Etude du système nerveux périphérique dans un modèle murin du syndrome de Schwartz-Jampel (rôle du perlecan dans le développement et la maintenance de la myélinisation et des interactions neurone-glie)

Le Syndrome de Schwartz-Jampel (SJS) est une maladie rare à transmission autosomique récessif. Elle est caractérisée par une raideur musculaire permanente résultant d une hyperactivité musculaire, associée à une chondrodystrophie. Elle résulte de mutations hypomorphes dans le gène codant pour le perlecan, un héparane sulphate protéoglycane présent dans toutes les membranes basales (MB). Le perlecan joue un rôle dans l organisation structurale et le maintien des MB et dans la signalisation cellulaire. Pour comprendre le mécanisme physiopathologique à l origine de la raideur musculaire du SJS, mon laboratoire a développé un modèle murin mimant le phénotype du SJS avec une hyperactivité musculaire apparaissant avec l âge. Pendant la 1ère partie de ma thèse, j ai démontré l existence d un effet dose du perlecan. J ai étudié deux lignées de souris mutantes au niveau phénotypique, moléculaire et morphologique. La 2ème partie de ma thèse s est attachée à identifier l origine de l hyperexcitabilité caractéristique du SJS et d étudier le rôle du perlecan dans le système nerveux périphérique (SNP). Une étude électromyographique chez nos souris a classifié le SJS comme une hyperexcitabilité nerveuse périphérique (HNP). J ai étudié le SNP de notre modèle afin de déterminer s il est morphologiquement affecté et la relation de ces modifications avec l HNP. Les résultats montrent qu ils n existent pas d anomalies majeures de myélinisation chez nos mutants en position proximale du nerf. Mais l étude des nœuds de Ranvier a montré un élargissement des nœuds et paranoeuds, une augmentation de l expression des canaux potassium et une augmentation du nombre d incisures de Schmidt-LantermanPARIS-BIUSJ-Biologie recherche (751052107) / SudocSudocFranceF

A combination of coenzyme Q10, feverfew and magnesium for migraine prophylaxis: a prospective observational study

Abstract Background Feverfew (Tanacetum parthenium L.), magnesium and coenzyme Q10 are frequently used for migraine prophylaxis. Supplementation with a fixed combination of these three agents (Antemig®, PiLeJe) was investigated in an observational study. Methods Adult patients suffering from migraine according to the criteria of the International Headache Society were enrolled by general practitioners (≥2 migraine attacks during previous month; exclusion of chronic migraine and medication overuse) and after a one-month baseline phase, supplemented with one tablet of 100 mg feverfew, 100 mg coenzyme Q10 and 112.5 mg magnesium per day for 3 months. Results Supplementation significantly reduced the number of days with migraine headache during third month of supplementation compared to baseline phase (1.3 days ±1.5 versus 4.9 days ±2.6, p < 0.0001; n = 68 intention to treat; primary criterion). The decrease was progressive over the period of supplementation and significant from first month (1st month: −2.5 days ±3.1, p < 0.0001; 2nd month: −3 days ±2.8, p < 0.0001). The proportion of patients with a reduction of at least 50% in the number of days with migraine headache was 75% (51/68) after 3 months, with a progressive increase over the period of supplementation (63.2% [43/68] after 1 month and 70.6% [48/68] after 2 months). The proportion of patients with anxiety and depressive symptoms (Hospital Anxiety and Depression Scale) decreased between baseline phase and third month of supplementation from 61.9% (39/63 patients with information available) to 35% (21/60) for depression and from 52.4% (33/63) to 30% (18/60) for anxiety. An improvement of quality of life (Qualité de Vie et Migraine questionnaire) was also observed. The combination was well tolerated. Conclusions Results suggest that the proprietary supplement containing feverfew, coenzyme Q10 and magnesium assessed could be beneficial and safe for the prevention of migraine in adult patients and merits further study. Trial registration ClinicalTrials.gov: NCT02901756 , retrospectively registered on August 24, 2016

