The type 4 phosphodiesterase inhibitors rolipram and YM976 facilitate recall of the weak version of the passive avoidance task in the day-old chick

This series of studies examined the effect of the PDE4 inhibitors rolipram and YM976 on the recall of the passive avoidance learning (PAL) task in the day old chick, with a particular focus on the role of D1 receptor in activating this pathway. The results indicated that 2.0 mg/kg rolipram administered 5 min before or immediately, 5, 15 or 30 min following training and 0.025 mg/kg YM976 administered 15 min before or immediately, 5, or 15 min following training facilitated recall of the weak form of the task (i.e. using 20% v/v methyl anthranilate (MeA) as the aversant) at 180 min following training. In each case the effect emerged from 60 min following the training, and was still observable from 180 min to 24 h after training. In addition, whilst administration of 0.5 mg/kg SCH23390, a D1 receptor antagonist, 10 min prior to training disrupted recall for the strong form of the task, co-administration of 2.0 mg/kg rolipram but not 0.025 mg/kg YM976 5 min prior to training prevented this disruption occurring. The results suggest a role for D1 receptor activation in the processes underlying the facilitation of memory by rolipram.