The arachidonic acid effect on platelet nitric oxide level

Dihydroxyeicosatrienoic Acid, a Metabolite of Epoxyeicosatrienoic Acids Upregulates Endothelial Nitric Oxide Synthase Expression Through Transcription: Mechanism of Vascular Endothelial Function Protection

The present study aimed to investigate the impacts and underlying mechanisms of 14,15-DHETs on eNOS and vascular endothelial functions. Bovine aortic endothelial cells (BAECs) were treated with various concentrations of 14, 15-DHET. The expressions of eNOS protein and mRNA were observed at different time points. The eNOS expression and phosphorylation were subsequently detected administered with 8,9-DHET, 11,12-DHET, and 14,15-DHET, respectively. Meanwhile, 14,15-DHET action on tube formation was observed in human umbilical vein endothelial cells (HUVECs). Finally, the aorta of male C57BL/6 mice was injected with 14,15-DHET via the tail vein. The impacts of 14,15-DHET (0.4 mg/kg body weight) on the expressions of eNOS protein and mRNA and endothelium-dependent vasodilation (EDV) were detected following 24 h. The expression of eNOS was greatly improved with the 14,15-DHET treatment compared with the BAECs, and eNOS phosphorylation sites at Ser1179, Ser635, and Thr497 were elevated. However, no statistically significant difference was revealed on total eNOS among the 8,9-DHET, 11,12-DHET, and 14,15-DHET treatment groups. Based on the upregulation of eNOS protein, eNOS mRNA levels were increased in BAECs and thoracic aorta of the male C57BL/6 mice treated with 14,15-DHET, suggesting that transcriptional activation was achieved in vascular eNOS. Moreover, 14,15-DHET enhanced tube formation abilities in HUVECs and acetylcholine(ACh)-induced EDV. These findings indicated that 14,15-DHET could improve the vascular endothelial diastolic functions of male C57BL/6 mice, and enhance the ability of tube formation, which might be related to the increase of eNOS expression.

Novel Approaches to Fine-Tune Therapeutic Targeting of Platelets in Atherosclerosis: A Critical Appraisal

The pathogenesis of atherosclerotic vascular disease is driven by a multitude of risk factors intertwining metabolic and inflammatory pathways. Increasing knowledge about platelet biology sheds light on how platelets take part in these processes from early to later stages of plaque development. Recent insights from experimental studies and mouse models substantiate platelets as initiators and amplifiers in atherogenic leukocyte recruitment. These studies are complemented by results from genetics studies shedding light on novel molecular mechanisms which provide an interesting prospect as novel targets. For instance, experimental studies provide further details how platelet-decorated von Willebrand factor tethered to activated endothelial cells plays a role in atherogenic monocyte recruitment. Novel aspects of platelets as atherogenic inductors of neutrophil extracellular traps and particularities in signaling pathways such as cyclic guanosine monophosphate and the inhibitory adaptor molecule SHB23/LNK associating platelets with atherogenesis are shared. In summary, it was our intention to balance insights from recent experimental data that support a plausible role for platelets in atherogenesis against a paucity of clinical evidence needed to validate this concept in humans.

Association of the coronary artery disease risk gene GUCY1A3 with ischaemic events after coronary intervention

Aim

A common genetic variant at the GUCY1A3 coronary artery disease locus has been shown to influence platelet aggregation. The risk of ischaemic events including stent thrombosis varies with the efficacy of aspirin to inhibit platelet reactivity. This study sought to investigate whether homozygous GUCY1A3 (rs7692387) risk allele carriers display higher on-aspirin platelet reactivity and risk of ischaemic events early after coronary intervention.

