Effect of growth hormone on estrogen receptor binding properties in the chick oviduct in vivo |
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Authors: | Tetsuya TAKAHASHI Hiroshi OGAWA Mitsuo KAWASHIMA |
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Affiliation: | Department of Biological Diversity and Resources, Gifu University, Gifu-shi and; Department of Zootechnical Science, Tokyo University of Agriculture, Atsugi-shi, Japan |
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Abstract: | The equilibrium dissociation constant (Kd) and the maximum binding capacity (Bmax) of estrogen receptor in cytosolic and nuclear fractions in oviduct of pullets following various daily injections (1–10 times) of growth hormone (GH: 50 µg/chick) were examined by Scathchard analysis of specific [3H]estradiol‐17β (E2) binding. The Kd values of receptor in both fractions decreased after three times of GH‐injection. In the Bmax values, three times of the injection caused a marked decrease in that value in the cytosolic fraction with a concomitant increase in that in the nuclear fraction, whereas the total Bmax (sum of Bmax in the cytosolic and nuclear fractions) did not change. A similar relationship between the Kd values in the binding of the two fractions was also observed in 4–10 times of GH‐injection. However, in 4–10 times of GH‐injection the Bmax of the both fractions and total Bmax was greater than that in vehicle‐injection (control). When the chicks were injected with 6–10 times of GH‐injection, the weight of oviduct was increased. No change in the plasma concentrations of E2 was found following GH‐ and vehicle‐injections into the chicks. The results suggest that growth hormone stimulates the growth of the chick oviduct by increasing the binding affinity and capacity of estrogen receptor. |
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Keywords: | chicken estrogen receptor growth hormone oviduct receptor binding |
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