Epigallocatechin suppression of proliferation of vascular smooth muscle cells: correlation with c-jun and JNK.

1. The mechanisms of the antiproliferative effect of epigallocatechin, one of the catechin derivatives found in green tea, in vascular smooth muscle cells were studied. The proliferative response was determined from the uptake of tritiated thymidine. 2. In the concentration range of 10(-6) to 10(-4) M, catechin, epicatechin, epigallocatechin, epicatechin gallate and epigallocatechin, epigallocatechin gallate, concentration-dependently inhibited the proliferative response stimulated by serum in rabbit cultured vascular smooth muscle cells. Catechin and epicatechin were less effective in inhibiting the serum-stimulated smooth muscle cell proliferation, indicating that the galloyl group may be important for full inhibitory activity. 3. Epigallocatechin (EGC) inhibited the proliferative responses in different cells including rat aortic smooth muscle cells (A7r5 cells), rabbit cultured aortic smooth muscle cells, human coronary artery smooth muscle cells, and human CEM lymphocytes in a concentration-dependent manner. The possible mechanisms of the antiproliferative effect of EGC were further studied in A7r5 cells. 4. The membranous protein tyrosine kinase activity stimulated by serum in A7r5 cells was significantly reduced by 10(-5) M EGC. In contrast, the cytosolic protein kinase C activity stimulated by phorbol ester was unaffected by directly incubating with EGC (10(-6)-10(-4) M). 5. We also performed Western blot analysis using the anti-phosphotyrosine monoclonal antibody PY20. EGC (10(-5) M) reduced the levels of tyrosine phosphorylated proteins with different molecular weights, indicating that EGC may inhibit the protein tyrosine kinase activity or stimulate the protein phosphatase activity. 6. Reverse transcription-polymerase chain reaction analysis of c-fos, c-jun and c-myc mRNA levels demonstrated that c-jun mRNA level after serum-stimulation was significantly reduced by 10(-5) M EGC. However, the reduction of c-fos and c-myc mRNA levels by 10(-5) M EGC did not achieve significance. 7. Western blot analysis using the antibody against JNK (c-jun N-terminal kinase) and ERK (extracellular signal-regulated kinase) demonstrated that the level of phosphorylated JNK1, but not phosphorylated ERK1 and ERK2, was reduced by 10(-5) M EGC. Direct measurement of kinase activity by immune complex kinase assay confirmed that JNK1 activity was inhibited by EGC treatment. These results demonstrate that EGC preferentially reduced the activation of JNK/SAPK (stress-activated protein kinase) signal transduction pathway. 8. It is suggested that the antiproliferative effect of epigallocatechin on vascular smooth muscle cells may partly be mediated through inhibition of protein tyrosine kinase activity, reducing c-jun mRNA expression and inhibiting JNK1 activation. Tea catechins may be useful as a template for the development of drugs to prevent the pathological changes of atherosclerosis and post-angioplasty restenosis.

[Effect of age on hemostasis and plasma level of TXB2 and 6-keto-PGF1 alpha].

UNLABELLED: Hemostasis (HS) in 134 healthy subjects of over 20 years old was investigated. The cases with HS symptom were 45.5%, which increased with age. TXB2, 6-keto-PGF1 alpha and T/K ratio were measured by radioimmuno assay (RIA). RESULTS: elevation of TXB2 was more significant in the middle age and old age than in the young group (P < 0.01). But the level of 6-keto-PGF1 alpha in various age group didn't changed significantly; while the ratio between TXB2 and 6-keto-PGF1 alpha was more significant in the aged than in the young person (P < 0.01). The results revealed that there was hypercoagulable tendency with the increase of age, and it was correlated with TXB2 and 6-keto-PGF1 alpha. It is significant in theory and practice to prevent and cure the cardiovascular and cerebrovascular disease as well as HS with the traditional Chinese medicine.

[Epidemiological study of blood stasis and plasma tissue plasminogen activator and its inhibitor activity in healthy aged].

According to the blood stasis survey of 77 healthy subjects in presenile geriatric period, in comparison with 35 healthy young people, it was found the 51.79% of healthy subjects had blood stasis. The detectable rate were significantly different among various age groups (P < 0.005), and the rate increase was age-dependent. Chromogenic peptide substrate analytical method was used to detect plasma tissue plasminogen activator (t-PA), tissue plasminogen activator inhibitor (PAI) activity and ratio of P/t. The result revealed that the activity of plasma t-PA in presenile geriatric period subjects was significantly higher than that of young people (P < 0.01), but the activity of PAI had no difference in various age groups, and the ratio of P/t was markedly decreased. It showed that this was the physiological compensatory reaction of aging organism against hypercoagulability, and it was an effective way to maintain the physiological balance of the aged.

The role of central 5-hydroxytryptamine in acupuncture analgesia.

The role played by central 5-hydroxytryptamine (5-HT) in acupuncture analgesia (AA) has been studied in rats with the tail-flick response as the antinociceptive test. The analgesic effect of acupuncture can be enhanced or lowered by the increment or the decrement of the 5-HT level in the CNS. Furthermore, the turnover rate of 5-HT in the CNS has been found to be greatly facilitated during the period of acupuncture. The results imply that 5-HT in the CNS may be one of the most important neurochemical agents mediating AA.