| Methadone Exposure (mg/kg) | Experimental Group | |||
| Control | 0.485 | 1.00 | 1.75 | |
| Number of Neurons | 103.4 ± 12.9 | 81.3 ± 12.0 | 14.8 ± 6.8 | 10.6 ± 2.8 |
| Number of Glial Cells | 3.8 ± 0.0 | 3.8 ± 1.8 | 4.9 ± 1.3 | 7.0 ± 2.3 |