Articles: histamine.
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Bacterial-derived compounds from the intestinal microbiome modulate host mucosal immunity. Identification and mechanistic studies of these compounds provide insights into host-microbial mutualism. Specific Lactobacillus reuteri strains suppress production of the proinflammatory cytokine, tumor necrosis factor (TNF), and are protective in a mouse model of colitis. ⋯ Comparative transcriptomics between wild-type and mutant L. reuteri strains revealed additional genes involved in immunomodulation, including previously identified hdc genes involved in histidine to histamine conversion. The folC2 mutant yielded diminished hdc gene cluster expression and diminished histamine production, suggesting a link between folate and histadine/histamine metabolism. The identification of genes and gene networks regulating production of bacterial-derived immunoregulatory molecules may lead to improved anti-inflammatory strategies for digestive diseases.
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Anesthesia and analgesia · Jul 2016
Histaminergic Pharmacology Modulates the Analgesic and Antiedematogenic Effects of Spinally Injected Morphine.
Histamine receptors are known to participate in spinal cord nociceptive transmission, and previous studies have suggested that histaminergic receptors are involved in the analgesic effects of morphine. Herein, we investigated the effect of intrathecal injection of histaminergic agonists and antagonists in a model of acute articular inflammation and their interaction with morphine. ⋯ Histamine seems to act at the spinal level via H1 and H3 receptors to modulate acute arthritis in rats. An H1R antagonist and H3R agonist were found to potentiate the analgesic and antiedematogenic effects of morphine, suggesting that histaminergic and opioid spinal systems may be explored for means of improving analgesia, as well as peripheral anti-inflammatory effects.
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This study investigated whether itch induced by intra-epidermal histamine is subjected to modulation by a standardized conditioned pain modulation (CPM) paradigm in 24 healthy volunteers. CPM was induced by computer-controlled cuff pressure algometry and histamine was introduced to the volar forearm by skin prick test punctures. Moreover, neurogenic inflammation and wheal reactions induced by histamine and autonomic nervous system responses (heart rate variability and skin conductance) were monitored. CPM did not modulate the intensity of histamine-induced itch suggesting that pruriceptive signaling is not inhibited by pain-recruited endogenous modulation, however, CPM was found to aggravate histamine-induced neurogenic inflammation, likely facilitated by efferent sympathetic fibers.
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Here we studied whether and through which mechanisms spinal administration of histamine dihydrochloride (histamine) attenuates pain behavior in neuropathic animals. Experiments were performed in rats with spinal nerve ligation-induced neuropathy and a chronic intrathecal catheter for spinal drug delivery. Mechanical hypersensitivity was assessed with monofilaments while radiant heat was used for assessing nociception. ⋯ Additionally, histamine prevented central (presumably postsynaptically-induced) facilitation of hypersensitivity induced by N-methyl-d-aspartate. The results indicate that spinal histamine at the dose range of 0.1-10µg selectively attenuates mechanical hypersensitivity and ongoing pain in neuropathy. The spinal histamine-induced antihypersensitivity effect involves histamine H2 and GABA(A) receptors and (presumably neuropathy-induced) co-activation of spinal α1-adrenoceptors.
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Raoultella ornithinolytica is a species of gram-negative encapsulated and aerobic bacteria belonging to the family Enterobacteriaceae and is mainly found in fish. The most distinctive feature of this bacterium is the ability to convert histidine to histamine; therefore, the consumption of decomposing fish infected by R. ornithinolytica causes rashes, diarrhea, flushing, sweating and vomiting. This food poisoning is also called histamine fish poisoning; however, human infections with R. ornithinolytica are extremely rare and have so far only affected patients with diseases suppressing the immune system. The current case report describes for the first time sepsis with evidence of bloodstream infection by R. ornithinolytica in an immunocompetent male patient and the successful antibiotic treatment.