Methods and results

The association of GUCY1A3 genotype and on-aspirin platelet reactivity was analysed in the genetics substudy of the ISAR-ASPI registry (n = 1678) using impedance aggregometry. The clinical outcome cardiovascular death or stent thrombosis within 30 days after stenting was investigated in a meta-analysis of substudies of the ISAR-ASPI registry, the PLATO trial (n = 3236), and the Utrecht Coronary Biobank (n = 1003) comprising a total 5917 patients. Homozygous GUCY1A3 risk allele carriers (GG) displayed increased on-aspirin platelet reactivity compared with non-risk allele (AA/AG) carriers [150 (interquartile range 91–209) vs. 134 (85–194) AU⋅min, P < 0.01]. More homozygous risk allele carriers, compared with non-risk allele carriers, were assigned to the high-risk group for ischaemic events (>203 AU⋅min; 29.5 vs. 24.2%, P = 0.02). Homozygous risk allele carriers were also at higher risk for cardiovascular death or stent thrombosis (hazard ratio 1.70, 95% confidence interval 1.08–2.68; P = 0.02). Bleeding risk was not altered.

Conclusion

We conclude that homozygous GUCY1A3 risk allele carriers are at increased risk of cardiovascular death or stent thrombosis within 30 days after coronary stenting, likely due to higher on-aspirin platelet reactivity. Whether GUCY1A3 genotype helps to tailor antiplatelet treatment remains to be investigated.

Pharmacological basis of the use of the root bark of Zizyphus nummularia Aubrev. (Rhamnaceae) as anti-inflammatory agent

BACKGROUND

The root bark of Zizyphus nummularia (Rhamnaceae) is traditionally used as an anti-inflammatory agent. The current study aimed to explore the anti-inflammatory activity (in vivo) of a crude ethanolic extract (EE) and the pure identified octadecahydro-picene-2,3,14,15-tetranone (IC) in the root bark of Z. nummularia. IC was further subjected to suitable in vitro and in silico studies to find out the mechanistic pharmacology.

METHODS

EE (100 and 200 mg/kg, p.o.) and (IC) (400 and 600 μg/kg, p.o.) were subjected to in vivo anti-inflammatory assays to evaluate the anti-inflammatory activity and predict the probable mechanism(s) of action. Suitable acute (carrageenan-induced paw edema, arachidonic acid-induced ear edema, xylene-induced ear edema) and chronic (cotton pellet granuloma) models were employed to investigate in vivo the anti-inflammatory activity. Based on in vivo observation, IC was further subjected to in vitro assays to estimate the inhibition of nitric oxide (NO), prostaglandin-E2 (PGE-2) and tumor necrosis factor-α (TNF-α) production in PBS stimulated RAW 264.7 cells. Based on the observation of in vitro studies, finally, ADME prediction and molecular docking studies of IC were performed for better understanding of interaction of IC with TNF-α.

RESULTS

Oral administration of EE (100 and 200 mg/kg) exhibited significant inhibition of carrageenan (p < 0.05) and arachidonic acid (p < 0.05) induced oedema, and the reduced the granuloma tissue formation (p < 0.05) in experimental mice. IC (400 and 600 μg/kg, p.o.) exhibited significant (p < 0.01) inhibition of carrageenan, xylene and arachidonic acid-induced edema, and reduced the granuloma tissue formation. In in vitro assays, IC caused a concentration-dependent inhibition of LPS stimulated NO (up to ~ 67.4% at 50 μM) and TNF-α (~84.5% at 50 μM) production. However, the PGE-2 inhibition did not follow dose dependent pattern. Based on in vitro observations, the molecular docking has been performed on the basis of interaction with TNF-α. In in silico studies, it was observed that IC showed hydrogen bonding with GLN 47 amino acid residue of TNF-α protein.

CONCLUSIONS

IC possibly produces anti-inflammatory activity through inhibition of TNF-α and NO production.

