Separate Microcircuit Modules of Distinct V2a Interneurons and Motoneurons Control the Speed of Locomotion

SummarySpinal circuits generate locomotion with variable speed as circumstances demand. These circuits have been assumed to convey equal and uniform excitation to all motoneurons whose input resistance dictates their activation sequence. However, the precise connectivity pattern between excitatory premotor circuits and the different motoneuron types has remained unclear. Here, we generate a connectivity map in adult zebrafish between the V2a excitatory interneurons and slow, intermediate, and fast motoneurons. We show that the locomotor network does not consist of a uniform circuit as previously assumed. Instead, it can be deconstructed into three separate microcircuit modules with distinct V2a interneuron subclasses driving slow, intermediate, or fast motoneurons. This modular design enables the increase of locomotor speed by sequentially adding microcircuit layers from slow to intermediate and fast. Thus, this principle of organization of vertebrate spinal circuits represents an intrinsic mechanism to increase the locomotor speed by incrementally engaging different motor units

Pharmacology of the 2nd type of diabetes mellitus - a review

This thesis was aimed to give a brief aspect of the most common endocrine disorder of the western world which is diabetes mellitus. Diabetes mellitus is a metabolic disorder in which there is an inability to oxidize carbohydrate due to disturbances in insulin function. The first part of the thesis covers the physiology of insulin, type and main complications of the disease. The main part describes most of the treatment methods available today and also provides a brief comparative study highlighting their main advantages and disadvantages. At the end, a short introduction into the novel treatment modalities - the Incretins (GLP-1 Agonists and DPP-4 Inhibitors) is discussed

Plasticity mechanisms in adult Zebrafish brain (Danio rerio): sexual differentiations

