Propranolol disrupts consolidation of emotional memory in Lymnaea

•The presentation of a stressor causes enhancement of memory formation.•These stressors on their own cause a non-emotional memory to be formed.•A combination of the two stressors, however, cause an emotional memory to be formed.•Propranolol injection obstructs memory consolidation for only non-emotional memory.•Propranolol injection before the stressors obstructs emotional memory formation. The therapeutic efficacy of the synthetic β-adrenergic receptor blocker, propranolol, for the treatment of post-traumatic stress disorder (PTSD) is currently being debated. Mixed results have been published regarding propranolol’s ability to disrupt the consolidation and reconsolidation of memories. Here, we use the invertebrate model Lymnaea to study propranolol’s ability to disrupt consolidation of memories formed under varying various types of stress which cause differing degrees of emotional memory. We show that when propranolol is administered immediately following operant conditioning, only the consolidation process of memories enhanced by individual stressors (i.e. a non-emotional memory) is susceptible to disruption. However, when propranolol is administered prior to training, only memories enhanced by a combination of stressors leading to an emotional memory are susceptible to disruption. These data suggest that the time of propranolol administration, as well as the type of memory formed play a key role in propranolol’s ability to obstruct memory consolidation.