Effect of I1 Imidazoline Receptor Agonist, Moxonidine, in Nitric Oxide-Deficient Hypertension in Pregnant Rats

The preventive effects of aspirin on preeclampsia based on network pharmacology and bioinformatics

This study aimed to reveal the key targets and molecular mechanisms of aspirin in preventing preeclampsia. We used bioinformatics databases to collect the candidate targets for aspirin and preeclampsia. The biological functions and signaling pathways of the intersecting targets were analyzed by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG). Then, the hub targets were identified by cytoscape plugin cytoHubba from the protein-protein interaction network. We collected 90 targets for aspirin in preventing preeclampsia. The biological processes of the intersecting targets are mainly involved in xenobiotic metabolic process, inflammatory response, negative regulation of apoptotic process, and protein phosphorylation. The highly enriched pathways were FoxO signaling pathway, circadian rhythm, insulin resistance, arachidonic acid metabolism, and drug metabolism-cytochrome P450. The hub targets for aspirin in preventing preeclampsia were tumor protein p53 (TP53), C-X-C motif chemokine ligand 8 (CXCL8), mitogen-activated protein kinase 3 (MAPK3), mitogen-activated protein kinase 1 (MAPK1), mitogen-activated protein kinase 14 (MAPK14), epidermal growth factor receptor (EGFR), estrogen receptor (ESR1), and prostaglandin-endoperoxide synthase 2 (PTGS2). Molecular docking results showed good bindings between the proteins and aspirin. In conclusion, these findings highlight the key targets and molecular mechanisms of aspirin in preventing preeclampsia.

Vitamin D restores angiogenic balance and decreases tumor necrosis factor-α in a rat model of pre-eclampsia

AIM

Deficiency of vitamin D is correlated with pre-eclampsia (PE), a hypertensive disorder of pregnancy, and is characterized by angiogenic imbalance and inflammation. The aim of this study was to investigate whether vitamin D supplementation can restore the angiogenic balance and ameliorate inflammation in a rat model of PE.

METHODS

PE was induced using l-nitroarginine methylester. Normal pregnant and PE-induced rats were supplemented with vitamin D on gestation days 14-19.

RESULTS

Blood pressure was significantly increased in PE-induced rats compared with normal pregnant rats (P < 0.05), and vitamin D supplementation ameliorated this difference. In addition, rats from the PE group had lower vascular endothelial growth factor (VEGF; P < 0.01), and higher plasma-soluble FMS-like tyrosine kinase-1 (sFlt-1) and tumor necrosis factor-α (TNF-α; P < 0.01 for both) compared with the normal pregnant group. The vitamin D treatment group had significantly increased VEGF, and reduced sFlt-1 and TNF-α compared with the untreated PE group. Moreover, vitamin D supplementation was able to reduce the oxidative stress by lowering the plasma oxidative stress marker malondialdehyde.

CONCLUSION

Vitamin D supplementation plays an important role in restoring angiogenic balance and reducing inflammation in pregnancy-induced hypertension.

Effects of chronic dietary exposure to monosodium glutamate on feeding behavior, adiposity, gastrointestinal motility, and cardiovascular function in healthy adult rats

BACKGROUND

Monosodium glutamate (MSG) is a flavor-enhancer widely used as a food additive. However, its safe dietary concentration and its toxicity, including its possible implication in the recent metabolic syndrome pandemia, is still a controversial issue. Therefore, a deep knowledge of its effects upon regular dietary use is needed. Our aim was to evaluate the effects of chronic exposure to MSG on feeding behavior, abdominal fat, gastrointestinal motility, and cardiovascular function in rats.

METHODS

Two groups of adult male Wistar rats were used: control and treated with MSG (4 g/L in drinking water) for 6 weeks. Different functional parameters were determined and the histological structure was analyzed in tissues of interest.

