The pharmacologic characteristics of glycine receptors (GlyRs) in the lateral superior olive (LSO) of circling mice, animal model for inherited deafness, were investigated using a GlyR alpha(1) subunit-specific receptor blocker (cyanotriphenylborate [CTB]). There was a statistically significant age-dependent increase in the antagonistic effect of CTB in heterozygous (+/cir) mice. In postnatal (P)0-P3 heterozygous (+/cir) mice, glycine currents evoked by glycine puffs were reduced to 20.4 +/- 2.6, 37.1 +/- 3.1, and 63.9 +/- 2.5% at 0.1, 1, and 10 mu M CTB (n = 13) compared to controls, while the glycine currents were reduced to 22.3 +/- 3.5, 52.9 +/- 4.1, and 78.3 +/- 3.5% at 0.1, 1, and 10 mu M CTB (n = 7) in P8-P12 heterozygous (+/cir) mice. In contrast, the antagonistic effect of CTB was not strong and even less than that of younger animals in older homozygous (cir/cir) mice. In P0-P3 homozygous (cir/cir) mice, the extent of inhibition was 20.2 +/- 3.7, 37.8 +/- 4.3, and 66.8 +/- 4.2% at 0.1, 1, and 10 mu M CTB (n = 6) compared to controls, while the extent of inhibition was 18.7 +/- 2.4, 28.1 +/- 3.9, and 39.1 +/- 8.2% (n = 6) in P8-P12 homozygous (cir/cir) mice. The age-dependent decrease in the antagonistic effect of CTB indicates the abnormal development of the alpha(1) subunit-containing GlyRs in homozygous (cir/cir) mice. (C) 2011 Elsevier Inc. All rights reserved.