Neuroscience letters
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Neuroscience letters · Aug 1998
Differential effects of treatment with nerve growth factor on thermal nociception and on calcitonin gene-related peptide content of primary afferent neurons in the rat.
We have investigated the effect of repeated systemic administration of nerve growth factor (NGF) to rats on (a) the calcitonin gene-related (CGRP) content of primary afferent neurons and (b) the thermal nociceptive threshold in normal and inflamed hind paws. NGF (0.1 mg/kg s.c.) was administered every other day for 7 days. After each injection of NGF there was transient thermal hyperalgesia lasting less than 23 h. ⋯ NGF treatment caused, however, a significant increase of the concentration of immunoreactive (IR) CGRP in the sciatic nerves and paw skin while it had no significant effect on CGRP-IR in the stomach or ureter. A separate set of experiments showed that intraplantar injection of complete Freund's adjuvant (CFA) in NGF-treated rats caused thermal hyperalgesia and edema that was not significantly different from values obtained in the control group. The results suggest that prolonged treatment of rats with moderate doses of NGF is sufficient to stimulate neuropeptide synthesis in primary afferent neurons without causing long-lasting changes in thermal nociceptive threshold.
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Neuroscience letters · Jul 1998
Increased capsaicin-induced secondary hyperalgesia as a marker of abnormal sensory activity in patients with fibromyalgia.
In this study, capsaicin-induced secondary hyperalgesia was assessed as a marker of abnormal nociceptive processing in patients with fibromyalgia (FM). The area of mechanical secondary hyperalgesia induced by a standard solution of capsaicin placed on the volar forearm was measured in ten patients with FM and the results compared to those obtained in ten patients with rheumatoid arthritis (RA) and ten normal subjects. ⋯ In the FM group the area of hyperalgesia correlated with the overall pain score and with the joint tenderness score. The results suggest that in FM there is enhanced sensitivity of nociceptive neurones at a spinal level, thereby supporting the concept of a generalised disturbance of pain modulation in this disorder.
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Neuroscience letters · Jul 1998
Crossed reduction of human motor cortex excitability by 1-Hz transcranial magnetic stimulation.
Electrophysiological studies have shown that 1-Hz repetitive transcranial magnetic stimulation (rTMS) of the primary motor area (M1) can produce a local decrease in excitability. Functional imaging data suggest that this change may be bilateral. ⋯ The slope of the curve relating MEP amplitude and stimulation intensity was decreased in the unstimulated hemisphere by active but not sham rTMS. This demonstrates that rTMS can condition cortical excitability at a distance of one or more synapses and suggest that decreased excitability to TMS is a correlate of decreased blood flow and metabolism.
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Neuroscience letters · Jun 1998
Increased interleukin-12 levels in human cerebrospinal fluid following severe head trauma.
An overwhelming intracranial inflammatory response occurs as a consequence of severe head trauma, leading to cerebral edema and secondary brain injury. Cytokines are important mediators of post-traumatic cerebral inflammation. ⋯ The mean IL-12 CSF levels were significantly elevated in all patients in the course of 14 days after trauma, compared to CSF samples from 15 control patients. Assessment of the IL-12 CSF/serum ratio and of the blood-brain barrier function, using the CSF/serum albumin ratio, suggest that elevated IL-12 CSF levels might be in part derived from intracerebral cytokine synthesis.
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Neuroscience letters · May 1998
Sevoflurane suppresses behavioral response in the rat formalin test: combination with intrathecal lidocaine produced profound suppression of the response.
We investigated the effects of intrathecal (i.t.) lidocaine, inhalation sevoflurane, and a combination of i.t. lidocaine and sevoflurane on the formalin test in rats. Group 1 (control) received i.t. saline 10 microl. Groups 2 and 3 received i.t. lidocaine 200 microg and 400 microg, respectively. ⋯ Group 7 received i.t. lidocaine 200 microg and 1.2% sevoflurane. The biphasic behavioral activity of the hindpaw of rats was observed. This study showed that i.t. lidocaine or inhalation sevoflurane before formalin injection, significantly suppressed the behavioral activity of the hindpaw of rats, and that this suppression was significantly potentiated by the co-administration of i.t. lidocaine and inhalation sevoflurane.