Toshihiko Fukuda

Kyushu University, Hukuoka, Fukuoka, Japan

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Publications (6)15.71 Total impact

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    ABSTRACT: Aim: In this study, we investigated the protective effect of ferulic acid (FA) on nitric oxide (NO) production in tumor necrosis factor (TNF)-α-stimulated inflammatory human umbilical vein endothelial cells (HUVECs), and elucidated the mechanism(s) involved. Main methods: The TNF-α-stimulated inflammatory HUVECs were treated with acetylcholine (ACh) and/or FA. NO productions were measured by monitoring nitrite and nitrate using a 2,3-diaminonaphthalene Kit. Expressions of mRNA and proteins were evaluated by RT-PCR and Western blotting, respectively. Key findings: FA treatment resulted in a dose-dependent (10-200μM) restoration of ACh-mediated NO production in TNF-α-treated HUVECs, whereas treatment with the FA analogues, coumaric acid, and apocynin resulted in no significant effect. FA treatment had no effect on O2(-) production in TNF-α-stimulated HUVECs. N(G)-monomethyl-l-arginine acetate (a nitric oxide synthase (NOS) inhibitor) and α-methyl-dl-aspartic acid (an argininosuccinate synthase (ASS) inhibitor) counteracted the effects of FA on the NO production. While FA treatment did not significantly affect the protein expression of p-eNOS or eNOS, the protein expression of ASS as well as mRNA expression was restored to normal levels upon exposure to FA in TNF-α-stimulated HUVECs. In nucleus, FA attenuated the increase of nuclear factor-kappa B (NF-κB) expression by TNF-α. Significance: FA treatment rescues the defect in ACh-induced NO production resulting from TNF-α-stimulation in inflammatory HUVECs. This effect was likely due, in part, to the FA-mediated up-regulation of ASS expression via the suppression of NF-κB inflammatory signaling cascade.
    No preview · Article · Dec 2015 · Life sciences
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    ABSTRACT: Aging deteriorates vascular functions such as vascular reactivity and stiffness. Thus far, various reports suggest that bioactive compounds can improve vascular functions. However, few age-related studies of natural bioactive compounds are available. The present study attempted to evaluate age-related vasorelaxation of bioactive cinnamic acids, caffeic acid, and ferulic acid using aged rat thoracic aorta. Vasorelaxation was evaluated in thoracic aorta from both 8, 18, and 40 weeks old Wistar-Kyoto rats (WKY) and spontaneously hypertensive rats (SHR) respectively. The result indicated that caffeic acid possessed the vasorelaxation regardless of aging in WKY and SHR. Moreover, the vasorelaxation of ferulic acid enhanced with aging in SHR. The vasorelaxation behavior was acted in an endothelium-independent manner. To access structure importance of enhanced vasorelaxation, analogues of ferulic acid were tested. In 40 weeks old SHR, 3,4-dimethoxycinnamic acid and coniferyl alcohol exhibited equivalent vasorelaxation activity with ferulic acid, providing the structural importance of methoxy-modified 3-position on the phenyl ring and 2-propenoic moiety. These results firstly demonstrated that enhanced vasorelaxation of ferulic acid with aging and 3,4-dimethoxycinnamic acid and coniferyl alcohol, along with ferulic acid, might exhibit the therapeutic potential of vasoactive power with aging.
    No preview · Article · Aug 2015 · Archiv für Experimentelle Pathologie und Pharmakologie
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    ABSTRACT: Age-related vascular diseases are induced by vascular dysfunction, which involves changes in the vasomotor response. The voltage-dependent L-type calcium channel (VDCC) protein is involved in the regulation of vessel function (contraction/relaxation action). In the present study, we evaluated age-related vasomotor function and expression of the signal-related target proteins, including VDCC, using thoracic aorta from both 8- and 40-week old Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR). In contraction experiments using aortic rings, vasomotor responses of both phenylephrine-induced contraction and acetylcholine-induced relaxation were significantly attenuated with age in SHR, whereas WKY did not lose activity with age. Contraction induced by angiotensin II was impaired only for the 40-week old SHR among all