Fig. 4. GABA (10 nmol l^–1–10 mmol l^–1) modulation of ³[H]-TBOB (t-butylbicycloorthobenzoate) binding in the CIC of young and aged F344 rats. The dose–response curve is shifted to the left. These data have functional implications since the aged GABA_A receptor must be more sensitive to GABA than the young GABA_A receptor for the channel to be open allowing TBOB to bind to the picrotoxin binding site. (Modified from Milbrandt et al., 1996.)