Therapeutic effect of frankincense in a rat model of Alzheimer’s disease

OBJECTIVE Frankincense improves memory in different models of learning. However, its influence on models of Alzheimer's disease (AD) has not been studied widely. In the present study, the therapeutic effect of frankincense was evaluated in a model of AD induced by i.c.v administration of streptozotocin. MATERIALS AND METHODS Under stereotaxic surgery, two guide cannulas were implanted in the lateral ventricles of adult male Wistar rats weighing 230-270 g. One group received streptozotocin (1.5 mg/kg/2μl/side) bilaterally on the first and third day of surgery. Another group received artificial cerebro-spinal fluid. Fourteen days after surgery, learning was evaluated using the passive avoidance paradigm. Four other groups of animals received frankincense (50 mg/kg) or its solvent after establishment of AD for 21 or 42 consecutive days, and then, memory retrieval was assessed. RESULTS Streptozotocin increased the number of stimulations required for induction of short-term memory and decreased step-through latency on the test day, significantly (p<0.05). Chronic injection of the aqueous extract of frankincense for 21 days did not affect learning parameters, but injection of it for 42 days, significantly increased step-through latency (p<0.05), decreased the number of step-through into the dark compartment (p<0.01) and decreased the time spent in the dark compartment (p<0.05). CONCLUSION The results indicate that chronic administration of frankincense has the potential to improve dementia type of AD induced by i.c.v injection of streptozotocin in a time-dependent manner.