Neuroscience
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RAB-GDP dissociation inhibitor 1 (GDI1) loss-of-function mutations are responsible for a form of non-specific X-linked Intellectual Disability (XLID) where the only clinical feature is cognitive impairment. GDI1 patients are impaired in specific aspects of executive functions and conditioned response, which are controlled by fronto-striatal circuitries. Previous molecular and behavioral characterization of the Gdi1-null mouse revealed alterations in the total number/distribution of hippocampal and cortical synaptic vesicles as well as hippocampal short-term synaptic plasticity, and memory deficits. ⋯ We previously showed that Gdi1-null mice are impaired in some hippocampus-dependent forms of associative learning assessed by aversive procedures. Here, using appetitive-conditioning procedures we further investigated associative learning deficits sustained by the fronto-striatal system. We report that Gdi1-null mice are impaired in attention and associative learning processes, which are a key part of the cognitive impairment observed in XLID patients.
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Nitric oxide donors are known to produce headache in healthy as well as migraine subjects, and to induce extracephalic cutaneous hypersensitivity in rodents. However, little is known on the effect of nitric oxide donors on cephalic cutaneous sensitivity. Combining behavioral, immunohistochemical, and in vivo electrophysiological approaches, this study investigated the effect of systemic administration of the nitric oxide donor, isosorbide dinitrate (ISDN), on cephalic and extracephalic cutaneous sensitivity and on neuronal activation within the medullary dorsal horn (MDH) in the rat. ⋯ Using in vivo electrophysiological unit recordings, we show that ISDN administration never affected the spontaneous activity of trigeminal wide dynamic range neurons, but, facilitated C-fiber-evoked responses in half the neurons tested. This research demonstrates that a nitric oxide donor, isosorbide dinitrate, induces selectively cephalic hyperalgesia that arises as a consequence of central sensitization in pain pathways that subserve meningeal nociception. This model better mimics the clinical condition and offers another possibility of studying the role of nitric oxide donor in the physiopathology of headache.
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Patients with multiple sclerosis (MS) often complain of neuropathic pain. According to the Gate Control Theory of Pain, spinal networks of GABAergic inhibitory interneurons are important in modulating nociceptive inputs from the periphery. Na+-K+-2Cl- co-transporter 1 (NKCC1) and K+-Cl- co-transporter 2 (KCC2) generally dictate the tone of GABA/glycine inhibition by regulating intracellular chloride concentrations. ⋯ Treatment with bumetanide, an NKCC inhibitor, had no effect on mechanical hypersensitivity seen in mice with EAE even though it reversed the changes in the levels of NKCC1 and KCC2. We noted that bumetanide treatment, while effective at reversing the changes in monomeric KCC2 levels was ineffective at reversing the changes in oligomeric KCC2 which remained repressed. These results indicate that mechanical hypersensitivity in EAE is not mediated by altered levels of NKCC1.
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Human Albumin is a unique pleiotropic protein with multiple properties. Previous clinical and laboratory studies have indicated a possible beneficial effect of Albumin in subarachnoid hemorrhage (SAH). The present study aimed to further define the preclinical characteristics of Albumin. ⋯ In female rats and spontaneously hypertensive rats, Albumin likewise improved neurological outcomes and early brain injury. In conclusion, Albumin could reduce both cerebral lesions and functional deficits in the early stage of SAH. The beneficial regimen occurs within a favorable therapeutic window and is reproducible in different high-risk subjects.
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The firing pattern of individual neurons is an important element for information processing and storing. During the first weeks of development, there is a transitional period during which CA1 pyramidal neurons display burst-spiking behavior in contrast to the adult regular-firing pattern. Spike after-depolarizations (ADPs) constitute a major factor underlying burst-spiking behavior. ⋯ In agreement with the development of the ADP waveform and burst-spiking behavior, voltage-clamp experiments in dissociated pyramidal neurons showed an increase in the LVA calcium current in P16-19 vs P9-12. Finally, we found that a reduction of extracellular calcium levels decreases the percentage of burst-spiking cells due to a reduction in the active component of the ADP. We conclude that a major contribution of LVA calcium channels to ADP determines the bursting capability of CA1 pyramidal neurons during a transitional postnatal period in contrast to adulthood.