Effects of cholecystokinin on luteinizing hormone release from perifused hypothalamus-pituitary in the castrated bulls.

  • KANEMATSU Shigeto
    Department of Animal Husbandry, Faculty of Agriculture, Iwate University
  • SATO Narichika
    Department of Animal Husbandry, Faculty of Agriculture, Iwate University
  • HASHIZUME Tsutomu
    Department of Animal Husbandry, Faculty of Agriculture, Iwate University

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Other Title
  • 去勢牛の視床下部一下垂体の<I>in vitro</I>灌流系における黄体形成ホルモン放出に及ぼすコレシストキニンの効果

Abstract

The effect of cholecystokinin (CCK)-8 was studied on the release of luteinizinghormone (LH) from perifused medial basal hypothalami (MBH) and/or adenohypophyses of castrated bulls in a sequential double chamber perifusion system. LH concentrations in the perifusion efflux from the pituitary in series with the hypothalamus decreased significantly (P<0.05) after perifusion of 10-8M CCK as compared with control levels. In the similar perifusion LH concentrations in the efflux from the pituitary alone decreased significantly (P<0.01) after perifusion of 10-8M CCK. 10-7M CCK induced neither inhibitory nor stimulatory effects in perifusions of the pituitary in series 'with the hypothalamus except one fraction. Similarly, 10-7M CCK failed to induce a significant change in LH release in perifusion of the pituitary alone. LH concentrations in the perifusion efflux from pituitary in series with the hypothalamus increased significantly at 50 and 60 min after the initiation of 10-6M CCK perifusion as compared with the control level (P<0.05). LH concentrations in the efflux from the pituitary alone increased significantly 40, 50, 60 and 80 min after the initiation of perifusion with 10-6M CCK.<BR>The results indicate that CCK acts directly on the adenohypophysis t modulate release of LH in cattle.

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