Table 3.
Summary of statistically calculated VTA and LC neuronal responses for ED10 BL compared with ED1 BL
| ED10 BL/ED1 BL |
||||||||
|---|---|---|---|---|---|---|---|---|
| MPD Dose, mg/kg | VTA |
LC |
||||||
| n | ↑ | ↓ | ≠ | n | ↑ | ↓ | ≠ | |
| Units recorded from all animals | ||||||||
| Saline | 36 | 0 (0%) | 1 (2.8%) | 35 (97.2%) | 56 | 3 (5.4%) | 3 (5.4%) | 50 (89.2%) |
| 0.6 | 115 | 28 (24.3%) | 30 (26%) | 57 (49.6%) | 109 | 21 (19.3%) | 34 (31.2%) | 54 (49.5%) |
| 2.5 | 135 | 55 (40.8%) | 30 (22.2%) | 50 (37%) | 132 | 59 (44.7%) | 40 (30.3%) | 33 (25%) |
| 10 | 117 | 74 (63.3%) | 34 (29%) | 9 (7.7%) | 112 | 84 (75%) | 14 (12.5%) | 14 (12.5%) |
| Units recorded from sensitized animals | ||||||||
| 0.6 | 38 | 10 (26.3%) | 4 (10.5%) | 24 (63.2%) | 47 | 9 (19.1%) | 13 (27.7%) | 25 (53.2%) |
| 2.5 | 80 | 46 (57.5%) | 18 (22.5%) | 16 (20%) | 61 | 36 (59%) | 12 (19.7%) | 13 (21.3%) |
| 10 | 92 | 61 (66.3%) | 24 (26.1%) | 7 (7.6%) | 81 | 63 (77.8%) | 9 (11.1%) | 9 (11.1%) |
| Units recorded from tolerant animals | ||||||||
| 0.6 | 77 | 18 (23.4%) | 26 (33.8%) | 33 (42.8%) | 62 | 12 (19.4) | 21 (33.9%) | 29 (46.8%) |
| 2.5 | 55 | 9 (16.4%) | 12 (21.8%) | 34 (61.8%) | 71 | 23 (32.4%) | 28 (39.4%) | 20 (28.2%) |
| 10 | 25 | 13 (52%) | 10 (40%) | 2 (8%) | 31 | 21 (67.8%) | 5 (16.1%) | 5 (16.1%) |
Values are statistically calculated VTA and LC neuronal responses following saline injection on ED10 after daily MPD injections (0.6, 2.5, and 10 mg/kg) for 6 days and 3 washout days compared with the initial neuronal responses to saline on ED1 (ED10 BL 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 saline exposure on ED10 compared with ED1. Down-arrow columns include the units that exhibited significant (P < 0.05) decreases in neuronal unit activity after saline exposure on ED10 compared with ED1. Unequal-to columns include the units that exhibited no significant change after saline exposure on ED10 compared with ED1. Data are shown for VTA and LC units recorded from all animals, for units from animals that exhibited behavioral sensitization after chronic MPD exposure, and for units from animals that exhibited behavioral tolerance after chronic MPD exposure.