The effect of early and long-term propranolol therapy on learning and memory in mice.

Propranolol is the treatment of choice for infantile hemangioma. We investigated the effects of long-term propranolol use in early infancy on learning and memory later in life in mice. At three weeks of age, mice were randomly divided into six experimental groups. Groups 1 and 2 (controls) received only saline for 21 days. Groups 3 and 4 received propranolol (2.5 mg/kg) for 21 days. Groups 5 and 6 received propranolol (5 mg/kg) for 21 days. Groups 1, 3 and 5 were tested at the end of 21 days of treatment (week 6). However, groups 2, 4 and 6 received a 2-week break and then (week 8) exposed to tests. In the Morris water maze test, propranolol (2.5 and 5 mg/kg) dose-dependently increased the time spent in the target quadrant in mice at weeks 6 and 8. However, propranolol did not affect the swimming speed in both time periods. There were no significant effects of propranolol on the number of errors evaluated during the radial arm maze tests. In conclusion, long-term use of propranolol in early infancy did not disrupt the learning and memory of mice.