In Aplysia, noxious stimuli induce sensitization of defensive responses. However, it remains largely unknown whether such stimuli also alter nondefensive behaviors. In this study, we examined the effects of noxious stimuli on feeding. Strong electric shocks, capable of inducing sensitization, also led to the suppression of feeding. The use of multiple training protocols revealed that the time c...

introduction: nucleus reticularis paragigantocellularis (pgi) is one of the major components of the rostral ventromedial medulla (rvm), which is involved in nociceptive processing and pain modulation. the aim of this study was to examine the effect of c fiber destruction on responsiveness of nucleus reticularis paragigantocellularis (pgi) to formalin, as a noxious stimulus, in normal and morphi...

Pain has long been thought to wax and wane in relative proportion to fluctuations in the intensity of noxious stimuli. Dynamic aspects of nociceptive processing, however, remain poorly characterized. Here we show that small decreases (+/-1-3 degrees C) in noxious stimulus temperatures (47-50 degrees C) evoked changes in perceived pain intensity that were as much as 271% greater than those of eq...

The Drosophila TRPA channel Painless is required for the function of polymodal nociceptors which detect noxious heat and noxious mechanical stimuli. These functions of Painless are reminiscent of mammalian TRPA channels that have also been implicated in thermal and mechanical nociception. A popular hypothesis to explain the mechanosensory functions of certain TRP channels proposes that a string...

The etiology of interstitial cystitis/bladder pain syndrome (IC/BPS) remains elusive and may involve multiple causes. To better understand its pathophysiology, many efforts have been made to create IC/BPS models. Most existing models of IC/BPS strive to recreate bladder-related features by applying noxious intravesical or systemic stimuli to healthy animals. These models are useful to help unde...

Calcium-calmodulin dependent protein kinase IV (CaMKIV) is a protein kinase that activates the transcription factor CREB. Our previous work demonstrated that mice lacking CaMKIV had a defect in fear memory while behavioral responses to noxious stimuli were unchanged. Here, we measured ultrasonic vocalizations (USVs) before and after fear conditioning and in response to a noxious injection of ca...

Notaspid snails are known for their defensive skin secretion of sulfuric acid (pH 1-2) in response to noxious stimuli. We observed acid secretion and behavior in five notaspid species, and studied them in detail in Pleurobranchaea californica. All species secreted acid in response to skin abrasion or compression. Moreover, all species showed stereotypic avoidance behavior to acidified sea water...

Nociception, warning of injury that should be avoided, serves an important protective function in animals. In this study, we show that adult Drosophila avoids noxious heat by a jump response. To quantitatively analyze this nociceptive behavior, we developed two assays. In the CO2 laser beam assay, flies exhibit this behavior when a laser beam heats their abdomens. The consistency of the jump la...

Recent studies indicate that descending pain modulatory pathways undergo time-dependent changes in excitability following inflammation involving both facilitation and inhibition. The cellular and molecular mechanisms of these phenomena are unclear. In the present study, we examined N-methyl-D-aspartate (NMDA) receptor gene expression and neuronal activity in the rostral ventromedial medulla (RV...

Recent advances in pain research provide a clear picture for the molecular mechanisms of acute pain; substantial information concerning plasticity that occurs during neuropathic pain has also become available. The peripheral mechanisms responsible for neuropathic pain are found in the altered gene/protein expression of primary sensory neurons. With damage to peripheral sensory fibers, a variety...