Dapagliflozin Ameliorates Cognitive Impairment in Aluminum-Chloride-Induced Alzheimer's Disease via Modulation of AMPK/mTOR, Oxidative Stress and Glucose Metabolism

Abstract

Alzheimer's disease (AD) is a progressive neurological illness characterized by memory loss and cognitive deterioration. Dapagliflozin was suggested to attenuate the memory impairment associated with AD; however, its mechanisms were not fully elucidated. This study aims to examine the possible mechanisms of the neuroprotective effects of dapagliflozin against aluminum chloride (AlCl₃)-induced AD. Rats were distributed into four groups: group 1 received saline, group 2 received AlCl₃ (70 mg/kg) daily for 9 weeks, and groups 3 and 4 were administered AlCl₃ (70 mg/kg) daily for 5 weeks. Dapagliflozin (1 mg/kg) and dapagliflozin (5 mg/kg) were then given daily with AlCl₃ for another 4 weeks. Two behavioral experiments were performed: the Morris Water Maze (MWM) and the Y-maze spontaneous alternation (Y-maze) task. Histopathological alterations in the brain, as well as changes in acetylcholinesterase (AChE) and amyloid β (Aβ) peptide activities and oxidative stress (OS) markers, were all evaluated. A western blot analysis was used for the detection of phosphorylated 5' AMP-activated protein kinase (p-AMPK), phosphorylated mammalian target of Rapamycin (p-mTOR) and heme oxygenase-1 (HO-1). Tissue samples were collected for the isolation of glucose transporters (GLUTs) and glycolytic enzymes using PCR analysis, and brain glucose levels were also measured. The current data demonstrate that dapagliflozin represents a possible approach to combat AlCl₃-induced AD in rats through inhibiting oxidative stress, enhancing glucose metabolism and activating AMPK signaling.

Keywords: AMPK pathway; Alzheimer’s disease; dapagliflozin; glucose metabolism; oxidative stress.

Figure 1

Effect of dapagliflozin (1 and 5 mg/kg) on (a) escape latency (seconds) and (b) time spent in target quadrant (seconds) during the induction of AD. Data expressed as mean ± standard deviation and analyzed using two-way ANOVA followed by Tukey’s comparison tests. a: significant versus control group, b: significant versus AlCl₃ (70 mg/kg), c: significant versus AlCl₃ (70 mg/kg) + dapagliflozin (1 mg/kg). AD: Alzheimer’s disease, AlCl₃: aluminum chloride. (n = 6).

Figure 2

Effect of dapagliflozin (1 and 5 mg/kg) on (a) spontaneous alternation (%) and (b) total arm entries during the induction of AD. Data expressed as mean ± standard deviation and analyzed using one-way ANOVA followed by Tukey’s comparison tests. a: significant versus control group, b: significant versus AlCl₃ (70 mg/kg), c: significant versus AlCl₃ (70 mg/kg) + dapagliflozin (1 mg/kg). AD: Alzheimer’s disease, AlCl₃: aluminum chloride. (n = 6).

Figure 3

Effect of dapagliflozin (1 and 5 mg/kg) on (a) AChE and (b) Aβ during the induction of AD. Data expressed as mean ± standard deviation and analyzed using one-way ANOVA followed by Bonferroni’s post hoc comparison tests. a: significant versus control group, b: significant versus AlCl₃ (70 mg/kg), c: significant versus AlCl₃ (70 mg/kg) + dapagliflozin (1 mg/kg). AD: Alzheimer’s disease, AlCl₃: aluminum chloride, AChE: acetylcholinesterase. (n = 6).

Figure 4

(A) Effect of dapagliflozin (1 and 5 mg/kg) treatment on (A) histopathological investigation of the brain during the induction of AD. (a1–4) Photomicrographs of cerebral cortex stained with H&E (X400) and (b1–4) Photomicrographs of hippocampus stained with H&E (X400). Examination showed remarkable AP (green arrow), normal structure of neurons (yellow arrow heads) and glial cells (yellow arrows), congested blood capillaries (black asterisk), pyknotic nuclei (black arrow head) and NFT (black arrow). AD: Alzheimer’s disease, AlCl₃: aluminum chloride, H&E: hematoxylin and eosin, AP: amyloid plaques, NFT: neurofibrillary tangles. (n = 6). (B) Histopathological scoring. The severity of degeneration of neurons was scored from 0 to 5 as follows (absent, mild, moderate, severe, very severe, extremely damaged). Quantitative data were analyzed using one-way analysis of variance (ANOVA) after assessing the normality by Shapiro–Wilk test followed by Bonferroni’s post hoc multiple comparisons test. Histological scores are expressed as median and quartiles and analyzed by Kruskal–Wallis test followed by Dunn’s multiple comparison at p > 0.05. (n = 6).

Figure 5

Effect of dapagliflozin (1 and 5 mg/kg) on (a) GLUT-1, (b) GLUT-3, (c) LDH-A and (d) PDK-1 during the induction of AD using PCR. Data expressed as mean ± standard deviation and analyzed using one-way ANOVA followed by Bonferroni’s post hoc comparison tests. a: significant versus control group, b: significant versus AlCl₃ (70 mg/kg), c: significant versus AlCl₃ (70 mg/kg) + dapagliflozin (1 mg/kg). AD: Alzheimer’s disease, AlCl₃: aluminum chloride, GLUT-1: glucose transporters-1, GLUT-3: glucose transporters-3, LDH-A: lactate dehydrogenase-A, PDK-1: pyruvate dehydrogenase kinase-1. (n = 4).

Figure 6

Effect of dapagliflozin (1 and 5 mg/kg) on (a) western blot of all groups with data normalized to β-actin, (b) p-AMPK, (c) p-mTOR and (d) HO-1 during the induction of AD. Data expressed as mean ± standard deviation and analyzed using one-way ANOVA followed by Bonferroni’s post hoc comparison tests. a: significant versus control group, b: significant versus AlCl₃ (70 mg/kg), c: significant versus AlCl₃ (70 mg/kg) + dapagliflozin (1 mg/kg). AD: Alzheimer’s disease, AlCl₃: aluminum chloride, p-AMPK: phosphorylated 5’ AMP-activated protein kinase, p-mTOR: phosphorylated mammalian target of Rapamycin, HO-1: heme oxygenase-1. (n = 3).

Figure 7

Schematic illustration of the present study.