DHEA-S selectively impairs contextual-fear conditioning: support for the antiglucocorticoid hypothesis.
The authors had reported that glucocorticoids play a selective role in fear conditioning. The adrenal steroid dehydroepiandrosterone (DHEA) has been reported to act as a functional antiglucocorticoid. If DHEA has antiglucocorticoid properties, then its effects on fear conditioning might resemble those produced by adrenalectomy. The authors now report that chronic exposure to high levels of dehydroepiandrosterone sulfate (DHEA-S; converted in vivo to DHEA) produced the same pattern of results as adrenalectomy. Specifically, treatment with DHEA-S impaired contextual fear conditioning 24 hr after conditioning but not immediately after conditioning, and like adrenalectomy, DHEA-S had no effect on auditory-cue fear conditioning. Preexposure to the context before drug treatment eliminated the amnestic effects of DHEA-S, suggesting that, like adrenalectomy, DHEA-S exerted its effect by interfering with the construction of a contextual memory representation. Thus, DHEA appears to act as a functional antiglucocorticoid in the processes that mediate learning and memory.