Hypericum perforatum and Its Potential Antiplatelet Effect.

BACKGROUND: Hypericum perforatum (HP) is currently one of the most consumed medicinal plants in the world. In traditional Chinese medicine, the herb hypericum (Guan Ye Lian Qiao) belongs to the group of plants that clarify heat. It is also used to treat various types of infection and inflammation. In contrast to the extensive literature on the antidepressant effects of HP, little is known about its action on platelets. The main objective of this work was to investigate the possible relevance of HP to platelet function. METHODS: We characterized the profile of platelet activation in the presence of HP extracts through an evaluation of molecular markers by flow cytometry: mobilization of intracellular Ca++ and expression of platelet receptors such as activated GPIIbIIIa and P-selectin (CD62). RESULTS: The results indicated a possible inhibitory effect of HP on the platelet activation response, which could be explained by the effect on intracellular calcium mobilization and the expression of activated GPIIbIIIa receptors. Despite of the limitations of an in vitro study, our results provide evidence of the possible mechanisms of action of HP. CONCLUSIONS: Further studies are needed to elucidate the effect of HP on hemostasis, but it may be recognized as a substance with antiplatelet properties.

Myocardial infarction before and after the age of 45: Possible role of platelet receptor polymorphisms.

INTRODUCTION: We examined the potential role of polymorphisms of the platelet genes GP1BA (rs2243093, rs6065 and VNTR), ITGB3 (rs5918), ITGA2 (rs938043469) and P2RY12 (rs2046934, rs6801273 and rs6798347) as risk factors for myocardial infarction (MI). METHODS: The study population was divided into three groups: controls (n=235), MI at age ≤45 years (MI ≤45, n=44), and MI at age >45 years (MI >45, n=78). The control group was further divided into two subgroups (control ≤45 and >45), and subgroups including only men were also considered for statistical analysis. Polymorphisms were detected by polymerase chain reaction and restriction fragment length polymorphism analysis. RESULTS: Regarding non-genetic risk factors, the control group differed statistically from the MI ≤45 group (p<00.5) in terms of smoking, hypertension, diabetes and obesity, and from the MI >45 group (p<0.05) in terms of hypertension, diabetes, obesity, family history of thrombosis and high cholesterol. For the studied ITGA2 polymorphism, a statistical difference was found when MI >45 was compared with the control group, with a higher risk of MI in the TT genotype (OR 2.852; 95% CI: 1.092-7.451; p=0.032). In the GP1BA rs6065 polymorphism, a statistically significant difference was found between control ≤45 only men and MI ≤45 only men, with a higher risk in the CT genotype (OR 5.568; 95% CI: 1.421-21.822; p=0.016), despite the low numbers included. The other polymorphisms studied did not show any statistically significant correlations. CONCLUSION: There is a statistically significant association between the TT genotype of the ITGA2 rs938043469 polymorphism and increased risk for MI >45.

Allelic and genotypic frequencies of platelet glycoprotein polymorphisms in a Portuguese population.

INTRODUCTION AND OBJECTIVES: We studied genotypic and allelic frequencies of polymorphisms that can affect platelet function, namely the Kozak, VNTR and HPA-2 polymorphisms of glycoprotein Ibα, the Pl(A) polymorphism of glycoprotein IIIa and the C807T polymorphism of glycoprotein Ia, in a Portuguese population composed of 227 donors. METHODS: PCR-RFLP was used to assess the Kozak, HPA-2, Pl(A) and C807T polymorphisms. The VNTR polymorphism was discriminated by different weight bands on electrophoresis. RESULTS: All genotypic frequencies were in Hardy-Weinberg equilibrium and do not differ from other Caucasian populations. Genotypic frequencies were 68.3%, 26.9% and 4.8% for Pl(A1/A1), Pl(A1/A2) and Pl(A2/A2) genotypes of the Pl(A) polymorphism, 79.3%, 20.3% and 0.4% for TT, TC and CC genotypes of the Kozak polymorphism, 81.1%, 18.9% and 0.0% for aa, ab and bb genotypes of the HPA-2 polymorphism, 15.4%, 0.9%, 70.5%, 11.5%, 1.3% and 0.4% for BC, BD, CC, CD, DD and CE genotypes of the VNTR polymorphism, and 39.7%, 50.2% and 10.1% for CC, CT and TT genotypes of the C807T polymorphism. CONCLUSIONS: The Portuguese population has now been characterized in terms of major platelet glycoprotein polymorphisms, which will be an important tool for further studies to assess the role of platelet glycoproteins in individual predisposition to prothrombotic conditions and response to antithrombotic therapy.

Inhibitory effects of alprazolam on the development of acute experimental autoimmune encephalomyelitis in stressed rats.

The progression and development of multiple sclerosis (MS) has long been hypothesized to be associated with stress. Benzodiazepines have been observed to reduce negative consequences of stress on the immune system in experimental and clinical models, but there are no data on their effects on MS, or experimental autoimmune encephalomyelitis (EAE), a model for human MS. We designed experiments conducted to ascertain whether alprazolam could modify the clinical, histological and neuroendocrine manifestations of acute EAE in Lewis rats exposed to a chronic auditory stressor. EAE was induced by injection of an emulsion of MBP and complete Freund's adjuvant containing Mycobacterium tuberculosis H37Ra. Stress application and treatment with drugs (placebo or alprazolam) were initiated 5days before inoculation and continued daily for the duration of the experiment (days 14 or 34 postinoculation).Our results show significant increases in the severity of neurological signs, the histological lesions of the spinal cord (inflammation), and the corticosterone plasmatic levels in stressed rats compared to those non-stressed ones. Treatment with alprazolam reversed the adverse effects of stress. These findings could have clinical implications in patients suffering from MS treated with benzodiazepines, so besides the psychopharmacological properties of alprazolam against stress, it has beneficial consequences on EAE.