TPMPA is a GABAA-Ρ1 (Ρ1 GABAC) receptor antagonist that is 8-fold selective for GABAA-Ρ1 over GABAA-Ρ2 (Ρ2 GABAC) receptors expressed in X. laevis oocytes (Kbs = 2 and 16 μM, respectively).1 In rat hippocampal slices, TPMPA blocks the inhibitory effect of the GABAB agonist 3-APMPA on excitatory postsynaptic currents (EPSCs) with an EC50 value of 490 μM.2 TPMPA (100 μM) increases light sensitivity and the maximal response of rat retinal ganglion cells without altering their dynamic range.3 In sleeping rats, TPMPA (50 μg, i.c.v.) increases waking from 45 to 62% compared to a vehicle control and decreases slow-wave and paradoxical sleep (REM) by 11 and 5.4%, respectively.4
1.Chebib, M., Mewett, K.N., and Johnston, G.A.GABAC receptor antagonists differentiate between human Ρ1 and Ρ2 receptors expressed in Xenopus oocytesEur. J. Pharmacol.357(2-3)227-234(1998) 2.Ragozzino, D., Woodward, R.M., Murata, Y., et al.Design and in vitro pharmacology of a selective γ-aminobutyric acidC receptor antagonistMol. Pharmacol.50(4)1024-1030(1996) 3.Jensen, R.J.Blocking GABAC receptors increases light responsiveness of retinal ganglion cells in a rat model of retinitis pigmentosaExp. Eye Res.10521-26(2012) 4.Arnaud, C., Gauthier, P., and Gottesmann, C.Study of a GABAC receptor antagonist on sleep-waking behavior in ratsPsychopharmacology (Berl)154(4)415-419(2001)