Chronic intracerebroventricular exposure to beta-amyloid(1-40) impairs object recognition but does not affect spontaneous locomotor activity or sensorimotor gating in the rat.
This study examined the cognitive effects of chronic in vivo exposure to beta-amyloid(1-40) via the intracerebroventricular route on two distinct paradigms. The first test evaluated a form of early attentional control referred to as sensorimotor gating in which an antecedent weak prepulse stimulus modulates the reactivity to a subsequent startle-eliciting stimulus. The second test utilized the spontaneous preference for a novel object over that of a familiar one in rats as a measure of object recognition memory. We found that beta-amyloid exposure leads to a severe deficit in the object memory test but spares sensorimotor gating. Moreover, unlike the water maze deficit induced by beta-amyloid (Nag et al., in preparation), the deficit on object recognition was resistant to amelioration by systemic physostigmine treatment at a dose of 0.06 mg/kg per day intraperitoneally. The present results add to previous reports that beta-amyloid exposure can lead to deficits on hippocampal lesion sensitive tasks, suggesting that dysfunction of the rhinal cortices in addition to that of the septohippocampal system is implicated in beta-amyloid-induced behavioral impairments. It therefore lends support to the hypothesis that beta-amyloid exposure can lead to severe impairment across multiple memory systems.
Nag
S
S
Department of Physiology, Faculty of Medicine, University of Hong Kong, PR China.
Tang
F
F
Yee
B K
BK
D000161:Acoustic Stimulation / Q000379:methods; D016229:Amyloid beta-Peptides / Q000494:pharmacology*; D000818:Animals; D002552:Cerebral Ventricles / Q000187:drug effects / Q000502:physiology; D002800:Cholinesterase Inhibitors / Q000494:pharmacology*; D018728:Entorhinal Cortex / Q000187:drug effects / Q000502:physiology; D006624:Hippocampus / Q000187:drug effects / Q000502:physiology; D008297:Male; D009043:Motor Activity / Q000187:drug effects* / Q000502:physiology; D010278:Parathion / Q000494:pharmacology*; D010446:Peptide Fragments / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D021641:Recognition, Psychology / Q000187:drug effects* / Q000502:physiology; D013216:Reflex, Startle / Q000187:drug effects* / Q000502:physiology
D016229:Amyloid beta-Peptides; D002800:Cholinesterase Inhibitors; D010446:Peptide Fragments; C078592:amyloid beta-protein (1-40); D010278:Parathion