The Evaluation of Amnesia Induced by Scopolamine on the Astrocytes Number in Rat's Dentate Gyrus

The relation between cholinergic system and muscarinic cholinergic receptors (mR) associated with learning and memory has been recognized. Because of astrocytes contact to synapses, they are undergoing remarkable structural and morphological changes in learning. The aim of this study was to evaluate amnesia induced by scopolamine (Antagonist mR) on the number of astrocytes in rat's dentate gyrus.

In this experimental study, 48 male Wistar rats, 200-250 gr were used in 6 groups and each group contains 8 rats. The animals were bilaterally implanted with chronic cannulae in the CA1 regions, trained in a step-through type inhibitory avoidance task, and immediately after training, animals received saline or different doses of scopolamine (0.5, 1 and 2 µg/rat, intra-CA1) and tested 24 h after training to measure step-through latency. Then all rats were sacrificed 48h after behavioural test and cross sections were taken from the dorsal hippocampal formation of the right cerebral hemispheres and stained with PTAH (the specific staining for astrocytes). The area densities of the astrocytes was measured in dentate gyrus and compared in the all groups.

Scopolamine injection can induce amnesia. There was a significant difference in astrocyte number between control and sham group which only had surgical stress (p<0.05). Whereas there was no significant increase in astrocyte number of scopolamine received groups compared to control group.

The results of this study showed that amnesia induced by scopolamine can little increase astrocytes number in the rats dentate gyrus.