1989 Fiscal Year Final Research Report Summary
Integration of the biowarning information through the hypothalamic neuronal network.
| Project/Area Number |
63480470
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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 |
医学一般
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| Research Institution | Kyushu University |
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Principal Investigator |
SHIMIZU Nobuaki Kyushu Univ., Fac. Med., Assist. Prof., 医学部, 講師 (50019634)
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| Co-Investigator(Kenkyū-buntansha) |
OOMURA Yutaka Kyushu Univ., Emeritus Prof., 名誉教授 (30019517)
KATAFUCHI Toshihiko Kyushu Univ., Fac. Med., Assist. Prof., 医学部, 助手 (80177401)
HORI Tetsuro Kyushu Univ., Fac. Med., Prof., 医学部, 教授 (00022814)
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| Project Period (FY) |
1988 – 1989
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| Keywords | stress / hypothalamus / feeding behavior / serotonin / immobilization / electrochemistry / microdialysis / rat |
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| Research Abstract |
The effects of stress on food intake and on neural activity in the lateral hypothalamic area (LHA) were investigated. Significant reduction of daily food intake was observed after 2 hr immobilization. Injection of methysergide (5 mg/kg, i.p.) antagonized the immobilization-induced anorexia for 3 hr, while injection of naloxone had no effect. To study LHA neuronal responses to immobilization stress, single neuron activity was recorded by chronically implanted wire electrodes. Activity of 16 of 20 LHA neurons were significantly decreased by immobilization stress. The mean firing rate (discharges/sec) decreased from a baseline of 27.1 <plus-minus> 2.4 to 8.1 <plus-minus> 1.0 during immobilization, and the mean latency to the steady .state response was 20.1 <plus-minus> 5.2 min. No neurons increased their firing rate following immobilization in this study. Injection of methysergide (5 mg/kg, i.p.), 60 min before immobilization, completely blocked the suppressive effect of immobilization. I
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n 5 neurons tested for the effect of methysergide, all responses were antagonized by preinjection of methysergide (-67.8 <plus-minus> 5.4% change in neural discharge by immobilization without methysergide, arnd -19.6 <plus-minus> 6.2% after injection of methysergide). Further more differential pulse voltammetry with a carbon fiber electrode or brain microdialysis with high-performance liquid chromatography and electrochemical detection were used to measure 5-hydroxyindoleacetic acid (5-HIAA), the metabolic product of the serotonin. A significant increase in 5-HIAA concentration in the LHA was detected after immobilization stress. Immobilization of rats resulted in rapid increase of 5-HIAA concentration in the LHA. The increased levels reached a maximum of 46.3 <plus-minus> 8.3% 45 min after starting the immobilization. The electrochemical signals gradually decayed immediately after cessation of immobilization and returned to the preimmobilization level within 180 min. These results suggest that immobilization-induced anorexia is mediated at least in partly through serotoninergic mechanisms in the h Less
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