Yuko Sakakibara

University of Yamanashi, Kōhu, Yamanashi, Japan

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Publications (7)6.51 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: The aim of this study was to elucidate whether dietary zinc-deficiency and its recovery play a role in controlling autonomic thermoregulation. We investigated the effects of dietary zinc-deficiency and its recovery on autonomic thermoregulation by measuring the rectal temperature, an index of deep body temperature. The weaned male Sprague Dawley rats were randomly divided into the dietary zinc-deficient diet (0.6 mg zinc/kg diet) group and the control diet (35.2 mg zinc/kg diet) group, and were fed for 4 weeks. In the recovery period, the rats of two groups were fed with the control diet for 3 weeks. The rectal temperature was significantly decreased throughout the period of zinc-deficiency and the hypothermic responses during the experimental period were recovered to the control group levels at least within 1 week in the recovery process from dietary zinc-deficiency. These results suggest that the deep temperature in rats was clearly associated with the dietary zinc intake levels.
    The Journal of Toxicological Sciences 10/2011; 36(5):681-5. · 1.38 Impact Factor
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    ABSTRACT: The purpose of this study was to elucidate the effects of the recovery from dietary zinc-deficiency on the number of total white blood cells (WBCs), neutrophils, eosinophils and basophils, and plasma zinc and corticosterone concentrations in weanling male Sprague Dawley rats. Rats (n=34) of the zinc-deficient diet (0.6 mg zinc/kg diet) and control diet (35.2 mg zinc/kg diet) groups were fed for 4 wk, and then rats of both groups were fed with the control diet for 3 wk. Zinc-deficiency increased duration-dependently and clearly the number of total WBCs, neutrophils and eosinophils, and the increased numbers of these cells recovered to the control levels in week 2 of the recovery. On the other hand, the number of basophils increased by the zinc-deficiency recovered to the control levels in week 1 of the recovery. Zinc-deficiency significantly decreased plasma zinc concentrations by 85%, and markedly increased plasma corticosterone concentrations by 317%, as compared with the control group. In the recovery period, plasma zinc and corticosterone concentrations recovered to the control levels in week 2 of the recovery. These results suggest that zinc-deficiency and its recovery responses in the number of granulocytes and total WBCs are reversible, and their recovery rates depend on the subsets of granulocytes in rats.
    Journal of Nutritional Science and Vitaminology 01/2011; 57(2):197-201. · 0.99 Impact Factor
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    ABSTRACT: Red peppers are used as a spice for enhancing the palatability of foods. Two major capsaicinoids, dihydrocapsaicin (DHC) and capsaicin (CAP) are responsible for up to 90% of the total pungency of pepper fruits. These capsaicinoids are known to enhance energy metabolism and thermogenesis. However, there is a little information on the effects of capsaicinoids on the lipolysis and carbohydrate metabolism. We studied the effects of DHC and CAP on plasma glucose, free fatty acid (FFA) and glycerol concentrations in rats. Male six-week-old Sprague Dawley rats were divided into the DHC, CAP and control groups. Each capsaicinoid (dose = 3 mg/kg BW/day) was subcutaneously administered to rats for 10 days. DHC increased markedly plasma glucose, FFA and glycerol concentrations on day 1-10 by 14-35%, 61-103% and 108-174%, respectively, as compared with those of the control group. CAP increased relatively plasma glucose concentrations on day 1-3 by 15-17%, as compared with the control group. However, there were no significant differences in plasma glucose concentrations on day 7-10 among three groups. On the contrary, CAP did not change plasma FFA and glycerol concentrations on day 1-3. However, CAP increased markedly plasma FFA and glycerol concentrations on day 7-10 by 54-89% and 92-98%, respectively, as compared with the control group. DHC and CAP did not change the weights of white (perirenal and periepididymal) and brown (interscapular) adipose tissues. In conclusion, the effects of capsaicinoids on plasma glucose, FFA and glycerol concentrations were relatively higher in the DHC than in the CAP, and capsaicinoids did not change the weight of white and brown adipose tissues.
    The Journal of Toxicological Sciences 01/2011; 36(1):109-16. · 1.38 Impact Factor
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    ABSTRACT: The purpose of the present study was to elucidate the effects of dietary zinc-deficient feeding and its recovery on liver cytosolic alcohol dehydrogenase (ADH; alcohol: NAD(+) oxidoreductase, EC1.1.1.1) activities and plasma zinc levels in rats. The weaned male Sprague Dawley rats were randomly divided into the zinc-deficient diet (ZDF: 1.9 mg zinc/kg diet) group and the control diet (53.5 mg zinc/kg diet) group, and were fed for 4 weeks. In the recovery periods, the rats of two groups were fed with the control diet for 3 weeks. Liver cytosolic protein content per body weight in the zinc-deficiency and its recovery period showed no significant changes between both groups. However, zinc-deficiency decreased significantly liver cytosolic ADH specific activity, total liver cytosolic ADH activity and total liver cytosolic ADH activity/body weight by 50%, 76% and 53%, respectively, as compared with the control diet group. Zinc-deficiency also decreased significantly plasma zinc concentration by 84%, as compared with the control diet group. On the contrary, no significant changes in liver cytosolic ADH specific activity, total liver cytosolic ADH activity and total liver cytosolic ADH activity/body weight in the recovery period were observed between both groups. Plasma zinc concentration in the recovery period was almost recovered to the control level. These results suggest that rat liver cytosolic ADH activity was clearly related to dietary zinc intake levels.
    The Journal of Toxicological Sciences 01/2011; 36(1):101-8. · 1.38 Impact Factor
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    ABSTRACT: The main pungent component of wasabi (Eutrema japonica) is known to be isothiocyanate and its derivatives, volatile substances. Allyl isothiocyanate (AITC) accounts for more than half of isothiocyanate derivatives. However, there is a little information on the effects of AITC on the immune system by analyzing the number of white blood cells (WBCs) over the course of days of AITC administration. In the present study, we studied the effects of AITC (dose=20 mg/kg body weight/day for 10 days, subcutaneous: s.c.) on the number of WBCs (total WBCs, lymphocytes, monocyte, neutrophil, basophil and eosinophil) and plasma corticosterone concentrations in adult male rats. Administration of AITC decreased significantly the number of total WBCs on days 1-4 post s.c. injection by 25-27%. Administration of AITC also decreased the number of lymphocytes on days 1-10 by 21-36% and monocyte on days 1-8 by 28-78%. However, administration of AITC increased the number of neutrophil on days 8-10 by 61-112%. AITC did not change the number of eosinophil and basophil. Plasma corticosterone concentrations during the experimental period were 4.7-8.4 times significantly higher in the AITC group than in the control group, indicating that AITC induced stress-responses. The relative weights of thymus and adrenals per body weight were significantly lower and clearly higher in the AITC group than in the control group, respectively. These results suggest that AITC-mediated stress-responses are at least in part attributable to changes in the number of circulating WBCs.
    The Journal of Toxicological Sciences 08/2010; 35(4):583-9. · 1.38 Impact Factor
  • Journal of Health Science - J HEALTH SCI. 01/2010; 56(3):347-354.
  • Journal of Health Science - J HEALTH SCI. 01/2010; 56(2):215-220.