| Co-Investigator(Kenkyū-buntansha) |
SAITO Noboru Nagoya University School of Agricultural Science Assistant Professor, 農学部, 助手 (40211924)
OHKUBO Takeshi Mie University Center of Mol.Biol.and Genetics Assistant Professor, 遺伝子実験施設, 助手 (70233070)
KUWAYAMA Takehito Tokyo Agricultural University Department of Zootechnical Sci.Lecturer, 農学部, 講師 (40215124)
KATO Yukio Gumma University Institute of Mol.Cell.Reg.Professor, 生体調節研, 助教授
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| Research Abstract |
Now commercial White Leghorn strain chicken dose not express incubation behavior, but Japanese native strain chicken and turkey hens still express incubation behavior. Therefore, in these birds, the incubation behavior lowers productivity of meat and egg laying, causing a lot of economic loss in poulty industries. Therefore, the poupose of present study is to reveal molecular mechanism of the incubation behavior and to establish the application for the removal of incubation behavior of these birds.
Turkey and Gifu-jidori hens still express incubation behavior. During the reproductive cycle in these birds, levels of plasma prolactin (PRL) and pituitary PRL mRNA increased during the incubation period but these levels were low in the laying period. These results suggest that PRL may regulate induction and maintaining of incubation behavior.
Using perifusion culture of the pituitary and cell culture of pituitary cells, we demonstrated that VIP induces PRL synthesis and release in the pituita
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ry gland via cAMP cascade. We cloned chicken VIP receptor mRNA.
There were no significant difference in the distribution of brain PRL receptor mRNA between chabohen displaying expression of incubation behavior and White Leghorn hens without expression of incubation behavior. In addition, during reproductive cycle in chabo hen the levels of brain PRL receptor mRNA did not change.
Effects of remobal of newly hatched chicks on incubation behavior were studied in the chabo hens. Those hens whose chicks were removed from the nest for 24 hr displayd again incubation behavior but those hens whose chicks were removed from the nest for 72 hr did not show incubation behavior again. The plasma levels of PRL decreased in all hens whose chicks were removed from the nest for 24 and 72hr. This results suggested that other factor may regulate the maintain of incubation behavior.
The administrations of VIP antibody into turkey and chicken hens markedly reduced plasma levels of PRL and inhibited incubation behavior. Less
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