Abstract
Novel neuroactive steroids were evaluated for their effects on operant responding, rotorod motor performance, and electroencephalogram recording in rats. Co 134444, Co 177843, and Co 127501 were compared with the prototypical γ-aminobutyric acidA-positive allosteric modulators triazolam, zolpidem, pentobarbital, pregnanolone, and CCD 3693. Each of the compounds produced a dose-related decrease in response rates under a variable-interval 2-min schedule of positive reinforcement in an operant paradigm. In addition, all compounds produced a dose-related increase in ataxia and significant increases in nonrapid eye movement sleep in this experiment or have been previously reported to do so. Co 134444, Co 177843, and Co 127501 increased nonrapid eye movement sleep at doses that had no effect on rapid eye movement sleep. All of the compounds were more potent at decreasing operant responding than they were at increasing ataxia. Furthermore, the potency of compounds to produce response-rate suppression in an operant paradigm appeared to be a better predictor of soporific potency than did potency in the rotorod assay. The screening for sedative-hypnotic activity resulted in the identification of the novel orally active neuroactive steroids Co 134444, Co 177843, and Co 127501.
Footnotes
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Send reprint requests to: Kimberly E. Vanover, Ph.D., CoCensys, Inc., 213 Technology Dr., Irvine, CA 92618. E-mail:kvanover{at}cocensys.com
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↵1 Current address: Sleep Research Center, Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Palo Alto, CA 94304.
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↵2 Current address: Dept. of Pharmacology, College of Medicine, University of California, Irvine, CA 92697-4625.
- Abbreviations:
- NREM
- nonrapid eye movement
- REM
- rapid eye movement
- CT
- circadian time
- EEG
- electroencephalogram
- GABA
- γ-aminobutyric acid
- MSD
- minimum significant dose
- SD50
- suppressive dose
- TD50
- toxic dose
- VI
- variable interval
- Received July 13, 1999.
- Accepted August 31, 1999.
- The American Society for Pharmacology and Experimental Therapeutics
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