KEY RESULTS

Compared to control animals, chronic MSG increased water intake but did not modify food ingestion or body weight gain. Neither the abdominal fat volume nor the fat fraction, measured by magnetic resonance imaging, was modified by MSG. Monosodium glutamate did not alter general gastrointestinal motility, but significantly increased the colonic response to mechanical stimulation. It slightly reduced endothelium-dependent relaxation in aorta, without significantly modifying any other cardiovascular parameters. No significant histological alterations were detected in salivary glands, intestinal wall, aorta, heart, and kidney.

CONCLUSIONS & INFERENCES

Chronic treatment with MSG in the adult rat increased water intake. This supports its potential to improve acceptance of low-fat regimens and to increase hydration in the elderly and sportspeople, often at risk of dehydration. Changes in colonic contractility and cardiovascular function could have some long-term repercussions warranting further research.

A combined supplementation of omega-3 fatty acids and micronutrients (folic acid, vitamin B12) reduces oxidative stress markers in a rat model of pregnancy induced hypertension

Objectives

Our earlier studies have highlighted that an altered one carbon metabolism (vitamin B₁₂, folic acid, and docosahexaenoic acid) is associated with preeclampsia. Preeclampsia is also known to be associated with oxidative stress and inflammation. The current study examines whether maternal folic acid, vitamin B₁₂ and omega-3 fatty acid supplementation given either individually or in combination can ameliorate the oxidative stress markers in a rat model of pregnancy induced hypertension (PIH).

Materials and Methods

Pregnant Wistar rats were assigned to control and five treatment groups: PIH; PIH + vitamin B₁₂; PIH + folic acid; PIH + Omega-3 fatty acids and PIH + combined micronutrient supplementation (vitamin B₁₂ + folic acid + omega-3 fatty acids). L-Nitroarginine methylester (L-NAME; 50 mg/kg body weight/day) was used to induce hypertension during pregnancy. Blood Pressure (BP) was recorded during pregnancy and dams were dissected at d20 of gestation.

Results

Animals from the PIH group demonstrated higher (p<0.01 for both) systolic and diastolic BP; lower (p<0.01) pup weight; higher dam plasma homocysteine (p<0.05) and dam and offspring malondialdehyde (MDA) (p<0.01), lower (p<0.05) placental and offspring liver DHA and higher (p<0.01) tumor necrosis factor–alpha (TNF–ά) levels as compared to control. Individual micronutrient supplementation did not offer much benefit. In contrast, combined supplementation lowered systolic BP, homocysteine, MDA and placental TNF-ά levels in dams and liver MDA and protein carbonyl in the offspring as compared to PIH group.

Conclusion

Key constituents of one carbon cycle (folic acid, vitamin B₁₂ and DHA) may play a role in reducing oxidative stress and inflammation in preeclampsia.

Protective Action of a Hydroalcoholic Extract of a Vinifera Grape Skin on Experimental Preeclampsia in Rats

OBJECTIVE

This study was designed to determine the protective effects of a vinifera grape skins extract (GSE, 200 mg/kg/day) on the deleterious effect observed in experimental preeclampsia, a condition where reduced nitric oxide production and increase in oxidative stress are present.

METHODS

A condition similar to preeclampsia was induced by chronic inhibition of nitric oxide synthesis by L-NAME (60 mg/kg/day, orally) in pregnant rats. Blood pressure (systolic, mean and diastolic) was measured with the tail cuff method on day 20 of pregnant control rats; pregnant rats treated with L-NAME, L-NAME plus GSE or GSE from day 13 to day 20 of pregnancy. Glucose was infused in anesthetized pregnant rats at day 20 and blood glucose and insulin were estimated at time zero, 15, 30, 45 and 60 minutes after beginning of glucose infusion. The number of fetus alive was also estimated at day 20 of pregnancy. In parallel, blood pressure was measured in non-pregnant and in non-pregnant rats treated with L-NAME during 7 days.

RESULTS

Increase in arterial pressure, reduction of alive fetus at the end of pregnancy and increase in insulin resistance was observed in pregnant L-NAME rats but not in pregnant L-NAME plus GSE rats or in pregnant GSE rats. Increase in arterial pressure was also observed in non-pregnant L-NAME rats.

