The Effects of Neurosteroids on Rat Behavior and 3 H-Muscimol Binding in the Brain

The Effects of Neurosteroids on Rat Behavior and 3 H-Muscimol Binding in the Brain The effects of ICV administration of metabolites of progesterone and deoxycorticosterone (i.e., neurosteroids: AP (3α-hydroxy-5α-pregnan-20-one, allopregnanolone), 5α-THDOC (3α-21-dihydroxy-5α-pregnan-20-one, 5α-tetrahydrodeoxycorticosterone), 5β-THDOC (3α-21-dihydroxy-5β-pregnan-20-one, 5β-tetrahydrodeoxycorticosterone), and PS (3β-hydroxy-5-pregnen-20-one sulfate, pregnenolone sulfate) were studied in the open-field test of neophobia and Vogel's test of conflict behavior in rats. The influence of in vivo administered 5β-THDOC, a positive allosteric modulator of the GABA A receptor complex, on 3 H-muscimol binding in different brain structures, was also studied with the help of quantitative autoradiography. The presented data did not reveal any anxioselective effects for a range of centrally active neurosteroids, in the ethologically orientated and conflict models of anxiety, after intracerebral drug administration. Their central effects appeared secondary to changes in rat gross behavior. It is possible that high local concentration of neurosteroids after ICV injection and production of a narrower range of behavioral effects than that of benzodiazepines, precluded manifestation of the antianxiety effects of AP, 5α-THDOC and 5β-THDOC. Autoradiography did not reveal any significant changes in the specific binding of 3 H-muscimol in brain structures after in vivo ICV administration of 5β-THDOC at the behaviorally active dose. Thus, the possibility that neuroactive neurosteroids may provide a novel potential site for therapeutic interventions in anxiety disorders is not supported. The part of the experiment with 5β-THDOC is interpreted as contributing to other results, suggesting the existence of a new category of neurosteroids acting as partial agonists of the GABA A receptor. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Pharmacology Biochemistry and Behavior Elsevier

The Effects of Neurosteroids on Rat Behavior and 3 H-Muscimol Binding in the Brain

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Publisher
Elsevier
Copyright
Copyright © 1999 Elsevier Science Inc.
ISSN
0091-3057
eISSN
1873-5177
DOI
10.1016/S0091-3057(99)00030-1
Publisher site
See Article on Publisher Site

Abstract

The effects of ICV administration of metabolites of progesterone and deoxycorticosterone (i.e., neurosteroids: AP (3α-hydroxy-5α-pregnan-20-one, allopregnanolone), 5α-THDOC (3α-21-dihydroxy-5α-pregnan-20-one, 5α-tetrahydrodeoxycorticosterone), 5β-THDOC (3α-21-dihydroxy-5β-pregnan-20-one, 5β-tetrahydrodeoxycorticosterone), and PS (3β-hydroxy-5-pregnen-20-one sulfate, pregnenolone sulfate) were studied in the open-field test of neophobia and Vogel's test of conflict behavior in rats. The influence of in vivo administered 5β-THDOC, a positive allosteric modulator of the GABA A receptor complex, on 3 H-muscimol binding in different brain structures, was also studied with the help of quantitative autoradiography. The presented data did not reveal any anxioselective effects for a range of centrally active neurosteroids, in the ethologically orientated and conflict models of anxiety, after intracerebral drug administration. Their central effects appeared secondary to changes in rat gross behavior. It is possible that high local concentration of neurosteroids after ICV injection and production of a narrower range of behavioral effects than that of benzodiazepines, precluded manifestation of the antianxiety effects of AP, 5α-THDOC and 5β-THDOC. Autoradiography did not reveal any significant changes in the specific binding of 3 H-muscimol in brain structures after in vivo ICV administration of 5β-THDOC at the behaviorally active dose. Thus, the possibility that neuroactive neurosteroids may provide a novel potential site for therapeutic interventions in anxiety disorders is not supported. The part of the experiment with 5β-THDOC is interpreted as contributing to other results, suggesting the existence of a new category of neurosteroids acting as partial agonists of the GABA A receptor.

Journal

Pharmacology Biochemistry and BehaviorElsevier

Published: Aug 1, 1999

References

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