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The Millennium Health Centers, Inc.

http://www.millenniumhealthcenters.com

Interventional Endocrinology

Actions of 3 alpha,5 alpha-tetrahydrodeoxycorticosterone on single neurones of the mesencephalic reticular formation in the rat. Ermirio R, Blanchi D, Ruggeri P, Cogo CE, Molinari C. Istituto di Fisiologia Umana, Universita degli Studi, Genova, Italy.

The effects of microinjections of 3 alpha,5 alpha-tetrahydrodeoxycorticosterone (3 alpha-THDOC) on single neurones of the mesencephalic reticular formation (MRF) were investigated in rats anaesthetized with urethan. Microinjections of approximately 100 nl of 0.5-2 microM 3 alpha-THDOC inhibited firing of 105 of 112 neurones (94%). Microinjections of approximately 100 nl of 100-250 nM of 3 alpha-THDOC did not alter neuronal activity, but in 52 of 68 cases (76%) it potentiated the inhibitory action of microiontophoretically applied gamma-aminobutyric acid (GABA). The 3 beta-isomer of tetrahydrodeoxycorticosterone did not elicit any changes in neuronal firing. The effects of 3 alpha-THDOC were reversibly antagonized by microiontophoretically applied bicuculline. This 'in vivo' study supports the hypothesis that 3 alpha-THDOC may function as endogenous modulator of GABAA-mediated inhibition in various physiopathological conditions.

[PubMed - indexed for MEDLINE]