Linked Life Data

8528703

Source:http://linkedlifedata.com/resource/pubmed/id/8528703

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
1996-1-30
pubmed:abstractText
The midbrain periaqueductal gray (PAG) and the central nucleus of the amygdala (CNA) are both known to be involved in fear and anxiety, analgesia, vocalization, cardiovascular and respiratory changes, and freezing. Anatomical studies have shown that a connection between these two regions exists but little is known about the physiology or the neurochemical constituents of this pathway. The goals of this study were to characterize the projection from the CNA to the PAG using electrophysiological techniques and to determine whether mu- and/or delta-opioid receptors, which play a large role in a majority of the functions of the PAG, are involved in this pathway. Of the 38 PAG cells tested with single shock stimulation of the CNA, 44% responded; of those, 46% were excited and 54% were inhibited. The latency to onset of response for the inhibitory cells (12.71 +/- 6.61 ms) was shorter than that of the excitatory cells (22.33 +/- 4.04 ms). Forty-six percent of the 129 PAG cells tested with train electrical stimulation of the CNA responded; 44% were excited and 56% were inhibited. Chemical stimulation of the CNA (10 mM D,L-homocysteic acid) produced similar results; 48% (62/128) of PAG cells responded; 45% of cells were excited and 55% were inhibited. The baseline firing rate of the inhibitory cells was significantly higher compared to the excitatory cells. Chemical stimulation of the CNA produced an increase in blood pressure in 12 animals, a decrease in two animals, and had no effect on the blood pressure of 68 animals. The blood pressure changes ranged between 8.5 and 26.3 mmHg with a mean of 16.2 +/- 2.2 mmHg. The effect of naloxone (given either on site in the PAG or systemically) on the response to CNA stimulation was tested in 21 cells. Twenty-five percent of the excitatory cells (2/8) and 77% (10/13) of the inhibitory cells were blocked by naloxone with the majority of the blocked cells located in the ventrolateral PAG. It is concluded that: (1) Approximately 50% of cells in the lateral and ventrolateral columns of the PAG respond to CNA stimulation; (2) the inhibitory response is mediated by a faster conducting or a more direct pathway than the pathway that mediates the excitatory response; (3) neurons that are inhibited by CNA stimulation have a significantly higher baseline firing rate than neurons that are excited, suggesting that they may be tonically active interneurons; and (4) at least one link in the CNA-PAG pathway utilizes mu- or delta-opioid receptors.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Aug
pubmed:issn
0006-8993
pubmed:author
pubmed:issnType
Print
pubmed:day
14
pubmed:volume
689
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
21-31
pubmed:dateRevised
2007-11-14
pubmed:meshHeading
pubmed:year
1995
pubmed:articleTitle
An electrophysiological characterization of the projection from the central nucleus of the amygdala to the periaqueductal gray of the rat: the role of opioid receptors.
pubmed:affiliation
Department of Molecular and Cellular Physiology, University of Cincinnati College of Medicine, OH 45267-0576, USA.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S.