Chronic psychosocial stress exacerbates impairment of cognition and long-term potentiation in beta-amyloid rat model of Alzheimer's disease.
BACKGROUND
Alzheimer's disease (AD) is a degenerative disorder that leads to progressive cognitive decline. Alzheimer's disease develops as a result of over-production and aggregation of beta-amyloid (Abeta) peptides in the brain. The reason for variation in the gravity of symptoms among AD patients is unknown and might result from patient-related factors including lifestyle. Individuals suffering from chronic stress are at an increased risk for developing AD. This study investigated the effect of chronic psychosocial stress in Abeta rat model of AD.


METHODS
Psychosocial stress was induced with a rat intruder model. The rat model of AD was induced by 14-day osmotic pump infusion of a mixture of 300 pmol/day Abeta(1-40)/Abeta(1-42). The effect of chronic stress on the severity of Abeta-induced spatial learning and memory impairment was tested by three approaches: behavioral testing in the radial arm water maze, in vivo electrophysiological recording in anesthetized rat, and immunoblot analysis to determine protein levels of learning- and memory-related molecules.


RESULTS
A marked impairment of learning and memory developed when stress was combined with Abeta, more so than that caused by Abeta alone. Additionally, there was a significantly greater impairment of early-phase long-term potentiation (E-LTP) in chronically stressed/Abeta-treated rats than in either the stressed or Abeta-treated rats. This might be a manifestation of the reduction in protein levels of calcium/calmodulin-dependent protein kinase II (CaMKII) and the abnormal increase in calcineurin levels.


CONCLUSIONS
Chronic stress significantly intensified Abeta-induced deficits of short-term memory and E-LTP by a mechanism involving decreased CaMKII activation along with increased calcineurin levels.
Srivareerat
Marisa
M
Department of Pharmacological and Pharmaceutical Sciences, College of Pharmacy, University of Houston, Houston, Texas 77204-5037, USA.
Tran
Trinh T
TT
Alzoubi
Karem H
KH
Alkadhi
Karim A
KA
D000544:Alzheimer Disease / Q000139:chemically induced / Q000150:complications*; D016229:Amyloid beta-Peptides / Q000008:administration & dosage; D000704:Analysis of Variance; D000818:Animals; D001522:Behavior, Animal; D001703:Biophysics; D019703:Calcineurin / Q000378:metabolism; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2 / Q000378:metabolism; D003072:Cognition Disorders / Q000209:etiology* / Q000473:pathology*; D004195:Disease Models, Animal; D015536:Down-Regulation / Q000187:drug effects / Q000502:physiology; D004558:Electric Stimulation; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology; D006624:Hippocampus / Q000503:physiopathology*; D017774:Long-Term Potentiation / Q000187:drug effects / Q000502:physiology*; D008297:Male; D018782:Maze Learning / Q000502:physiology; D018408:Patch-Clamp Techniques; D010446:Peptide Fragments / Q000008:administration & dosage; D051381:Rats; D017208:Rats, Wistar; D013315:Stress, Psychological / Q000150:complications* / Q000209:etiology
D016229:Amyloid beta-Peptides; D010446:Peptide Fragments; C078592:amyloid beta-protein (1-40); C075222:amyloid beta-protein (1-42); D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D019703:Calcineurin