| Project/Area Number |
07557008
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 展開研究 |
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| Research Field |
Environmental physiology (including Physical medicine and Nutritional physiology)
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| Research Institution | KYUSHU UNIVERSITY |
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Principal Investigator |
AOU Shuji Kyushu University, Dept.of Physiology, Assistant Professor, 医学部, 助教授 (40150908)
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| Co-Investigator(Kenkyū-buntansha) |
OOMURA Yutaka Nihonzoki Pharmaceut, Inst Bioactive Sci, Senior adviser, 生物活性科学研究所, 顧問 (30019517)
KATO Masakatsu Nippon Medical School, Dept.of Physiology, Assistant Professor, 医学部, 助手 (90143239)
TATEMOTO Kazuhiko Gunma University, Dept.of Molec.Physiol., Professor, 生体調節研究所, 教授 (60240694)
KATAFUCHI Toshihiko Kyushu University, Dept.of Physiology, Assistant Professor, 医学部, 講師 (80177401)
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| Project Period (FY) |
1995 – 1997
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| Keywords | hypothalamus / paraventricular nucleus / hypocalcemia / calcium metabolism / histamine / platelet activating factor / stomach-derived hypocalcemic factor / stress |
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| Research Abstract |
1. Blood calcium levels decreased during immobilization stress or water restraint stress. The stress-induced hypocalcemia was eliminated by gastric vagotomy or pretreatment of atropine and histamine H2 blochers, Intravenous injection of gastrin or histamine also induced hypocalcemia in intact rats but not in gastrectomized animals.
2. Intravenous injection of certain extract of gastric mucosa reduced blood calcium levels. The hypocalcemic action of the mucosal extracts reduced or abolished after purification.
3. Intravenous injection of platelet activating factor (PAF) induced sevior hypocalcemia and gastric mucosal lesions. Antgonist of PAF receptors eliminated hypocalcemic action of PAF but histamine H2 blocker did not. In contrast, hypocalcemic effect of histamine was blocked by H2 antagonist but not by PAF antagonist.
4. Intracellular calcium concentration of adhesive cells of the gastric mucosa increased after application of histamine or PAF.Gastrin showed no effect. One of the possible targets of histamine and PAF might be gastric macrophages.
5. Intracerebroventricular injection of rat parathyroid hormone (PTH1-34) eliminated urethane-induced hypocalcemia in a dose dependent manner. Intravenous injection or intracisternal injection of PTH1-34 at the same dose was ineffective. About 40% of neurons of the ventromedial hypothalamic nucleus decreased in activity after appplication of PTH1-34. PTH may act on hypothalmic neurons which are involved in central control of calcium homeostasis. PTH may act on the brain to regulate calcium homeostasis.
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