Introduction: Long-term use of narcotics causes hyperalgesia in some patients with an unknown mechanism known as opioid-induced (OIH). Case Presentation: Testosterone was prescribed to a 43-year-old man suffering from the effects OIH syndrome due long-term methadone. prescription significantly reduced hyperalgesia. Conclusions: may have therapeutic value OIH.

background: diabetes mellitus in some clinical cases is accompanied with hyperalgesia. in this study, we evaluated the possible beneficial effect of chronic pelargonidin (pg) treatment on hyperalgesia in streptozotocin (stz)-diabetic neuropathic rat. methods: male wistar rats (n = 56) were divided into seven groups, i.e. control, diabetic, pg-treated control, pg (single- and multiple-dose)-trea...

introduction: glial activation and secretion of cytokines at the spinal level is known as part of chronic pain pathogenesis. although changes in tnfα at the supraspinal level are reported during chronic pain, its exact role and site of action remain to be elucidated. we investigated the effect of microinfusion of tnfα into the lc in a rat model of neuropathic pain. methods: male wistar rats wer...

Subpopulations of primary nociceptors (C- and Aδ-fibers), express the TRPV1 receptor for heat capsaicin. During cutaneous inflammation, these afferents may become sensitized, leading to hyperalgesia. It is known that TRPV1+ are involved in hyperalgesia; however, their involvement mechanical hyperalgesia unclear. This study explored contribution capsaicin-sensitive development humans following u...

This study tested a modified experimental model of heat-induced hyperalgesia, which improves the efficacy to induce primary and secondary hyperalgesia and the efficacy-to-safety ratio reducing the risk of tissue damage seen in other heat pain models. Quantitative sensory testing was done in eighteen healthy volunteers before and after repetitive heat pain stimuli (60 stimuli of 48°C for 6 s) to...

introduction: peripheral nerve injury leads to neuropathic pain syndromes and different sensation like allodynia and hyperalgesia. different animal models of neuropathic pain are used to study the neuropathic pain mechanisms. the present study was performed on two models, (sni). the purpose of this study was comparing the behavioral responses of yhese two models and the role of saphenous and su...

We investigated the role of nitric oxide (NO) in inflammatory hyperalgesia. Coinjection of prostaglandin E2 (PGE2) with the nitric oxide synthase (NOS) inhibitor NG-methyl-L-arginine (L-NMA) inhibited PGE2-induced hyperalgesia. L-NMA was also able to reverse that hyperalgesia. This suggests that NO contributes to the maintenance of, as well as to the induction of, PGE2-induced hyperalgesia. Con...

Recently, we have shown that the interaction between NGF and sensory neurons in early postnatal periods is restricted to nociceptive afferents (Ritter et al., 1991; Lewin et al., 1992a; Ritter and Mendell, 1992). Here we show that administration of excess NGF to neonatal or mature animals can lead to a profound behavioral hyperalgesia. Neonatal NGF treatment (postnatal day 0-14) resulted in a p...

BACKGROUND Descending influences from the rostral medial medulla (RMM) contribute to secondary hyperalgesia in persistent inflammatory, neuropathic, and visceral pain models. The current study examined if descending inhibition or facilitation from the RMM modulates primary and secondary hyperalgesia after incision in the rat hind limb. METHODS Bilateral RMM lesions were produced using the som...

Tissue injury is associated with sensitization of nociceptors and subsequent changes in the excitability of central (spinal) neurons, termed central sensitization. Nociceptor sensitization and central sensitization are considered to underlie, respectively, development of primary hyperalgesia and secondary hyperalgesia. Because central sensitization is considered to reflect plasticity at spinal ...