Figure 8.

BQCA has no effect and does not potentiate the CCh effect on sEPSCs in M₁ receptor KO mice. a, Sample traces from individual cells in slices made from wild-type (left panels) and M₁ receptor KO mice (right panels) showing the robust effects of 30 μm CCh on both sEPSC amplitude in frequency compared to the milder effect in the M₁ receptor KO slice (top panels). b, Bottom panels illustrate the lack of effect of 10 μm BQCA in both the WT and M₁ receptor KO and contrast the increase in amplitude and frequency with the addition of BQCA and 10 μm CCh to the lack of effect in the M₁ receptor KO. c, Cumulative probability plots of the interevent intervals from the two cells shown in bottom panels above. d, Averaged amplitude and frequency of sEPSCs measured in wild-type (black bars: 3 μm CCh, n = 3; 30 μm CCh, n = 5; 10 μm BQCA and 10 μm BQCA + 3 μm CCh, n = 5) and M₁ receptor KO slices (white bars: 3 μm CCh, n = 4; 30 μm CCh, n = 4; 10 μm BQCA and 10 μm BQCA + 3 μm CCh, n = 5). In wild-type slices, 3 μm CCh had no significant effect on amplitude or frequency (102.6 ± 11.7%, p = 0.6381 and 83.2 ± 47.1% of control, p = 0.4423, respectively) whereas 30 μm CCh increased both (143.1 ± 22.0%, p = 0.0306 for amplitude, 398.3 ± 56.2%, p = 0.0342 for frequency). BQCA had no effect on amplitude or frequency but potentiated the response to 3 μm CCh (Amplitudes: 10 μm BQCA, 97.3 ± 11.3%, p = 0.7642 compared to control; 10 μm BQCA/3 μm CCh, 137.2 ± 16.7%, p = 0.0052 compared to control. Frequencies: 10 μm BQCA, 99.8 ± 11.3%, p = 0.7261 compared to control; 10 μm BQCA/3 μm CCh, 500.5 ± 212.3%, p = 0.0209 compared to control. In M₁ receptor KO slices, 3 μm CCh decreased amplitude but had no significant effect on frequency (79.4 ± 14.9%, p = 0.0490 and 186.3 ± 187.4% of control, p = 0.7656, respectively). Thirty micromolars CCh also significantly decreased amplitude and increased frequency although the effect on frequency was less dramatic than that seen in WT controls (80.7 ± 5.2%, p = 0.0092 for amplitude, 271.7 ± 310.4%, p = 0.6010 for frequency). While the difference between the 30 μm CCh effect on amplitude was significant between genotypes (p = 0.0229), the effect on frequency was not (p = 0.4756). BQCA had no effect alone in KO slices (amplitude, 96.9 ± 10.6%, p = 0.4925; frequency, 101.3 ± 26.1%, p = 0.7286) and there was no difference in this lack of effect between genotypes (amplitude, p = 0.9596; frequency, p = 0.9133). When applied with 3 μm CCh, BQCA had no significant effect on amplitude or frequency (amplitude, 84.5 ± 25.3%, p = 0.3383; frequency, 86.6 ± 17.3%, p = 0.1388 compared to KO control), and both effects were significantly different those in WT slices (p = 0.0046 for amplitude, p = 0.0025 for frequency). All changes in amplitude and frequency were compared to baseline control and are represented as mean ± SEM. Asterisks indicate significant differences from control or between drug conditions (*p < 0.05; **p < 0.01; paired or unpaired t test).