Document Detail

N-methyl D-aspartate (NMDA) evoked changes in blood pressure and heart rate from the rat superior colliculus.
MedLine Citation:
PMID:  2192905     Owner:  NLM     Status:  MEDLINE    
Electrical stimulation and microinjections of the GABA antagonist bicuculline methiodide into the superior colliculus (SC) of the anaesthetized rat can evoke changes in blood pressure and heart rate. The long latency of bicuculline evoked responses, however, raises the possibility that they may have been produced by the diffusion of bicuculline to surrounding tissue, in particular, the periaqueductal gray. Thus, the purpose of the present study was to investigate whether such changes could have been produced by the activation of extracollicular neural elements. This was achieved by assessing the relative regional sensitivity of the SC and underlying structures (periaqueductal gray and dorsal tegmentum) with microinjections of the excitatory amino acid N-methyl D-aspartate (NMDA) for the production of short latency pressor responses. Dorsal midbrain injections of NMDA (200 nl of 100 mM) in the Saffan anaesthetized rat evoked clear short latency (single or double phase) increases in blood pressure accompanied in most cases by a longer latency increase in heart rate and respiration. Two regions within the dorsal midbrain contained significantly higher proportions of active sites compared with surrounding tissue: i) the superficial and intermediate layers of rostromedial SC, and ii) the caudal periaqueductal gray. The distribution of active sites indicated that pressor responses elicited from the rostromedial SC could not be explained by the diffusion of NMDA to underlying tissue. The question of whether the rostromedial SC might represent an early link in the circuitry responsible for organizing defensive movements and appropriate physiological changes to potentially dangerous overhead stimuli is considered.
K A Keay; P Dean; P Redgrave
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Experimental brain research     Volume:  80     ISSN:  0014-4819     ISO Abbreviation:  Exp Brain Res     Publication Date:  1990  
Date Detail:
Created Date:  1990-08-01     Completed Date:  1990-08-01     Revised Date:  2013-12-13    
Medline Journal Info:
Nlm Unique ID:  0043312     Medline TA:  Exp Brain Res     Country:  GERMANY, WEST    
Other Details:
Languages:  eng     Pagination:  148-56     Citation Subset:  IM    
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MeSH Terms
Aspartic Acid / analogs & derivatives*,  pharmacology
Blood Pressure / drug effects*
Cardiovascular Physiological Phenomena
Cardiovascular System / drug effects*
Heart Rate / drug effects*
Mesencephalon / drug effects,  physiology*
Superior Colliculi / physiology*
Reg. No./Substance:
30KYC7MIAI/Aspartic Acid; 6384-92-5/N-Methylaspartate

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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