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Jarod a écrit :Glutamate and GABA Function in Autism Spectrum Disorders: A Proton Magnetic Resonance Spectroscopic Study
http://www.youtube.com/watch?v=bafclwPo9Qs
danielt a écrit :
Oui, pour moi l'autisme est un calibrage différent du cerveau qui conduit à un fonctionnement inadapté à une société neurotypique. Il y a donc beaucoup de possibilités.
anonymous a écrit :Vous oubliez dans vos discussions ce qui a été mis en évidence dernièrement : les neurones immatures dans l'autisme sont trop chargés en chlore et induisent un effet excitateur du GABA au lieu d'inhibiteur.
C'est ce qui est ciblé par le bumetanide.
viewtopic.php?p=45619#p45619
De son côté, l'équipe d'Angela Sirigu (Centre de neurosciences cognitives, Lyon), avec la Fondation FondaMental, explore la piste de l'ocytocine, une hormone synthétisée dans l'hypothalamus. En 2010, cette chercheuse (contributrice du cahier "Science & techno" du Monde) avait montré qu'une administration d'ocytocine en spray augmente les contacts sociaux chez des autistes de haut niveau. Ses derniers travaux (publiés le 1er novembre dans Cerebral Cortex) confirment que le taux de cette hormone dans le plasma est corrélé au degré d'extraversion d'un individu.
Les effets comportementaux étaient également contrôlés
en mesurant les concentrations d’ocytocine plasmatique
dans le sang avant et après administration du spray nasal.
La concentration d’ocytocine dans le plasma des patients à
l’état basal était significativement inférieure aux valeurs des
sujets normaux (patients : 1.08 pg/ml ± 1.04 ; sujets sains :
7.28 pg/ml ± 4.49). Le taux d’ocytocine est significativement
augmenté (2.66 pg/ml ± 2.20) après inhalation d’ocytocine.
L'ocytocine, ou oxytocine, est une hormone peptidique synthétisée par les noyaux paraventriculaire et supraoptique de l'hypothalamus
Glutamate and aspartate impair memory retention and damage hypothalamic neurons in adult mice.
Park CH, Choi SH, Piao Y, Kim S, Lee YJ, Kim HS, Jeong SJ, Rah JC, Seo JH, Lee JH, Chang K, Jung YJ, Suh YH.
Source
Department of Pharmacology, College of Medicine and Neuroscience Research Institute, MRC, Seoul National University, 28 Yongon-dong, Chongno-gu, Seoul, South Korea.
Abstract
We examined the effects of systemic administration of monosodium glutamate (MSG) or aspartate (ASP) on the memory retention and neuronal damage in the brains of adult mice. Compared with the control mice, a single intraperitoneal injection of either 4.0 mg/g MSG or 0.5 mg/g ASP after acquisition trial significantly shortened the response latency in the passive avoidance test, accompanying by the transient weight loss. Histopathological analysis of the brains of these mice revealed that neurons in the arcuate nucleus of hypothalamus were damaged markedly by MSG (4.0 mg/g) or ASP (0.5 mg/g). Other brain areas including cerebral cortex and hippocampus did not show any pathological changes. These findings suggest that systemic administration of MSG or ASP could impair memory retention and damage hypothalamic neurons in adult mice.
danielt a écrit :Jarod a écrit :Jarod a écrit :Glutamate and GABA Function in Autism Spectrum Disorders: A Proton Magnetic Resonance Spectroscopic Study
http://www.youtube.com/watch?v=bafclwPo9Qs
Le slide de la présentation fait lors de cette conférence : http://www.autismconsortium.com/symposi ... posium.pdf
Aller voir page 14.
Une dose élevée du glutamate et faible du GABA correspond à un état de l'anxiété. Est-ce que cette anxiété existe à l'origine et est-ce le cœur de l'autisme ? Ou c'est une anxiété provoquée par les problèmes sociaux ?
Les récepteurs neuronaux au N-methyl-D-aspartate (NMDA) jouent un rôle important dans les processus de mémorisation. Il semble que lors de la maladie d'Alzheimer ces récepteurs soient hyperstimulés par le glutamate, ce qui serait délétère. Elle est réservée aux stades moyens ou avancés166.
Neuroimage. 2013 May 23. pii: S1053-8119(13)00568-5. doi: 10.1016/j.neuroimage.2013.05.068. [Epub ahead of print]
GABA estimation in the Brains of Children on the Autism Spectrum: Measurement precision and regional cortical variation.
Gaetz W, Bloy L, Wang DJ, Port RG, Blaskey L, Levy SE, Roberts TP.
Source
Lurie Family Foundations' MEG Imaging Center; Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA. Electronic address: gaetzw@email.chop.edu.
