PSD-95 in CA1 area regulates spatial choice depending on age

Cognitive processes that require spatial information rely on synaptic plasticity in the dorsal CA1 area (dCA1) of the hippocampus. Since the function of the hippocampus is impaired in aged individuals, it remains unknown how aged animals make spatial choices. Here, we used IntelliCage to study behavioural processes that support spatial choices of aged female mice living in a group. As a proxy of training-induced synaptic plasticity, we analysed the morphology of dendritic spines and expression of a synaptic scaffold protein, PSD-95. We observed that spatial choice training in young adult mice induced correlated shrinkage of dendritic spines and downregulation of PSD-95 in dCA1. Moreover, long-term depletion of PSD-95 by shRNA in dCA1 limited correct choices to a reward corner, while reward preference was intact. In contrast, old mice used behavioural strategies characterised by an increased tendency for perseverative visits and social interactions. This strategy resulted in a robust preference for the reward corner during the spatial choice task. Moreover, training decreased the correlation between PSD-95 expression and the size of dendritic spines. Furthermore, PSD-95 depletion did not impair place choice or reward preference in old mice. Thus, our data indicate that while young mice require PSD-95-dependent synaptic plasticity in dCA1 to make correct spatial choices, old animals observe cage-mates and stick to a preferred corner to seek the reward. This strategy is resistant to the depletion of PSD-95 in the CA1 area. Overall, our study demonstrates that aged mice combine alternative behavioral and molecular strategies to approach and consume rewards in a complex environment

Whole-body clearing, staining and screening of calcium deposits in the mdx mouse model of Duchenne muscular dystrophy

Abstract Background Duchenne muscular dystrophy (DMD) is a fatal, X-linked genetic disorder. Although DMD is the most common form of muscular dystrophy, only two FDA-approved drugs were developed to delay its progression. In order to assess therapies for treating DMD, several murine models have recently been introduced. As the wide variety of murine models enlighten mechanisms underlying DMD pathology, the question on how to monitor the progression of the disease within the entire musculoskeletal system still remains to be answered. One considerable approach to monitor such progression is histological evaluation of calcium deposits within muscle biopsies. Although accurate, histology is limited to small tissue area and cannot be utilized to evaluate systemic progression of DMD. Therefore, we aimed to develop a methodology suitable for rapid and high-resolution screening of calcium deposits within the entire murine organism. Methods Procedures were performed on adult male C57BL/10-mdx and adult male C57BL mice. Animals were sacrificed, perfused, paraformaldehyde-fixed, and subjected to whole-body clearing using optimized perfusion-based CUBIC protocol. Next, cleared organisms were stained with alizarin red S to visualize calcium deposits and subjected to imaging. Results Study revealed presence of calcium deposits within degenerated muscles of the entire C57BL/10-mdx mouse organism. Calcified deposits were observed within skeletal muscles of the forelimb, diaphragm, lumbar region, pelvic region, and hindlimb. Calcified deposits found in quadriceps femoris, triceps brachii, and spinalis pars lumborum were characterized. Analysis of cumulative frequency distribution showed different distribution characteristics of calcified deposits in quadriceps femoris muscle in comparison to triceps brachii and spinalis pars lumborum muscles (p < 0.001) and quadriceps femoris vs spinalis pars lumborum (p < 0.001). Differences between the number of calcified deposits in selected muscles, their volume, and average volume were statistically significant. Conclusions In aggregate, we present new methodology to monitor calcium deposits in situ in the mouse model of Duchenne muscular dystrophy. Sample imaging with the presented setup is feasible and applicable for whole-organ/body imaging. Accompanied by the development of custom-made LSFM apparatus, it allows targeted and precise characterization of calcium deposits in cleared muscles. Hence, presented approach might be broadly utilized to monitor degree to which muscles of the entire organism are affected by the necrosis and how is it altered by the treatment or physical activity of the animal. We believe that this would be a valuable tool for studying organs alternations in a wide group of animal models of muscle dystrophy and bone-oriented diseases

Stressors Length and the Habituation Effect—An EEG Study

The research described in this paper aimed to determine whether people respond differently to short and long stimuli and whether stress stimuli repeated over time evoke a habituation effect. To meet this goal, we performed a cognitive experiment with eight subjects. During this experiment, the subjects were presented with two trays of stress-inducing stimuli (different in length) interlaced with the main tasks. The mean beta power calculated from the EEG signal recorded from the two prefrontal electrodes (Fp1 and Fp2) was used as a stress index. The main results are as follows: (i) we confirmed the previous finding that beta power assessed from the EEG signal recorded from prefrontal electrodes is significantly higher for the STRESS condition compared to NON-STRESS condition; (ii) we found a significant difference in beta power between STRESS conditions that differed in length—the beta power was four times higher for short, compared to long, stress-inducing stimuli; (iii) we did not find enough evidence to confirm (or reject) the hypothesis that stress stimuli repeated over time evoke the habituation effect; although the general trends aggregated over subjects and stressors were negative, their slopes were not statistically significant; moreover, there was no agreement among subjects with respect to the slope of individual trends

