Journal of the peripheral nervous system : JPNS
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J. Peripher. Nerv. Syst. · Sep 2002
Comparative StudyMolecular forms of NGF in human and rat neuropathic tissues: decreased NGF precursor-like immunoreactivity in human diabetic skin.
Precursors of NGF have been shown to be the predominant forms of this neurotrophin in human brain and peripheral tissues, and proNGF has been shown recently to preferentially bind p75NTR with high affinity. In our studies of human and rat skin and nerve extracts, a 53 kDa band was detected by Western blot using antibodies against rhNGF or prepro-NGF (-91 to -60), that could correspond to a previously described modified prepro-NGF-like molecule. ⋯ Prepro-NGF antibody immunostained rat large/medium sensory neurons, whereas only small sensory neurons were stained with antibodies to mature rhNGF, suggesting that prepro-NGF may be preferentially taken up and transported by p75NTR. The different molecular forms derived from prepro-NGF are likely to be of importance in sensory mechanisms, and deserve further investigation.
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J. Peripher. Nerv. Syst. · Dec 2001
Randomized Controlled Trial Clinical TrialRelative sensitivity to alfentanil and reliability of current perception threshold vs von Frey tactile stimulation and thermal sensory testing.
Recent technological advances claim to allow quantitative measurement of the functional integrity of both large and small diameter sensory nerve fibers using the current perception threshold (CPT) sensory testing device. This device has yet to be validated against the corresponding gold standard references for sensory testing (thermal sensory testing [TST]) and von Frey tactile hair stimulation [VF]) to correlate its evaluation of similar sensory nerve perceptions. A baseline neurosensory examination using the CPT, TST and VF methods was performed on 19 healthy volunteers. ⋯ In addition, there was no effect of alfentanil on the VF or the CPT 2000 Hz thresholds. However, we did not see the predicted relation between the 250 Hz CPT stimulus and cool sensation. From these studies, there is some evidence that similar fiber tracts may be measured between the CPT, TST, and VF methods, especially with the CPT 5 Hz measures and C-fiber tract activity.
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J. Peripher. Nerv. Syst. · Jun 2001
Etanercept reduces hyperalgesia in experimental painful neuropathy.
Etanercept, a recombinant tumor necrosis factor receptor (p75)-Fc fusion protein competitively inhibits tumor necrosis factor-alpha (TNF). Etanercept has been successfully used in patients with rheumatoid arthritis, where it reduces pain and inflammation. Because locally produced proinflammatory cytokines play a role in pain after nerve injury, we investigated whether etanercept can reduce pain and hyperalgesia in an animal model of painful neuropathy, the chronic constriction injury of the sciatic nerve. ⋯ Treatment with etanercept reduced thermal hyperalgesia and mechanical allodynia significantly in both modes of application. The effect of etanercept was present in animals that were treated from the time of surgery and in those that were treated from day 6, when hyperalgesia was already present. These results suggest the potential of etanercept as a treatment option for patients with neuropathic pain.
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J. Peripher. Nerv. Syst. · Jun 2000
Epineurial application of TNF elicits an acute mechanical hyperalgesia in the awake rat.
Tumor necrosis factor alpha (TNF) injected into the sciatic nerve and neutralizing antibodies to its receptor injected around the nerve are respectively associated with inducing and blocking pain behavior beginning 1 to 3 days post-injection. This study examined the acute effects of TNF applied around the nerve trunk on the mechanical threshold (determined with von Frey hairs) and withdrawal latency to radiant heat. TNF (0.9 and 7.7 ng in 90 microL) injected onto the nerve via an indwelling catheter elicited a decrease in mechanical threshold. ⋯ Identical doses of TNF injected near, but not on the nerve, 90 ng of TNF injected on the nerve, and vehicle were without effect on either modality. These data indicate that effects of acutely administered TNF to the nerve trunk are capable of producing modality specific pain behavior. These changes may represent a first step in TNF-induced neuropathic pain.
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J. Peripher. Nerv. Syst. · Mar 2000
Variation in rat sciatic nerve anatomy: implications for a rat model of neuropathic pain.
We discovered a variation of rat sciatic nerve anatomy as an incidental finding during the anatomical exploration of the nerve lesion site in a rat neuropathic pain model. To confirm the composition and distribution of rat sciatic nerve, macroscopic anatomical investigation was performed in both left and right sides in 24 adult Sprague-Dawley rats. In all rats, the L4 and L5 spinal nerves were fused tightly to form the sciatic nerve. ⋯ Also, the L3 spinal nerve sent a thin branch to the L4 spinal nerve or sciatic nerve in 6 rats (25%). We conclude that the components of sciatic nerve in Sprague-Dawley rats vary from L3 to L6; however, the major components are L4 and L5 macroscopically. This finding is in contrast to the standard textbooks of rat anatomy which describe the sciatic nerve as having major contributions from L4, L5, and L6.