Effects of baicalein with memantine on aluminium chloride-induced neurotoxicity in Wistar rats

Abstract

Alzheimer's disease is a progressive neurodegenerative condition. It is one of the most common 28 forms of dementia accounting for 60-80% of people suffering from dementia. There are very few medications that are approved for the treatment of Alzheimer's disease. Baicalein, belonging to the flavone subclass of flavonoids, has been reported to have a neuroprotective effect by reducing oxidative stress and neuroinflammation, inhibiting the AChE enzyme, and reducing amyloid protein aggregation and toxicity. Memantine is one of the most important drugs used for treating Alzheimer's disease. The purpose of this work was to study the effect of baicalein with memantine on aluminum chloride-induced neurotoxicity in Wistar rats. Aluminum chloride (100 mg/kg p.o.) was administered for 42 days in male Wistar rats to induce neurotoxicity. Baicalein alone (10 mg/kg) and a combination of baicalein (5 mg/kg and 10 mg/kg) with memantine (20 mg/kg) were administered for 42 days. Treatment of baicalein with memantine showed significant improvement in behavioral parameters. The combination reduced oxidative stress and the formation of β-Amyloid plaques and increased brain-derived neurotrophic factor (BDNF) expression. Based on findings, it can be concluded that treatment with baicalein and memantine may slow the progression of neurodegeneration in rats.

Keywords: AlCl3; Alzheimer’s disease; BDNF; baicalein; neurodegeneration; oxidative stress; β-Amyloid.

FIGURE 1

Effects of baicalein and baicalein with memantine on behavioral assessment. (A) Actophotometer, (B) Morris Water Maze, (C) Elevated Plus Maze, (D) Passive Avoidance. Data are expressed as mean ± SEM (n = 6), with ###p < 0.001 when compared to the normal control group, *p < 0.05, **p < 0.01, and ***p < 0.001 when compared to the disease control group. @p < 0.05, @@p < 0.01, @@@p < 0.001 when compared with memantine treatment group. SEM: Standard error of the mean. MB: Memantine + baicalein.

FIGURE 2

Effects of baicalein and baicalein with memantine on AChE Activity (A). Hippocampus, (B). Cortex. Data are expressed as mean ± SEM (n = 6), with ###p < 0.001 when compared to the normal control group, *p < 0.05, **p < 0.01, and ***p < 0.001 when compared to the disease control group, @p < 0.05, @@p < 0.01 when compared to the memantine treatment group. SEM: Standard Error of the Mean.

FIGURE 3

Effects of baicalein and baicalein with memantine on H&E-stained hippocampus tissue (400X), (A) Normal control: showing normal histology and normal neuronal cells in the hippocampus (small arrow) (B) Disease control: hippocampus neuronal degeneration with pyknotic nuclei (small arrow), hippocampus neuronal cell layer reduction (large arrow) (C) Memantine (20 mg/kg): hippocampus neuronal degeneration with pyknotic nuclei (small arrow), hippocampus neuronal cell layer reduction (large arrow) (D) Baicalein (10 mg/kg): hippocampus neuronal degeneration with pyknotic nuclei (small arrow), hippocampus neuronal cell layer reduction (large arrow) (E) Memantine + baicalein (20+5 mg/kg): hippocampus neuronal degeneration with pyknotic nuclei (small arrow) (F) Memantine + baicalein (20 + 10 mg/kg): hippocampus neuronal degeneration with pyknotic nuclei (small arrow).

FIGURE 4

Effects of baicalein and baicalein with memantine on H&E-stained cortex tissue (400X), (A) Normal control: showing normal histology and normal neuronal cells in the parietal cortex (small arrow) (B) Disease control: showing neuronal degeneration with pyknotic nuclei in the cortex (small arrow) (C) Memantine (20 mg/kg): showing normal histology, normal neuronal cells in the parietal cortex (small arrow), (D) Baicalein (10 mg/kg): showing neuronal degeneration with pyknotic nuclei in the cortex (small arrow), (E) Memantine + baicalein (20+5 mg/kg): showing neuronal degeneration with pyknotic nuclei in the cortex (small arrow), (F) Memantine + baicalein (20 + 10 mg/kg): showing neuronal degeneration with pyknotic nuclei in the cortex (small arrow).

FIGURE 5

Effects of baicalein and baicalein with memantine on Congo red staining of the hippocampus tissue (400X), (A) Normal control: showing normal histology, normal neuronal cells in the hippocampus (small arrow), (B) Disease control: showing β-Amyloid deposition (small arrow) in the hippocampus, (C) Memantine (20 mg/kg): showing β-Amyloid deposition (small arrow) in the hippocampus, (D) Baicalein (10 mg/kg): showing β-Amyloid deposition (small arrow) in the hippocampus, (E) Memantine + baicalein (20+5 mg/kg): showing β-Amyloid deposition (small arrow) in the hippocampus, (F) Memantine + baicalein (20 + 10 mg/kg): showing β-Amyloid deposition (small arrow) in the hippocampus.

FIGURE 6

Effects of baicalein and baicalein with memantine on Congo red staining of the cortex tissue (400X), (A) Normal control: showing normal histology, normal neuronal cells in the parietal cortex (small arrow), (B) Disease control: showing β-Amyloid deposition (small arrow) in the parietal cortex, (C) Memantine (20 mg/kg): showing β-Amyloid deposition (small arrow) in the parietal cortex, (D) Baicalein (10 mg/kg): showing β-Amyloid deposition (small arrow) in the parietal cortex, (E) Memantine + Baicalein (20+5 mg/kg): showing β-Amyloid deposition (small arrow) in the parietal cortex, (F) Memantine + baicalein (20 + 10 mg/kg): showing β-Amyloid deposition (small arrow) in the parietal cortex.

