Figure 4.

THP inhibits tonic GABAergic current recorded from the hippocampal slice at puberty. (a) Outward current recorded from CA1 hippocampal pyramidal cells in the slice by whole-cell patch clamp (ECl = −70 mV, −50 holding potential, pipet solution, K-gluconate; bath, 200 nM gabazine to block synaptic current and 2 mM kynurenic acid to block excitatory current). Pre-pubertal, Pre-pub; pubertal, Pub. Inset, THP effects on the inward tonic current at puberty. (b) THP-evoked change in outward and inward tonic current, Averaged data. THP withdrawal, THP Wd. (mean ± SEM, n = 8 – 12 cells for each group). (c) Tight-seal cell-attached current-clamp recording³¹ of the holding potential during dendritic application of the GABA agonist gaboxadol (5 μM) to the stratum radiatum. (Representative of cells from 5 pubertal mice). (d) Perforated patch voltage-clamp recordings from the soma of a CA1 pyramidal cell of the post-synaptic response to bath applied THP. Inset, the change in access resistance determined from the current response to a 10 mV step before and after perforation. (Bath, 1 μM TTX and 1 μM GABA; also 200 nM gabazine and L-65,708, to block synaptic current and α5-GABA_A receptors, respectively; 10 μM CGP 55845, 5 mM TEA and 50 μM kynurenic acid to block GABA_B receptors, K+ channels and excitatory amino acid receptors, respectively.) (e) Averaged data, n = 5 cells for each group. *P < 0.01 versus pre-THP, **P < 0.001 versus Pre-pub.