 gravidae with diabetes/impaired glucose tolerance (IGT) and 10 healthy gravidae. Umbilical and placental vessel segments were incubated for determination of prostacyclin and thromboxane synthesis, and tissues histologically examined. Non-parametric statistical tests at a two-tailed P<0.05 were used.

RESULTS

Placental lesions were more common in diabetes/IGT and, although not being an uniform finding, in general associated with a higher vascular synthesis of thromboxane and/or lower prostacyclin/thromboxane synthesis ratio. As an exception, ischemic villitis was associated with a higher ratio and higher UA flow resistance.

CONCLUSIONS

Placental lesions are associated with an altered vascular prostanoid synthesis in diabetes/IGT, but not until structural signs of ischemia develop is a rise of UA blood flow resistance detected.

Signs of platelet activation, but not lipid peroxidation, in fetal blood associated with functional and structural umbilicoplacental lesions in pregnancies complicated by impaired glucose metabolism

OBJECTIVES

To study the influence of platelet activation and lipid peroxidation in fetal blood on umbilical vascular prostanoid synthesis and placental morphology in diabetic pregnancy.

METHODS

The concentrations of thromboxane A2 (TxA2) and malondialdehyde (MDA) were determined in umbilical cord plasma in 21 women with diabetes mellitus/impaired glucose tolerance (DM/IGT) and ten healthy women. Segments from the umbilical artery and vein were incubated and prostacyclin (PGI2) and TxA2 metabolites were determined. Prostanoid synthesis was stimulated with calcium ionophore at a second incubation. Histological examination was carried out in samples from the umbilical cord, membranes and placental parenchyma. Non-parametric statistical analysis was used, with a two-tailed p < 0.05 considered statistically significant.

RESULTS

Cord plasma TxA2, but not MDA, was higher among DM/IGT women (p = 0.07). There were indications that cord plasma TxA2, but not MDA, was positively correlated with vascular prostanoid synthesis and synthesis capacity. In the umbilical vein, both the basal and stimulated PGI2 production and the stimulated TxA2 production were lower in the DM/IGT group. Ischemic placental lesions were associated with a high TxA, and a low MDA concentration in cord plasma.

CONCLUSIONS

Even in less severe forms of impaired glucose metabolism, disturbances in platelet activation significantly affect both biochemical and morphological vessel wall and tissue functions in the umbilicoplacental unit. This could indicate an abnormal programming of fetal cell functions and designate cases at increased risk of developing cellular and organ damage.

Prostanoid production in the umbilicoplacental arterial tree relative to impaired glucose tolerance

The purpose of this study was to investigate prostanoid synthesis in different segments of the umbilicoplacental vascular tree and its relationship to impaired maternal glucose tolerance. Segments from the umbilical artery and vein, allantochorionic artery branches, and the cotyledon artery from 21 women with diabetes or impaired glucose tolerance and 10 healthy women were studied. Production of prostacyclin (PGI2) and thromboxane (TxA2) metabolites was determined. The Mann-Whitney U test, Wilcoxon signed-ranks matched-pairs test, Kruskal-Wallis test, analysis of variance, and simple linear regression analysis were used. A two-tailed P value of < 0.05 was considered statistically significant. From the umbilical artery distal to the cotyledon artery, the PGI2 synthesis decreased and the TxA2 synthesis increased gradually towards the periphery in normal pregnancy. The PGI2/TxA2 ratio was more than 200 times higher in the umbilical artery than in the cotyledon artery. The TxA2 production tended in general to be higher in the diabetic group than in the control group, resulting in significantly lower PGI2/TxA2 ratios in some vessels. The prostanoid production was not significantly correlated to maternal HbA1c or cord C-peptide concentrations. The balance between vascular prostacyclin and thromboxane synthesis in the umbilicoplacental arterial tree changed gradually towards the periphery: the more peripheral, the lower the prostacyclin and the higher the thromboxane production. The physiological role of this phenomenon is unknown, but may be of importance for the equilibration of vascular tone between arteries of different calibers. The altered prostanoid balance found in diabetic pregnancy was not directly attributable to the degree of maternal glycemic control, but may reflect increased free radical activity and peroxide production in diabetes.