Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0162473 (Frey)
 2,599 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Snakebites are a relevant public health problem in Central and South America. Snake bite envenomations cause intense pain, not relieved by anti-venom. The fangs of many species are short, causing subcutaneous injection. Fangs of larger species inflict subcutaneous or intramuscular envenomation. To understand pain induced by subcutaneous venom, this study examined spinal mechanisms involved in pain-enhancing effects of subcutaneous Lys49 and Asp49 secretory phospholipase-A(2) (sPLA2), two components of Bothrops asper snake venom showing highly different enzymatic activities. Unilateral intraplantar sPLA2-Lys49 (catalytically inactive) or sPLA2-Asp49 (catalytically active) into rat hindpaws each induced mechanical hyperalgesia (Randall-Selitto test), whereas only catalytically active sPLA2-Asp49 caused mechanical allodynia (von Frey test). Effects induced by both sPLA2s were inhibited by intrathecal fluorocitrate, a reversible glial metabolic inhibitor. In support, immunohistochemical analysis revealed activation of dorsal horn astrocytes and microglia after intraplantar injection of either sPLA2. Spinal proinflammatory cytokines, nitric oxide, and prostanoids each appear to be involved in the pain-enhancing effects of these sPLA2s. Blockade of interleukin-1 (IL1) inhibited hyperalgesia induced by both sPLA2s, while leaving allodynia unaffected. Blockade of tumor necrosis factor reduced responses to sPLA2-Asp49. An inhibitor of neuronal nitric oxide synthase, 7-nitroindazole (7-NI), inhibited hyperalgesia induced by both sPLA2s, without interfering with allodynia induced by sPLA2-Asp49. On the other hand, L-N(6)-(1-iminoethyl)lysine (L-NI), an inhibitor of the inducible nitric oxide synthase, did not alter any sPLA2-induced effect. Lastly, celecoxib, an inhibitor of cyclooxygenase-2, attenuated sPLA2 actions. These data provide the first evidence of spinal mediators involved in pain facilitation induced by subcutaneous venoms.
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PMID:Snake venom components enhance pain upon subcutaneous injection: an initial examination of spinal cord mediators. 1532 10

Ghrelin is a peptide released from gastric endocrine cells that has an orexigenic effect via a vagal pathway. Here we determine the effect of ghrelin on mechanosensitivity of upper-intestinal vagal afferent fibers in ferret and mouse. The responses of gastroesophageal vagal afferents to graded mechanical stimulation were determined in vitro before and during application of ghrelin to their peripheral endings. Three types of vagal afferent were tested: tension receptors responding to circumferential tension, mucosal receptors responding only to mucosal stroking, and tension/mucosal (TM) receptors in ferret esophagus that responded to both stimuli. In the mouse, ghrelin did not significantly affect the response of mucosal receptors to mucosal stroking with calibrated von Frey hairs. However, it significantly reduced responses of tension receptors to circumferential tension (P < 0.005; two-way ANOVA) by up to 40%. This inhibition was reversed by the ghrelin receptor antagonist [d-Lys-3]-growth hormone-releasing peptide (GHRP)-6. In the ferret, ghrelin significantly reduced the response of mucosal and TM receptors to mucosal stroking with calibrated von Frey hairs. Surprisingly, ghrelin did not significantly alter the response to circumferential tension in either tension or TM receptors. RT-PCR analysis indicated that both ghrelin and its receptor are expressed in vagal afferent cell bodies in mouse nodose ganglia. In conclusion, ghrelin selectively inhibits subpopulations of mechanically sensitive gastroesophageal vagal afferents; there is also potential for ghrelin release from vagal afferents. However, the subpopulation of afferents inhibited differs between species. These data have broad implications for ghrelin's role in food intake regulation and reflex control of gastrointestinal function.
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PMID:Ghrelin selectively reduces mechanosensitivity of upper gastrointestinal vagal afferents. 1729 11

