Ken-Ichi Noritake

Publications (2)4.69 Total impact

• Article: Involvement of neurokinin receptors in the control of pulsatile luteinizing hormone secretion in rats.

  Ken-ichi Noritake, Toshiki Matsuoka, Tetsuya Ohsawa, Kazuhiro Shimomura, Atsushi Sanbuissho, Yoshihisa Uenoyama, Kei-ichiro Maeda, Hiroko Tsukamura
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  ABSTRACT: It has recently been shown that neurokinin B, a tachykinin, is associated with GnRH pulse generation in sheep and goats. The aim of the present study was to clarify the role of tachykinin receptors in the control of LH secretion in rats. To this end, we evaluated the effect of CS-003, an antagonist for all three neurokinin receptors (NK1, NK2 and NK3 receptors), on pulsatile LH secretion in both sexes of rats with different routes of administration. Both oral and third ventricular administration of CS-003 suppressed LH secretion in both sexes of gonadectomized animals. Furthermore, intact male rats with oral administration of CS-003 showed decreased serum testosterone levels, which might be due to suppressed LH secretion. None of the three subtype-specific neurokinin receptor antagonists showed a significant effect on LH secretion in ovariectomized rats when each antagonist was singly administered. The present results suggest that neurokinins play a role in the control of pulsatile GnRH/LH secretion via multiple neurokinin receptors in both male and female rats.
  Journal of Reproduction and Development 02/2011; 57(3):409-15. · 1.46 Impact Factor
• Article: Testicular toxicity induced by a triple neurokinin receptor antagonist in male dogs.

  Ken-Ichi Noritake, Junko Suzuki, Toshiki Matsuoka, Toshihiko Makino, Hitoshi Ohnishi, Kazuhiro Shimomura, Yoshihisa Uenoyama, Hiroko Tsukamura, Kei-Ichiro Maeda, Atsushi Sanbuissho
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  ABSTRACT: Mechanism mediating the testicular toxicity induced by CS-003, a triple neurokinin receptor antagonist, was investigated in male dogs. Daily CS-003 administrations showed testicular toxicity, such as a decrease in the sperm number, motility and prostate weight; and an increase in sperm abnormality, accompanying histopathological changes in the testis, epididymis and prostate. A single CS-003 administration suppressed plasma testosterone and LH levels in intact and castrated males. The suppressed LH release was restored by GnRH agonist injection, suggesting that pituitary sensitivity to GnRH is not impaired by CS-003. Treatment with SB223412, a neurokinin 3 receptor antagonist, caused a similar effect to CS-003, such as toxicity in the testis, prostate and epididymis and decreased plasma level of LH and testosterone. In conclusion, CS-003-induced testicular toxicity is caused by the inhibition of neurokinin B/neurokinin 3 receptor signaling probably at the hypothalamic level in male dogs.
  Reproductive Toxicology 12/2010; 31(4):440-6. · 3.23 Impact Factor