CONCLUSION

The present study demonstrated a protective effect of GSE in experimental preeclampsia since the deleterious effect induced by L-NAME that is, increased in stillbirth, hypertension and insulin resistance were significantly reduced by oral treatment with the extract. Probably an endothelium-dependent vasodilator effect and an antioxidant action play an important role on the effects of GSE in experimental preeclampsia.

Sympathoinhibitory mechanism of moxonidine: role of the inducible nitric oxide synthase in the rostral ventrolateral medulla

AIMS

The central antihypertensive drug moxonidine lowers blood pressure (BP) through stimulating an imidazoline receptor within the rostral ventrolateral medulla (RVLM). Nitric oxide (NO) generated by the inducible NO synthase (iNOS) in the RVLM has been suggested to be involved in tonic sympathetic inhibition. The aim of this study was to determine the role of NO generated by iNOS in mediating moxonidine-induced cardiovascular inhibition in rats.

METHODS AND RESULTS

In anaesthetized rats, the cardiovascular response to local or systemic injection of moxonidine was observed after treatment with the selective iNOS inhibitor S-methylisothiourea (SMT) in the brain. Using immunohistochemical staining and western blot techniques, the protein expression of iNOS in the RVLM was measured in the moxonidine-infused rats. Intracerebroventricular (ICV) injection of SMT (1-100 nmol) dose-dependently attenuated the moxonidine (20 nmol, ICV)-induced decrease in BP and heart rate. Prior injection of SMT (20 and 200 pmol) into the RVLM also dose-dependently prevented the decrease in BP and renal sympathetic nerve activity evoked by RVLM microinjection of moxonidine (5 nmol) or intravenous injection of moxonidine (50 microg/kg). We further found that expression of iNOS protein following chronic ICV infusion of moxonidine (20 nmol, 2 weeks) is selectively upregulated in the RVLM but not in the nucleus tractus solitarius.

CONCLUSION

The present data suggest that an NO mechanism generated by iNOS in the RVLM plays an important role in mediating the sympathetic inhibition of the centrally acting drug moxonidine.

The effect of moxonidine on endothelial dysfunction in metabolic syndrome

BACKGROUND

Endothelial dysfunction has been reported in patients with type 2 diabetes mellitus and even in healthy obese individuals with a normal metabolic profile. Sympathetic activity commonly is increased in obese hypertensive patients, and moxonidine is effective in lowering BP and improving insulin sensitivity.

OBJECTIVE

To evaluate the effect of moxonidine on endothelial dysfunction in patients with metabolic syndrome.

METHODS

Twenty-six patients with mild hypertension were treated with moxonidine and a hypocaloric diet for 3 months, while a second normotensive group (n = 26) were followed-up with calorie restriction alone. Anthropometric (body mass index, waist and hip circumferences, and waist-to-hip ratio) and metabolic features (fasting plasma glucose and insulin, aminotransferases, gamma-glutamyl transpeptidase, triglycerides, and cholesterol levels) and flow-mediated dilatation (FMD) were evaluated. Insulin resistance was calculated by using the homeostasis model assessment formula. Insulin sensitivity was calculated according to the quantitative insulin-sensitivity check index (QUICKI).

RESULTS

SBP and DBP (both p < 0.001) and waist circumference (p = 0.02) were higher, and QUICKI (p = 0.043) and FMD (p = 0.01) were lower in the hypertensive group at baseline. After 3 months, nearly all the study parameters improved in both treatment groups. The decrease in BP, increase in FMD, and improvements in metabolic and anthropometric parameters were significantly greater in the moxonidine-treated group than in those treated with diet alone.

CONCLUSION

Moxonidine is proposed as a valuable option for treating mild-to-moderate hypertension in obese and insulin-resistant patients with metabolic syndrome as it appears to improve endothelial dysfunction in these patients.