The common step in the actions of members of the radical SAM superfamily of enzymes is the one-electron reductive cleavage of S-adenosyl-l-methionine (SAM) into methionine and the 5'-deoxyadenosyl radical. The source of the electron is the [4Fe-4S]1+ cluster characterizing the radical SAM superfamily, to which SAM is directly ligated through its methionyl carboxylate and amino groups. The energetics of the reductive cleavage of SAM is an outstanding question in the actions of radical SAM enzymes. The energetics is here reported for the action of lysine 2,3-aminomutase (LAM), which catalyzes the interconversion of l-lysine and l-beta-lysine. From earlier work, the reduction potential of the [4Fe-4S]2+/1+ cluster in LAM is -0.43 V with SAM bound to the cluster (Hinckley, G. T., and Frey, P. A. (2006) Biochemistry 45, 3219-3225), 1.4 V higher than the reported value for trialkylsulfonium ions in solution. The midpoint reduction potential upon binding l-lysine has been estimated to be -0.6 V from the values of midpoint potentials measured with SAM bound to the cluster and l-alanine in place of l-lysine, with S-adenosyl-l-homocysteine (SAH) bound to the cluster in the presence of l-lysine, and with SAH bound to the cluster in the presence of l-alanine or of l-alanine and ethylamine in place of l-lysine. The reduction potential for SAM has been estimated to be -0.99 V from the measured value for S-3',4'-anhydroadenosyl-l-methionine. The reduction potential for the [4Fe-4S] cluster is lowered 0.17 V by the binding of lysine to LAM, and the binding of SAM to the [4Fe-4S] cluster in LAM elevates its reduction potential by 0.81 V. Thus, the binding of l-lysine to LAM contributes 4 kcal mol-1, and the binding of SAM to the [4Fe-4S] cluster in LAM contributes 19 kcal mol-1 toward lowering the barrier for reductive cleavage of SAM from 32 kcal mol-1 in solution to 9 kcal mol-1 at the active site of LAM.
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PMID:Binding energy in the one-electron reductive cleavage of S-adenosylmethionine in lysine 2,3-aminomutase, a radical SAM enzyme. 1794 92

Recent studies have suggested that melanocortins contribute to the generation and/or maintenance of pathological pain. Experimental evidence indicates a primary role for melanocortin 4 (MC4) receptors in pathological pain. In a previous study, we described the presence of MC4 receptor transcripts in the dorsal root ganglia (DRG). This finding prompted us to investigate the peripheral antinociceptive effects of MC4 receptor antagonists. In addition, we assess the expression of MC4 receptors in the spinal cord and the DRG of rats subjected to neuropathic pain induced by chronic constriction injury (CCI) of the sciatic nerve. Injection of the MC4 receptor antagonists Asp3-Lys8- Ac-Nle-Asp-His-D-Nal(2')-Arg-Trp-Lys-NH(2) (SHU9119) and Mpr1-Cys8-Mpr-Glu-His-(D-Nal)-Arg-Trp-Gly-Cys-Pro-Pro-Lys-Asp-NH(2) (JKC-363) into the ipsilateral paw resulted in a significant and dose-dependent alleviation of mechanical allodynia (assayed by the von Frey test) and thermal hyperalgesia (assayed by the Hargreaves test). Compared to naive control animals, immunohistochemistry revealed a 40% and 22% increase in MC4 receptor-immunoreactivity (IR) in the dorsal horn of the spinal cord ipsilateral to the injury at 3 and 14 days after CCI, respectively. Similarly, in the ipsilateral L4-L5 DRG, a 21.1% enhancement in MC4 receptor-IR was seen 3 days after CCI, as well as a 40.5% increase 14 days after CCI. Together, painful neuropathy resulted in the up-regulation of MC4 receptors in the spinal and peripheral nociceptive pathways. This up-regulation of MC4 receptors promotes the pronociceptive action of their endogenous ligands. Therefore, a block of the MC4 receptors results in the antagonism of neuropathic pain and such treatment could be beneficial therapeutically for individuals with chronic neuropathic pain.
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PMID:Peripheral antinociceptive effects of MC4 receptor antagonists in a rat model of neuropathic pain - a biochemical and behavioral study. 2008 Dec 44

