Cocaine sensitization in periadolescent and adult rats. J Pharmacol Exp Ther

Periadolescent rats have been reported to be affected differ-entially by catecholaminergic agents when compared with younger or adult animals. The present study evaluated the behavioral responsivity of periadolescent (34- to 39-day-old) and adult (60- to 70-day-old) Sprague-Dawley rats of both sexes to i.p. cocaine (Coc) administration (0, 1 0 or 20 mg/kg, once daily for 4 days). All animals received injections of both saline and Coc every day paired with a different context, with one-half of the animals receiving the drug in the home cage (Coc-Home) and the other half in the testing chamber (Coc-Test). Forty-eight hours after the last drug injection, all animals were challenged with 1 0 mg/kg i.p. of Coc, and their behavior in the test chamber was scored. As expected, acute Coc in-duced a prominent increase in a number of behaviors, and this response profile was less marked in penadolescent relative t