Age-related cognitive decline in hypercholesterolemic LDL receptor knockout mice (LDLr-/-): evidence of antioxidant imbalance and increased acetylcholinesterase activity in the prefrontal cortex.
There is increasing evidence that hypercholesterolemia during midlife may represent a predictor of subsequent mild cognitive impairments and dementia decades later. However, the exact mechanism underlying this phenomenon remains unknown since plasmatic cholesterol is not able to cross the blood-brain barrier. In the present study, we evaluated the hypothesis that cognitive impairments triggered by hypercholesterolemia during aging may be related to brain oxidative stress and altered brain acetylcholinesterase (AChE) activity. We also performed a neuropathological investigation in order to analyze whether the cognitive impairments may be associated with stroke-related features. To address these questions we used three- and fourteen-month-old low-density lipoprotein receptor-deficient mice (LDLr-/-). The current findings provide new evidence that aged LDLr-/- mice, exposed to over three-fold cholesterol levels from early life, show working, spatial reference, and procedural memory impairments, without alterations in motor function. Antioxidant imbalance and oxidative damage were evidenced by a marked increase in lipid peroxidation (thiobarbituric acid reactive substances levels) and glutathione metabolism (increase in glutathione levels, glutathione reductase, and glutathione peroxidase activities) together with a significant increase in the AChE activity in the prefrontal cortex of aged hypercholesterolemic LDLr-/- mice. Notably, hypercholesterolemia was not related to brain infarcts and neurodegeneration in mice, independent of their age. These observations provide new evidence that hypercholesterolemia during aging triggers cognitive impairments on different types of learning and memory, accompanied by antioxidant imbalance, oxidative damage, and alterations of cholinergic signaling in brain areas associated with learning and memory processes, particularly in the prefrontal cortex.
Departamento de Farmacologia, Universidade Federal de Santa Catarina, Florianópolis, SC, Brazil.
Eduardo Luiz Gasnhar
EL
Moreira
Jade
J
de Oliveira
Jean Costa
JC
Nunes
Danúbia Bonfanti
DB
Santos
Fernanda Costa
FC
Nunes
Daniella Serafim Couto
DS
Vieira
Rosa Maria
RM
Ribeiro-do-Valle
Fabrício Alano
FA
Pamplona
Andreza Fabro
AF
de Bem
Marcelo
M
Farina
Roger
R
Walz
Rui Daniel
RD
Prediger
D000110:Acetylcholinesterase / Q000378:metabolism*; D000367:Age Factors; D000375:Aging / Q000235:genetics / Q000378:metabolism / Q000523:psychology*; D000818:Animals; D003071:Cognition / Q000502:physiology; D003072:Cognition Disorders / Q000235:genetics* / Q000378:metabolism; D003213:Conditioning, Psychological / Q000502:physiology; D005239:Fear / Q000502:physiology; D006937:Hypercholesterolemia / Q000235:genetics / Q000378:metabolism / Q000523:psychology*; D018782:Maze Learning / Q000502:physiology; D008568:Memory / Q000502:physiology; D051379:Mice; D018345:Mice, Knockout; D009043:Motor Activity / Q000502:physiology; D017397:Prefrontal Cortex / Q000378:metabolism*; D011973:Receptors, LDL / Q000235:genetics* / Q000378:metabolism
D011973:Receptors, LDL; D000110:Acetylcholinesterase