the rat groups tested, although enhanced AT1R/reduced AT2R expression with age was observed for both WKY and SHR. In contrast, a vasomotor responsiveness to Bay K 8644 (a VDCC agonist) at the initial contraction phase was significantly attenuated in both 40-week WKY and SHR with significant reduction of VDCC protein expression. The reduced VDCC expression in 40-week old rats significantly lowered the relaxation activity of VDCC blockers, such as verapamil and Trp-His, but did not affect that of nifedipine. Taken together, we provided the first evidence that aging caused a reduction of VDCC expression in rat aorta, irrespective of the rat strain, along with diminishment of the therapeutic potential of VDCC blockers.
    Full-text · Article · Feb 2014 · PLoS ONE
  • Toshihiko Fukuda · Yutaro Kobayashi · Mitsuru Tanaka · Toshiro Matsui
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    ABSTRACT: Objective: A series of our studies provided evidences that vasorelaxant di-peptide, Trp-His (WH), exhibits an anti-atherogenic effect and partly inhibited a Ca2+ influx like dihydropyridine type-voltage-dependent L-type Ca2+ channel (VDCC) blocker. However, further inhibitory potential(s) in intracellular Ca2+-signaling pathways are still unclear. In this study, we attempted to elucidate alternative vasoprotective mechanism of WH in the intracellular Ca2+-signaling pathways. Methods: Vascular smooth muscle cells (VSMCs) from 8-wk-old WKY rats were used to determine [Ca2+]i. Measurement of [Ca2+]i was performed using Fura-2, a Ca2+-specific probe, monitored at of dual-excited fluorescence at 340/380 nm (Emission: 500 nm). Activities of Protein Kinase C (PKC)s and calmodulin-dependent kinase II (CaMK II) were measured by ELISA and phosphorylation of VDCC was evaluated by Western blot. Results: WH (300 [mu]M, not its corresponding amino acids) strongly suppressed the increase in [Ca2+]i in angiotensin II (Ang II)-stimulated VSMCs ([DELTA][Ca2+]i: Control; 620.0 nM, WH; 53.3 nM, P < 0.01). WH did not attenuate Ang II-induced Ca2+ release from the endoplasmic/sarcoplasmic reticulum, while significantly inhibited phospholipase C (PLC)-activated [Ca2+]i elevation in m-3M3FBS (a PLC activator)-stimulated VSMCs ([DELTA][Ca2+]i: Control; 221.8 nM, WH; 63.2 nM, P < 0.01). In PLC-related signaling pathways, involving the facilitation of VDCC by Ca2+-related kinases such as CaMK II, WH inhibited CaMK II activity (P < 0.05). Furthermore, WH suppressed the phosphorylation of VDCC (P < 0.05). Conclusions: In AngII-induced vasoconstriction signaling pathway, we demonstrated for the first time that WH regulates [Ca2+]i in VSMCs through the suppression of PLC/CaMK II/VDCC phosphorylation pathway.
    No preview · Article · Sep 2012 · Journal of Hypertension
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    Yutaro Kobayashi · Toshihiko Fukuda · Mitsuru Tanaka · Toshiro Matsui
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    ABSTRACT: Trp-His is the only vasoactive di-peptide known to regulate intracellular Ca(2+) ([Ca(2+)]i) and prevent the onset of atherosclerosis in mice. In this study, we showed that Trp-His reduced the [Ca(2+)]i elevation in phospholipase C-activated vascular smooth muscle cells (VSMCs), while a mixture of the corresponding constituent amino acids did not show significant reduction. Furthermore, Trp-His suppressed calmodulin-dependent kinase II (CaMK II) activity in angiotensin II-stimulated VSMCs, resulting in the inhibition of phosphorylation of voltage-dependent L-type Ca(2+) channels (VDCC). Therefore, Trp-His potentially regulates the VDCC phosphorylation cascade through Ca(2+)-CaM/CaMK II.
    Preview · Article · Apr 2012 · FEBS Open Bio
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    ABSTRACT: Adenine had a concentration-dependent relaxation action on the phenylephrine-contracted aorta ring, with an EC(50) value of 0.40±0.12 mM. This effect was also observed in the endothelium-denuded aorta. Among the adenine analogues, N-methyladenine and benzimidazole still evoked an apparent relaxation effect, while 1-, 3- or 7-methyladenine and imidazole were no longer vasodilators. These findings demonstrate that the imino group from the uncharged imidazolium moiety in adenine played a key role in the relaxation of the contracted aorta.
    No preview · Article · Apr 2012 · Bioscience Biotechnology and Biochemistry