St. John's Wort reduces beta-amyloid accumulation in a double transgenic Alzheimer's disease mouse model-role of P-glycoprotein.

The adenosine triphosphate-binding cassette transport protein P-glycoprotein (ABCB1) is involved in the export of beta-amyloid from the brain into the blood, and there is evidence that age-associated deficits in cerebral P-glycoprotein content may be involved in Alzheimer's disease pathogenesis. P-glycoprotein function and expression can be pharmacologically induced by a variety of compounds including extracts of Hypericum perforatum (St. John's Wort). To clarify the effect of St. John's Wort on the accumulation of beta-amyloid and P-glycoprotein expression in the brain, St. John's Wort extract (final hyperforin concentration 5%) was fed to 30-day-old male C57BL/6J-APP/PS1(+/-) mice over a period of 60 or 120 days, respectively. Age-matched male C57BL/6J-APP/PS1(+/-) mice receiving a St. John's Wort-free diet served as controls. Mice receiving St. John's Wort extract showed (i) significant reductions of parenchymal beta-amyloid 1-40 and 1-42 accumulation; and (ii) moderate, but statistically significant increases in cerebrovascular P-glycoprotein expression. Thus, the induction of cerebrovascular P-glycoprotein may be a novel therapeutic strategy to protect the brain from beta-amyloid accumulation, and thereby impede the progression of Alzheimer's disease.

Busulfan induces activin A expression in vitro and in vivo: a possible link to venous occlusive disease.

PURPOSE: Hepatic venous occlusive disease is a severe side effect after administration of busulfan before hematopoietic stem cell transplantation. The syndrome is characterized by liver enlargement, fluid retention, jaundice, and weight gain. Endothelial injury has been described as the precipitating factor. The link between busulfan administration and endothelial damage has not been established thus far. METHODS: Complementary deoxyribonucleic acid expression arrays were used to screen for busulfan responsive genes in ECV304 cells. Specific messenger ribonucleic acid and protein levels were examined by real-time polymerase chain reaction and enzyme-linked immunosorbent assay, respectively. Serum samples of 15 pediatric patients with leukemia were analyzed for busulfan and cytokine levels. RESULTS: We identified a member of the transforming growth factor beta superfamily, activin A, to be induced in the human cell line ECV304 after exposure to busulfan in a time- and concentration-dependent manner. Maximum effects were observed at 120 and 168 hours for activin A messenger ribonucleic acid and protein, respectively. Preincubation with the protein kinase C inhibitor bisindolylmaleimide I (10 nmol/L) abolished activin A induction by busulfan (P <.05). Activin receptors were detected in ECV304. Both tissue factor and cyclooxygenase 2 were significantly induced by busulfan (P <.05). In a parallel in vivo study a significant increase in serum activin A concentration was found 4.5 hours after the second dose of busulfan. CONCLUSION: The data demonstrate that busulfan induces activin A both in vitro and in vivo. In view of the multiple targets of activin A (inflammation, proliferation, apoptosis, and coagulation), these findings may be of relevance to our understanding of venous occlusive disease.