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Dopamine 02 receptor plays a critical role in cell proliferation and proopiomelanocortin expression in the pituitary
Author(s) -
Yamaguchi Hiroo,
Aiba Atsu,
Nakamura Kenji,
Nakao Kazuki,
Sakagami Hiroyuki,
Goto Kaoru,
Kondo Hisatake,
Katsuki Motoya
Publication year - 1996
Publication title -
genes to cells
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.912
H-Index - 115
eISSN - 1365-2443
pISSN - 1356-9597
DOI - 10.1046/j.1365-2443.1996.d01-238.x
Subject(s) - biology , dopamine receptor d2 , proopiomelanocortin , medicine , endocrinology , dopaminergic , striatum , dopamine , enkephalin , receptor , hormone , genetics , opioid
Background : It has been suggested that the dopaminergic system is involved in the inhibitory control of secretion of pituitary hormones and in the regulation of motor function in the striatum. To elucidate the specific role of the dopamine D2 receptor (D2R) in the pituitary and brain, we generated D2R deficient (D2R mutant) mice using the gene targeting method. Results : Electrophysiological studies as well as ligand binding assays show no functional D2R in mutant mice. The D2R mutant mice display a hypoactivity and a slow, creeping movement. The expression of enkephalin mRNA in the striatum is increased in the mutant mice, but not that of dynorphin and substance P. D2R mutant mice have significantly darker coat colour than their wild‐type littermates and show an elevation of plasma alpha‐melanocyte stimulating hormone (a‐MSH) levels. We found corresponding hyperplastic changes of intermediate lobe of the pituitary and the increased expression of proopiomelanocortin (POMC) in the pituitary in D2R mutant mice. Conclusion : D2R plays a critical role in the inhibitory regulation of endocrine cell proliferition and the transcription of POMC mRNA, and consequently in the regulation of a‐MSH in plasma. D2R might be involved in the regulation of enkephalin expression in the striatum, and hence might affect the movement and the behaviour.