Thesis (Ph.D.) - Cairo University - Faculty of Pharmacy - Department of Pharmacology and Toxicology

Overactivation of angiotensin-converting enzyme/angiotensin 2/angiotensin receptor-1 (ACE/Ang2/AT1) axis provokes amyloid-Ý-induced apoptosis and neurodegeneration in Alzheimer's disease (AD). Moreover, activation of AT1 impairs the survival pathway phosphoinositide 3-kinase/protein kinase B (PI3K/Akt). Interestingly, the coupling between ACE2/Ang(1-7)/Mas receptor (MasR) axis and PI3K/Akt activation opposes AT1-induced apoptosis. However, the effect of in vivo stimulation of MasR against AD and its correlation to PI3K/Akt is not yet elucidated. Thus, the present study aimed to investigate the relationship between PI3K/Akt pathway and the activation of ACE2/MasR in the AD model of D-galactose-ovariectomized rats. AD features were induced following 8-week injection of D-galactose (150 mg/kg, i.p.) in ovariectomized female rats. The ACE2 activator dimenazine (15 mg/kg, i.p.) was daily administered for 2 months. DIZE administration boosted the hippocampal expression of ACE2 and Mas receptors while suppressing AT1 receptor. Notably, dimenazine enhanced the expression of phosphorylated survival factors (PI3K, Akt, signal transducer, and activator of transcription-3) and neuroplasticity proteins such as cyclic adenosine monophosphate-responsive element-binding protein and brain-derived neurotrophic factor along with nicotinic and glutamatergic receptors

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