3α-hydroxy-3β-trifluoromethyl-5α-pregnan-20-one (Co 2-1970): A partial agonist at the neuroactive steroid site of the γ-Aminobutyric acidA receptor

Jon E. Hawkinson, John A. Drewe, Catherine L. Kimbrough, Jie Sheng Chen, Derk J. Hogenkamp, Nancy C. Lan, Kelvin W. Gee, Ke-Zhong Shen, Edward R. Whittemore, Richard M. Woodward

Research output: Contribution to journalArticle

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Abstract

Neuroactive steroids bind to a unique site on the γ-aminobutyric acidA (GABAA) receptor complex and allosterically modulate the binding of convulsant ([35S]t-butylbicyclophosphorothionate, [35S]TBPS), GABA ([3H]muscimol), and benzodiazepine ([3H]flunitrazepam) site ligands. In rat cortical membranes, 3α-hydroxy-5α-pregnan-20-one (3α,5α-P) is a full agonist at the steroid site, inhibiting 96% of specific [35S]TBPS binding and enhancing [3H]flunitrazepam and [3H]muscimol binding 95% and 69% above control levels, respectively. In contrast, the synthetic steroid 3α-hydroxy-3β-trifluoromethyl-5α-pregnan-20-one (Co 2-1970) has limited efficacy for modulating the binding of [35S]TBPS (44% inhibition), [3H]flunitrazepam (41% enhancement), and [3H]muscimol (A receptors stably expressed in human embryonic kidney 293 cells. Co 2-1970 inhibited [35S]TBPS binding with limited efficacy (39-65% inhibition) in the five receptor combinations examined and, at 10 μM, reduced the apparent potency of 3α,5α-P 57-fold for inhibiting [35S]TBPS binding to α1β1γ2L receptors. To verify these findings functionally, the effects of 3α,5α-P and Co 2-1970 were examined electrophysiologically in Xenopus oocytes expressing α1β1γ2L receptors. Co 2-1970 showed limited efficacy potentiation of GABA-evoked chloride currents relative to 3α,5α-P (28% and 86% of the GABA maximum current, respectively). Moreover, Co 2-1970 produced a concentration-dependent antagonism of the 3α,5α-P-induced potentiation that was associated with a reduction in the apparent affinity of 3α,5α-P (11-fold at 10 μM Co 2-1970). Taken together, these data indicate that Co 2-1970 is a partial agonist at the neuroactive steroid site associated with GABAA receptors.

Original languageEnglish (US)
Pages (from-to)897-906
Number of pages10
JournalMolecular Pharmacology
Volume49
Issue number5
StatePublished - May 1996

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Steroids
Flunitrazepam
GABA-A Receptors
gamma-Aminobutyric Acid
Muscimol
Convulsants
Xenopus
Co 2-1970
pregnane-20-one
Benzodiazepines
Oocytes
Chlorides
tert-butylbicyclophosphorothionate
Ligands
Kidney
Membranes

ASJC Scopus subject areas

  • Pharmacology

Cite this

Hawkinson, J. E., Drewe, J. A., Kimbrough, C. L., Chen, J. S., Hogenkamp, D. J., Lan, N. C., ... Woodward, R. M. (1996). 3α-hydroxy-3β-trifluoromethyl-5α-pregnan-20-one (Co 2-1970): A partial agonist at the neuroactive steroid site of the γ-Aminobutyric acidA receptor. Molecular Pharmacology, 49(5), 897-906.

3α-hydroxy-3β-trifluoromethyl-5α-pregnan-20-one (Co 2-1970) : A partial agonist at the neuroactive steroid site of the γ-Aminobutyric acidA receptor. / Hawkinson, Jon E.; Drewe, John A.; Kimbrough, Catherine L.; Chen, Jie Sheng; Hogenkamp, Derk J.; Lan, Nancy C.; Gee, Kelvin W.; Shen, Ke-Zhong; Whittemore, Edward R.; Woodward, Richard M.

In: Molecular Pharmacology, Vol. 49, No. 5, 05.1996, p. 897-906.

Research output: Contribution to journalArticle

Hawkinson, JE, Drewe, JA, Kimbrough, CL, Chen, JS, Hogenkamp, DJ, Lan, NC, Gee, KW, Shen, K-Z, Whittemore, ER & Woodward, RM 1996, '3α-hydroxy-3β-trifluoromethyl-5α-pregnan-20-one (Co 2-1970): A partial agonist at the neuroactive steroid site of the γ-Aminobutyric acidA receptor', Molecular Pharmacology, vol. 49, no. 5, pp. 897-906.
Hawkinson, Jon E. ; Drewe, John A. ; Kimbrough, Catherine L. ; Chen, Jie Sheng ; Hogenkamp, Derk J. ; Lan, Nancy C. ; Gee, Kelvin W. ; Shen, Ke-Zhong ; Whittemore, Edward R. ; Woodward, Richard M. / 3α-hydroxy-3β-trifluoromethyl-5α-pregnan-20-one (Co 2-1970) : A partial agonist at the neuroactive steroid site of the γ-Aminobutyric acidA receptor. In: Molecular Pharmacology. 1996 ; Vol. 49, No. 5. pp. 897-906.
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