The aim of this study is to determine possible sex-related differences in plasticity mechanisms in the adult zebrafish brain. Detailed mapping of glucose brain utilization observed to be heterogeneously distributed throughout the brain. In general, the female demonstrated higher glucose uptake rates than male individuals. Statistical analysis of the data revealed sexdimorphisms in [¹⁴C]2-deoxyglucose uptake in all studied hypothalamic areas, in optic tectum, in torus semicircularis, in superficial reticular formation and in valvula cerebellum. In all of these areas the female zebrafish showed higher glucose utilization rates than males. We studied possible gender-related differences in the localization and density of α₂- and β-adrenoceptors (AR) in the adult zebrafish (Danio rerio) brain, using in vitro quantitative autoradiography with the selective ligands [³H]RX821002 and [³H]CGP12177 to label the adrenoceptors. Binding sites were observed to be heterogeneously distributed throughout the brain. In both sexes dense α₂-ARs were observed in the locus coeruleus (LC), magnocellular octaval nucleus (MaON) and dorsal telencephalic (Dc, Dp) nuclei. However, β-ARs were found in dense binding in LC, in all cerebellar subdivisions, in dorsal zone of periventricular hypothalamus (Hd), and in ventral telencephalic nuclei. In addition we performed immunohistochemical studies to reveal the regional distribution of α₂A-ARs, β₂-ARs and adrenaline in the adult zebrafish brain. Detailed mapping showed labeling of α₂A-ARs, in neuropil, neuronal somata and fibers, glial processes and blood vessels. High density of α₂A-AR, β₂-ARs and adrenaline immunoreactivity was found in the ventral telencephalic area, preoptic, pretectal, hypothalamic areas, torus semicircularis, oculomotor nucleus (NIII), locus coeruleus (LC), medial raphe, medial octavolateralis nucleus (MON), magnocellular octaval nucleus (MaON), reticular formation (SRF, IMRF, IRF), cerebellar Purkinje cell layer and especially α₂A-ARs found in rhombencephalic nerves roots (DV, V, VII, VIII, X). Moderate levels of α₂A-ARs, β2-ARs and adrenaline were observed in the dorsal telencephalic area, in the periventricular gray zone of optic tectum, in the dorsomedial part of optic tectum layers, in the molecular and granular layer of all cerebellum subdivisions. Glial processes were found to express α₂A -ARs in rhombencephalon, intermingled with neuronal fibers. Medium size neurons were labelled in telencephalic, diencephalic and mesencephalic areas, while densely labelled large neurons were found in rhombencephalon, in the locus coeruleus, the reticular formation, the oculomotor, the medial octavolateralis and magnocellular octaval nuclei and Purkinje cell somata. From double labelled experiments also both neuronal and glial localization of β₂ARs and adrenaline were revealed. Dimorphisms in the density of α₂-ARs binding was identified in dorsal telencephalic Dl nucleus, preoptic PPa and PPp nuclei, hypothalamic nucleus (Hd), central gray (GC), and in granular layer of corpus and caudal lobe of cerebellum (CCe gr, LCa gr). In all these areas the females showed higher [³H]RX821002 binding than males. However, only four areas showed sex dimorphisms in the density of β-ARs, the Hd, GC, CCe gr and LCa gr. In Hd and GC females showed higher [³H]CGP12177 binding levels than males, while males demonstrated higher levels than females in CCe gr and LCa gr. The localization of [³H]RX821002 and [³H] CGP12177 binding sites and the sex dimorphisms in adrenoceptor densities in particular brain regions, indicates that the adrenergic/noradrenergic system could be associated with the control of essential functions as sex determination, reproductive behaviour, and other sex-specific behaviours.Αυτή είναι η πρώτη εργασία µε στόχο τη µελέτη των µηχανισµών πλαστικότητας του ενήλικου εγκεφάλου του zebrafish για την ανάδειξη φυλετικών διαφοροποιήσεων. Στην παρούσα ερευνητική προσπάθεια µελετήθηκε η µεταβολική δραστηριότητα του εγκεφάλου µε χρήση της in vivo αυτοραδιογραφικής µεθόδου της [¹⁴C]2-deoxyglucose καθώς και η έκφραση των α₂ και β αδρενεργικών υποδοχέων µε χρήση in vitro αυτοραδιογραφικών ποσοτικών µεθόδων και ανοσοϊστοχηµικών µεθόδων. Επιπρόσθετα, µελετήθηκε η ανοσοέκφραση της αδρεναλίνης η οποία είναι ο φυσικός προσδέτης των αδρενεργικών υποδοχέων. Καθώς είναι η πρώτη φορά που µελετάτε η έκφραση των αδρενεργικών υποδοχέων στο κ εντρικό νευρικό σύστηµα ενηλίκων ατόµων zebrafish κρίθηκε αναγκαία η χαρτογράφηση της θέσης των αδρενεργικών υποδοχέων και η µελέτη των χαρακτηριστικών τους, µε πειράµατα κορεσµού. Τα πειράµατα χαρτογράφησης της απορρόφησης της γλυκόζης ανέδειξαν την υψηλή ετερογένεια της µεταβολικής δραστηριότητας στον ενήλικο εγκέφαλο του zebrafish. Γενικά, τα θηλυκά άτοµα εµφάνισαν υψηλότερο ρυθµό απορρόφησης της γλυκόζης σε σχέση µε τα αρσενικά άτοµα. Η στατιστική ανάλυση των αποτελεσµάτων έδειξε την ύπαρξη φυλετικών διµορφισµών σε όλες τις περιοχές του υποθαλάµου που µελετήθηκαν, στην οπτική καλύπτρα, στο επιµήκες κέρας, στον ανώτερο δικτυωτό σχηµατισµό και στην πρόσθια ή βαλβιδική παρεγκεφαλίδα. Σε όλες τις προαναφερθείσες περιοχές τα θηλυκά είχαν υψηλότερο ρυθµό µεταβολικής δραστηριότητας σε σχέση µε τα αρσενικά άτοµα. Οι µελέτες κορεσµού έδειξαν την υψηλής συγγένειας πρόσδεση των [³Η]RX811002 και [³Η]CGP12177 στους α₂ και β αδρενεργικούς υποδοχείς αντίστοιχα. Υψηλά επίπεδα εντοπισµού και των δύο αδρενεργικών υποδοχέων εντοπίστηκαν στον υποµέλανα τόπο, και στην ραχιαία ζώνη του περικοιλιακού υποθαλάµου (Hd). Η κεντρική και οπίσθια ζώνη της ραχιαίας τελεγκεφαλικής περιοχής (Dc, Dp), η κατιούσα ρίζα του τριδύµου (DV) και ο µεγακυτταρικός πυρήνας του ακουστικού νεύρου (MaON) διέθεταν υψηλές πυκνότητες α₂ αδρενεργικών υποδοχέων. Υψηλή πυκνότητα των β αδρενεργικών υποδοχέων εντοπίστηκε στον πλάγιο και κοιλιακό πυρήνα της κοιλιακής τελεγκεφαλικής περιοχής (Vl, Vv), στον πρόσθιο και οπίσθιο µεγακυτταρικό προοπτικό πυρήνα (PPa, PPp), και σε όλες της περιοχές της παρεγκεφαλίδας. Η στατιστική επεξεργασία των αποτελεσµάτων έδειξε την ύπαρξη φυλετικών διµορφισµών στην πυκνότητα των α2 αδρενεργικών υποδοχέων στην πλευρική ζώνη της ραχιαίας τελεγκεφαλικής περιοχής (Dl), στους προοπτικούς πυρήνες PPa και PPp, στον υποθαλαµικό πυρήνα Hd, στην κοκκώδη στοιβάδα του παρεγκεφαλιδικού σώµατος (CCe gr) και του οπίσθιου λοβού της παρεγκεφαλίδας (LCa gr) και στην περιοχής κεντρική φαιάς ουσίας (GC), σε όλες αυτές τις περιοχές τα θηλυκά άτοµα διέθετα υψηλότερες συγκεντρώσεις α₂ αδρενεργικών υποδοχέων από τα αρσενικά άτοµα. Η µελέτη της πυκνότητας των β αδρενεργικών υποδοχέων έδειξε την ύπαρξη διαφοροποιήσεων στον υποθαλαµικό πυρήνα Hd, στις παρεγκεφαλιδικές περιοχές CCe gr και LCa gr, και στην περιοχής κεντρική φαιάς ουσίας (GC). Στις παρεγκεφαλιδικές περιοχές τα αρσενικά διέθεταν µεγαλύτερη συγκέντρωση β αδρενεργικών υποδοχέων από τα θηλυκά άτοµα. Αντίθετα, στον Ηd και στον GC, µεγαλύτερες πυκνότητες β αδρενεργικών υποδοχέων εντοπίστηκαν στα θηλυκά άτοµα από τα αρσενικά ενήλικα zebrafish. Η ανοσο-χαρτογράφηση της αδρεναλίνης και των α₂A , α₂C και β₂ αδρενεργικών υποδοχέων στον ενήλικο εγκέφαλο του zebrafish, εµφανίσθηκε να είναι ετερογενής. Οι αδρενεργικοί υποδοχείς καθώς και η αδρεναλίνη εντοπίστηκαν σε ίνες, σε κιρσοειδής ίνες, στο νευροπήλιµα, σε εντοπίστηκαν σε ίνες, σε κιρσοειδής ίνες, στο νευροπήλιµα, σε κυτταρικά σώµατα και οι α₂A αδρενεργικοί υποδοχείς εντοπίστηκαν και σε αιµοφόρα αγγεία. Επιπρόσθετα, εντοπίστηκαν νευρικά κυτταρικά σώµατα και ίνες γλοίας που εξ έφραζαν τους αδρενεργικούς υποδοχείς. Ωστόσο δεν εντοπίστηκαν φυλετικές διαφοροποιήσεις στον ανοσοεντοπισµό των αδρενεργικών υποδοχέων και της αδρεναλίνης. Τα βιοχηµικά χαρακτηριστικά, το πρότυπο κατανοµής, και ο νευρικός ή γλοιακός χαρακτήρας των υποδοχέων στον εγκέφαλο του τελεόστεου ιχθύ zebrafish ενισχύει το παρόµοιο πρότυπο της αδρενεργικής-νοραδρενεργικής νεύρωσης των υπολοίπων σπονδυλωτών

