Experimental neurology
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Experimental neurology · Aug 2007
Pain behaviors after spinal cord contusion injury in two commonly used mouse strains.
We have characterized spontaneous and evoked pain behaviors that develop in a model of severe spinal contusion injury using two commonly used strains of mice. Using the Infinite Horizon Tissue Impactor to produce these contusion injuries, we were able to set strict limits on the injury parameters (i.e., force of impact and tissue displacement). This helps to generate a uniform population of spinal cord injury severity and allows for meaningful comparisons to be made across the two strains of mice. ⋯ However, the magnitude and intensity of this increase was more pronounced in BALB/c mice. PKCgamma is an important mediator of persistent pain behaviors after peripheral nerve injury and inflammation. Our results suggest that PKCgamma may also contribute to neuropathic pain behaviors after direct lesion to the spinal cord.
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Experimental neurology · Jul 2007
Dorsal raphe nuclei integrate allostatic information evoked by depletion-induced sodium ingestion.
Structures of the lamina terminalis (LT) sense and integrate information reflecting the state of body water and sodium content. Output from the LT projects into a neural network that regulates body fluid balance. Serotonin (5-HT) and the dorsal raphe nuclei (DRN) have been implicated in the inhibitory control of salt intake (i.e., sodium appetite). ⋯ Ninety minutes after the termination of the intake test, the animals were perfused and their brains were processed for immunohistochemical detection of Fos and FG. Compared to sham-depleted animals there was a significantly greater number of Fos-/FG-ir double-labeled cells in the subfornical organ, the organum vasculosum of the lamina terminalis and the median preoptic nucleus in rats that ingested NaCl. Projections from the LT cells may contribute to inhibitory mechanisms involving 5-HT neurons in the DRN that limit the intake of sodium and prevent excess volume expansion.
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Experimental neurology · Jul 2007
Pallidal stimulation modifies after-effects of paired associative stimulation on motor cortex excitability in primary generalised dystonia.
To determine the effect of globus pallidus internus (GPi) deep brain stimulation (DBS) on motor cortex plasticity in patients with primary generalised dystonia. ⋯ After PAS, patients with primary generalised dystonia showed a similar pattern of increased motor cortex excitability as healthy subjects when GPi DBS was OFF but not with GPi DBS ON. These results suggest that GPi DBS may reduce LTP-like motor cortex plasticity, which could contribute to its mechanism of action in dystonia.
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Experimental neurology · Jul 2007
Spinal cord injury in neonates alters respiratory motor output via supraspinal mechanisms.
Upper cervical spinal cord injury (SCI) alters respiratory output and results in a blunted respiratory response to pH/CO2. Many SCI studies have concentrated on respiratory changes in neural function caudal to injury; however few have examined whether neural plasticity occurs rostral to SCI. Golder et al. (2001a) showed that supraspinal changes occur to alter respiratory output after SCI. ⋯ Western blot analysis demonstrated significant changes in glutamate receptor subunits (NR1, NR2B and GluR2), adenosine receptors (A1, A2A), glutamic acid decarboxylase (65) and neurokinin-1 receptors in medullary tissue ipsilateral and contralateral to injury. These data show that supraspinal plasticity in the respiratory system occurs after SCI in neonate rats. The mechanisms remain unknown, but may involve alterations in receptor proteins involved in neurotransmission.
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Experimental neurology · Jul 2007
Reversal of ERK activation in the dorsal horn after decompression in chronic constriction injury.
Injury-induced neuropathic pain is related to changes in the central terminals of dorsal root ganglia neurons, i.e., dorsal horn plasticity. We investigated the influences of decompression by removing ligatures producing chronic constriction injury (CCI) in Sprague-Dawley rats at postoperative week (POW) 4, the decompression group; for comparison, all ligatures remained through the experimental period in the CCI group. ⋯ At POW 8, thermal hyperalgesia and mechanical allodynia had completely disappeared with a normalization of dorsal horn index (1.17+/-0.11 vs. 1.02+/-0.12 at POW 0, p=0.07) in the decompression group; in contrast, the dorsal horn index remained elevated in the CCI group (2.48+/-0.30, p<0.001) with persistent neuropathic pain behaviors at POW 8. This report suggests that ERK activation in the dorsal horn is correlated with neuropathic pain behaviors and its normalization reflects the reversal of neuropathic pain behaviors after decompression.