1995 Fiscal Year Final Research Report Summary
Hypothalamic neuron responses in the vestibulo-autonomic reflex with special reference to the cerebellar nucleus and brainstem
| Project/Area Number |
05671434
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Otorhinolaryngology
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| Research Institution | Kyushu University |
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Principal Investigator |
INOKUCHI Akira Kyushu University Faculty of Medicine Lecturer, 医学部, 講師 (90193622)
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| Project Period (FY) |
1993 – 1995
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| Keywords | Hypothalamus / Vestibulo-autonomic reflex / Guinea pig / Electrophysiology / Caloric stimulation / Cerebellar nucleus / Brainstem / Blood pressure |
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| Research Abstract |
Posterior hypothalamic (PH)neurons responded excitatory in response to superior and lateral vesutibular nuclei(VN)stimulation and not to medial and inferior VN stimulation. The neurons in the PH and hypothalamic paraventricular nucleus(PVN) responded either excitatory or inhibitory to caloric stimulstion, and the individual neurons excitaion/inhibition response pattern was ssimilar when stimulated with either hot or cold water and on either the contralateral or ipsilateral labyrinth. These responses were almost disappeared after sectioning the vestibular nerve or labyrinthectomy, suggesting that the above responses were vestibular in origin. Furthermore, these responses were diminished, disappeared or reversed by intravenous H_2 and H_2 blocker infusion. This indicates that the histaminergic systemparticipates in the vestibular information transduction in the brain. The spontaneous discharge of PH neurons gradually changed after the rotation began and these changes lasted for several minutes even after the rotation ended. Caloric stimulation produced a decrease in blood pressure (BP)and this change was related to the activity change of PVN neurons. Although electric destruction of the fastigial nucleus in the cerebellum produced little effect on the BP change, electric destruction of the hypothalamus almost totally abolished the BP change in responses to the caloric stimulation. This means that the acsending pathway from the vestibularcleus to the hypothalamus via the brainstem reticular formation has a crucial role in the vestibulo-sutonomic reflex., The neurons in the dorsal nucleus of the vagus showed mainly excitation in response to either ipsilateral or contralateral caloric stimulation.
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