[Effect of different doses of ACTH fragments on the bodies of white rats].

ACTH fragments improved the establishing of food--rewarded behaviour in white rats. The effective dose of ACTH4-7 (0.05 mg/kg) was higher as compared to that of ACTH4-10 (0.015 mg/kg). The further increase in the dose of the peptides induced no enhancement of their behavioral effect but produced general excitation of the rats (increase in their motor activity, O2 consumption, heart rate). The peptides seem to produce a direct effect on the mechanisms of learning, which is independent of their general excitatory action.