A lymphofollicular microenvironment is required for pathological prion protein deposition in chronically inflamed tissues from scrapie-affected sheep

In sheep scrapie, pathological prion protein (PrPSc) deposition occurs in the lymphoreticular and central nervous systems. We investigated PrPSc distribution in scrapie- affected sheep showing simultaneous evidence of chronic lymphofollicular, lymphoproliferative/non-lymphofollicular,and/or granulomatous inflammations in their mammary gland, lung, and ileum. To do this, PrPSc detection was carried out via immunohistochemistry and Western Blotting techniques, as well as through inflammatory cell immunophenotyping. Expression studies of gene coding for biological factors modulating the host’s inflammatory response were also carried out. We demonstrated that ectopic PrPSc deposition occurs exclusively in the context of lymphofollicular inflammatory sites, inside newly formed and well-organized lymphoid follicles harboring follicular dendritic cells. On the contrary, no PrPSc deposition was detected in granulomas, even when they were closely located to newly formed lymphoid follicles. A significantly more consistent expression of lymphotoxin α and β mRNA was detected in lymphofollicular inflammation compared to the other two types, with lymphotoxin α and β signaling new lymphoid follicles’ formation and, likely, the occurrence of ectopic PrPSc deposition inside them. Our findings suggest that, in sheep co-affected by scrapie and chronic inflammatory conditions, only newly formed lymphoid follicles provide a suitable micro-environment that supports the scrapie agent’s replication in inflammatory sites, with an increased risk of prion shedding through body secretions/excretions.[...

Mir-132/212 is required for maturation of binocular matching of orientation preference and depth perception

MicroRNAs (miRNAs) are known to mediate post-transcriptional gene regulation, but their role in postnatal brain development is still poorly explored. We show that the expression of many miRNAs is dramatically regulated during functional maturation of the mouse visual cortex with miR-132/212 family being one of the top upregulated miRNAs. Age-downregulated transcripts are significantly enriched in miR-132/miR-212 putative targets and in genes upregulated in miR-132/212 null mice. At a functional level, miR-132/212 deletion affects development of receptive fields of cortical neurons determining a specific impairment of binocular matching of orientation preference, but leaving orientation and direction selectivity unaltered. This deficit is associated with reduced depth perception in the visual cliff test. Deletion of miR-132/212 from forebrain excitatory neurons replicates the binocular matching deficits. Thus, miR-132/212 family shapes the age-dependent transcriptome of the visual cortex during a specific developmental window resulting in maturation of binocular cortical cells and depth perception

Morphological, physiological and behavioural evaluation of a ‘Mice in Space’ housing system

Environmental conditions likely affect physiology and behaviour of mice used for life sciences research on Earth or in Space. Here, we analysed the effects of cage confinement on the weightbearing musculoskeletal system, behaviour and stress of wild-type mice (C57BL/6JRj, 30 g b.wt., total n = 24) housed for 25 days in a prototypical ground-based and fully automated life support habitat device called “Mice in Space” (MIS). Compared with control housing (individually ventilated cages) the MIS mice revealed no significant changes in soleus muscle size and myofiber distribution (type I vs. II) and quality of bone (3-D microarchitecture and mineralisation of calvaria, spine and femur) determined by confocal and micro-computed tomography. Corticosterone metabolism measured non-invasively (faeces) monitored elevated adrenocortical activity at only start of the MIS cage confinement (day 1). Behavioural tests (i.e., grip strength, rotarod, L/D box, elevated plus-maze, open field, aggressiveness) performed subsequently revealed only minor changes in motor performance (MIS vs. controls). The MIS habitat will not, on its own, produce major effects that could confound interpretation of data induced by microgravity exposure during spaceflight. Our results may be even more helpful in developing multidisciplinary protocols with adequate scenarios addressing molecular to systems levels using mice of various genetic phenotypes in many laboratories

Modulation of [35S]TBPS binding by ligands with preferential affinity for benzodiazepine BZ1 sites in the cerebral cortex of newborn and adult rats

The present study was designed to compare the allosteric coupling between the Cl- channel of the GABA, receptor and the different benzodiazepine recognition site subtypes (BZ sites) in the cerebral cortex of newborn (5-day-old) and adult rats (90-day-old). To this aim, we reexamined the heterogeneity of cortical GABA(A) receptors in self- and cross-competition binding experiments using [H-3]flunitrazepam and two ligands with higher affinity for benzodiazepine BZ(1) sites relative to benzodiazepine BZ(2) sites, the triazolopyridazine 3-methyl-6-[3-(trifluoromethyl)phenyl]-1,2,4-triazolo [4,3-b] pyridazine (CL 218,872) and the imidazopyridine N,N,6-trimethyl-2-(4-methylphenyl)-imidazo[1,2-a]-pyridine-3-acetamide hemitartrate (zolpidem). Benzodiazepine BZ(1) sites accounted for 52% of the total number of binding sites in adult rats, but were not detected in newborn rats. On the other hand, two classes of benzodiazepine BZ(2) sites with high and low affinity for zolpidem were present in newborn and adult rats. These sites were designated as benzodiazepine BZ(2H) (high affinity for zolpidem, K-d similar to 150 nM) and benzodiazepine BZ(2L) (low affinity for zolpidem, K-d similar to 3000 nM). High densities of benzodiazepine BZ(2H) sites were measured in both newborn and adult rats (75% and 41% of the total number of [H-3]flunitrazepam binding sites, respectively), whereas benzodiazepine BZ(2L) sites accounted for 25% and 7% of the total number of cortical sites in neonates and adults, respectively. Flunitrazepam, CL 218,872 and zolpidem inhibited in a concentration-dependent manner the binding of [S-35]t-butylbicyclophosphorothionate ([S-35]TBPS) to the convulsant site of cortical GABA, receptors in newborn and adult rats. The IC50 for flunitrazepam was about 3-fold greater in adults than in neonates. This rightward shift in the concentration-response curve may be due to a decrease with age in the intrinsic efficacy of flunitrazepam. In contrast, CL 218,872 and zolpidem were 4-fold more potent at inhibiting [S-35]TBPS binding in adult rats relative to neonates. The different affinities of CL 218,872 and zolpidem for benzodiazepine BZ(1) and BZ(2) receptors may account, at least in part, for the age-related changes in their inhibitory potencies. These results demonstrate that benzodiazepine BZ(2) sites mediate the modulation of [S-35]TBPS binding by benzodiazepine recognition site ligands in the cerebral cortex of newborn rats. Further, benzodiazepine BZ(2) sites may be involved in the inhibition of [S-35]TBPS binding by flunitrazepam, CL 218,872 and zolpidem in the cerebral cortex of adult rats