| Noradrenergic excitation of magnocellular neurons in the rat hypothalamic paraventricular nucleus via intranuclear glutamatergic circuits. | |
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MedLine Citation:
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PMID: 9852597 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Noradrenergic projections to the hypothalamus play a critical role in the afferent control of oxytocin and vasopressin release. Recent evidence for intrahypothalamic glutamatergic circuits prompted us to test the hypothesis that the excitatory effect of noradrenergic inputs on oxytocin and vasopressin release is mediated in part by local glutamatergic interneurons. The voltage response to norepinephrine (30-300 microM) was tested with whole-cell recordings in putative magnocellular neurons of the paraventricular nucleus (PVN) in hypothalamic slices (400 micrometers). Norepinephrine elicited an alpha1 receptor-mediated direct depolarization in 23% of the magnocellular neurons tested; however, the most prominent response, seen in 42% of the magnocellular neurons, was an alpha1 receptor-mediated increase in the frequency of EPSPs. The norepinephrine-induced increase in EPSPs was blocked by tetrodotoxin and by ionotropic glutamate receptor antagonists, suggesting that norepinephrine excited presynaptic glutamate neurons to cause an increase in spike-mediated transmitter release. The increase in EPSPs also was observed in a surgically isolated PVN preparation (64% of cells) and with microdrop applications of norepinephrine (1 mM, 33% of cells) and glutamate (0.5-1 mM, 28%) in the PVN, indicating that the norepinephrine-sensitive presynaptic glutamate neurons are located within the PVN. Biocytin injection and subsequent immunohistochemical labeling revealed that both oxytocin and vasopressin neurons responded to norepinephrine. Our data indicate that magnocellular neurons of the PVN receive excitatory inputs from intranuclear glutamatergic neurons that express alpha1-adrenoreceptors. These glutamatergic interneurons may serve as an excitatory relay in the afferent noradrenergic control of oxytocin and vasopressin release under certain physiological conditions. |
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Authors:
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S S Daftary; C Boudaba; K Szabó; J G Tasker |
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Publication Detail:
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Type: In Vitro; Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S. |
Journal Detail:
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Title: The Journal of neuroscience : the official journal of the Society for Neuroscience Volume: 18 ISSN: 0270-6474 ISO Abbreviation: J. Neurosci. Publication Date: 1998 Dec |
Date Detail:
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Created Date: 1999-02-25 Completed Date: 1999-02-25 Revised Date: 2007-11-14 |
Medline Journal Info:
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Nlm Unique ID: 8102140 Medline TA: J Neurosci Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 10619-28 Citation Subset: IM |
Affiliation:
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Molecular and Cellular Biology Program, Tulane University, New Orleans, Louisiana 70118, USA. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Animals Excitatory Postsynaptic Potentials / drug effects Glutamic Acid / physiology* Immunohistochemistry Interneurons / physiology* Male Neural Pathways / drug effects Neurons / chemistry, drug effects Norepinephrine / pharmacology* Organ Specificity Oxytocin / analysis Paraventricular Hypothalamic Nucleus / drug effects*, physiology* Patch-Clamp Techniques Rats Rats, Sprague-Dawley Synapses / drug effects Vasopressins / analysis |
| Grant Support | |
ID/Acronym/Agency:
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NS31187/NS/NINDS NIH HHS |
| Chemical | |
Reg. No./Substance:
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11000-17-2/Vasopressins; 50-56-6/Oxytocin; 51-41-2/Norepinephrine; 56-86-0/Glutamic Acid |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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