Neuroendocrine responses to an emotional stressor: Evidence for involvement of the medial but not the central amygdala

Dayas, C. V., Buller, K. M. and Day, T. A. (1999) Neuroendocrine responses to an emotional stressor: Evidence for involvement of the medial but not the central amygdala. European Journal of Neuroscience, 11 7: 2312-2322. doi:10.1046/j.1460-9568.1999.00645.x


Author Dayas, C. V.
Buller, K. M.
Day, T. A.
Title Neuroendocrine responses to an emotional stressor: Evidence for involvement of the medial but not the central amygdala
Journal name European Journal of Neuroscience   Check publisher's open access policy
ISSN 0953-816X
Publication date 1999-01-01
Sub-type Article (original research)
DOI 10.1046/j.1460-9568.1999.00645.x
Volume 11
Issue 7
Start page 2312
End page 2322
Total pages 11
Place of publication Oxford, UK
Publisher Blackwell
Language eng
Subject C1
320700 Neurosciences
730104 Nervous system and disorders
1103 Clinical Sciences
1109 Neurosciences
Abstract The amygdala plays a pivotal role in the generation of appropriate responses to emotional stimuli. In the case of emotional stressors, these responses include activation of the hypothalamic-pituitary-adrenal (HPA) axis. This effect is generally held to depend upon the central nucleus of the amygdala, but recent evidence suggests a role for the medial nucleus. In the present study, c-fos expression, amygdala lesion and retrograde tracing experiments were performed on adult rats in order to re-evaluate the role of the central as opposed to the medial amygdala in generating neuroendocrine responses to an emotional stressor. Brief restraint (15 min) was used as a representative emotional stressor and was found to elicit c-fos expression much more strongly in the medial than central nucleus of the amygdala; relatively few Fos-positive cells were seen in other amygdala nuclei. Subsequent experiments showed that ibotenic acid lesions of the medial amygdala, but not the central amygdala, greatly reduced restraint-induced activation of cells of the medial paraventricular nucleus, the site of the tuberoinfundibular corticotropin-releasing factor cells that constitute the apex of the HPA axis. Medial amygdala lesions also reduced the activation of supraoptic and paraventricular nucleus oxytocinergic neurosecretory cells that commonly accompanies stress-induced HPA axis activation in rodents. To assess whether the role of the medial amygdala in the control of neuroendocrine cell responses to emotional stress might involve a direct projection to such cells, retrograde tracing of amygdala projections to the paraventricular nucleus was performed in combination with Fos immunolabelling. This showed that although some medial amygdala cells activated by exposure to an emotional stressor project directly to the paraventricular nucleus, the number is very small. These findings provide the first direct evidence that it is the medial rather than the central amygdala that is critical to hypothalamic neuroendocrine cell responses during an emotional response, and also provide the first evidence that the amygdala governs oxytocin as well as HPA axis responses to an emotional stressor.
Keyword Neurosciences
Amygdala
Emotional Stress
Hypothalamic-pituitary-adrenal Axis
Oxytocin
Paraventricular Nucleus
Restraint
Corticotropin-releasing Factor
Messenger-rna Expression
C-fos Expression
Hypothalamic Paraventricular Nucleus
Conditioned Stress
Rat Hypothalamus
Corticosterone Responses
Electrical-stimulation
Behavioral-responses
Endocrine Responses
Q-Index Code C1

Document type: Journal Article
Sub-type: Article (original research)
Collection: Faculty of Science Publications
 
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Created: Wed, 11 Jun 2008, 01:03:30 EST