beta-Lactotensin (His-Ile-Arg-Leu) is an ileum- contracting tetrapeptide isolated from bovine beta-lactoglobulin. We previously reported that a neurotensin agonist beta-lactotensin shows antinociceptive effect through neurotensin NT2 receptor. We found that centrally or orally administered beta-lactotensin at a dose of 60 nmol/mouse or 300-500 mg/kg, respectively, increased memory consolidation in the step-through-type inhibitory avoidance test in mice. The memory-enhancing activity of beta-lactotensin was inhibited by the dopamine D-2 receptor antagonist raclopride but not the D-1 receptor antagonist SCH23390. Taken together, beta-lactotensin might improve memory consolidation through activating the dopamine D-2 receptor. (C) 2007 Elsevier Inc. All rights reserved.