الفهرس 
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Abstract
Alzheimer’s disease (AD) is clinically characterized by progressive loss of cognitive abilities. Although the primary cause of AD remains unclear, changes in brain monoamine levels, oxidative stress, metabolic deficits, and genetic factors lead to neuroinflammation may be considered the principal pathogenic factors.
The present study was constructed to investigate the anti-amnestic effect of Urtica dioica plant parts (leaves and roots) separately, known as stinging nettle on scopolamine (SCOP) induced behavioral, biochemical, and genetic changes in rats compared with two synthetic drugs sermion (SR); and donepezil (DON). Donepezil (1mg/kg), SR (2mg /kg), nettle leaves (NL) (100mg/kg), and nettle root (NR) (100mg/kg) were orally administered for 19 successive days. Amnesia was induced by SCOP (1 mg/kg; i.p.) daily injection through the experiment duration. Seventy-two male albino rats were divided into 6 equal groups (n=12) as bellow: 1- control {received (1ml /100 g bwt of rat) of (0.5/100 ml/rat) of (0.5/100 w/v) carboxy methyl cellulose (CMC)+ (1 ml/kg/day) from saline; i.p.}, 2- SCOP, group, 3- SCOP+ NL , 4- SCOP+NR, 5- SCOP+SR and 6- SCOP+DON. Y-maze test was conducted at 18th and 19th day, 30-45 min thereafter drug receive. In the 20th day, rats were sacrificed and homogenates of cortical and hippocampal tissues were used for the estimation of dopamine (DA), norepinephrine (NE) and serotonin (5-HT) contents along with the mRNA expression of heat shock protein70 (hsp70) and phosphorylated tau protein (p-tau). In addition, oxidant/antioxidant profile, and energy carrier molecules were assessed.
The result showed that NR extract could attenuate memory deficits together with the improvement of the monoaminergic system. In addition, NR extract upregulated the expression of hsp70-mRNA and downregulated the expression of p-tau-mRNA. In contrast, NR extracts had a poor effect on memory improvement, monoamines levels and the expression of hsp70-mRNA, and increased the p-tau-mRNA expression. On the other side, both extracts (NR and NL) decreased total GSSG %, GSSG, NO, MDA, ADP, and AMP level and increased GSH/GSSG ratio, GSH, and ATP level
Therefore, it may be concluded that NR extract had an anti-amnesic effect due to its impact on the monoaminergic system. Nettle root extract also protects against DNA misfolding by increasing hsp70-mRNA expression. Moreover, NR extract prevented the hyper-phosphorylation of tau protein and protect from neuroinflammation. It may be suggested also that both extracts (NL and NR) had an impact on brain metabolism, in addition to a neuroprotective effect due to antioxidant and free radical scavenging activity.