Comparison of physiological properties and phasic cholinergic responsiveness in hippocampal pyramidal neurons from different genetic backgrounds
| Genotype | Layer | n | RMP, mV | RN, MΩ | Sag, % | SK Response, mV, | Spike Acceleration, % |
|---|---|---|---|---|---|---|---|
| Wild-type (WT) | CA1 | 12 | −79 ± 1 | 114 ± 10 | 18 ± 1 | −2.8 ± 0.1 | +131 ± 18 |
| WT in atropine | CA1 | 4 | −79 ± 1 | 110 ± 13 | 21 ± 2 | −0.1 ± 0.1* | −6 ± 1* |
| M3/M5 DKO | CA1 | 12 | −79 ± 1 | 134 ± 12 | 18 ± 1 | −3.5 ± 0.4 | +208 ± 21* |
| M1 KO | CA1 | 12 | −79 ± 1 | 111 ± 7 | 20 ± 1 | +0.2 ± 0.0* | +20 ± 6* |
| M1/M3 DKO | CA1 | 7 | −75 ± 1* | 113 ± 9 | 22 ± 2 | 0.0 ± 0.0* | +5 ± 4* |
| Wild-type (WT) | CA3 | 12 | −86 ± 1† | 128 ± 17 | 4 ± 1† | +0.4 ± 0.4† | +175 ± 41 |
| WT in atropine | CA3 | 5 | −84 ± 2 | 217 ± 10* | 3 ± 1 | +0.3 ± 0.1 | +3 ± 3* |
| M3/M5 DKO | CA3 | 10 | −87 ± 1 | 140 ± 12 | 3 ± 1 | +0.8 ± 0.2 | +148 ± 32 |
| M1 KO | CA3 | 12 | −86 ± 1 | 259 ± 33* | 5 ± 1 | +0.1 ± 0.1 | +27 ± 8* |
| M1/M3 DKO | CA3 | 12 | −81 ± 1* | 294 ± 47* | 5 ± 1 | −0.1 ± 0.2 | +4 ± 4* |
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Values are means ± SE. Comparison of physiological characteristics and phasic cholinergic responses at resting membrane potentials (“SK response”) or during current-evoked action potential firing (“spike acceleration”). Numbers in boldface type indicate the presence of significant (P < 0.05) acetylcholine-induced “SK” responses and/or spike acceleration (paired t-test). Asterisks indicate P < 0.01 when values were compared with those in wild-type cells in the same hippocampal region (one-way ANOVA with post-tests). Daggers indicate P < 0.01 when values in wild-type CA3 neurons are compared with those in wild-type CA1 neurons (unpaired t-test). M1 KO, genetic knockout for M1 receptor; DKO, double-knockout for indicated mAChR subtypes; RMP, resting membrane potential; RN, input resistance; sag, percentage voltage rectification at steady state relative to peak potential reached during negative current injections.