| Co-Investigator(Kenkyū-buntansha) |
KOGA Hisao Departments of Physiology and Neurosurgry, Saga Medical School, Saga., 医学部, 助手 (30153513)
KIYOHARA Toshikazu Department of Physiology, Saga Medical School, Saga., 医学部, 助教授 (50071874)
MORI Toshinori Department of Physiology, Saga Medical School, Saga., 医学部, 助手 (40200373)
NAKASHIMA Toshihiro Department of Physiology, Saga Medical School, Saga., 医学部, 助手 (30128136)
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| Research Abstract |
Responsiveness of hypothalamic thermsensitive neurons to non-thermel homeostatic parameters and hypothalamic peptides was studied in anesthetized rats of in the rat's hypothalamic tissue slices in vitro. 1) Many (60-70 %) thermosensitive neurons, but not non-thermosensitive neurons, were found to teceive afferent inputs from baro/volume receptors in the circulatory control and also from peripheral osmoreceptors. Furthermor, similar proportions of thermosensitive neurons were directly osmosensitive. These findings may emplain the reduced thermoregulation during hypohydration and the hypothermia after acute blood loss, both of which have been generally recognized to be the abaptive responses in conflicting situations created by thermoregulatory drives and osmoregulatory of circulatory drives. 2) Angiotensin II and vasopressin, both having roles in osmoregulation and circulatory regulation, activated and depressed warm-sensitive neurons and cold-sensitive neurons, respectively. The respon
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ses are compatible with the hypothermia induced by these peptides. 3) peptides having profound effects on the energy metabolism (bombesin, neurotensin and TRH) affected the activity of hypothalamic thermosensitive neurons appropriately, explaining the poikilothermia and decreased metabolism induced by bombesin and neurotensin and the hyperthermia and increased metabolism by TRH. 4) Muramyl peptide, interleukin-1 and interferon <alpha>, all of which induce fever, sleep and anorexia, depressed and excited warm-sensitive neurons and coldsensitive neurons respectively. Interleukin-1 and interferon<alpha> also incresaed the activity of glucosensitive neurons in the entromedial hypothalamus. 5) The results suggest the coordination of different homeostatic function may be achieved partly by the multiple responsiveness of hypothalamic neurons th different ferent homeostatic parameters and partly by the actions of hypothalamic peptides having the roles in the control of different functions on the neurons, in addition to the mutual neuronal connections among different homeostatic control systems. Less
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