PP32 Antipsoriatic activity of GYY4137 (a slow-releasing hydrogen sul- phide donor) microemulsion system using a mouse skin model of psoriasis Tuanny P. Schmidt a , Luciana B. Lopes a , Leandro Rodrigues a , Mark Wood b , Matthew Whiteman b , Marcelo N. Muscará a , Soraia K.P. Costa a a Department of Pharmacology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil b University of Exeter, St. Luke’s Campus, Exeter, Devon, UK We have previously shown that the systemic administration of fast-releasing hydrogen sulphide (H2S) donors results in signifi- cant inhibition of the acute itching and associated cutaneous inflammation induced by either histamine or the mast cell degranulator compound 48/80, thus supporting the use of H2S donors as therapeutic alternatives for controlling itch sensation (Nitric Oxide 2013; 31:S54–S55). On the other hand, the systemic administra- tion of H2S can be potentially life threatening and might have long- term side effects. The aim of this investigation was to assess the antipruritic and anti-inflammatory efficiency of a microemulsion as a drug delivery for the slow-releasing H2S donor GYY4137 in the therapy of a psoriasis-like skin model. Under isoflurane anaesthe- sia, the dorsal skin of BALB/c mice was shaved (6 cm 2 ), and psoriasis was induced by the topical application of the TLR-7 receptor agonist imiquimod (IMQ, as a 5% cream; 65 mg/animal; Germed, Brazil), on the dorsal skin and ear surface during 5 consecutive days. Control- treated mice received an equivalent amount of vaseline. Mice with psoriasis were concomitant treated with a microemulsion system containing GYY4137, at 1, 2 or 4 %, or its vehicle (poloxamer + oleic acid and monolein 9:1 w/w; 65 mg/day). The severity of psoriasis- like skin (area and severity index – PASI) and ears was scored daily during six days. The spontaneous itching behaviour was recorded during 30min at days 1, 4 and 6, when myeloperoxidase activity (MPO, a marker of leucocyte infiltration) was also evaluated. At day 6, the mice were euthanized and skin collected. The single daily topical administration of the GYY4137 microemulsion greatly reduced, in a non-dependent concentration fashion, the increased MPO (12.6 ± 4.2 U/mg for control and 1.1 ± 0.4, 2.8 ± 1.9 and 2.3 ± 2.1U/mg for GYY4137 at 1, 2 and 4% doses respectively; n = 5), and partially inhibited erythema score(7.5 ± 1.3 control and 4.8 ± 0.3* AUC GYY4137 at 4% dose; n = 5), but only fairly reduced PASI, scaly skin, ear thickness and spontaneous itching, as compared to pso- riatic control mice. We conclude that besides the partial beneficial effect that has been demonstrated by the GYY4137 microemulsion, further changes of the current formulation should be performed in order to improve the topic delivery of GYY4137, and thus better sup- press PASI and itching in this murine psoriasis-like disease. Financial support: FAPESP, CNPq, CAPES. Acknowledgments: We thank Mrs. Irene M. Gouvea and Mr. Antonio Soares Jr. for the technical assistance. http://dx.doi.org/10.1016/j.niox.2015.02.062 PP33 H2S-induced increase in hepatic glucose production and the un- derlying mechanisms Ashley Anne Untereiner a,b,c , Rui Wang a,d , Lingyun Wu a,b,c a The Cardiovascular and Metabolic Research Unit, Lakehead University, ON, Canada b Department of Health Sciences, Lakehead University, ON, Canada c Thunder Bay Regional Research Institute, Thunder Bay, ON, Canada d Department of Biology, Lakehead University, ON, Canada Glucose homeostasis is critical for maintaining the physiologi- cal function of our body, whereby its sustained disturbance may lead to the metabolic syndrome. The liver is the major glucose-producing organ where gluconeogenesis (the de novo synthesis of glucose) occurs via stimulation from the cAMP/protein kinase A (PKA) and glucocorticoid signaling pathways. In the present study, we focused on the crucial role of cystathionine γ-lyase (CSE)-generated hydro- gen sulfide (H 2S) in hepatic glucose production under physiological conditions. We found that CSE-knockout (KO) mice had a reduced rate of gluconeogenesis, which was reversed upon administration of NaHS (an H2S donor) (i.p.). Interestingly, isolated CSE-KO hepa- tocytes exhibited a reduced glycemic response to chemical-induced activation of the cAMP/PKA and glucocorticoid pathways com- pared to wild-type (WT) hepatocytes. Treatment with the inhibitors for PKA (KT 5720) or glucocorticoid receptor (RU-486) signifi- cantly reduced H2S-stimulated glucose production from both WT and CSE-KO mouse hepatocytes. NaHS treatment up-regulated the protein levels of key gluconeogenic factors, such as peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α), phos- phoenolpyruvate carboxykinase (PEPCK), and CCAAT-enhancer- binding proteins-β (C/EBP-β). Additionally, the enzymatic activities of the major gluconeogenic enzymes, fructose-1,6-bisphosphatase (FBPase) and glucose-6-phosphatase (G6Pase), were reduced in CSE- KO hepatocytes compared to WT hepatocytes, which were rescued with exogenous H2S. Indeed, the sulfhydration levels of PEPCK and FBPase were significantly lower in CSE-KO hepatocytes compared to their WT counterparts, whereby exogenous H2S significantly en- hanced the sulfhydrated forms of both proteins. Finally, knockdown of PGC-1α, but not C/EBP-β, significantly decreased NaHS-induced glucose production from the primary hepatocytes. This study dem- onstrates the stimulatory effect of endogenous H2S on liver glucose production and reveals three underlying mechanisms; i.e. the glu- cocorticoid receptor pathway-mediated up-regulation of PGC-1α and PEPCK; the cAMP/PKA-mediated up-regulation of PGC-1α; and the increased activities of G6Pase and FBPase. The current study may offer clues for the homeostatic regulation of glucose metabolism under physiological conditions and its dysregulation in the meta- bolic syndrome. Acknowledgments: This research has been supported by an op- erating grant from the Canadian Institutes of Health Research (CIHR) to R. Wang and a Grant-in-aid from the Heart and Stroke Founda- tion of Canada to L. Wu. L. Wu is supported by a Heart and Stroke Foundation – Ontario Mid-Career Investigator Award and A.A. Untereiner is supported by a Doctoral Research Award from CIHR. http://dx.doi.org/10.1016/j.niox.2015.02.063 PP34 The role of hydrogen sulfide in enhanced sphingomyelinase induced vasorelaxation in db/db mice Ane S. Dybvig, Gabriella Marosi, Zsuzsa Straky, Dávid Korda, Zoltán Benyó, Éva Ruisanchez, Levente Kiss Institute of Human Physiology and Clinical Experimental Research, Semmelweis University, Budapest, Hungary Sphingomyelinase (SMase) induces changes in vascular tone with an initial contraction and subsequent relaxation in aortic rings of wild type mice and – remarkably – these effects are more pro- nounced in db/db animals. However, the exact mechanism of these increased effects is not understood; therefore we aimed to inves- tigate the reasons behind the enhanced vasorelaxation. Thoracic aorta segments were isolated from adult db/db and non-diabetic litter- mate mice. The effect of 0.2 U/ml SMase was investigated after precontraction with 0.1 μM phenylephrine under isometric S26 Abstracts/Nitric Oxide 47 (2015) S14–S60