Investigating the Mechanisms Involved in Scopolamine-Induced Memory Degradation

In the present study, the mechanisms involved in scopolamine-induced memory impairment have been investigated. The molecular events that take place during memory mostly include mechanisms that are seen in the acquisition phase. Results show that one of the mechanisms of memory destruction caused by scopolamine, in addition to weakening the cholinergic system, is the indirect effect of scopolamine on other neurotransmitter systems, including the glutamatergic system. Scopolamine injection increases dopamine by inhibiting M۲/۴ muscarinic auto receptors. These auto receptors are located on dopaminergic presynaptic neurons, and their activation reduces the release of dopamine. Therefore, blocking these auto receptors by scopolamine can increase the release of dopamine. Both D۱ and D۲ receptors are involved in the process of learning and memory. In general, stimulation of dopamine D۱ receptors follows an inverted U-shaped dose-response curve, meaning that both insufficient and excessive amounts of dopamine cause memory impairment. Therefore, one of the mechanisms of scopolamine-induced memory impairment can be an indirect effect on the dopaminergic system. Effect on cell membrane potential, effect on neuron plasticity and interaction with acetylcholine. Serotonin plays a complex role in memory and learning. Serotonin receptors (۵-HT۲A) also play a role in memory function through their effect on calcium transport. This action is similar to dopamine receptors and other G-protein-coupled receptors, which activate phospholipase C, enter calcium into the cell, and activate calcineurin. Activation of ۵-HT۲A receptors as well as ۵-HT۴ receptors by specific agonists of these receptors enhances LTP, which plays a very important role in memory. On the other hand, specific ۵-HT۳ receptor antagonist improves LTP. ۵-HT۶ receptor antagonist can improve memory function. Therefore, different serotonin receptors have different roles on memory function, and the interaction between scopolamine and these receptors needs further study. It has been shown that histamine increases the secretion of acetylcholine in the hippocampus and postsynaptic H۱ and presynaptic H۳ receptors play an important role in memory and learning, but whether scopolamine can cause memory impairment through interaction with histamine receptors, not reviewed.

کلیدواژه ها:

Mechanism Involved in Memory Degradation ، Scopolamine ، Non-selective Antagonist ، acetylcholine