Objectives: 

The plant of dragonhead (Dracocephalum moldavica L.,Lamiaceae)

is reported to have a wide range of pharmacological activities such as in anxiety, in healing, haematuria, insect stings and in dressing of surgical wounds. It is also used as anti-bacterial and as diuretic,astringent,carminative in treatment of dysentery and diarrhea and as a sudorific.To determine the myelogenic effect of dragonhead leaves, we investigated the effects of ethanolic extract of dragonhead leaves and its interaction with cholinergic system on memory retention of passive avoidance learning in rats.

Materials: 

Post-training intracerebroventricular (i.c.v) injections were carried out in all the experiments except ethanolic extract (intraperitoneally i.p.).

Results: 

Administration of ethanolic extract (0/025 mg/kg), pilocarpine (0/01 ,0/1 ,and 0.5 mg/rat), the muscarinic cholinoceptor agonist, and nicotine (0/01 ,0/05 and 0.1 mg/rat) increased, while scopolamine (1 and 5 mg/rat), the muscarinic cholinoceptor antagonist, and succinylcholine (0.01 and 0.1 mg/rat), the nicotine cholinoceptor antagonist decreased memory retention in rats.Activation of muscarinic cholinoceptors by pilocarpine potentiated the response of ethanolic extract.Also, pharmacological blockade of scopolamine attenuated potentiating effect of ethanolic extract. Activation of nicotinic cholinoceptor by nicotine potentiated the response of ethanolic extract. Blockade of nicotinic cholinoceptor by mecamylamine attenuated the response of ethanolic extract.

Conclusions: 

It is concluded that the ethanolic extract of Dracocephalum moldavica potentiated memory retention and also it has an interaction with muscarinic and nicotinic cholinergic systems that is involved in the memory retention process.