FIGURE 7

Effects of baicalein and baicalein with memantine on β-Amyloid expression in hippocampus tissue (400X), (A) Normal control: showing normal neuronal cells without immunoreactivity at the hippocampus (small arrow), (B) Disease control: showing moderately enhanced β-Amyloid expression as evidenced by brown coloration in the hippocampus (small arrow), (C) Memantine (20 mg/kg): showing mildly enhanced β-Amyloid expression as evidenced by brown coloration in the hippocampus (small arrow), (D) Baicalein (10 mg/kg): showing mildly enhanced β-Amyloid expression as evidenced by brown coloration in the hippocampus (small arrow), (E) Memantine + baicalein (20+5 mg/kg): showing mildly enhanced β-Amyloid expression as evidenced by brown coloration in the hippocampus (small arrow), (F) Memantine + baicalein (20 + 10 mg/kg): showing mildly enhanced β-Amyloid expression as evidenced by brown coloration in the hippocampus (small arrow), (G) OD data for ICH. Data are expressed as mean ± SEM, with ###p < 0.001 when compared to the normal control group, **p < 0.01, and ***p < 0.001 when compared to the disease control group. AlCl₃, Aluminum chloride; SEM, Standard error of the mean; IHC, Immunohistochemistry.

FIGURE 8

Effects of baicalein and baicalein with memantine on β-Amyloid expression in cortex tissue (400X), (A) Normal control: showing normal neuronal cells without immunoreactivity at the cortex (small arrow), (B) Disease control: showing moderately enhanced β-Amyloid expression as evidenced by the brown coloration of cortical neurons (small arrow), (C) Memantine (20 mg/kg): showing mildly enhanced β-Amyloid expression as evidenced by the brown coloration of cortical neurons (small arrow), (D) Baicalein (10 mg/kg): showing moderately enhanced β-Amyloid expression as evidenced by the brown coloration of cortical neurons (small arrow), (E) Memantine + baicalein (20+5 mg/kg): showing mildly enhanced β-Amyloid expression as evidenced by the brown coloration of cortical neurons (small arrow), (F) Memantine + Baicalein (20 + 10 mg/kg): showing mildly enhanced β-Amyloid expression as evidenced by the brown coloration of cortical neurons (small arrow), (G) OD data for ICH. Data are expressed as mean ± SEM, with ###p < 0.001 when compared to the normal control group, and *p < 0.05, **p < 0.01, and ***p < 0.001 when compared to the disease control group. AlCl₃, Aluminum chloride; SEM, Standard error of the mean; IHC, Immunohistochemistry.

FIGURE 9

Effects of baicalein and baicalein with memantine on BDNF expression in hippocampus tissue (400X), (A) Normal control: showing moderately enhanced BDNF expression, as evidenced by the brown coloration of hippocampus neurons (small arrow), (B) Disease control: showing mild BDNF expression, as evidenced by brown coloration at Hippocampus neurons (small arrow), (C) Memantine (20 mg/kg): showing moderately enhanced BDNF expression, as evidenced by the brown coloration of hippocampus neurons (small arrow), (D) Baicalein (10 mg/kg): showing mild BDNF expression, as evidenced by brown coloration of hippocampus neurons (small arrow), (E) Memantine + baicalein (20+5 mg/kg): showing moderately enhanced BDNF expression, as evidenced by brown coloration of hippocampus neurons (small arrow), (F) Memantine + baicalein (20 + 10 mg/kg): showing moderately enhanced BDNF expression, as evidenced by the brown coloration of hippocampus neurons (small arrow), (G) OD data for ICH. Data are expressed as mean ± SEM, with ###p < 0.001 when compared to the normal control group, and *p < 0.05, **p < 0.01, and ***p < 0.001 when compared to the disease control group. AlCl₃, Aluminum chloride; SEM, Standard error of the mean; BDNF, Brain-derived neurotrophic factor; IHC, Immunohistochemistry.

FIGURE 10

Effects of baicalein and baicalein with memantine on BDNF expression in cortex tissue (400X), (A) Normal control: showing moderately enhanced BDNF expression, as evidenced by brown coloration in cortical neurons (small arrow), (B) Disease control: showing reduced BDNF expression, as evidenced by brown coloration in cortical neurons (small arrow), (C) Memantine (20 mg/kg): showing moderately enhanced BDNF expression, as evidenced by brown coloration in cortical neurons (small arrow), (D) Baicalein (10 mg/kg): showing mild BDNF expression, as evidenced by brown coloration in cortical neurons (arrow), (E) Memantine + Baicalein (20+5 mg/kg): showing mildly enhanced BDNF expression, as evidenced by brown coloration in cortical neurons (small arrow), (F) Memantine + baicalein (20 + 10 mg/kg): showing moderately enhanced BDNF expression, as evidenced by brown coloration in cortical neurons (small arrow), (G) OD data for ICH. Data are expressed as mean ± SEM, with ###p < 0.001 when compared to the normal control group, *p < 0.05, **p < 0.01, and ***p < 0.001 when compared to the disease control group. AlCl₃, Aluminum chloride; SEM, Standard error of the mean; BDNF, Brain-derived neurotrophic factor; IHC, Immunohistochemistry.