Stereotaxic injection of a viral vector for conditional gene manipulation in the mouse spinal cord.

Intraparenchymal injection of a viral vector enables conditional gene manipulation in distinct populations of neurons or particular regions of the central nervous system. We demonstrate a stereotaxic injection technique that allows targeted gene expression or silencing in the dorsal horn of the mouse spinal cord. The surgical procedure is brief. It requires laminectomy of a single vertebra, providing for quick recovery of the animal and unimpaired motility of the spine. Controlled injection of a small vector suspension volume at low speed and use of a microsyringe with beveled glass cannula minimize the tissue lesion. The local immune response to the vector depends on the intrinsic properties of the virus employed; in our experience, it is minor and short-lived when a recombinant adeno-associated virus is used. A reporter gene such as enhanced green fluorescent protein facilitates monitoring spatial distribution of the vector, and the efficacy and cellular specificity of the transfection.journal articleresearch support, n.i.h., extramuralvideo-audio media2013 Mar 182013 03 18importe

NMDA Receptor Activation Underlies the Loss of Spinal Dorsal Horn Neurons and the Transition to Persistent Pain after Peripheral Nerve Injury

Peripheral nerve lesions provoke apoptosis in the dorsal horn of the spinal cord. The cause of cell death, the involvement of neurons, and the relevance for the processing of somatosensory information are controversial. Here, we demonstrate in a mouse model of sciatic nerve injury that glutamate-induced neurodegeneration and loss of γ-aminobutyric acid (GABA)ergic interneurons in the superficial dorsal horn promote the transition from acute to chronic neuropathic pain. Conditional deletion of Grin1, the essential subunit of N-methyl-d-aspartate-type glutamate receptors (NMDARs), protects dorsal horn neurons from excitotoxicity and preserves GABAergic inhibition. Mice deficient in functional NMDARs exhibit normal nociceptive responses and acute pain after nerve injury, but this initial increase in pain sensitivity is reversible. Eliminating NMDARs fully prevents persistent pain-like behavior. Reduced pain in mice lacking proapoptotic Bax confirmed the significance of neurodegeneration. We conclude that NMDAR-mediated neuron death contributes to the development of chronic neuropathic pain

Differential modulation of inhibitory synaptic transmission by compartmentalized synthesis of neurosteroids in the dorsal horn of the spinal cord

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Modulation différentielle de la transmission synaptique inhibitrice par la synthèse localisée de neurostéroïdes dans la corne dorsale de la moelle épinière de rat

Nous avons tout d’abord caractérisé et comparé les propriétés de la transmission synaptique inhibitrice dans les laminae II et III-IV de la corne dorsale (CD) de la moelle épinière, qui sont impliquées dans le traitement des informations sensorielles. Nos résultats indiquent que la transmission synaptique glycinergique est prépondérante et que la cotransmission GABA/glycine est absente dans les laminae III-IV. Ensuite, nous avons étudié la possibilité d'un contrôle différentiel de la production de stéroïdes 35-réduits et ses conséquences sur la transmission GABAergiques dans les laminae II et III-IV. Nos résultats indiquent que la cinétique de déactivation des courants postsynaptiques inhibiteurs miniatures GABAergique est en grande partie contrôlée par les stéroïdes 35-réduits qui peuvent être synthétisés à partir de stéroïdes circulants et/ou localement par la modulation de l'activité de TSPO, notamment suite à une inflammation périphérique.First, we have characterised and compared the properties of inhibitory synaptic transmission in laminae II and III-IV of the dorsal horn (DH), which are involved in the processing of nociceptive and non-nociceptive sensory information. Our results indicate that inhibitory synaptic transmission in laminae III-IV is characterised by a dominant role of glycinergic inhibition and the absence of a functional GABA/glycine cotransmission. Second, we examined the possibility of a differential spatial control in the endogenous production of 35-reduced steroids and its consequences on GABAA receptor-mediated mIPSCs in laminae II and III-IV of the DH. Our results indicate that the decay kinetics of GABAA receptor-mediated mIPSCs in the DH of the spinal cord are largely controlled by 35-reduced steroids which can be produced from circulating steroid precursors and/or, in a spatially-restricted manner, by the modulation of the activity of TSPO, in particular by peripheral inflammation

Modulation différentielle de la transmission synaptique inhibitrice par la synthèse localisée de neurostéroïdes dans la corne dorsale de la moelle épinière de rat

STRASBOURG-Sc. et Techniques (674822102) / SudocSudocFranceF

Modulation différentielle de la transmission synaptique inhibitrice par la synthèse localisée de neurostéroïdes dans la corne dorsale de la moelle épinière de rat

STRASBOURG-Sc. et Techniques (674822102) / SudocSudocFranceF

Neuronal networks and nociceptive processing in the dorsal horn of the spinal cord

International audienc

Daily and estral regulation of RFRP-3 neurons in the female mice

Female reproductive success relies on proper integration of circadian- and ovarian- signals to the hypothalamic-pituitary-gonadal axis in order to synchronize the preovulatory LH surge at the end of the ovarian follicular stage with the onset of the main active period. In this study, we used a combination of neuroanatomical and electrophysiological approaches to assess whether the hypothalamic neurons expressing Arg-Phe amide-related peptide (RFRP-3), a gonadotropin inhibitory peptide, exhibit daily and estrous stage dependent variations in female mice. Furthermore, we investigated whether arginine vasopressin (AVP), a circadian peptide produced by the suprachiamatic nucleus regulates RFRP-3 neurons. The number of c-Fos–positive RFRP-3 immunoreactive neurons is significantly reduced at the day-to-night transition with no difference between diestrus and proestrus. Contrastingly, RFRP neuron firing rate is higher in proestrus as compared to diestrus, independently of the time of the day. AVP immunoreactive fibers contact RFRP neurons with the highest density observed during the late afternoon of diestrus and proestrus. Application of AVP increases RFRP neurons firing in the afternoon (ZT6-10) of diestrus, but not at the same time point of proestrus, indicating that AVP signaling on RFRP neurons may depend on circulating ovarian steroids. Together, these studies show that RFRP neurons integrate both daily and estrogenic signals, which downstream may help to properly time the preovulatory LH surge

Nociception, douleur et autisme

Les sujets autistes présentent fréquemment des anomalies sensorielles. Celles concernant la nociception ainsi que sa potentielle résultante, la douleur, sont d’un intérêt capital. En effet, du fait de nombreuses comorbidités, les sujets autistes sont plus souvent exposés à des situations douloureuses que la population générale. Alors qu’ils sont souvent considérés comme moins sensibles, les études expérimentales sur ce point sont loin de faire consensus. Utiliser des modèles animaux pourrait permettre de s’affranchir de certaines sources de variabilité et d’apporter, dans le cadre de l’autisme, une vue d’ensemble des altérations potentielles du système nociceptif aux niveaux cellulaire et moléculaire