| Co-Investigator(Kenkyū-buntansha) |
TANAKA Katuhide Tokyo University of Agriculture, Faculty of Agriculture, Proressor, 農学部, 教授 (20021678)
KAMIYOSHI Michiharu Gifu University, Faculty of Agriculture, Professor, 農学部, 教授 (00021709)
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| Keywords | Vasoactive intestinal polypeptide, / Receptor, / Hen, / Hypothalamus, / Pituitary, / Ovarian granulosa cell, / Progesterone, / Prolactin, |
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| Research Abstract |
The membrane fractions of hypothalamic tissues involving the preoptic (HPOA) or mediam eminence (HMEA) areas, anterior pituitary, and ovarian granulosa cells in hens were found to possess a vasoactive intestinal polypeptide (VIP)-binding component having characteristics of a receptor such as high affinity, limited capacity, reversible binding, and binding specificity. The equilibrium dissociation constant (Kd) was 0.70(]SY.+-。[)0.07nM (Mean(]SY.+-。[)SEM) in HPOA,1.02(]SY.+-。[)0.15nM in HMEA,0.092(]SY.+-。[)0.008nM in anterior pituitary, and 0.38(]SY.+-。[)0.04nM in ovarian granulosa cells as estimated by Scatchard analysis of saturation studies, respectively, and was 0.91(]SY.+-。[)0.011nM (HPOA), 1.25(]SY.+-。[)0.09nM (HMEA), 0.091(]SY.+-。[)0.002nM (anterior pituitary), and 0.41(]SY.+-。[)0.03nM (ovarian granulosa cells) as determined by a kinetic analysis, respectively. The maximum binding capacity (Bmax) obtained by Scatchard analysis was 167(]SY.+-。[)19fmol/mg protein (HPOA), 133(]SY.+-
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。[)17fmol/mg protein (HMEA), 631(]SY.+-。[)41fmol/mg protein (anterior pituitary), and 1.48(]SY.+-。[)0.18pmol/mg ptotein (ovarian granulosa cells), respectively. In the hypothalamus, the Kd and Bmax values obtained by Scatchard analysis were similar in the two areas and in both laying and nonlaying hens. Administration of VIP in vivo caused a decrease in specific VIP binding. In anterior pituitary, the Kd value obtained from Scatchard analysis was not significantly different between the laying and nonlaying hens. The Bmax in laying hens was greater than that in nonlayign hens. The administration of VIP to nonlaying hens caused a narked decrease in the VIP receptor binding in the anterior pituitary with a concomitant increase in the blood serum concentrations of prolactin. In ovarian granulosa cells, when the cells were incubated in vitro with various concentrations of VIP,the production of the VIP-stimulated progesterone was increased. These results suggest a direct action of VIP on the hypothalamicpituitary system of the hen to the release of prolactin from anterior pituitary, and on the ovarian granulosa cells of the hen to the increase of progesterone production. Less
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