Disruption of the brain growth spurt in adolescent rats by chronic phenobarbital administration.

Postweanling rats received daily injections of either 60 mg/kg phenobarbital, 15 mg/kg phenobarbital, or the drug vehicle from their postnatal days 25 through 39. Even though there were no differences among the groups in body weight, the group receiving 50 mg/kg phenobarbital had significantly smaller whole brain weights and larger liver weights than the other groups. These data suggest that, (i) brain growth may be vulnerable to disruption even in its late stages and (ii) barbiturates may constitute a threat to normal brain growth.