Experimental neurology
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Experimental neurology · Sep 2009
Selective inhibition of JNK with a peptide inhibitor attenuates pain hypersensitivity and tumor growth in a mouse skin cancer pain model.
Cancer pain significantly affects the quality of cancer patients, and current treatments for this pain are limited. C-Jun N-terminal kinase (JNK) has been implicated in tumor growth and neuropathic pain sensitization. We investigated the role of JNK in cancer pain and tumor growth in a skin cancer pain model. ⋯ In contrast, repeated injections of morphine (5 mg/kg), a commonly used analgesic for terminal cancer, produced analgesic tolerance after 1 day and did not inhibit tumor growth. Our data reveal a marked peripheral neuropathy in this skin cancer model and important roles of the JNK pathway in cancer pain development and tumor growth. JNK inhibitors such as D-JNKI-1 may be used to treat cancer pain.
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Experimental neurology · Sep 2009
Characterization of juvenile and young adult mice following induction of hydrocephalus with kaolin.
Hydrocephalus is a common neurological problem in humans, usually caused by an impairment of cerebrospinal fluid (CSF) flow or absorption. A reliable induced model of chronic hydrocephalus in mice would be useful to test hypotheses using genetic mutants. Our goal was to characterize behavioral and histological changes in juvenile and young adult mice with kaolin (aluminum silicate)-induced hydrocephalus. ⋯ Glial fibrillary acidic protein content was significantly higher in juvenile and young adult hydrocephalic mice at 7 and 14 days, but myelin basic protein content was not significantly altered. In conclusion, hydrocephalus induced by percutaneous injection of kaolin in juvenile and young adult mice is feasible. The associated periventricular alterations are essentially the same as those reported in rats of comparable ages.
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Experimental neurology · Sep 2009
Treatment of intracerebral hemorrhage in rats with 12 h, 3 days and 6 days of selective brain hypothermia.
Intracerebral hemorrhage (ICH) is a devastating stroke with no proven treatment to reduce brain injury. In this study we modeled ICH by injecting 100 microL of autologous blood into the striatum of rats. We then tested whether hypothermia would reduce brain injury and improve recovery as has been repeatedly observed for ischemic and traumatic brain damage. ⋯ Only the limb use asymmetry deficit was significantly mitigated by hypothermia, and then only by the longest treatment. Lesion volume, which averaged 16.9 mm3, was not affected. These results, in conjunction with earlier studies, suggest that prolonged mild hypothermia will not be a profound neuroprotectant for patients with striatal ICH, but it may nonetheless improve functional recovery in addition to its use for treating cerebral edema.
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Experimental neurology · Sep 2009
Post-ischemic leakiness of the blood-brain barrier: a quantitative and systematic assessment by Patlak plots.
The Patlak plot analysis of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) allows estimation of blood-brain barrier (BBB) leakage following temporary focal cerebral ischemia. Thus far, a systematic and quantitative in vivo evaluation of post-ischemic BBB leakage is lacking. Here, using DCE-MRI and the Patlak plot method, we quantitatively assessed BBB leakage in rats at the following time-points after reperfusion: 25 min, 2, 4, 6, 12, 18, 24, 36, 48, and 72 h, and 1, 2, 3, 4, and 5 weeks. ⋯ Both ADC values (r=-0.58, p=0.02) and ischemic lesion volumes (r=0.75, p=0.0015) correlated with K(i) values. These results suggest that after ischemia-reperfusion in rats, BBB leakage is continuous during a 4-week period. Its magnitude diminishes over time and correlates with severity and extent of ischemic injury.
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Experimental neurology · Sep 2009
Colitis induces calcitonin gene-related peptide expression and Akt activation in rat primary afferent pathways.
Previous study has shown that colitis-induced increases in calcitonin gene-related peptide (CGRP) immunoreactivity in bladder afferent neurons result in sensory cross-sensitization. To further determine the effects of colitis on CGRP expression in neurons other than bladder afferents, we examined and compared the levels of CGRP mRNA and immunoreactivity in the lumbosacral dorsal root ganglia (DRG) and spinal cord before and during colitis in rats. We also examined the changes in CGRP immunoreactivity in colonic afferent neurons during colitis. ⋯ In S1 spinal cord, colitis caused the increases in the intensity of CGRP fibers in the regions of dorso-lateral tract, and caused the increases in the level of phospho-Akt in the superficial dorsal horn of the spinal cord. In spinal cord slice culture, exogenous CGRP increased the phosphorylation level of Akt but not the phosphorylation level of extracellular-signal regulated kinase ERK1/2 even though our previous studies showed that colitis increased the phosphorylation level of ERK1/2 in L1 and S1 spinal cord. These results suggest that CGRP is synthesized in the DRG and may transport to the spinal cord where it initiates signal transduction during colitis.