Abstract
1H-magnetic resonance spectroscopy (1H-MRS) and spectral editing methods, such as MEGA-PRESS, allow researchers to investigate metabolite and neurotransmitter concentrations in-vivo. Here we address the utilization of 1H-MRS for the investigation of GABA concentrations in the ASD brain, in three locations; motor, visual and auditory areas. An initial repeatability study (5 subjects, 5 repeated measures separated by~5days on average) indicated no significant effect of reference metabolite choice on GABA quantitation (p>0.6). Coefficients of variation for GABA+/NAA, GABA+/Cr and GABA+/Glx were all of the order of 9-11%. Based on these findings, we investigated creatine-normalized GABA+ratios (GABA+/Cr) in a group of (n=17) children with autism spectrum disorder (ASD) and (n=17) typically developing children (TD) for Motor, Auditory and Visual regions of interest (ROIs). Linear regression analysis of grey matter (GM) volume changes (known to occur with development) revealed a significant decrease of GM volume with Age for Motor (F(1,30)=17.92; p<0.001) and Visual F(1,16)=14.41; p<0.005 but not the Auditory ROI(p=0.55). Inspection of GABA+/Cr changes with Age revealed a marginally significant change for the Motor ROI only (F(1,30)=4.11; p=0.054). Subsequent analyses was thus conducted for each ROI separately using Age and GM volume as covariates. No group differences in GABA+/Cr were observed for the Visual ROI between TD vs. ASD children. However, the Motor and Auditory ROI showed significantly reduced GABA+/Cr in ASD (Motor p<0.05; Auditory p<0.01). The mean deficiency in GABA+/Cr from the Motor ROI was approximately 11% and Auditory ROI was approximately 22%. Our novel findings support the model of regional differences in GABA+/Cr in the ASD brain, primarily in Auditory and to a lesser extent Motor but not Visual areas.
Copyright © 2013. Published by Elsevier Inc.
J Neurophysiol. 2013 May 29. [Epub ahead of print]
Postnatal maturation of GABAergic transmission in the rat basolateral amygdala.
Ehrlich DE, Ryan SJ, Hazra R, Guo JD, Rainnie DG.
Source
1Emory.
Abstract
Many psychiatric disorders, including anxiety and autism spectrum disorders, have early ages of onset and high incidence in juveniles. To better treat and prevent these disorders, it is important to first understand normal development of brain circuits that process emotion. Healthy and maladaptive emotional processing involve the basolateral amygdala (BLA), dysfunction of which has been implicated in numerous psychiatric disorders. Normal function of the adult BLA relies on a fine balance of glutamatergic excitation and GABAergic inhibition. Elsewhere in the brain, GABAergic transmission changes throughout development, but little is known about the maturation of GABAergic transmission in the BLA. Here we used whole-cell patch clamp recording and single-cell RT-PCR to study GABAergic transmission in rat BLA principal neurons at postnatal days (P)7, 14, 21, 28, and 35. GABAA currents exhibited a significant, two-fold reduction in rise-time and nearly 25% reduction in decay time-constant between P7 and P28. This corresponded with a shift in expression of GABAA receptor subunit mRNA from the α2 to the α1 subunit. The reversal potential for GABAA receptors transitioned from depolarizing to hyperpolarizing with age, from around -55mV at P7 to -70mV by P21. There was a corresponding shift in expression of opposing chloride pumps that influence the reversal, from NKCC1 to KCC2. Finally, we observed short-term depression of GABAA postsynaptic currents in immature neurons that was significantly and gradually abolished by P28. These findings reveal that, in the developing BLA, GABAergic transmission is highly dynamic, reaching maturity at the end of the first postnatal month.
KEYWORDS:
Amygdala, Chloride Transporter, Development, GABA(A) receptor, Parvalbumin
PMID:
23719209
[PubMed - as supplied by publisher]
Attention-deficit/hyperactivity disorder (ADHD) is a common neurodevelopmental disorder with impairments across the lifespan. The persistence of ADHD is associated with considerable liability to neuropsychiatric co-morbidity such as depression, anxiety and substance use disorder. The substantial heritability of ADHD is well documented and recent genome-wide analyses for risk genes revealed synaptic adhesion molecules (e.g. latrophilin-3, LPHN3; fibronectin leucine-rich repeat transmembrane protein-3, FLRT3), glutamate receptors (e.g. metabotropic glutamate receptor-5, GRM5) and mediators of intracellular signalling pathways (e.g. nitric oxide synthase-1, NOS1). These genes encode principal components of the molecular machinery that connects pre- and postsynaptic neurons, facilitates glutamatergic transmission, controls synaptic plasticity and empowers intersecting neural circuits to process and refine information. Thus, identification of genetic variation affecting molecules essential for the formation, specification and function of excitatory synapses is refocusing research efforts on ADHD pathogenesis to include the long-neglected glutamate system.
The EU researchers have discovered a link between the lack of a particular gene – neuroligin-3 – and inherited cases of autism. Mice missing this gene have overactive glutamate receptors and this causes problems with learning and brain development.
When the production of neuroligin-3 in the mice was reactivated, the nerve cells reduced the production of the glutamate receptors to a normal level and the structural defects in the brain typical for autism were gone. Consequently, these glutamate receptors could be targeted in the development of drugs that could stop autism from developing or even reverse it.
lliw a écrit :.
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