The Protective Effect of Usnic Acid on Impairment Learning and Memory , Antioxidant Capacity and Necrosis Cell Death on Hippocampus Following Methamphetamine Neurotoxicity

 Nowadays, methamphetamine addiction among teenagers and young people has attracted great concern in Iran. Long-term use of methamphetamine damages the brain's dopaminergic, serotonergic, and metabolic systems. Moreover, due to the effects of neurotoxicity in the brain, the patient suffers from cognitive disorders such as memory and learning disorders, mood disorders, and anxiety. Usnic acid has various biological properties, including antioxidant and anti-inflammatory activities. Therefore, the purpose of this study was to investigate the protective effects of usnic acid against the neurotoxicity of methamphetamine.

Methamphetamine neurotoxicity was induced by 40 mg/kg of METH in four intraperitoneally (IP) injections (e.g., 4×10 mg/kg q. 2-h, IP.). Usnic acid (25 mg/kg) was inserted at 30- min, 24-h, and 48 h after the final injection of METH. The Morris water maze test was used to study spatial memory. The brains were removed for biochemical assessments and Nissl staining.

Behavioral tests show that usnic acid treatment could significantly improve spatial memory deficits and learning (P<0.05) versus the METH group. Usnic acid treatment significantly increased superoxide dismutase (P<0.01) and reduced malondialdehyde (P<0.05). Moreover, usnic acid significantly reduced necrosis cell death (P<0.05) in the CA1 area of the hippocampus.

According to the findings, usnic acid improves memory and learning function in rats by reducing cell death.