A new transgenic reporter line reveals expression of protocadherin 9 at a cellular level within the zebrafish central nervous system

The wiring of neuronal networks is far from understood. One outstanding question is how neurons of different types link up to form subnetworks within the greater context. Cadherins have been suggested to create an inclusion code where interconnected neurons express the same subtypes. Here, we have used a CRISPR/Cas9 knock-in approach to generate a transgenic zebrafish reporter line for protocadherin 9 (pcdh9), which is predominantly expressed within the central nervous system. Expression of eGFP was detected in subsets of neurons in the cerebellum, retina and spinal cord, in both larvae and juveniles. A closer characterization of the spinal locomotor network revealed that a portion of distinct classes of both excitatory and inhibitory interneurons, as well as motor neurons, expressed pcdh9. This transgenic line could thus be used to test the cadherin network hypothesis, through electrophysiological characterization of eGFP positive cells, to show if these are synaptically connected and form a discrete network within the spinal cord

Lifelong regeneration of cerebellar Purkinje cells after induced cell ablation in zebrafish

Zebrafish have an impressive capacity to regenerate neurons in the central nervous system. However, regeneration of the principal neuron of the evolutionary conserved cerebellum, the Purkinje cell (PC), is believed to be limited to developmental stages based on invasive lesions. In contrast, non-invasive cell type-specific ablation by induced apoptosis closely represents a process of neurodegeneration. We demonstrate that the ablated larval PC population entirely recovers in number, quickly reestablishes electrophysiological properties, and properly integrates into circuits to regulate cerebellum-controlled behavior. PC progenitors are present in larvae and adults, and PC ablation in adult cerebelli results in an impressive PC regeneration of different PC subtypes able to restore behavioral impairments. Interestingly, caudal PCs are more resistant to ablation and regenerate more efficiently, suggesting a rostro-caudal pattern of de- and regeneration properties. These findings demonstrate that the zebrafish cerebellum is able to regenerate functional PCs during all stages of the animal's life

