Articles: hyperalgesia.
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J. Neuropathol. Exp. Neurol. · Sep 2005
Comparative StudyInhibition of type 1 diabetic hyperalgesia in streptozotocin-induced Wistar versus spontaneous gene-prone BB/Worchester rats: efficacy of a selective bradykinin B1 receptor antagonist.
Insulin-dependent type 1 diabetes (T1D) is linked to a series of complications, including painful diabetic neuropathy (PDN). Several neurovascular systems are activated in T1D, including the inducible bradykinin (BK) B1 receptor (BKB1-R) subtype. We assessed and compared the efficacy profile of a selective BKB1-R antagonist on hyperalgesia in 2 models of T1D: streptozotocin (STZ) chemically induced diabetic Wistar rats and spontaneous BioBreeding/Worchester diabetic-prone (BB/Wor-DP) rats. ⋯ BB/Wor-DP rats also developed hyperalgesia over time that preceded hyperglycemia, starting at the age of 6 weeks (9% decrease in the hot plate reaction time) and stabilizing over the age of 16 to 24 weeks to a maximum (60% decrease in the hot plate reaction time). Single, acute subcutaneous administration of the selective BKB1-R antagonist induced significant time- and dose-dependent attenuation of hyperalgesia in both STZ diabetic and BB/Wor-DP rats. Thus, selective antagonism of the inducible BKB1-R subtype may constitute a novel and potential therapeutic approach for the treatment of PDN.
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Anesthesia and analgesia · Sep 2005
The antiallodynic and antihyperalgesic effects of neurotropin in mice with spinal nerve ligation.
Although Neurotropin(R) (NTP) has been used clinically as an analgesic in Japan for many years, its effect on neuropathic pain in animal models has not been examined in detail. Its main effect has been indicated to be activation of the descending monoaminergic pain inhibitory systems. To study the effect of NTP on neuropathic pain, we subjected mice to spinal nerve ligation. ⋯ When the effect of NTP was examined after depletion of monoamines in the spinal cord by intrathecal neurotoxins, the antiallodynic and antihyperalgesic effects were still observed after serotonergic denervation, but not after noradrenergic denervation. In addition, intracerebroventricular NTP increased withdrawal threshold and latency although intrathecal or local administration of NTP did not. These results suggest that the antiallodynic and antihyperalgesic effect of NTP on neuropathic pain induced by spinal nerve ligation is mediated principally through the action at supraspinal sites and through activation of spinal noradrenergic systems, possibly via the descending inhibitory pathway.
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An in vivo rat model of transient cervical nerve root compression. ⋯ Results imply a force threshold exists less than 10 gf for persistent pain symptoms following transient cervical nerve root compression. Findings also suggest that spinal glial activation may be related to behavioral sensitivity and may modulate cervical nerve root mediated pain.
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Clinical Trial
Secondary heat hyperalgesia detected by radiant heat stimuli in humans: evaluation of stimulus intensity and duration.
Diverging observations on secondary hyperalgesia to heat stimuli have been reported in the literature. No studies have investigated the importance of heat stimulus intensity and duration for the assessment of secondary heat hyperalgesia. ⋯ The stimulus conditions were systematically varied between three intensity levels (0.8, 1.0 and 1.2 x heat pain threshold (PT)) and four duration steps (200, 350, 500 and 750 ms). The present study shows that long duration (350-750 ms) and low intensity (0.8 and 1.0 x PT) radiant heat stimuli were adequate to detect secondary heat hyperalgesia.
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We developed a mouse model of cancer pain to investigate its underlying mechanisms. SCC-7, squamous cell carcinoma (SCC) derived from C3H mice, was inoculated subcutaneously into either the plantar region or thigh in male C3H/Hej mice. Heat and mechanical sensitivity as well as spontaneous behavior were measured at the plantar surface of the ipsilateral hind paw after the inoculation. ⋯ Intraperitoneal administration of the competitive TRPV1 antagonist capsazepine inhibited hyperalgesia induced by tumor cell-inoculation in either plantar- or thigh-inoculated animals. This study indicated that inoculation of SCC resulted in spontaneous pain, heat hyperalgesia and mechanical allodynia. The altered expression of TRPV1 in the DRG may be involved in behavioral changes in this model.