Neuroreport
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Comparative Study
Expression of kinin B1 receptors in the spinal cord of streptozotocin-diabetic rat.
Previous studies have reported cardiovascular and nociceptive responses after intrathecal injection of kinin B1 receptor (B1R) agonists in the model of streptozotocin (STZ)-diabetic rat (diabetic). The aim of this study was to measure the early up-regulation of B1R binding sites and mRNA in the thoracic spinal cord of diabetic and control rats. ⋯ Levels of mRNA were significantly increased (+68%) at 2 and 7 days but not at 21 days. These data bring the first molecular evidence for an early up-regulation of B1R in the spinal cord of diabetic rat.
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Comparative Study
Relationship between change detection and pre-change [corrected] activity in visual area V1.
Humans are poor at detecting changes to visual scenes occurring during brief disruptions. It is unclear whether this 'change blindness' results from failure to process the relevant item before the change, or failure to compare/recall the item after the change. We recorded pre-change multi-unit activity in area V1 of monkeys performing a change detection task. ⋯ Figure-ground related activity was observed, even when no correct saccade was made. However, for the changing figure, pre-change activity was stronger in correct trials than in incorrect trials. We conclude that small differences in pre-change figure-ground segregation have predictive value in whether the change will be successfully detected.
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Comparative Study
High activity of K+-dependent plasmalemmal Na+/Ca2+ exchangers in hippocampal CA1 neurons.
Ca(2+) influx via reversed K(+)-dependent (NCKX) and/or K(+)-independent (NCX) plasmalemmal Na(+)/Ca(2+) exchangers may play a role in neuronal death following global brain ischemia to which CA1 neurons are particularly vulnerable. Therefore, this work tested whether the rates of Ca(2+) influx via reversed NCKX or NCX in cultured rat CA1 neurons differ from those in forebrain neurons (FNs) or cerebellar granule cells (CGCs). ⋯ NCKX reversal inhibitors are not yet available. Their development would greatly facilitate further testing the role of NCKX in ischemic death of CA1 neurons.
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Proteinase-activated receptor 2 (PAR-2) is expressed on many nociceptive neurons. Application of PAR-2 agonists has been shown to induce behavioral signs of hyperalgesia. We investigated effects of the rat PAR-2 agonist SLIGRL-NH2 in the isolated rat skin-saphenous nerve preparation. ⋯ The PAR-2-inactive control peptide LRGILS-NH2 had no effect. The mechanical sensitivity of C-fibers was not affected by SLIGRL-NH2. PAR-2-mediated excitation and sensitization of primary nociceptors may contribute to PAR-2-mediated hyperalgesia.
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The anti-migraine agent sumatriptan constricts cerebral blood vessels, and also blocks neuropeptide release from meningeal sensory neurons. We investigated whether sumatriptan can also affect neuronal discharge, by recording the activity of dural primary afferent neurons during dural application of sumatriptan in anesthetized rats. ⋯ The suppressive effect of calcium removal was not a result of a general decrease in excitability, because calcium removal produced a pronounced increase in mechanically evoked discharge. The excitatory effect on dural afferent discharge might underlie the initial worsening of the headache that can occur following sumatriptan administration, prior to the subsequent onset of headache relief.