Table 1.
Effects of the exposure to D1R- and PKA-acting drugs on the percentage of the area occupied by MAP2 immunolabeling as well as density and average area of the soma of MAP2-expressing cells in cultures obtained from the cortex of the frontal lobe of E15 mouse fetuses
| Total days in culture | Hours of treatment | Drugs | % of Culture area occupied by MAP2 immunostaining | Number of MAP2-immunolabeled cells per 0.1 mm2 | Average soma area of MAP2-immunolabeled cells (μm2) |
|---|---|---|---|---|---|
| 3 | 0 | None | 15.8 ± 1.4 | 87 ± 11 | 66.9 ± 5.7 |
| 3 | 2 | SKF82958 (5 × 10−5m) | 12.1 ± 1.3* | 90 ± 13 | 71.4 ± 6.5 |
| 3 | 2 | SKF82958 (5 × 10−5m) H-89 (10−6m) | 16.0 ± 1.7 | 85 ± 14 | 65.5 ± 5.6 |
| 3 | 2 | Sp-cAMPS (10−6m) | 11.8 ± 1.5* | 85 ± 15 | 67.8 ± 5.1 |
| 4 | 0 | None | 17.2 ± 1.5 | 91 ± 8 | 68.3 ± 4.3 |
| 4 | 24 | SKF82958 (5 × 10−5m) | 12.4 ± 1.6* | 86 ± 12 | 70.0 ± 5.3 |
| 5 | 0 | None | 18.6 ± 2.5 | 88 ± 13 | 66.5 ± 6.8 |
| 5 | 48 | SKF82958 (5 × 10−5m) | 9.9 ± 1.7** | 85 ± 13 | 73.1 ± 6.6 |
| 6 | 0 | None | 19.9 ± 2.6 | 83 ± 11 | 63.4 ± 5.4 |
| 6 | 72 | SKF82958 (5 × 10−5m) | 7.6 ± 1.4** | 89 ± 14 | 72.6 ± 6.3 |
| 6 | 72 | Sp-cAMPS (10−6m) | 7.9 ± 1.5** | 84 ± 13 | 67.3 ± 4.9 |
| 7 | 0 | None | 21.8 ± 3.6 | 84 ± 11 | 69.9 ± 4.7 |
| 7 | 96 | SKF82958 (10−7m) | 18.3 ± 2.8 | 95 ± 17 | 64.7 ± 5.2 |
| 7 | 96 | SKF82958 (10−6m) | 15.6 ± 2.3 | 87 ± 12 | 74.1 ± 7.3 |
| 7 | 96 | SKF82958 (10−5m) | 12.0 ± 2.4* | 93 ± 14 | 64.8 ± 6.0 |
| 7 | 96 | SKF82958 (5 × 10−5m) | 7.7 ± 1.1** | 89 ± 14 | 67.5 ± 5.9 |
| 7 | 96 | SKF82958 (5 × 10−5m) SCH23390 (10−5m) | 21.5 ± 2.6 | 82 ± 13 | 68.9 ± 6.0 |
| 7 | 96 | SCH23390 (10−5m) | 22.9 ± 3.5 | 87 ± 12 | 66.7 ± 5.8 |
The cultures were allowed to grow in drug-free media for 3 d and then some of them were exposed to drugs. The time course of the effects of D1R agonists was examined by comparing cultures exposed to 5 × 10−5m of these ligands for 2, 24, 48, 72, and 96 hr with the age-matched drug-free cultures (exemplified here by the data produced by SKF82958). The dose dependence of the effects of D1R agonists was examined in cultures exposed for 96 hr to 0–5 × 10−5m of these ligands (also exemplified here by the data produced by SKF82958). The D1 receptor specificity of the effects of the agonists was demonstrated by the addition of 10−5m of D1R antagonist, SCH23390. The ability of the PKA stimulator, Sp-cAMPS, to replicate the effects of D1R agonists was examined in cultures exposed to 10−6m of this drug for 2 and 72 hr, and the ability of 10−6m of the PKA inhibitor, H-89, to block the effects D1R agonists was examined in cultures exposed to a combination of these drugs for only 2 hr (longer exposure to H-89 was not used because of significant decline in cell viability). Each data point represents a mean of seven separately performed experiments ± SEM. The statistically significant differences between drug-exposed cultures and the age-matched drug-free controls are marked by asterisks (*p < 0.05; **p < 0.01; Tukey's post-test). Note D1R agonist-induced dose- and time-dependent reductions in the percentage of the area occupied by MAP2-immunolabeled cells without any significant changes either in the density or in the area of the soma of these cells. The addition of a D1R antagonist blocked this reduction, whereas the antagonist alone had no effect. Furthermore, PKA stimulator replicated the effects of D1R agonists, whereas PKA inhibitor counteracted the effects of these agonists.