ISSN:
1432-2013
Keywords:
Amygdala
;
Anaesthesia
;
Vasoconstriction
;
Vasodilatation
;
Psychomotor behaviour
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Abstract 1. Stimulation within the amygdaloid complex elicited two different behavioural and cardiovascular patterns of response. In the awake animal stimulation of the magnocellular part of the basal amygdala resulted in a defence reaction. Stimulation parameters eliciting only the first stage of this behaviour induced a moderate tachycardia and a shortlasting decrease in arterial pressure followed by an increase. Aortic blood flow measured distal to the renal arteries was increased; hence calculated peripheral vascular resistance was decreased. The increase in blood flow was blocked by both atropine sulphate and methyl-atropine. 2. Stimulation of the central amygdala in the awake cat elicited a behaviour which was different from a typical defence reaction. The response appeared to be more similar to attack or a superimposition of attack on the defence reaction. Stimulation of this area with lower stimulus intensities elicited a cardiovascular pattern consisting of tachycardia, which was sensitive to β-blockade, increased arterial pressure, which remained elevated for the entire period of stimulation and increased calculated peripheral resistance. These latter changes were blocked by application of phenoxybenzamine as well as of phentolamine. Moreover, there was a marked post-stimulation bradycardia, which was abolished by application of atropine sulphate. 3. Intravenous administration of sodium pentobarbitone did not alter the cardiovascular patterns induced by stimulation of the central or basal amygdala if the dose of pentobarbitone did not exceed 25 mg/kg. However, stimulus intensities had to be increased by a factor of 2 to 3 in order to elicit comparable cardiovascular responses. If the dose of pentobarbitone exceeded 25 mg/kg, the well-defined cardiovascular patterns elicited by stimulation of the two different amygdaloid nuclei could not be observed. In contrast, stimulation of sites within the ventromedial hypothalamus, performed in the same animal, showed that the cardiovascular responses could be elicited also after application of 40–45mg/kg of pentobarbitone. Hence it is concluded that anaesthetic agents such as pentobarbitone act largely on neuronal elements between the amygdala and hypothalamus.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00581581
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