BACKGROUND The role of serotonin (5-hydroxytrptamine, 5-HT) in the modulation of pain has been widely studied. Previous work led to the hypothesis that 5-hydroxyindolacetic acid (5-HIAA), a main metabolite of serotonin, might by itself influence pain thresholds. RESULTS In the present study, we investigated the role of 5-HIAA in inflammatory pain induced by intraplantar injection of complete ...

Development of peripheral neuropathy, which can present as painful neuropathy or loss of sensation, sometimes limit the use of paclitaxel in the treatment of solid tumors such as breast cancer. Previous studies reported development of thermal hyperalgesia in mice treated with paclitaxel. In this study an automated flinch detection system for the formalin test (20 μl of 5% formalin injected subc...

BACKGROUND This study tests the hypothesis that loss of spinal activity of gamma-aminobutyric acid (GABA) contributes to the allodynia and hyperalgesia observed after peripheral nerve injury. METHODS Intrathecal catheters were implanted in male Sprague-Dawley rats. Antinociception was assessed by measuring withdrawal latency to immersion of the tail in a 52 degrees C water bath. Nerve injury ...

It is currently accepted that superoxide anion (O2•-) is an important mediator in pain and inflammation. The role of superoxide anion in pain and inflammation has been mainly determined indirectly by modulating its production and inactivation. Direct evidence using potassium superoxide (KO2), a superoxide anion donor, demonstrated that it induced thermal hyperalgesia, as assessed by the Hargrea...

To study the neuropathic pain mechanism, various behavioral responses of animals in to different neuropathic models were considered. Adult male Sprague-Dawley rats weighing 230-280 g were used. Anesthesia was initially induced with pentobarbital I.P. (50 mg/kg). These models included (1): chronic constriction injury (CCI) by loose ligation of the sciatic nerve (2) Spared nerve injury (SNI) by a...

Activation of protease-activated receptors (PARs) in non-neural tissue results in prostaglandin production. Because PARs are found in the spinal cord and increased prostaglandin release in the spinal cord causes thermal hyperalgesia, we hypothesized that activation of these spinal PARs would stimulate prostaglandin production and cause a cyclooxygenase-dependent thermal hyperalgesia. PARs were ...

Tolerance to the analgesic effects of opioids occurs after their chronic administration, a pharmacological phenomenon that has been associated with the development of abnormal pain sensitivity such as hyperalgesia. In the present study, we investigated the role of TRPV1, which is crucial for the transduction of noxious chemical and thermal stimuli, in morphine tolerance and tolerance-associated...

INTRODUCTION The area of secondary hyperalgesia following brief thermal sensitization (BTS) of the skin and heat pain detection thresholds (HPDT) may both have predictive abilities in regards to pain sensitivity and clinical pain states. The association between HPDT and secondary hyperalgesia, however, remains unsettled, and the dissimilarities in physiologic properties suggest that they may re...

BACKGROUND The mechanisms underlying cyclin-dependent kinase 5 (Cdk5)-mediated thermal hyperalgesia induced by inflammation remain poorly understood. In the present study, we examined thermal hyperalgesia provoked by peripheral injection of complete Freund׳s adjuvant (CFA) to test for Cdk5 signaling in the spinal dorsal horns of rats through the p38 mitogen-activated protein kinase (p38 MAPK) s...