Neuroprotective role of medicinal plant extracts evaluated in a scopolamine-induced rat model of Alzheimer's disease.

Alzheimer's disease is a debilitating neurological brain disease with memory impairment among the first signs. Scopolamine (SCO), a muscarinic receptor antagonist that disrupts cognition and memory acquisition, is considered a psychopharmacological AD model. We investigate the effectiveness of medicinal plants in mitigating the SCO-induced neurobehavioural damage in rats. Animals were injected with Scopolamine hydrobromide trihydrate (2.2 mg/kg IP.) daily for 2 months. Each treatment group was administered one of four medicinal spice extracts (Nigella sativa, 400 mg/kg; rosemary, 200 mg/kg; sage, 600 mg/kg and ginseng; 200 mg/kg 90 minutes after SCO injection. Animals were subjected to cognitive-behavioural tests (NOR, Y-maze and MWM). After the experiment, we extracted the brains for histopathological examination and biochemical assessment for oxidative stress (levels of TT, CAT and TBARS) and gene expression of acetylcholinesterase and brain monoamines. As expected, SCO treatment impaired memory and cognition, increased oxidative stress, decreased neurotransmitters and caused severe neurodegenerative changes in the brain. Surprisingly, these effects were measurably moderated by the administration of all four plant extracts, indicating a neuroprotective action that we suggest could alleviate AD disease manifestations.