Background: Studies have shown that the morphine can affect several neurotransmitter systems in the brain and impair memory retrieval. Moreover, it has been reported that the hydroalcoholic extract of Salvia officinalis can potentiate memory retention. Therefore, this study was conducted to evaluate the effect of hydroalcoholic extract of Salvia officinalis on memory impaired by post-training administration of morphine using a passive avoidance paradigm in rat.

Materials and Methods: In this study, rats (220-250g) were trained in a step–through type passive avoidance task (1.5 mA shock for 3 seconds). Immediately after training, the animals received systemic injections of morphine (2.5, 5 and 7.5 mg/kg, s.c.) or Salvia officinalis (20, 40 and 60 mg/kg, s.c.). Another group received Salvia officinalis (20 mg/kg, s.c.) before training and morphine (7.5 mg/kg, s.c.) after training. All animals were tested 24 h after training to measure the step-through latency.

Results: Findings indicated that post-training subcutaneous administration of morphine (5 and 7.5 mg/kg, s.c.) and Salvia officinalis (40 and 60 mg/kg, s.c.) impaired and enhanced memory retrieval, respectively in animals on the test day. Moreover, a systemic injection of Salvia officinalis (20 mg/kg, s.c.) before training restored the memory impairment induced by post-training morphine (7.5 mg/kg, s.c.).

Conclusion: It seems that hydroalcoholic extract of Salvia officinalis can prevent the morphine-induced impairment of memory functions.