Effect of locomotor training on muscle performance in the context of nerve-muscle communication dysfunction

International audienceIntroduction: The effects of locomotor training (LT) on skeletal muscle after peripheral nerve injury and acetylcholinesterase deficiency are not well documented. Methods: We determined the effects of LT on mouse soleus muscle performance after sciatic nerve transection with excision (full and permanent denervation), nerve transection (partial functional reinnervation), nerve crush (full denervation with full functional reinnervation), and acetylcholinesterase deficiency (alteration in neuromuscular junction functioning). Results: We found no significant effect of LT on the recovery of soleus muscle weight, maximal force in response to muscle stimulation, and fatigue resistance after nerve transection with or without excision. However, LT significantly increased soleus muscle fatigue resistance after nerve crush and acetylcholinesterase deficiency. Moreover, hindlimb immobilization significantly aggravated the deficit in soleus muscle maximal force production and atrophy after nerve crush. Conclusions: LT is beneficial, and reduced muscle use is detrimental for intrinsic muscle performance in the context of disturbed nervemuscle communication. Muscle Nerve, 201

A Probiotic Mixture Induces Anxiolytic- and Antidepressive-Like Effects in Fischer and Maternally Deprived Long Evans Rats

International audienceA role of the gut microbiota in psychiatric disorders is supported by a growing body of literature. The effects of a probiotic mixture of four bacterial strains were studied in two models of anxiety and depression, naturally stress-sensitive Fischer rats and Long Evans rats subjected to maternal deprivation. Rats chronically received either the probiotic mixture (1.10(9) CFU/day) or the vehicle. Anxiety- and depressive-like behaviors were evaluated in several tests. Brain monoamine levels and gut RNA expression of tight junction proteins (Tjp) and inflammatory markers were quantified. The gut microbiota was analyzed in feces by 16S rRNA gene sequencing. Untargeted metabolite analysis reflecting primary metabolism was performed in the cecal content and in serum. Fischer rats treated with the probiotic mixture manifested a decrease in anxiety-like behaviors, in the immobility time in the forced swimming test, as well as in levels of dopamine and its major metabolites, and those of serotonin metabolites in the hippocampus and striatum. In maternally deprived Long Evans rats treated with the probiotic mixture, the number of entries into the central area in the open-field test was increased, reflecting an anxiolytic effect. The probiotic mixture increased Tjp1 and decreased Ifn gamma mRNA levels in the ileum of maternally deprived rats. In both models, probiotic supplementation changed the proportions of several Operational Taxonomic Units (OTU) in the gut microbiota, and the levels of certain cecal and serum metabolites were correlated with behavioral changes. Chronic administration of the tested probiotic mixture can therefore beneficially affect anxiety- and depressive-like behaviors in rats, possibly owing to changes in the levels of certain metabolites, such as 21-deoxycortisol, and changes in brain monoamines

A mouse model of Schwartz-Jampel syndrome reveals myelinating Schwann cell dysfunction with persistent axonal depolarization in vitro and distal peripheral nerve hyperexcitability when perlecan is lacking

Congenital peripheral nerve hyperexcitability (PNH) is usually associated with impaired function of voltage-gated K(+) channels (VGKCs) in neuromyotonia and demyelination in peripheral neuropathies. Schwartz-Jampel syndrome (SJS) is a form of PNH that is due to hypomorphic mutations of perlecan, the major proteoglycan of basement membranes. Schwann cell basement membrane and its cell receptors are critical for the myelination and organization of the nodes of Ranvier. We therefore studied a mouse model of SJS to determine whether a role for perlecan in these functions could account for PNH when perlecan is lacking. We revealed a role for perlecan in the longitudinal elongation and organization of myelinating Schwann cells because perlecan-deficient mice had shorter internodes, more numerous Schmidt-Lanterman incisures, and increased amounts of internodal fast VGKCs. Perlecan-deficient mice did not display demyelination events along the nerve trunk but developed dysmyelination of the preterminal segment associated with denervation processes at the neuromuscular junction. Investigating the excitability properties of the peripheral nerve suggested a persistent axonal depolarization during nerve firing in vitro, most likely due to defective K(+) homeostasis, and excluded the nerve trunk as the original site for PNH. Altogether, our data shed light on perlecan function by revealing critical roles in Schwann cell physiology and suggest that PNH in SJS originates distally from synergistic actions of peripheral nerve and neuromuscular junction changes

