Table 4.
Quantitative autoradiography of μ receptor binding in wild-type (+/+) and homozygous (−/−) A2A mutant mice
| Region | Segments from rat atlas | [3H]DAMGO-specific binding (fmol/mg) | % Change in binding | |
|---|---|---|---|---|
| Wild-type (+/+) | Homozygous (−/−) | (−/−) | ||
| Cervical | C1 and C6 | |||
| Superficial layers (laminas I and II) | 96.2 ± 4.1 | 95.9 ± 3.0 | −0.3 | |
| Laminas III–VI | 31.2 ± 2.2 | 30.2 ± 2.2 | −3.2 | |
| Lamina X | 27.2 ± 1.7 | 28.9 ± 2.4 | 6.3 | |
| Ventral horn (laminas VII–IX) | 18.9 ± 1.8 | 19.1 ± 2.1 | 1.1 | |
| Dorsal horn (laminas I–VI) | 43.0 ± 1.7 | 41.3 ± 3.1 | −4.0 | |
| Thoracic | T3 and T6 | |||
| Superficial layers (laminas I and II) | 99.5 ± 4.6 | 91.5 ± 3.6 | −8.0 | |
| Laminas III–VI | 30.5 ± 2.7 | 34.5 ± 3.0 | 13.1 | |
| Lamina X | 22.6 ± 2.4 | 18.8 ± 1.6 | −16.8 | |
| Ventral horn (laminas VII–IX) | 17.4 ± 3.0 | 20.5 ± 2.0 | 17.8 | |
| Dorsal horn (laminas I–VI) | 48.9 ± 2.6 | 48.8 ± 2.4 | −0.2 | |
| Sacral | S4 | |||
| Superficial layers (laminas I and II) | 91.5 ± 8.6 | 92.4 ± 4.9 | 1.0 | |
| Laminas III–VI | 31.6 ± 3.1 | 31.1 ± 2.6 | −1.6 | |
| Lamina X | 29.7 ± 4.5 | 29.4 ± 6.7 | −1.0 | |
| Ventral horn (laminas VII–IX) | 23.7 ± 1.7 | 19.7 ± 2.9 | −16.9 | |
| Dorsal horn (laminas I–VI) | 47.5 ± 4.2 | 44.6 ± 4.7 | −6.1 | |
The mean specific binding (n = 4) of [3H]DAMGO (femtomoles per milligram) ± SEM in spinal cord regions of wild-type (+/+) and homozygous (−/−) A2A receptor knock-out mice. Measurements in the regions were performed at the bregma coordinates taken from the rat atlas ofPaxinos and Watson (1986). Regional determinates were made from both left and right sides of the sections, which were cut 300 μm apart. The labeling was performed on sections from +/+ and −/− mice in a completely paired protocol. Specific binding was >90% in all regions. Comparison of genotypes was not statistically significant (p > 0.05; ANOVA). The percentage (%) change in binding represents the change in binding levels in −/− spinal cords compared with +/+. A minus sign indicates a percentage decrease in binding levels. The overall mean and median percentage changes across regions were −1 and −0.9%, respectively.