%0 Journal Article
%T Amyloid Beta Peptides Differentially Affect Hippocampal Theta Rhythms In Vitro
%A Armando I. Guti¨¦rrez-Lerma
%A Benito Ordaz
%A Fernando Pe£¿a-Ortega
%J International Journal of Peptides
%D 2013
%I Hindawi Publishing Corporation
%R 10.1155/2013/328140
%X Soluble amyloid beta peptide (A¦Â) is responsible for the early cognitive dysfunction observed in Alzheimer's disease. Both cholinergically and glutamatergically induced hippocampal theta rhythms are related to learning and memory, spatial navigation, and spatial memory. However, these two types of theta rhythms are not identical; they are associated with different behaviors and can be differentially modulated by diverse experimental conditions. Therefore, in this study, we aimed to investigate whether or not application of soluble A¦Â alters the two types of theta frequency oscillatory network activity generated in rat hippocampal slices by application of the cholinergic and glutamatergic agonists carbachol or DHPG, respectively. Due to previous evidence that oscillatory activity can be differentially affected by different A¦Â peptides, we also compared and for their effects on theta rhythms in vitro at similar concentrations (0.5 to 1.0£¿¦ÌM). We found that reduces, with less potency than , carbachol-induced population theta oscillatory activity. In contrast, DHPG-induced oscillatory activity was not affected by a high concentration of but was reduced by . Our results support the idea that different amyloid peptides might alter specific cellular mechanisms related to the generation of specific neuronal network activities, instead of exerting a generalized inhibitory effect on neuronal network function. 1. Introduction Alzheimer¡¯s disease (AD) is a dementia of increasing prevalence [1], which is produced, at least in its early stages, by the extracellular accumulation of amyloid beta protein (A¦Â) [2¨C4]. Early deterioration of hippocampal function, likely induced by soluble A¦Â, contributes to the initial memory deficits observed in AD patients [4¨C8]. Interestingly, A¦Â encompasses several peptide species which differ in their length, solubility, biological activity, toxicity, and aggregation propensity [3, 4, 9]. and are the most abundant A¦Â peptides found in senile plaques and vascular deposits of AD patients [10, 11]; however, these deposits also contain A¦Â peptides with shorter sequences such as [12¨C14]. can be produced in AD patients by enzymatic cleavage of at its hydrophobic C-terminus [14, 15], and it has been proposed that constitutes one of the biologically active fragments of A¦Â [12, 16, 17]. Despite the extensive literature showing that the effects produced by are mostly reproduced by the full-length sequence [3, 12, 16, 18¨C28], other reports indicate that this is not always the case. For instance, it has been shown that the reduction in long term
%U http://www.hindawi.com/journals/ijpep/2013/328140/