Additional file 1: of Whole-body clearing, staining and screening of calcium deposits in the mdx mouse model of Duchenne muscular dystrophy

Figure S1. Implementation of apparatus for macroscopic imaging using light-sheet illumination. (a) General view. (b) Side view. (c) Front view. (1) camera, (2) stepper motor, (3) z-axis line module (here light microscope body, Zeiss), (4) base holder, (5) glass container, (6) line lasers, (7) metal block, (8) laser power supply. Figure S2. Perfusion-based CUBIC cleared rat organs stained with propidium iodide. Bright field images of whole rat organs (a) intestine, (b) kidney, (c) heart, (d) cerebellum and (e) spleen. Single squares in all panels - 5 × 5 mm. This figure has been adapted from the original article “Optimized perfusion-based CUBIC protocol for the efficient whole-body clearing and imaging of rat organs” by P. Matryba et al., J Biophotonics 2017, doi./10.1002/jbio.201700248 . Reproduced with permission 4358370973288. Figure S3. Comparison between optical and standard histopathology sectioning of Alizarin red S stained mdx mouse muscles. (a) Representative optical sections acquired during imaging with custom-made LSFM. Control animals present no staining-positive tissue. (b) Representative histopathology 4 μm sections observed with low and (c) high magnification. It has to be noted that histopathology images stay in line with optical sectioning, presenting petite deposits in triceps brachii and similar amount of deposits between quadriceps femoris and spinalis pars lumborum. White scale bar, 1 mm, black scale bar, 200 μm. Figure S4. Quantitative volume analysis of calcified deposits in mdx mouse. (a) Triceps brachii muscles from left and right side of the animals were compared. Differences between left vs. right side presented as % mineralization of muscle volume were not statistically significant (Wilcoxon test (W = 0.0, number of pairs = 3), p > 0.999). (b) Analysis of volume of muscles replaced by calcific deposits. Percent of mineralization in triceps brachii, quadriceps femoris and spinalis pars lumborum muscles was significantly different (Kruskal-Wallis test (K-W statistic = 5.6), p = 0.05, n = 3 per each muscle group). Figure S5. Perfusion-based CUBIC clearing does not alter microstructure of muscle. Perfusion-based CUBIC cleared triceps brachii and quadriceps femoris muscles of mdx and C57BL/10 control animals were subjected to standard hematoxylin and eosin histological staining. Low (10×) and high (20×) magnification representative images present microstructure preservation. It has to be noted that centrally positioned nuclei, a prominent feature of dystrophy, is maintained during mdx clearing. Scale bar, 100 μm. (ZIP 12014 kb

Metabolic syndrome is associated with similar long-term prognosis in non-obese and obese patients. An analysis of 45 615 patients from the nationwide LIPIDOGRAM 2004-2015 cohort studies

Aims We aimed to evaluate the association between metabolic syndrome (MetS) and long-term all-cause mortality. Methods The LIPIDOGRAM studies were carried out in the primary care in Poland in 2004, 2006 and 2015. MetS was diagnosed based on the National Cholesterol Education Program, Adult Treatment Panel III (NCEP/ATP III) and Joint Interim Statement (JIS) criteria. The cohort was divided into four groups: non-obese patients without MetS, obese patients without MetS, non-obese patients with MetS and obese patients with MetS. Differences in all-cause mortality was analyzed using Kaplan-Meier and Cox regression analyses. Results 45,615 participants were enrolled (mean age 56.3, standard deviation: 11.8 years; 61.7% female). MetS was diagnosed in 14,202 (31%) by NCEP/ATP III criteria, and 17,216 (37.7%) by JIS criteria. Follow-up was available for 44,620 (97.8%, median duration 15.3 years) patients. MetS was associated with increased mortality risk among the obese (hazard ratio, HR: 1.88 [95% CI, 1.79-1.99] and HR: 1.93 [95% CI 1.82-2.04], according to NCEP/ATP III and JIS criteria, respectively) and non-obese individuals (HR: 2.11 [95% CI 1.85-2.40] and 1.7 [95% CI, 1.56-1.85] according to NCEP/ATP III and JIS criteria respectively). Obese patients without MetS had a higher mortality risk than non-obese patients without MetS (HR: 1.16 [95% CI 1.10-1.23] and HR: 1.22 [95%CI 1.15-1.30], respectively in subgroups with NCEP/ATP III and JIS criteria applied). Conclusions MetS is associated with increased all-cause mortality risk in non-obese and obese patients. In patients without MetS obesity remains significantly associated with mortality. The concept of metabolically healthy obesity should be revised