| Abstract: | This study aimed to identify the ontogenetic period during which long-term expression of behavioral sensitization to cocaine begins to emerge. Rat pups aged 4, 8, 12, or 16 days received a pretreatment of 4 daily injections of 15 mg/kg sc: cocaine paired with the test chamber for 45 min. Pups were then tested for sensitization in that context after abstinence intervals ranging from 2 to 10 days. On test days, pups were videotaped, and their behavior was scored later. Sensitization was detected after intervals of 2, 4, 5, or 9 days in pups aged 4–7, 8–11, 12–15, or 16–19 days during pretreatment, respectively. These results suggest that the mechanisms for long-term retention of sensitization mature incrementally in the rat, starting to emerge gradually after the 1st week of age, whereas those relevant to short-term retention and initiation of sensitization are present earlier. (PsycINFO Database Record (c) 2010 APA, all rights reserved) |
