The Study of the Protective Effect of Methanolic Extract of Protoparmeliopsis Moralis Lichen on learning and Spatial Memory Disorders and Necrotic Cell Death in the Hippocampus of Male Rats in a Methamphetamine Neurotoxicity Model

Abstract

Introduction: Methamphetamine use leads to a reduction in hippocampal volume and neuronal damage, impairing the brain's ability to form new memories and learn. Protoparmeliopsis moralis, a lichen with antioxidant, anti-inflammatory, and restorative properties, was studied to evaluate its potential protective effects against methamphetamine-induced neuronal toxicity.

Methods: In this experimental study, 28 male Wistar rats (250–280 g) were randomly assigned to four groups (7 rats per group): a control group, a group receiving methamphetamine at a dose of 10 mg/kg, a group receiving methamphetamine at a cumulative dose of 40 mg/kg (administered as 4 doses of 10 mg/kg at two-hour intervals) plus 50 mg/kg of methanolic extract of Protoparmeliopsis moralis, and a group receiving the same methamphetamine regimen plus 100 mg/kg of the extract. The methanolic extract was administered intraperitoneally at 30 minutes, 24 hours, and 48 hours after the final methamphetamine dose. Following spatial memory testing, the rats' brains were collected for the assessment of necrotic cell death.

Result: Behavioral data showed that learning improved in the groups treated with Protoparmeliopsis moralis extract compared to the methamphetamine group. In the probe test, treated animals spent significantly more time in the target area, indicating enhanced memory performance P<0.01. Additionally, the methamphetamine group exhibited increased necrotic cell death in the CA1 region of the hippocampus, which was significantly reduced by treatment with the lichen extract P<0.05.

Conclusion: Protoparmeliopsis moralis, a lichen species, may improve methamphetamine-induced memory and learning impairments by reducing neuronal cell death.