One-Year Outcomes of CGuard Double Mesh Stent in Carotid Artery Disease: A Systematic Review and Meta-Analysis

Background: Prospective single and multicenter studies have shown improved outcomes of patients who underwent carotid artery stenting with the novel CGuard dual-layer mesh stent at 1 year. Objectives: The aim of this study is to conduct a systematic review and meta-analysis of all published studies to assess 1-year efficacy and outcomes of CGuard in patients with carotid stenting. Methods: A systematic search was performed. All studies enrolling at least 20 patients were included in our analysis. The primary endpoints were death (all-cause, cardiovascular and ipsilateral stroke-related death) and stroke rate at 1 year. The secondary endpoint was in-stent restenosis at 1 year. Results: The final analysis included 1709 patients. The one-year all-cause mortality rate was 2.97% (39/1699, 95% CI: 1.26–6.86%, I2 = 67%, t2 = 0.3442, p 2 = 34%, t2 = 0.2302, p = 0.18), and ipsilateral stroke-related death was 0.3% (1/1649, 95% CI: 0.1–0.87%, I2 = 0%, t2 = 0, p = 0.69). The one-year ipsilateral stroke rate was 1.21% (16/1649, 95% CI: 0.58–2.5%, I2 = 28%, t2 = 0.1433, p = 0.23), transient ischemic attacks (TIAs) rate was 1.78% (19/1149, 95% CI: 1.11–2.84%, I2 = 0%, t2 = 0, p = 0.69), and total composite 1-year stroke/TIA rate was 2.97% (32/1149, 95% CI: 1.84–4.77%, I2 = 0%, t2 = 0, p = 0.41). The in-stent restenosis rate at 1 year was 1.06% (13/1653, 95% CI: 0.48–2.34%, I2 = 28%, t2 = 0.2308, p = 0.22). Conclusions: This meta-analysis shows that CAS with CGuard is safe with minimal neurological adverse events and in-stent restenosis rate at 1 year

High cardiomyocyte diversity in human early prenatal heart development

Summary: Cardiomyocytes play key roles during cardiogenesis, but have poorly understood features, especially in prenatal stages. Here, we characterized human prenatal cardiomyocytes, 6.5–7 weeks post-conception, by integrating single-cell RNA sequencing, spatial transcriptomics, and ligand-receptor interaction information. Using a computational workflow developed to dissect cell type heterogeneity, localize cell types, and explore their molecular interactions, we identified eight types of developing cardiomyocyte, more than double compared to the ones identified in the Human Developmental Cell Atlas. These have high variability in cell cycle activity, mitochondrial content, and connexin gene expression, and are differentially distributed in the ventricles, including outflow tract, and atria, including sinoatrial node. Moreover, cardiomyocyte ligand-receptor crosstalk is mainly with non-cardiomyocyte cell types, encompassing cardiogenesis-related pathways. Thus, early prenatal human cardiomyocytes are highly heterogeneous and develop unique location-dependent properties, with complex ligand-receptor crosstalk. Further elucidation of their developmental dynamics may give rise to new therapies

Neuron-glia interaction through Serotonin-BDNF-NGFR axis enables regenerative neurogenesis in Alzheimer's model of adult zebrafish brain.

It was recently suggested that supplying the brain with new neurons could counteract Alzheimer's disease (AD). This provocative idea requires further testing in experimental models in which the molecular basis of disease-induced neuronal regeneration could be investigated. We previously found that zebrafish stimulates neural stem cell (NSC) plasticity and neurogenesis in AD and could help to understand the mechanisms to be harnessed for developing new neurons in diseased mammalian brains. Here, by performing single-cell transcriptomics, we found that amyloid toxicity-induced interleukin-4 (IL4) promotes NSC proliferation and neurogenesis by suppressing the tryptophan metabolism and reducing the production of serotonin. NSC proliferation was suppressed by serotonin via down-regulation of brain-derived neurotrophic factor (BDNF)-expression in serotonin-responsive periventricular neurons. BDNF enhances NSC plasticity and neurogenesis via nerve growth factor receptor A (NGFRA)/ nuclear factor 'kappa-light-chain-enhancer' of activated B-cells (NFkB) signaling in zebrafish but not in rodents. Collectively, our results suggest a complex neuron-glia interaction that regulates regenerative neurogenesis after AD conditions in zebrafish