Table 11.
Trials-to-criterion and latency (sec) for passive avoidance in F1 Sprague–Dawley rats treated with thiacloprid a .
| 0 ppm | 50 ppm | 300 ppm | 500 ppm | ||
|---|---|---|---|---|---|
| Females | |||||
| Session 1 (acquisition) | |||||
| Trials-to-criterion | 4.8 ± 1.9 | 4.1 ± 0.7 | 4.0 ± 0.9 | 3.7 ± 1.0 | |
| Trial 1 | 10.2 ± 8.7 | 10.9 ± 9.6 | 11.0 ± 5.0 | 16.0 ± 14.5 | |
| Trial 2 | 29.2 ± 22.5 | 33.8±23.3 | 43.3±21.9* | 51.6±14.7** | |
| Session 2 (retention) | |||||
| Trials-to-criterion | 2.8 ± 0.7 | 3.1 ± 0.8 | 3.0 ± 0.7 | 3.1 ± 0.4 | |
| Trial 1 | 27.2 ± 26.2 | 20.8 ± 20.4 | 26.6 ± 21.9 | 23.6 ± 20.0 | |
| Males | |||||
| Session 1 (acquisition) | |||||
| Trials-to-criterion | 4.3 ± 1.2 | 5.0 ± 2.8 | 4.2 ± 1.0 | 3.9 ± 1.3 | |
| Trial 1 | 8.2 ± 7.4 | 7.8 ± 5.2 | 11.2 ± 11.1 | 16.2 ± 15.9 | |
| Trial 2 | 32.8 ± 22.1 | 27.0 ± 22.8 | 32.9 ± 19.7 | 44.6 ± 19.5 | |
| Session 2 (retention) | |||||
| Trials-to-criterion | 3.0 ± 0.8 | 3.0 ± 0.5 | 3.3 ± 1.1 | 3.0 ± 0.5 | |
| Trial 1 | 31.4 ± 26.3 | 18.5 ± 13.8 | 24.4 ± 21.5 | 18.9 ± 19.4 | |
*p ≤ 0.05. **p ≤ 0.01; n = 19–20/sex/dietary level (one pup/sex/litter) (EPA 2002b).
Acquisition was measured on PND 23–25 as the latency to cross from a lighted compartment where the animal was placed to the adjacent darkened compartment in a shuttle box. Upon crossing, a mild shock was delivered via the metal grid floor as an aversive stimulus. Acquisition was measured as an increase in latency to cross to the darkened side, compared with previous trials, and the number of trials to achieve criterion performance (failure to cross within the maximum 180 s trial duration on two consecutive trials). Retention was evaluated 7 d later, based on latency to cross for Trial 1, compared with Trial 1 of acquisition. The values shown in bold are the principal findings discussed in the text.
Mean ± SD.