Table 1.
Repeated in vivo cocaine altered membrane properties of NAc shell and core neurons
| Early abstinence (1–3 d) |
Late abstinence (10–14 d) |
|||||||
|---|---|---|---|---|---|---|---|---|
| Shell |
Core |
Shell |
Core |
|||||
| SAL | COC | SAL | COC | SAL | COC | SAL | COC | |
| Passive membrane properties | ||||||||
| RMP (mV) | −80.5 ± 0.4 | −80.7 ± 0.5 | −78.6 ± 0.50 | −79.0 ± 0.5 | −78.8 ± 0.5 | −78.5 ± 0.4 | −79.4 ± 0.8 | −78.3 ± 0.8 |
| Ri (MΩ) | 180.2 ± 10.1 | 174.1 ± 8.5 | 141.6 ± 6.8 | 135.6 ± 8.8 | 174.8 ± 8.4 | 188.0 ± 7.1 | 151.9 ± 11.6 | 165.4 ± 8.6 |
| Active membrane properties | ||||||||
| Rheobase (current togenerate a spike, pA) | 124 ± 5.8 | 139.4 ± 7.6 | 137.5 ± 10.0 | 116.2 ± 4.4 | 130.0 ± 9.7 | 135.5 ± 7.8 | 132.7 ± 11.8 | 134 ± 8.8 |
| Spike threshold (mV) | −35.3 ± 0.8 | −33.7 ± 0.8 | −33.2 ± 0.5 | −35.2 ± 0.6* | −35.2 ± 0.8 | −32.6 ± 0.6** | −34.9 ± 0.7 | −34.4 ± 0.9 |
| Spike amplitude (mV) | 69.4 ± 2.2 | 69.7 ± 1.5 | 77.1 ± 1.0 | 83.8 ± 1.8** | 76.8 ± 1.6 | 72.0 ± 1.4* | 78.3 ± 1.6 | 79.6 ± 2.2 |
| Spike duration (ms) | 2.60 ± 0.06 | 2.69 ± 0.06 | 2.57 ± 0.06 | 2.45 ± 0.04 | 2.39 ± 0.03 | 2.57 ± 0.04*** | 2.56 ± 0.06 | 2.62 ± 0.06 |
| AHP amplitude (mV) | 15.2 ± 0.6 | 14.2 ± 0.4 | 15.3 ± 0.4 | 15.6 ± 0.4 | 15.0 ± 0.2 | 15.8 ± 0.4 | 16.7 ± 0.6 | 15.2 ± 0.4 |
| Spike rise (10%–90%, ms) | 0.76 ± 0.04 | 0.82 ± 0.04 | 0.72 ± 0.04 | 0.60 ± 0.02* | 0.62 ± 0.03 | 0.74 ± 0.03*** | 0.69 ± 0.04 | 0.69 ± 0.04 |
Values represent the mean± SEM (*p < 0.05; **p < 0.01; ***p < 0.001; with two-tailed Student's t test used to compare with their respective saline control group). The RMP and the spike threshold were not adjusted for the liquid junction potential (∼8 mV). Spike characteristics were obtained from the first spike evoked by the minimal depolarizing current pulse in every NAc neuron recorded; the spike threshold was obtained by using the maximum of the third differential during the rising phase. The other characteristics were measured as follows: spike amplitude, difference between spike threshold and peak; spike duration, measured at 20 pA above threshold; AHP amplitude, difference between spike threshold and maximum hyperpolarization after the spike; spike rise, time difference between 10 and 90% of the spike peak.