A mouse model of Schwartz-Jampel syndrome reveals myelinating Schwann cell dysfunction with persistent axonal depolarization in vitro and distal peripheral nerve hyperexcitability when perlecan is lacking

Congenital peripheral nerve hyperexcitability (PNH) is usually associated with impaired function of voltage-gated K(+) channels (VGKCs) in neuromyotonia and demyelination in peripheral neuropathies. Schwartz-Jampel syndrome (SJS) is a form of PNH that is due to hypomorphic mutations of perlecan, the major proteoglycan of basement membranes. Schwann cell basement membrane and its cell receptors are critical for the myelination and organization of the nodes of Ranvier. We therefore studied a mouse model of SJS to determine whether a role for perlecan in these functions could account for PNH when perlecan is lacking. We revealed a role for perlecan in the longitudinal elongation and organization of myelinating Schwann cells because perlecan-deficient mice had shorter internodes, more numerous Schmidt-Lanterman incisures, and increased amounts of internodal fast VGKCs. Perlecan-deficient mice did not display demyelination events along the nerve trunk but developed dysmyelination of the preterminal segment associated with denervation processes at the neuromuscular junction. Investigating the excitability properties of the peripheral nerve suggested a persistent axonal depolarization during nerve firing in vitro, most likely due to defective K(+) homeostasis, and excluded the nerve trunk as the original site for PNH. Altogether, our data shed light on perlecan function by revealing critical roles in Schwann cell physiology and suggest that PNH in SJS originates distally from synergistic actions of peripheral nerve and neuromuscular junction changes

Evidence of a dosage effect and a physiological endplate acetylcholinesterase deficiency in the first mouse models mimicking Schwartz-Jampel syndrome neuromyotonia.

International audienceSchwartz-Jampel syndrome (SJS) is a recessive neuromyotonia with chondrodysplasia. It results from hypomorphic mutations of the gene encoding perlecan, leading to a decrease in the levels of this heparan sulphate proteoglycan in basement membranes (BMs). It has been suggested that SJS neuromyotonia may result from endplate acetylcholinesterase (AChE) deficiency, but this hypothesis has never been investigated in vivo due to the lack of an animal model for neuromyotonia. We used homologous recombination to generate a knock-in mouse strain with one missense substitution, corresponding to a human familial SJS mutation (p.C1532Y), in the perlecan gene. We derived two lines, one with the p.C1532Y substitution alone and one with p.C1532Y and the selectable marker Neo, to down-regulate perlecan gene activity and to test for a dosage effect of perlecan in mammals. These two lines mimicked SJS neuromyotonia with spontaneous activity on electromyogramm (EMG). An inverse correlation between disease severity and perlecan secretion in the BMs was observed at the macroscopic and microscopic levels, consistent with a dosage effect. Endplate AChE levels were low in both lines, due to synaptic perlecan deficiency rather than major myofibre or neuromuscular junction disorganization. Studies of muscle contractile properties showed muscle fatigability at low frequencies of nerve stimulation and suggested that partial endplate AChE deficiency might contribute to SJS muscle stiffness by potentiating muscle force. However, physiological endplate AChE deficiency was not associated with spontaneous activity at rest on EMG in the diaphragm, suggesting that additional changes are required to generate such activity characteristic of SJS