Barbiturate-enhanced paired-pulse depression in neonatal rats.

Paired-pulse depression of the population spike in the hippocampal formation of barbiturate anaesthetized mature rats is increased compared to that in urethane unanaesthetized rats. This barbiturate-induced increase in depression is greatly enhanced in immature animals, which are also known to be behaviorally more sensitive to barbiturates. These results suggest an increased sensitivity of the recurrent inhibitory (possible GABAergic) system to barbiturates in the immature central nervous system.