Tolerance to the local antiallodynic effects of morphine, DPDPE ([D-Pen(2),D-Pen(5)]-Enkephalin) or JWH-015 ((2-methyl-1-propyl-1H-indol-3-yl)-1-naphthalenylmethanone) after their repeated administration during neuropathic pain was evaluated. The role of the nitric oxide-cGMP-protein kinase G (PKG)-c-Jun N-terminal kinase (JNK) signaling pathway on the peripheral morphine-induced tolerance after the chronic constriction of sciatic nerve in mice was also assessed. The mechanical and thermal antiallodynic effects produced by a high dose of morphine, DPDPE or JWH-015 subplantarly administered daily from days 10 to 20 after nerve injury were estimated with the von Frey filaments and cold plate tests. The antiallodynic effects of the repeated administration of morphine combined with a sub-analgesic dose of a selective inducible nitric oxide synthase (NOS2) (L-N(6)-(1-iminoethyl)-lysine; L-NIL), L-guanylate cyclase (1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one; ODQ), PKG ((Rp)-8-(para-chlorophenylthio)guanosine-3',5'-cyclic monophosphorothioate; Rp-8-pCPT-cGMPs) or JNK (anthra[1,9-cd]pyrazol-6(2H)-one; SP600125) inhibitor from days 10 to 20 after injury were also evaluated. The repeated administration of morphine, but not DPDPE or JWH-015, produced a rapid development of tolerance to its mechanical and thermal antiallodynic effects in sciatic nerve-injured mice. The co-administration of morphine with L-NIL, ODQ, Rp-8-pCPT-cGMPs or SP600125 avoided the development of morphine antiallodynic tolerance after nerve injury. These findings reveal that the repeated local administration of DPDPE or JWH-015 did not induce antinociceptive tolerance after sciatic nerve injury-induced neuropathic pain. Our data also indicate that the peripheral nitric oxide-cGMP-PKG-JNK signaling pathway participates in the development of morphine tolerance after nerve injury and propose the inactivation of this pathway as a promising strategy to avoid morphine tolerance during neuropathic pain.
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PMID:The inhibition of the nitric oxide-cGMP-PKG-JNK signaling pathway avoids the development of tolerance to the local antiallodynic effects produced by morphine during neuropathic pain. 2254 33

The neural balance between facilitation and inhibition determines the final tendency of central sensitization. Nerve injury-induced hypersensitivity was considered as the results from the enhanced ascending facilitation and the diminished descending inhibition. The role of dopaminergic transmission in the descending inhibition has been well documented, but its underlying molecular mechanisms are unclear. Previous studies demonstrated that the lysine dimethyltransferase G9a/G9a-like protein (Glp) complex plays a critical role in cocaine-induced central plasticity, and given cocaine's role in the nerve system is relied on its function on dopamine system, we herein proposed that the reduced inhibition of dopaminergic transmission was from the downregulation of tyrosine hydroxylase expression by G9a/Glp complex through methylating its gene Th After approval by the Animal Care and Use Committee, C57BL/6 mice were used for pain behavior using von Frey after spared nerve injury, and Th CpG islands methylation was measured using bisulfite sequencing at different nerve areas. The inhibitor of G9a/Glp, BIX 01294, was administered intraventricularly daily with bolus injection. The protein levels of G9a, Glp, and tyrosine hydroxylase were measured with immunoblotting. Dopamine levels were detected using high-performance liquid chromatography. The expression of G9a but not Glp was upregulated in ventral tegmental area at post-injury day 4 till day 49 (the last day of the behavioral test). Correspondingly, the Th CpG methylation is increased, but the tyrosine hydroxylase expression was downregulated and the dopamine level was decreased. After the intracerebroventriclar injection of BIX 01294 since the post-injury days 7 and 14 for consecutive three days, three weeks, and six weeks, the expression of tyrosine hydroxylase was upregulated with a significant decrease in Th methylation and increase in dopamine level. Moreover, the pain after G9a/Glp inhibitor was attenuated significantly. In sum, methytransferase G9a/Glp complex partially controls dopaminergic transmission by methylating Th in peripheral nerve injury-induced neuropathic pain.
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PMID:Dopaminergic inhibition by G9a/Glp complex on tyrosine hydroxylase in nerve injury-induced hypersensitivity. 2756 35


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