Abstract
Learned helplessness (LH) is induced by exposure to an inescapable or uncontrollable stressor which results in an inability to escape or avoid the same stressor when subsequently presented in a different context. In order to understand which central mechanisms may influence the expression of the learned helpless phenotype, we have pursued an experimental approach that seeks to elucidate the behavioral effects of glucocorticoid (GC) hormones in this animal model of depression. We have previously shown that the induction of LH behavior is enhanced by adrenalectomy, an effect that is reversed by corticosterone. In this study, our aim was to attempt to locate CNS sites responsible for the observed effects of glucocorticoids on learned helpless behavior by introducing the type II GC receptor antagonist, RU 38486 to discrete brain regions. We did not observe a significant effect in LH with acute systemic, acute dentate gyrus or intracerebroventricular injection of RU 38486 in contrast to previous studies using the Porsolt swim test, another animal model of depression. However, we were able to observe a significant change upon chronic administration to the dentate gyrus. These findings suggest that glucocorticoids exert a long-term influence on stress-induced behavior, presumably by affecting glucocorticoid responsive genes in the dentate gyrus.
Original language | English (US) |
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Pages (from-to) | 304-309 |
Number of pages | 6 |
Journal | Brain research |
Volume | 615 |
Issue number | 2 |
DOIs | |
State | Published - Jul 2 1993 |
Keywords
- Antiglucocorticoid
- Dentate gyrus
- Learned helplessness
- RU 38486
ASJC Scopus subject areas
- General Neuroscience
- Molecular Biology
- Clinical Neurology
- Developmental Biology