Protective effect of verapamil on learning and memory deficits induced by methamphetamine in rat

Methamphetamine is a strong central nervous system stimulant that mimics the action of certain neurotransmitters. Methamphetamine causes the release of dopamine, serotonin and it increases glutamate levels in the brain. Methamphetamine abuse causes cognitive abnormalities and neurodegenerative changes in the brain. Verapamil hydrochloride is a calcium channel blocker that binds with high affinity to α -subunit of the L-type calcium channel complex and blocks it. Since, calcium is a major neurotoxic mediator of methamphetamine, calcium channel inhibition and consequent reduction in calcium entry may reduce the detrimental effects of methamphetamine on learning and memory.

In this study, male Wistar rats (220-240 g) were used. Chronic methamphetamine (2 mg/kg) was injected intraperitoneally for 5 consecutive days. The 5th day was the training day and retention test was done 24h after training. Verapamil hydrochloride (2.5, 5, 10 mg/kg) was intraperitoneally administered one hour before the retrieval test. Finally, the effect of verapamil on passive avoidance learning (PAL) and memory impairment induced by chronic methamphetamine was assessed.

Metformin at concentration of 20 μM increased survival of HUVECs exposed to H2O2. ROS and MDA levels increased in H2O2-treated endothelial cells. Metformin could significantly decrease H2O2-induced ROS and MDA elevation. It also increased total thiol groups and TAP.

It seems verapamil can be introduced as a neuroprotective substance in memory deficit induced by methamphetamine.