Involvement of corticotropin-releasing factor subtype 1 receptor in the acquisition phase of learned helplessness in rats

To determine if CRF receptor subtype 1 (CRF1) is involved in the acquisitio n phase of LH, we administered CRF receptor antagonists, CRA1000 and CP-154 ,526, 60 min before (acquisition phase) or immediately after (consolidation phase) inescapable shocks on day 1, and 60 min before (retention phase) es cape test on day 2. CRA1000 (10 mg/kg, p.o.) and CP-154,526 (30 mg/kg, p.o. ) decreased the number of escape failures in the acquisition phase, but not in consolidation and retention phases. The tricyclic antidepressant, imipr amine did not affect the number of escape failures in all 3 phases. Thus, t he CRF1 receptor is apparently involved in the resultant escape failures in the acquisition phase of LH in rats. (C) 2001 Elsevier Science Inc. All ri ghts reserved.