Table 2.
Summary of statistically calculated VTA and LC neuronal responses for ED1 MPD compared with ED1 BL
| ED1 MPD/ED1 BL (Acute) |
||||||||
|---|---|---|---|---|---|---|---|---|
| MPD Dose, mg/kg | VTA |
LC |
||||||
| n | ↑ | ↓ | ≠ | n | ↑ | ↓ | ≠ | |
| Units recorded from all animals | ||||||||
| Saline | 36 | 0 (0%) | 2 (5.6%) | 34 (94.4%) | 56 | 1 (1.8%) | 3 (5.3%) | 52 (92.9%) |
| 0.6 | 115 | 26 (22.6%) | 20 (17.4%) | 69 (60%) | 109 | 21 (19.3%) | 37 (33.9%) | 51 (46.8%) |
| 2.5 | 135 | 43 (31.9%) | 30 (22.2%) | 62 (45.9%) | 132 | 52 (39.4%) | 29 (22%) | 51 (38.6%) |
| 10 | 117 | 86 (73.5%) | 8 (6.8%) | 23 (19.7%) | 112 | 89 (79.5%) | 13 (11.6%) | 10 (8.9%) |
| Units recorded from sensitized animals | ||||||||
| 0.6 | 38 | 11 (28.9%) | 2 (5.3%) | 25 (65.8%) | 47 | 9 (19.1%) | 5 (10.7%) | 33 (70.2%) |
| 2.5 | 80 | 36 (45%) | 17 (21.3%) | 27 (33.7%) | 61 | 28 (45.9%) | 16 (26.2%) | 17 (27.9%) |
| 10 | 92 | 73 (79.4%) | 4 (4.3%) | 15 (16.3%) | 81 | 63 (77.8%) | 11 (13.6%) | 7 (8.6%) |
| Units recorded from tolerant animals | ||||||||
| 0.6 | 77 | 15 (19.5%) | 18 (23.4%) | 44 (57.1%) | 62 | 12 (19.4%) | 32 (51.6%) | 18 (29%) |
| 2.5 | 55 | 7 (12.7%) | 13 (23.7%) | 35 (63.6%) | 71 | 24 (33.8%) | 13 (18.3%) | 34 (47.9%) |
| 10 | 25 | 13 (52%) | 4 (16%) | 8 (32%) | 31 | 26 (83.9%) | 2 (6.4%) | 3 (9.7%) |
Values are statistically calculated VTA and LC neuronal responses on ED1 following acute 0.6, 2.5, and 10 mg/kg MPD exposure compared with the initial neuronal responses to saline on ED1 (ED1 MPD/ED1 BL); n = no. of units in each group. Up-arrow columns include the number and percentage of VTA and LC units that exhibited significant (P < 0.05) increases in neuronal unit activity after acute MPD exposure. Down-arrow columns include the number and percentage of units that exhibited significant (P < 0.05) decreases in neuronal unit activity after acute MPD exposure. Unequal-to columns include the number and percentage of units that exhibited no significant change after acute MPD exposure. Data are shown for VTA and LC units recorded from all animals, for units recorded from animals that exhibited behavioral sensitization after chronic MPD exposure, and for units recorded from animals that exhibited behavioral tolerance after chronic MPD exposure.