Open field test.

<p>Spontaneous activity and exploratory behaviour of CTR (black, n = 17), HET (half tone, n = 16) and cKO mice (white, n = 18) was recorded over a time period of 20 min in the open field arena. Means + SEM are shown. (A) Total distance of movement during the habitation period in the open field (P = 0.138). (B) Illustration of two representative sample tracks from a CTR (left) and cKO (right) animal. (C) Percentage of total time spent in the inner squares of the open field. (D) Average speed of mice during movement within the central (left) and peripheral (right) area. ### <i>P</i><0.01; *** <i>P</i><0.001 (Kruskal-Wallis one way ANOVA on ranks & Dunn's post hoc test)</p

Immunohistochemical comparison of the expression pattern of Ca_V2.1 in the forebrain and cerebellum of CTR and cKO mice shows a selective knock-out in the hippocampus and neocortex of cKO mice.

<p>(A) Ca_V2.1 immunofluorescence staining in cerebellum demonstrating a high expression of Ca_V2.1 in Purkinje cell layers of both CTR and cKO mice indicating that the NEX/Cre-mediated knock out strategy did not affect Ca_V2.1 expression in cerebellum. (B) to (D) Ca_V2.1 immunofluorescence staining of horizontal sections of the dentate gyrus, neocortex and hippocampal CA1 to CA3 regions demonstrates expression of Ca_V2.1 throughout CA1, CA2, CA3, dentate gyrus and neocortex in CTR and a hardly detectable expression of Ca_V2.1 in cKO mice. Ca_V2.1 expression is shown in red, DAPI in blue. Scale bars: (A) 100 µm (inset 50 µm); (B) 100 µm (inset 50 µm); (C) 50 µm; (D) 50 µm.</p

Object recognition task.

<p>Evaluation of the non-spatial hippocampal memory of CTR (black, n = 18), HET (half tone, n = 15) and cKO mice (white, n = 18). (A) Object recognition index is defined as follows: The object recognition index (OR_index) was defined as OR_index =  [T_cone/(T_orb + T_cone)]×100. (T_orb  =  interaction time with the familiar and T_cone interaction time with the new object). Chance level is indicated by the dashed line. Error bars indicate SEM. (B) Total object-interaction time (means + SEM) as an indicator for exploratory drive. # P<0.05; ## P<0.03 (one-way ANOVA & Student-Newman-Keuls post hoc test)</p

Synaptic transmission at Schaffer collateral-mediated inputs onto CA1 pyramidal cells of cKO mice is impaired.

<p>(A) Confocal image stack of an intracellular labeled CA1 pyramidal cell (PC) in a cKO mouse counterstained with DAPI. Inset, superimposed voltage traces of the same PC in response to a 100 pA depolarizing and 50 pA hyperpolarizing current injection (1 s). (B) Representative traces of pyramidal cell EPSCs evoked by extracellular stimulation of Schaffer collaterals (stimulation intensity 100 volts), in CTR (gray) and cKO mice (blue). Arrow marks the time point of stimulation. (C) Summary plot of amplitudes of EPSCs evoked by Schaffer collaterals stimulation at different intensities in CTR (n = 7) and cKO (n = 10) PCs. Means + SEM are shown. (D) Left, average of EPSCs evoked by a train of 100 stimulation pulses at 50 Hz (Black dots indicate the time points of extracellular stimulation, stimulation artifacts have been removed for clarity). Right, synaptic charge transferred during trains of Schaffer collateral-mediated EPSCs is characterized by an early facilitation in both CTR and cKO animals, but strong multiple-pulse facilitation in cKO PCs (n = 9) and multiple-pulse depression in CTR PCs (n = 6) of mice. * <i>P</i>≤0.05; ** <i>P</i>≤0.01; *** <i>P</i>≤0.001 (Two-tailed student <i>t</i>-test)</p

Ablation of Ca_V2.1 Voltage-Gated Ca²⁺ Channels in Mouse Forebrain Generates Multiple Cognitive Impairments

<div><p>Voltage-gated Ca_V2.1 (P/Q-type) Ca²⁺ channels located at the presynaptic membrane are known to control a multitude of Ca²⁺-dependent cellular processes such as neurotransmitter release and synaptic plasticity. Our knowledge about their contributions to complex cognitive functions, however, is restricted by the limited adequacy of existing transgenic Ca_V2.1 mouse models. Global Ca_V2.1 knock-out mice lacking the α1 subunit <i>Cacna1a</i> gene product exhibit early postnatal lethality which makes them unsuitable to analyse the relevance of Ca_V2.1 Ca²⁺ channels for complex behaviour in adult mice. Consequently we established a forebrain specific Ca_V2.1 knock-out model by crossing mice with a floxed Cacna1a gene with mice expressing Cre-recombinase under the control of the <i>NEX</i> promoter. This novel mouse model enabled us to investigate the contribution of Ca_V2.1 to complex cognitive functions, particularly learning and memory. Electrophysiological analysis allowed us to test the specificity of our conditional knock-out model and revealed an impaired synaptic transmission at hippocampal glutamatergic synapses. At the behavioural level, the forebrain-specific Ca_V2.1 knock-out resulted in deficits in spatial learning and reference memory, reduced recognition memory, increased exploratory behaviour and a strong attenuation of circadian rhythmicity. In summary, we present a novel conditional Ca_V2.1 knock-out model that is most suitable for analysing the <i>in vivo</i> functions of Ca_V2.1 in the adult murine forebrain.</p></div

Elevated plus maze.

<p>Explorative activity of CTR (black, n = 19), HET (half tone, n = 18) and cKO mice (white, n = 19) was recorded over a time period of 5 min during an elevated plus maze test. Means + SEM are shown for (A) to (C). (A) Percentage of time spent at the open arms of the elevated plus maze. (B) Percentage of the covered distance only at the open arms. (C) Total distance covered during exploration of the elevated plus maze (P = 0.428). (D) Percentage of crashes during the trial. * <i>P</i><0.005; ** <i>P</i><0.003 (Kruskal-Wallis one way ANOVA on ranks & Dunn's post hoc test)</p

Circadian wheel running activity.

<p>Voluntary wheel running activity was recorded for 14 days for 10 CTR and 10 cKO mice (horizontal tracks). Each track shows running activity for 12 h nighttime (grey) and 12 h daytime (white). Within each area black bars indicate the percentage of running time shown for a 15-min time window each.</p

Expression of functional Ca_V2.1 channels is strongly reduced in the hippocampus of cKO mice.

<p>(A and B) Representative EPSCs recorded in CA1 PCs evoked by extracellular stimulation of the stratum radiatum before (gray) and after (black) bath-application of ω-conotoxin GVIA (left) or ω -agatoxin IVA (right). PC recordings were obtained from CTR (A) and cKOs (B). (C) Bar graph summarizes the residual peak amplitude of EPSCs after toxin application for CTR (each 6 experiments) and cKO (5 vs. 6 experiments) mice. Means + SEM are shown. *** <i>P</i>≤0.001 (Two-tailed Student’s <i>t</i>-test)</p

Additional file 1: of The NOTCH3 score: a pre-clinical CADASIL biomarker in a novel human genomic NOTCH3 transgenic mouse model with early progressive vascular NOTCH3 accumulation

Supplemental materials. (DOCX 2768 kb

La Petite presse : journal quotidien... / [rédacteur en chef : Balathier Bragelonne]

21 juin 18691869/06/21 (A4,N1159)