Neuroscience letters
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Neuroscience letters · Mar 2005
Comparative StudyDevelopmental changes in hyperexcitability of CA1 pyramidal neurons induced by repeated brief episodes of hypoxia in the rat hippocampal slices.
We have previously demonstrated that repeated exposure of adult rat hippocampal slices to brief episodes of hypoxia induce a sustained decrease in the threshold of stimulus-evoked population spike discharges in CA1 pyramidal neurons [O. Godukhin, A. Savin, S. ⋯ In comparison with P60-70 hippocampal slices, CA1 pyramidal neurons in P13-14 and P600-650 slices showed intrinsically (without repeated brief hypoxa) an increased propensity to generate epileptiform stimulus-evoked population spike discharges. However, in contrast to adult and old animals, repeated brief episodes of hypoxia are incapable to induce a sustained decrease in the threshold of stimulus-evoked population spike discharges in CA1 pyramidal neurons of hippocampal slices prepared from of P13-14 rats, though they transform paired-pulse inhibition to paired-pulse facilitation and induce hypoxic LTP in CA3-CA1 synapses. The role of some other factors in the developmental changes in hyperexcitability of CA1 pyramidal neurons in response to repeated brief episodes of hypoxia is discussed.
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Neuroscience letters · Mar 2005
Increased facilitation of the primary motor cortex following 1 Hz repetitive transcranial magnetic stimulation of the contralateral cerebellum in normal humans.
Connections between the cerebellum and the contralateral motor cortex are dense and important, but their physiological significance is difficult to measure in humans. We have studied a group of 10 healthy subjects to test whether a modulation of the excitability of the left cerebellum can affect the excitability of the contralateral motor cortex. We used repetitive transcranial magnetic stimulation (rTMS) at 1 Hz frequency to transiently depress the excitability of the left cerebellar cortex and paired-pulse TMS testing of intracortical inhibition (ICI) and intracortical facilitation (ICF) to probe the excitability of cortico-cortical connections in the right motor cortex. ⋯ The effect lasted for up to 30 min afterward and was specific for the contralateral (right) motor cortex. The cortical silent period was unaffected by cerebellar rTMS. The implication is that rTMS of the cerebellar cortex can shape the flowing of inhibition from Purkinje cells toward deep nuclei, thereby increasing the excitability of interconnected brain areas.
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Neuroscience letters · Mar 2005
Modulation of short-term social memory in rats by adenosine A1 and A(2A) receptors.
The recognition of an unfamiliar juvenile rat by an adult rat has been shown to imply short-term memory processes. The present study was designed to examine the role of adenosine receptors in the short-term social memory of rats using the social recognition paradigm. ⋯ Furthermore, acute administration of caffeine (10.0-30.0 mg/kg, i.p.), DPCPX (1.0-3.0 mg/kg, i.p.) or ZM241385 (0.5-1.0 mg/kg, i.p.) improved the short-term social memory in a specific manner. These results indicate that adenosine modulates the short-term social memory in rats by acting on both A1 and A(2A) receptors, with adenosine receptor agonists and antagonists, respectively, disrupting and enhancing the social memory.
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Neuroscience letters · Mar 2005
Changes of expression of glial cell line-derived neurotrophic factor and its receptor in dorsal root ganglions and spinal dorsal horn during electroacupuncture treatment in neuropathic pain rats.
Injury to the nervous system occasionally leads to intense and persistent neuropathic pain, which is resistant to conventional analgesic methods. It was reported that electroacupuncture (EA) had potent analgesic effect on neuropathic pain by activating various endogenous transmitters such as the opioid peptides. ⋯ The results showed that both protein and mRNA levels of GDNF and GFRalpha-1 in the dorsal root ganglions (DRG), as well as GDNF protein in the spinal dorsal horn, were significantly increased after chronic constriction injury (CCI) of the rats' sciatic nerve and could be further enhanced by EA treatment. The present data demonstrated that EA could activate endogenous GDNF and GFRalpha-1 system of neuropathic pain rats and this might underlie the effectiveness of EA in the treatment of neuropathic pain.
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Neuroscience letters · Mar 2005
Comparative StudyLoss of functional neuronal nicotinic receptors in dorsal root ganglion neurons in a rat model of neuropathic pain.
Recent evidence has suggested that the anti-allodynic effect of neuronal acetylcholine receptor (nAChR) agonists may have a peripheral component [L. E. Rueter, K. ⋯ Reduced responsiveness to nAChR agonists covered the range of DRG neuron sizes. The decrease in the responsiveness to nAChR agonists was not seen in neighboring uninjured L4 neurons. The significant decrease in the number of cells with nAChR agonist responses, compounded with the significant decrease in response amplitude, indicates that there is a marked down regulation of functional nAChRs in DRG somata associated with SNL.