Lack of tissue glucocorticoid reactivation in 11 beta-hydroxysteroid dehydrogenase type 1 knockout mice ameliorates age-related learning impairments

J L W Yau, J Noble, C J Kenyon, C Hibberd, Y Kotelevtsev, J J Mullins, J R Seckl

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

11 beta -hydroxysteroid dehydrogenase type 1 (11 beta -HSD-1) intracellularly regenerates active corticosterone from circulating inert 11-dehydrocorticosterone (11-DHC) in specific tissues. The hippocampus is a brain structure particularly vulnerable to glucocorticoid neurotoxicity with aging. In intact hippocampal cells in culture, 11 beta -HSD-1 acts as a functional 11 beta -reductase reactivating inert 11-DHC to corticosterone, thereby potentiating kainate neurotoxicity. We examined the functional significance of 11 beta -HSD-1 in the central nervous system by using knockout mice. Aged wild-type mice developed elevated plasma corticosterone levels that correlated with learning deficits in the watermaze. In contrast, despite elevated plasma corticosterone levels throughout life, this glucocorticoid-associated learning deficit was ameliorated in aged 11 beta -HSD-1 knockout mice, implicating lower intraneuronal corticosterone levels through lack of 11-DHC reactivation. Indeed, aged knockout mice showed significantly lower hippocampal tissue corticosterone levels than wild-type controls. These findings demonstrate that tissue corticosterone levels do not merely reflect plasma levels and appear to play a more important role in hippocampal functions than circulating blood levels. The data emphasize the crucial importance of local enzymes in determining intracellular glucocorticoid activity. Selective 11 beta -HSD-1 inhibitors may protect against hippocampal function decline with age.

Original languageEnglish
Pages (from-to)4716-4721
Number of pages6
JournalProceedings of the National Academy of Sciences (PNAS)
Volume98
Issue number8
DOIs
Publication statusPublished - 10 Apr 2001

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