Presynaptic serotonin mechanisms in rats subjected to inescapable shock

Edwards, E., Kornrich, W., Houtten, P. V., Henn, F. A. (April 1992) Presynaptic serotonin mechanisms in rats subjected to inescapable shock. Neuropharmacology, 31 (4). pp. 323-30. ISSN 0028-3908 (Print)0028-3908

DOI: 10.1016/0028-3908(92)90063-U


After exposure to uncontrollable shock training, two distinct groups of rats can be defined in terms of their performance in learning to escape from a controllable stress. Learned helpless rats do not learn to terminate the controllable stress, whereas non-learned helpless rats learn this response as readily as naive control rats do. The present studies were designed to examine the correlations between the behavioral differences and the changes of presynaptic serotonergic activity, seen in these groups of rats. The major findings concerned presynaptic serotonergic effects in the hippocampus and hypothalamus of learned helpless rats. In the hippocampus, these included a statistically significant increase in three presynaptic 5-hydroxytryptamine (5-HT) mechanisms: K(+)-induced release of [3H]serotonin, high affinity uptake of [3H]serotonin and maximum density of binding sites for uptake of 5-HT, measured with [3H]paroxetine. In the hypothalamus, there was a differential modulation of all three presynaptic 5-HT mechanisms. A significant decrease in: K(+)-induced release of [3H]serotonin, in high affinity uptake of [3H]serotonin and the maximum binding site density of [3H]paroxetine binding was observed. No changes in uptake site binding was seen in other regions of the brain examined. These results implicate presynaptic serotonin mechanisms in the behavioral deficit caused by uncontrollable shock. In addition, a limbic-hypothalamic pathway may serve as a control center for the behavioral response to stress.

Item Type: Paper
Uncontrolled Keywords: Analysis of Variance Animals Biological Transport Brain/*metabolism *Electroshock *Escape Reaction Helplessness, Learned Hippocampus/metabolism Hypothalamus/metabolism Male Models, Psychological Paroxetine Piperidines/metabolism Potassium/pharmacology Rats Rats, Inbred Strains Receptors, Serotonin/metabolism Serotonin/*metabolism Serotonin Antagonists/metabolism Stress, Psychological/*physiopathology Synapses/drug effects/*physiology
Subjects: diseases & disorders > mental disorders > mood disorders > depression
organs, tissues, organelles, cell types and functions > cell types and functions > cell functions > neurotransmitter
organs, tissues, organelles, cell types and functions > cell types and functions > cell functions > presynaptic transmission
CSHL Authors:
Communities: CSHL labs > Henn lab
Depositing User: Matt Covey
Date: April 1992
Date Deposited: 09 Jul 2014 14:52
Last Modified: 09 Jul 2014 14:52
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