Non-selective calcium channel blocker bepridil decreases secondary pathology in mice after photothrombotic cortical lesion.

Experimental studies have identified a complex link between neurodegeneration, β-amyloid (Aβ) and calcium homeostasis. Here we asked whether early phase β-amyloid pathology in transgenic hAPPSL mice exaggerates the ischemic lesion and remote secondary pathology in the thalamus, and whether a non-selective calcium channel blocker reduces these pathologies. Transgenic hAPPSL (n = 33) and non-transgenic (n = 30) male mice (4-5 months) were subjected to unilateral cortical photothrombosis and treated with the non-selective calcium channel blocker bepridil (50 mg/kg, p.o., once a day) or vehicle for 28 days, starting administration 2 days after the operation. Animals were then perfused for histological analysis of infarct size, Aβ and calcium accumulation in the thalamus. Cortical photothrombosis resulted in a small infarct, which was associated with atypical Aβ and calcium accumulation in the ipsilateral thalamus. Transgenic mice had significantly smaller infarct volumes than non-transgenic littermates (P<0.05) and ischemia-induced rodent Aβ accumulation in the thalamus was lower in transgenic mice compared to non-transgenic mice (P<0.01). Bepridil decreased calcium load in the thalamus (P<0.01). The present data suggest less pronounced primary and secondary pathology in hAPPSL transgenic mice after ischemic cortical injury. Bepridil particularly decreased calcium pathology in the thalamus following ischemia

Rodent β-amyloid (Aβ) staining following cortical photothrombosis.

<p>Digital photomicrographs showed atypical, Aβ deposits in the thalamus ipsilateral to the cortical lesion (<b>A–D</b>). The inserts <b>A1–D1</b> at higher magnification are taken from the same brain sections. The genotype had a significant effect on rodent Aβ load (two-way ANOVA, <i>P</i><0.05) being more pronounced in non-transgenic mice (<b>E</b>). Values are presented as mean±s.e.m. Scale bar: 500 µm (<b>A–D</b>), 20 µm (<b>A1–D1</b>).</p

Cellular localization of rodent Aβ deposits in the thalamus following cortical photothrombosis.

<p>Double immunofluorescence staining for rodent Aβ and NeuN <b>(A)</b> or rodent Aβ and GFAP <b>(B)</b> did not show co-localization in AD transgenic mice (arrows).</p

Rose Bengal induced cortical photothrombosis.

<p>(<b>A</b>) The cold light was positioned to illuminate the skull 2.4 mm right from Bregma. (<b>B</b>) Nissl-stained sections show a typical photothrombotic lesion in the right sensorimotor cortex (arrows). (<b>C</b>) The genotype had a significant effect on lesion size (two-way ANOVA, <i>P</i><0.05) with smaller lesions in transgenic mice. Values are presented as mean±s.e.m. Scale bar: 1 mm (<b>B</b>).</p

Confirmation of the transgenic Aβ phenotype.

<p>Human specific W0-2 staining against Aβ showed a relative high staining intensity in transgenic mice due to intracellular Aβ typical to young transgenic animals (A). A few plaques were observed (arrows). Only some non-specific staining was observed in non-transgenic mice due to degenerative processes (<b>B</b>). Scale bar: 400 µm.</p

Calcium staining (Alizarin Red) following cortical photothrombosis.

<p>Digital photomicrographs showed atypical, calcium deposits in the thalamus ipsilateral to the cortical lesion (<b>A–D</b>). The inserts <b>A1–D1</b> at higher magnification are taken from the same brain sections. Treatment had a significant effect on calcium accumulation (two-way ANOVA, <i>P</i><0.001) (<b>E</b>). Values are presented as mean±s.e.m. Scale bar: 500 µm (<b>A–D</b>), 20 µm (<b>A1–D1</b>).</p