Differential effect of low doses of intracerebroventricular corticotropin-releasing factor in forced swimming test

In this work, we studied the effect of low doses of intracerebroventricular corticotropin-releasing factor (CRF) in six sessions of forced swimming te st (FST). When CRF (0.01 and 0.1 mug) was administered pre-test, results sh owed that the 0.1-mug dose significantly increased swimming in SESSION2, SE SSION3 and SESSION4, while the 0.01-mug dose proved ineffective. When CRF ( 0.1 and 0.03 mug) was administered post-test to evaluate retention of swimm ing response, the dose of 0.1 mug impaired retention, while the dose of 0.0 3 mug improved it, although these effects only reached significance in SESS ION2. In an additional session (SESSION6), testing long-term retention of t his swimming response, the 0.1-mug dose significantly impaired retention, w hereas the 0.03-mug dose proved ineffective. A high dose of CRF (1 mug) was also included as a control of previous results [Garcia-Lecumberri C, Ambro sio E. Role of corticotropin-releasing factor in forced swimming test. Eur J Pharmacol 1998;343:17-26]. In all the FST sessions, this high dose increa sed swimming when administered pre-test, while impairing retention when adm inistered post-test. Preliminary data obtained with low doses of CRF sugges t that a differential effect on retention of swimming response seems to exi st depending on the dose, whereas a high dose of CRF clearly impairs retent ion. The role of CRF in learning and memory processes in FST is discussed. (C) 2000 Elsevier Science Inc. All rights reserved.