Comparison of Co 2-6749 and allopregnanolone inhibition of [35S]TBPS binding in rat brain membranes and human recombinant GABAA receptors expressed in HEK293 cells
| Receptor | GABA | Co 2-6749 | Allopregnanolone | ||||
|---|---|---|---|---|---|---|---|
| IC50 | Imax | Hill Slope | IC50 | Imax | Hill Slope | ||
| μM | nM | % | nM | % | |||
| Rat brain | 5 | 230 ± 20 | 97 ± 2 | 1.16 ± 0.04 | 511-a | 95 | 1.0 |
| α1β2γ2L | 5 | 200 ± 40 | 105 ± 4 | 1.4 ± 0.3 | 17.51-b | 103 | 1.0 |
| α2β2γ2L | 5 | 200 ± 50 | 110 ± 20 | 1.4 ± 0.3 | 411-b | 105 | 1.0 |
| α3β2γ2L | 10 | 96 ± 9 | 96 ± 4 | 1.35 ± 0.05 | 201-b | 109 | 0.75 |
| α4β3γ2L | 10 | 2300 ± 300 | 114 ± 3 | 1.4 ± 0.3 | 1900 ± 500 | 78 ± 6 | 1.4 ± 0.3 |
| α5β2γ2L | 1 | 210 ± 10 | 104 ± 7 | 1.9 ± 0.4 | 211-b | 112 | 1.0 |
| α6β3γ2L | 5 | 2000 ± 200 | 101 ± 5 | 1.2 ± 0.1 | 1100 ± 100 | 74 ± 7 | 1.081-c |
IC50, Imax, and Hill slope values for inhibition of 2 nM [35S]TBPS binding to rat brain cortical membranes and human recombinant GABAA receptor subunit combinations expressed in HEK293 cells. GABA concentration in the incubation was either the approximate IC50 for inhibition of TBPS binding (rat brain) or the concentration producing the peak TBPS binding (recombinant receptors). Values are means ± S.E.M. of at least three independent experiments.