2001 Fiscal Year Final Research Report Summary
Roles of the neurohypophyseal hormones released from the dendrites in the control of stress responses
| Project/Area Number |
12670066
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Environmental physiology (including Physical medicine and Nutritional physiology)
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| Research Institution | Jichi Medical School |
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Principal Investigator |
ONAKA Tatstushi Jichi Medical School, Department of Physiology, Associate Professor, 医学部, 助教授 (90177254)
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| Project Period (FY) |
2000 – 2001
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| Keywords | stress / vasopressin / oxytocin / noradrenaline / dendrites / microdialysis / hypothalamus / medulla oblongata |
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| Research Abstract |
Vasopressin and oxytocin are synthesized in the magnocellular neurosecretory neurones in the hypothalamus, transported to the axon terminals in the neurohypophysis, and released into the blood stream. Not only from the axon terminals, vasopressin and oxytocin are released also from the dendrites in the hypothalamus. In the present study, we examined roles of vasopressin or oxytocin released from the dendrites in neurosecretory responses to stressful stimuli. We firstly demonstrated that noradrenaline neurons in the A1 region of the medulla oblongata mediate oxytocin release from the neurohypophysis after noxious stimuli, while A2 noradrenergic neurons mediate oxytocin responses to conditioned fear stimuli. We then confirmed that stressful stimuli such as intermittent footshocks facilitate vasopressin release from the dendrites/cell bodies in the hypothalamus via a microdialysis method. We also examined effects of vasopressin or oxytocin upon noradrenaline release in the hypothalamus. Exogenous application of vasopressin or oxytocin facilitated noradrenaline release in response to high K^+ solution, and a vasopressin or oxytocin receptor antagonist attenuated them. An oxytocin receptor antagonist also impaired noradrenaline release in the hypothalamus and oxytocin release from the neurohypophysis after noxious stimuli. From all these data we conclude that vasopressin or oxytocin released from the dendrites has an augmentative role in the activity of neurosecretory neurons via facilitation of noradrenaline release in the hypothalamus.
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[Publications] Leng G., Brown CH., Bull PM., Brown D., Scullion S., Currie J., Blackburn-Munro RE., Feng J., Onaka T., Verbalis JG., Russell JA., Ludwig M.: "Responses of magnocellular neurons to osmotic stimulation involves coactivation of excitatory and inhibitory input: an experimental and theoretical analysis"J Neurosci.. 21. 6967-77 (2001)
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