ABSTRACT
BACKGROUND AND PURPOSE: Aß-induced neuronal toxicity and memory loss is thought to be dependent on neuroinflammation, an important event in Alzheimer's disease (AD). Previously, we demonstrated that the blockage of the kinin B2 receptor (B2R) protects against the memory deficits induced by amyloid ß (Aß) peptide in mice. In this study, we aimed to investigate the role of B2R on Aß-induced neuroinflammation in mice and the beneficial effects of B2R blockage in synapses alterations. EXPERIMENTAL APPROACH: The selective kinin B2R antagonist HOE 140 (50 pmol/site) was given by intracerebroventricular (i.c.v.) route to male Swiss mice 2 h prior the i.c.v. injection of Aß(1-40) (400 pmol/site) peptide. Animals were sacrificed, at specific time points after Aß(1-40) injection (6 h, 1 day or 8 days), and the brain was collected in order to perform immunohistochemical analysis. Different groups of animals were submitted to behavioral cognition tests on day 14 after Aß(1-40) administration. KEY RESULTS: In this study, we report that the pre-treatment with the selective kinin B2R antagonist HOE 140 significantly inhibited Aß-induced neuroinflammation in mice. B2R antagonism reduced microglial activation and the levels of pro-inflammatory proteins, including COX-2, iNOS and nNOS. Notably, these phenomena were accompanied by an inhibition of MAPKs (JNK and p38) and transcription factors (c-Jun and p65/NF-κB) activation. Finally, the anti-inflammatory effects of B2R antagonism provided significant protection against Aß(1-40)-induced synaptic loss and cognitive impairment in mice. CONCLUSIONS AND IMPLICATIONS: Collectively, these results suggest that B2R activation may play a critical role in Aß-induced neuroinflammation, one of the most important contributors to AD progression, and its blockage can provide synapses protection.