Anti-inflammatory and anti-ulcer activities of carvacrol, a monoterpene present in the essential oil of oregano

This study reports a pharmacological evaluation of anti-inflammatory and anti-ulcer activities of carvacrol, a phenolic monoterpene constituent of essential oils produced by oregano and other several aromatic plants and spices, in experimental models of edema induced by different phlogistic agents and gastric lesions induced by acetic acid. In models of paw edema induced by dextran or histamine, carvacrol was effective at 50 mg/kg (46% and 35%, respectively); in these models, cyproheptadine reduced edema formation (61% and 43%, respectively). In edema induced by substance P, carvacrol (100 mg/kg) and ruthenium red (3 mg/kg) also decreased the edema formation (46% and 40%, respectively). Carvacrol significantly reduced the ear edema induced by 12-O-tetradecanoylphorbol acetate and arachidonic acid at 0.1 mg per ear (43% and 33%, respectively), similar to indomethacin at 0.5 mg per ear or 2.0 mg per ear (55% and 57%, respectively). Carvacrol (at doses of 25, 50, and 100 mg/kg) showed a healing capacity on gastric lesions induced by acid acetic (60%, 91%, and 81%, respectively) after 14 days of treatment. These results suggest that carvacrol acts on different pharmacological targets, probably interfering in release and/or synthesis of inflammatory mediators, such as the prostanoids, and thus favoring the healing process for gastric ulcers.

Temporal and spatial changes in collateral formation and function during chronic myocardial ischemia

BACKGROUND

We investigated time dependence and spatial progression of cardiac function and angiogenesis signaling in a porcine model of chronic myocardial ischemia.

STUDY DESIGN

Yorkshire mini-swine (n = 7/group) were subjected to chronic myocardial ischemia by placing an ameroid constrictor on the left circumflex coronary artery under general anesthesia. Swine were sacrificed after either 4 or 7 weeks of ischemia. Myocardial function, angiographic evidence of angiogenesis, microvessel function, molecular signaling, and levels of apoptosis and oxidative stress were assessed.

RESULTS

Flow reserve was significantly increased at 7 versus 4 weeks. Myocardial function (+dP/dt) improved 1.5-fold by 7 weeks. In the ischemic territory, microvessels at 4 weeks displayed abnormal contraction responses to serotonin, which diminished at 7 weeks. Delta-like ligand 4 protein expression decreased at 7 weeks; expression of vascular endothelial growth factor (VEGF) and phospho-endothelial nitric acid synthase (eNOS) increased. The number of apoptotic cells was decreased at 7 weeks, and antiapoptotic markers heat shock protein (HSP) 27 and HSP 90 were upregulated at 7 weeks. There was an increase in proliferating endothelial cells at 7 weeks as compared with 4 weeks. In the adjacent normal ventricle, microvessels demonstrated smaller contraction responses to endothelin-1 and serotonin at 7 weeks. There was an increase in protein peroxidation in the ischemic territory at 7 weeks.

CONCLUSIONS

Over time, myocardial perfusion, function, and angiogenic signaling improved in the ischemic myocardium and adjacent normal territory compared with what is observed shortly after coronary occlusion.

Antiplatelet activity of alpha-lipoic acid

Alpha-lipoic acid (ALA) is often used as a dietary supplement to prevent and treat chronic diseases associated with excessive oxidative stress. The aim of this study was to investigate the mechanisms of the antiplatelet activity of ALA. ALA significantly inhibited collagen-induced platelet aggregation, thromboxane B(2) (TXB(2)) formation, Ca(2+) mobilization, and protein kinase Calpha (PKCalpha) activation, but ALA itself increased cyclic AMP formation in rabbit washed platelets. However, the effects of ALA on the above platelet responses were markedly reversed by the addition of 2'5'-ddAdo, an adenylate cyclase inhibitor. Additionally, increased reactive oxygen species (ROS) formation and cyclooxygenase-1 activity stimulated by arachidonic acid were inhibited by ALA. In conclusion, we demonstrated that ALA possesses an antiplatelet activity, which may be associated with an elevation of cyclic AMP formation, involving subsequent inhibition of TXA(2), Ca(2+) mobilization, and PKCalpha-mediated pathways. Moreover, inhibition of ROS formation and increase of platelet membrane fluidity may also involve its actions.