imidapril and Alzheimer-Disease

The purpose of this work was to test whether brain-penetrating angiotensin-converting enzyme (ACE) inhibitors (e.g., perindopril), as opposed to non-brain-penetrating ACE inhibitors (e.g., enalapril and imidapril), may reduce the cognitive decline and brain injury in Alzheimer's disease (AD). We first compared the effect of perindopril, enalapril, and imidapril on cognitive impairment and brain injury in a mouse model of AD induced by intracerebroventricular (i.c.v.) injection of amyloid-β (Aβ)₁₋₄₀. Perindopril, with significant inhibition of hippocampal ACE, significantly prevented cognitive impairment in this AD mouse model. This beneficial effect was attributed to the suppression of microglia/astrocyte activation and the attenuation of oxidative stress caused by iNOS induction and extracellular superoxide dismutase down-regulation. In contrast, neither enalapril nor imidapril prevented cognitive impairment and brain injury in this AD mouse. We next examined the protective effects of perindopril on cognitive impairment in PS2APP-transgenic mice overexpressing Aβ in the brain. Perindopril, without affecting brain Aβ deposition, significantly suppressed the increase in hippocampal ACE activity and improved cognition in PS2APP-transgenic mice, being associated with the suppression of hippocampal astrocyte activation and attenuation of superoxide. Our data demonstrated that the brain-penetrating ACE inhibitor perindopril, as compared to non-brain-penetrating ACE inhibitors, protected against cognitive impairment and brain injury in experimental AD models.

Topics: Alzheimer Disease; Amyloid beta-Peptides; Angiotensin-Converting Enzyme Inhibitors; Animals; Astrocytes; Disease Models, Animal; Enalapril; Hippocampus; Imidazolidines; Mice; Mice, Inbred ICR; Mice, Transgenic; Microglia; Nitric Oxide Synthase Type II; Oxidative Stress; Peptide Fragments; Peptidyl-Dipeptidase A; Perindopril; Superoxide Dismutase

Angiotensin-converting enzyme (ACE) inhibitors have clinically been widely used as anti-hypertensive agents. In the present study, we compared the effects of a centrally active ACE inhibitor, perindopril, with those of non-centrally active ACE inhibitors, imidapril and enalapril, on cognitive performance in amyloid beta(Abeta) (25-35)-injected mice, a rodent model of Alzheimer's disease. We also determined the brain ACE activity in order to elucidate the relationship between the cognitive function and ACE inhibition in the brain. Abeta(25-35)-injected mice showed a cognitive impairment in spontaneous alteration and object recognition tests, the indices of immediate working memory and relatively long-term recognition memory, respectively. As indicated by these tests, the oral administration of perindopril (0.1, 0.3 or 1mg/kg/day) significantly reversed the cognitive impairment in these mice, whereas neither imidapril (0.3, 1 or 3mg/kg/day) nor enalapril (1, 3 or 10mg/kg/day) had any effect on cognitive performance. Perindopril (1mg/kg/day), imidapril (3mg/kg/day), or enalapril (10mg/kg/day) all inhibited the plasma ACE activities by more than 90%. Using the same dosing regimen, only perindopril inhibited the brain ACE activities by more than 50%, whereas imidapril and enalapril showed much less potent effects. These results suggest that perindopril ameliorated the cognitive impairment in the Alzheimer's disease model mice through the inhibition of brain ACE activity, but not peripheral ACE activity. Based on our observations, we concluded that a centrally active ACE inhibitor, perindopril, may therefore have a beneficial effect on Alzheimer's disease as well as hypertension.

Topics: Alzheimer Disease; Angiotensin-Converting Enzyme Inhibitors; Animals; Behavior, Animal; Cognition; Disease Models, Animal; Enalapril; Exploratory Behavior; Humans; Imidazolidines; Memory; Memory, Long-Term; Mice; Peptidyl-Dipeptidase A; Perindopril; Recognition, Psychology