It was demonstrated that the anesthetic steroid 3 alpha-hydroxy-5 alpha-pregnan-20-one mediates the loss of the righting response (LRR) in mice, in contrast to its metabolites, which are formed in vivo. To reach these conclusions, it was necessary to quantitate levels for 3 alpha-hydroxy-5 alpha-pregnan-20-one and its metabolites at the time of LRR. Methods were used that blocked the production of essentially all of the metabolites. Chromatography of brain extracts by thin-layer chromatography and high-performance liquid chromatography after anesthesia with 3 alpha-hydroxy-5 alpha-[3H]pregnan-20-one showed only a single peak that corresponded to 3 alpha-hydroxy-5 alpha-[3H]pregnan-20-one.
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http://dx.doi.org/10.1016/0039-128x(93)90046-p | DOI Listing |
Behav Neurosci
April 2006
Department of Psychology, University at Albany, State University of New York, Albany, NY 12222, USA.
Duration and intensity of lordosis is mediated by actions of the progesterone (P) metabolite, 3 alpha-hydroxy-5 alpha-pregnan-20-one (3 alpha,5 alpha-THP) at GABA-sub(A) receptors in the midbrain ventral tegmental area. Because rats selectively bred for infantile vocalizations may differ in endogenous 3 alpha,5 alpha-THP secretion, their sexual behavior, midbrain, and plasma 3 alpha,5 alpha-THP levels as adult rats in behavioral estrus was examined. Rats bred for high rates of infantile vocalizations had shorter latencies and intervals between intromissions and ejaculation, higher lordosis quotients and ratings, more pacing of their sexual contacts, and had higher P and 3 alpha,5 alpha-THP levels in plasma and midbrain than did rats bred for low rats of infantile vocalizations.
View Article and Find Full Text PDFBehav Brain Res
April 2005
Department of Psychology, Williams College, 18 Hoxsey Street, Williamstown, MA 01267, USA.
Allopregnanolone, 3 alpha-hydroxy-5 alpha-pregnan-20-one (3 alpha,5 alpha-THP), a progesterone metabolite, is an endogenous neurosteroid mediating affective behaviors via its positive modulation of GABA(A) receptors. In order to better understand the role of this neurosteroid in individual differences in affective behavior, we used an animal model based on selective breeding for an infantile affective trait, ultrasonic vocalizations (USV). Adult male and female (in either proestrus or diestrus) rats that had been bred for low (low line) or high (high line) rates of USV after maternal separation were tested in a series of affective behavioral tests: open field, emergence, social interaction, defensive freezing, and the Porsolt forced swim task.
View Article and Find Full Text PDFPsychopharmacology (Berl)
May 2005
Department of Psychiatry, University of North Carolina at Chapel Hill, CB#7160, Chapel Hill, NC 27599-7178, USA.
Rationale: The neuroactive steroid, 3alpha-hydroxy-5alpha-pregane-20-one (allopregnanolone) is a potent modulator of GABA(A) receptor function. Moreover, pharmacologically relevant concentrations of allopregnanolone are found in brain during physiological conditions (stress, pregnancy and menstrual cycle) and pharmacological challenge (ethanol, fluoxetine, olanzapine). Enhanced levels of neurosteroids are thought to contribute to the therapeutic effects of fluoxetine and various effects of ethanol via GABA(A) receptors.
View Article and Find Full Text PDFAlcohol Clin Exp Res
August 2004
Departments of Psychiatry and Pharmacology, University of North Carolina, Chapel Hill, Chapel Hill, North Carolina 27599, USA.
Background: Ethanol administration elevates the levels of GABAergic neuroactive steroids in brain and contributes to some of its behavioral actions. In the present study, we investigated whether such elevation of GABAergic neuroactive steroids contributes to the motor incoordinating effects of ethanol.
Methods: Sprague-Dawley rats were administered ethanol (2 g/kg intraperitoneally) or saline, and the level of 3alpha-hydroxy-5alpha-pregnan-20-one (3alpha,5alpha-THP) was measured across time in cerebral cortex and in various brain regions at the peak time by radioimmunoassay.
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