Reated WT mice at the highest agonist concentration (Figure 8C, Table
Reated WT mice at the highest agonist concentration (Figure 8C, Table 2). Although beyond the scope of the present investigation, further experiments could involve testing the effects of selective B2R antagonists on the biphasic response to BK.SSR240612 effects on brain and vascular BK receptorseNOS protein levels were increased in cerebral arteries (+40 to 50 ; P <0.05), and both were normalized by SSR240612 administration independent of treatment duration (Figure 9C).The effects of SSR240612 on brain and vascular BK receptors were measured using western blot. B1R protein levels were significantly increased only in the hippocampus from APP mice, as shown in the two mouse cohorts treated for 5 or 10 weeks (+41 , P <0.01; and +32 , P <0.05; respectively) (Figure 9A,B). SSR240612 treatment slightly reduced this upregulation in hippocampus, bringing B1R protein levels in treated APP mice indistinguishable from those of PubMed ID:https://www.ncbi.nlm.nih.gov/pubmed/28298493 WT controls after 10 weeks of drug delivery (Figure 9B, right). Neither genotype nor treatment altered B2R protein levels in cortex and hippocampus. Knowing that B2R and endothelial NOS (eNOS) activation mediate the effects of BK on brain arteries [33], their protein levels were measured in pial vessels. B1R protein was not detected in vascular extracts (Figure 9C), confirming our immunohistochemical observations. However, in APP mice, B2R andDiscussion Our study i) shows a selective astrocytic upregulation of B1R, being almost exclusively associated with A plaques, in the hippocampus of APP mice with impaired memory, and ii) demonstrates that chronic blockade of B1R significantly improves learning and memory performances, cerebrovascular function, as well as several anatomopathological AD hallmarks in APP mice with a fully PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/27766426 developed pathology. These findings strongly support a deleterious effect of kinin B1R in AD pathogenesis.Selective B1R upregulation on A plaque-associated astrocytes in hippocampus of APP micePrevious in vivo studies in rats [17] or mice [18] showed increases in brain B1R binding sites or protein levels after a single i.c.v. infusion of human A1-40. Here, with western blot analysis we found an upregulation of B1R protein levels in the hippocampus, but not cerebralACBF response ( increase)Dilatation ( induced tone)B*80 60 40 2010 9 8 7 6CDiameter ( induced tone)0 -50 -10 9 8 7 620 10+ -* **+WTAPPACh [-log M]BK [-log M]Figure 8 SSR240612 improved evoked CBF responses to sensory stimulation in vivo and cerebrovascular reactivity ex vivo. (A) In APP mice, B1R antagonism (+) significantly ameliorated, but did not fully restore, the cerebral blood flow (CBF) response evoked by whisker stimulation. (B,C) Isolated and pressurized middle cerebral artery segments from APP mice () displayed impaired dilation to I-CBP112 site acetylcholine (ACh) (B) and reduced, albeit non-significantly, the biphasic response (contraction followed by relaxation) to bradykinin (BK) (C). Treatment with SSR240612 in APP mice () completely rescued dilation to ACh (B) but had no significant effect on vascular responses to BK (C). Error bars represent SEM. *P <0.05; **P <0.01, ***P <0.001, Two-way ANOVA followed by Newman-Keuls post hoc test. N = 4 to 6/group. ( WT; WT treated). APP, amyloid precursor protein; B1R, bradykinin receptor 1; WT, wild-type.Lacoste et al. Journal of Neuroinflammation 2013, 10:57 http://www.jneuroinflammation.com/content/10/1/Page 13 ofTable 2 Effects of SSR240612 treatments on cerebrovascular responses to ACh and BKSSR 5.