Gaboxadol (4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol, THIP), a GABA_A receptor δ-subunit specific agonist, when present at low (μM) concentrations, preferentially binds and activates extrasynaptic (non-γ2, δ-subunit-containing) GABA_ARs (Storustovu and Ebert, 2006; Richardson et al., 2011, 2013).

In this prototype saturation binding experiment, a series of concentrations of [3H]gaboxadol (5, 10, 25, 50, 75, 100, 250 and 400 nM) will be used. GABA at 200 μM will be added into binding mixtures as a cold displacer for [³H]gaboxadol. Slide mailers are used and each requires 7 ml binding mixture. Pre-, post-washing and binding buffer is 50 mM Tris-Citrate (pH 7.1). The detailed procedure is outlined below.