1993 Fiscal Year Final Research Report Summary
Significance of central mechanism of calcium regulation in responses to environmental stresses
| Project/Area Number |
03454136
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
環境生理学(含体力医学･栄養生理学)
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| Research Institution | KYUSHU UNIVERSITY |
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Principal Investigator |
AOU Shuji KYUSHU UNIV., Fac. Med., ASSOC.PROF., 医学部, 助教授 (40150908)
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| Co-Investigator(Kenkyū-buntansha) |
KATAFUCHI Toshihiko KYUSHU UNIV., Fac. Med., ASSIST.PROF., 医学部, 助手 (80177401)
SHIMIZU Nobuaki SHIMIZU UNIV., Fac. Technol., ASSOC.PROF., 工学部, 助教授 (50019634)
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| Project Period (FY) |
1991 – 1993
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| Keywords | Stress / stress-responses / central mechanisums of calcium regulation / calcium homeostasis / stress-induced hypocalcemia / autonomic nervous system / hypothlamus |
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| Research Abstract |
1. Etiology of stress-induced hupocalcemia : Muscarinic antagonist, gastric vagotomy, gastrin release inhibitors or histamine H_2 receptor antagonists diminished the immobilization (IMB) -induced hypocalcemia. The concentration of serum gastrin increased significantly during IMB.Either an antrectomy (removal of the source of gastrin) or a fundectomy (depriving the origin of gastric histamine and gastric acid) was also sufficient for eliminating IMB-induced hypocalcemia. These findings suggest that the antrum and the fundus of the stomach play essential roles in IMB-induced hypocalcemia through the vagus-induced release of gastrin and histamine.
2. Hypothalamic involvement in stress-induced hypocalcemia : Bilateral lesions of the ventromedial nucleus of the hypothalamus (VMH), but not those of the paraventricular hypothalamic nucleus or the lateral hypothalamic area, eliminated immobilization (IMB)-induced hypocalcemia, and electrical stimulation of the VMH decrease the blood calcium level.
3. Hypothalamic linkage of stress-induced hypocalcemia and gastric lesions are closely related and are also influenced by behavioral responsiveness in a strain dependent manner. VMH lesion diminished or attenuated stress-induced hypocalcemia, gastric lesions, and behavioral despair, while the PVN has an opposite effect.
4. Hypothalamic control of blood calcium homeostasis : Stimulation studies revealed that the LHA and the PVN have a hypocalcemic function which is mediated, at least n part, bby the vagus nerve innervating the stomach and the thyroid/parathyhroid glands, respectively.
5. Central effect of parathyroid hormone : Intracerebroventricular injection of PTH prevented urethan-induced hypocalcemia. Hypothalamic injection of PTH prevented urethan-induced hypocalcemia. Hypothalamic injection of PTH also showed a hypercalcemic effect. PTH inhibited activity of VMH neurons through postsynaptic mechanism mediated by PTH receptors.
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