Abstract
Beta‐amyloid (Aβ) is a neuro‐peptide implicated in the pathogenesis of Alzheimer's disease (AD). Aβ‐peptide is known to disrupt cellular processes, including synaptic plasticity. To date, the precise mechanisms leading to the Aβ‐mediated impairment of normal neurophysiological function still remains elusive. A rise in the pro‐inflammatory cytokine interleukin‐1‐β (IL‐1β) has been previously reported, following Aβ peptide insult. IL‐1β in turn, activates a cascade of pro‐apoptotic markers, gradually leading to cell death. In this work, we have investigated the possible protective effects of interleukin‐1 receptor antagonist (IL‐1ra) on the effects of Aβ‐peptide on long‐term potentiation (LTP) in the CA1 region of the rat hippocampus in vivo. We observed a significant depression of LTP in the group of animals that received intracerebroventricular (icv) injection of Aβ‐peptide (1–40) compared with control animals injected with vehicle. Administration of IL‐1ra alone (icv) also resulted in a depression of LTP; however, there was no change in the baseline synaptic response. Combined injection of Aβ(1–40) + IL‐1ra caused an attenuation of the effects observed with Aβ(1–40) alone for a period of up to 15 min following LTP induction; rescuing post‐tetanicpotentiation (PTP). Gradually however, EPSP‐values declined to produce a level of LTP similar to that observed following treatment with Aβ(1–40) alone. These results suggest that the acute Aβ‐mediated impairment of PTP and LTP may be partial as a result of activation of an inflammatory response and the release of IL‐1β. The attenuation of plasticity by IL‐1ra alone supports the theory that low levels of IL‐1β are required for normal synaptic plasticity. The limited rescue of the Aβ‐mediated effects on LTP, in the presence of IL‐1ra, may represent the short half life found with this receptor antagonist in vivo. © 2008 Wiley‐Liss, Inc.