| Project/Area Number |
18591014
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Endocrinology
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| Research Institution | Hirosaki University |
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Principal Investigator |
SUDA Toshihiro Hirosaki University, Hirosaki University, Graduate School of Medicine, Professor (30075452)
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| Co-Investigator(Kenkyū-buntansha) |
IWASAKI Yasumasa Kochi University, University Hospital, Lecturer (30303613)
KAGEYAMA Kazunori Hirosaki University, University Hospital, Lecturer (30343023)
NIGAWARA Takeshi Hirosaki University, University Hospital, Assistant Professor (90333731)
SAKIHARA Satoru Hirosaki University, University Hospital, Assistant Professor (80333722)
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| Project Period (FY) |
2006 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥3,740,000 (Direct Cost: ¥3,200,000、Indirect Cost: ¥540,000)
Fiscal Year 2007: ¥2,340,000 (Direct Cost: ¥1,800,000、Indirect Cost: ¥540,000)
Fiscal Year 2006: ¥1,400,000 (Direct Cost: ¥1,400,000)
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| Keywords | Stress / Hypothalamus / Pituitary / Steroid / CRF / Receptor |
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| Research Abstract |
Corticotropin-releasing factor (CRF) is produced in the hypothalamic paraventricular nucleus (PVN) in response to stress and stimulates the release of adrenocorticotropic hormone in the corticotrophs. We demonstrated the dominant expression of estrogen receptor typeβ(ERβ) and found that a physiologically relevant dose of estradiol (E2) and an Erβ agonist stimulated CRF gene transcription in hypothalamic 4B cells. E2 stimulated interleukin (IL)-6 transcriptional activity via ERβ, and subsequently the levels of IL-6 mRNA and protein. We also found that treatment with IL-6 significantly reduced cell viability. Thus, these data suggest the important effects of E2 on the regulation of CRF gene and IL-6 production via Erβ in hypothalamic 4B cells.
Microfluorimetric experiments showed that CRF (0.2 nM) and urocortin (UCN) 1 (0.2 nM) elevated [Ca^<2+>]_I levels. Both CRF and UCN 1 effects were attenuated by astressin, a non-selective CRF receptor antagonist. Antisauvagine-30, a selective CRF_2
… More
receptor antagonist, appeared to enhance the UCN 1 effect on the elevation of [Ca^<2+>]_i. The CRF effect on the elevation of [Ca^<2+>]_i was inhibited by the addition of UCN 3. Taken together, the activation of CRF_2 receptor antagonizes the CRF_1 receptor-stimulated Ca^<2+> influx.
We also found that G protein-coupled receptor kinase (GRK) 2 (but not GRK3) mRNA and protein were expressed in rat anterior pituitary cells and AtT-20 cells (a line of mouse corticotroph tumor cells). In order to determine the role of GRK2 in CRF-induced desensitization of CRF_1 receptor in mouse corticotrophs, AtT-20 cells were transfected with a dominant negative mutant GRK2 construct. CRF desensitized the cAMP-dependent response by CRF_1 receptor. Desensitization of CRF_1 receptor by CRF was significantly less in AtT-20 cells transfected with the dominant negative mutant GRK2 construct compared with desensitization in control AtT-20 cells. These results suggest that GRK2 is involved in CRF-induced desensitization of CRF_1 receptor in AtT-20 cells, and protein kinase A pathway may also have an important role in desensitization of CRF_1 receptor by CRF seen in cortivotrophic cells. Less
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