The role of PKA and PKC epsilon pathways in prostaglandin E(2)-mediated hypernociception

Background and purpose: Protein kinase (PK) A and the epsilon isoform of PKC (PKC epsilon) are involved in the development of hypernociception (increased sensitivity to noxious or innocuous stimuli) in several animal models of acute and persistent inflammatory pain. The present study evaluated the contribution of PKA and PKC epsilon to the development of prostaglandin E(2) (PGE(2))-induced mechanical hypernociception. Experimental approach: Prostaglandin E(2)-induced mechanical hypernociception was assessed by constant pressure rat paw test. The activation of PKA or PKC epsilon was evaluated by radioactive enzymic assay in the dorsal root ganglia (DRG) of sensory neurons from the hind paws. Key results: Hypernociception induced by PGE(2) (100 ng) by intraplantar (i.pl.) injection, was reduced by i.pl. treatment with inhibitors of PKA [A-kinase-anchoring protein St-Ht31 inhibitor peptide (AKAPI)], PKC epsilon (PKC epsilon I) or adenylyl cyclase. PKA activity was essential in the early phase of the induction of hypernociception, whereas PKC activity was involved in the maintenance of the later phase of hypernociception. In the DRG (L4-L5), activity of PKA increased at 30 min after injection of PGE(2) but PKC activity increased only after 180 min. Moreover, i.pl. injection of the catalytic subunit of PKA induced hypernociception which was markedly reduced by pretreatment with an inhibitor of PKC epsilon, while the hypernociception induced by paw injection of PKC epsilon agonist was not affected by an inhibitor of PKA (AKAPI). Conclusions and implications: Taken together, these findings are consistent with the suggestion that PKA activates PKC epsilon, which is a novel mechanism of interaction between these kinases during the development of PGE(2)-induced mechanical hypernociception.

Nitric oxide-mediated anxiolytic-like and antidepressant-like effects in animal models of anxiety and depression

The effects of microinjection of the nitric oxide (NO) precursor L-arginine (L-Arg), the NO synthase (NOS) inhibitors N-methyl-L-arginine (L-NAME) and 7-nitroindazole (7-NI), and the cyclic guanosine 3`,5`-monophosphate (cGMP) analog 8-Br-cGMP into the dorsal raphe nucleus (DRN) were assessed in rats using the elevated plus maze (EPM) and the forced swim test (FST). L-Arg (100 and 200 nmol) produced an anxiolytic-like effect in the EPM. 8-Br-cGMP (25 and 50 nmol) dose-dependently increased locomotor activity. In the FST, antidepressant-like effects were produced by L-Arg (50 and 100 nmol) and 8-Br-cGMP (12.5 and 25 nmol). Dual effects were observed with NOS inhibitors L-NAME and 7-NI in both the EPM and FST. While low doses of L-NAME (25 nmol) or 7-NI (1 nmol) induced a selective increase in EPM open arm exploration and a decrease in immobility time in the FST, high doses (L-NAME 400 nmol, 7-NI 10 nmol) decreased locomotor activity. These results show that interference with NO-mediated neurotransmission in the DRN induced significant and complex motor and emotional effects. Further studies are needed to elucidate the mechanisms involved in these effects. (C) 2007 Elsevier Inc. All rights reserved.

Involvement of LTB4 in zymosan-induced joint nociception in mice: participation of neutrophils and PGE(2)

Leukotriene B-4 (LTB4) mediates different inflammatory events such as neutrophil migration and pain. The present study addressed the mechanisms of LTB4-mediated joint inflammation-induced hypernociception. It was observed that zymosan-induced articular hypernociception and neutrophil migration were reduced dose-dependently by the pretreatment with MK886 (1-9 mg/kg; LT synthesis inhibitor) as well as in 5-lypoxygenase-deficient mice (5LO(-/-)) or by the selective antagonist of the LTB4 receptor (CP105696; 3 mg/kg). Histological analysis showed reduced zymosan-induced articular inflammatory damage in 5LO(-/-) mice. The hypernociceptive role of LTB4 was confirmed further by the demonstration that joint injection of LTB4 induces a dose (8.3, 25, and 75 ng)-dependent articular hypernociception. Furthermore, zymosan induced an increase in joint LTB4 production. Investigating the mechanism underlying LTB4 mediation of zymosan-induced hypernociception, LTB4-induced hypernociception was reduced by indomethacin (5 mg/kg), MK886 (3 mg/kg), celecoxib (10 mg/kg), antineutrophil antibody (100 mu g, two doses), and fucoidan (20 mg/kg) treatments as well as in 5LO(-/-) mice. The production of LTB4 induced by zymosan in the joint was reduced by the pretreatment with fucoidan or antineutrophil antibody as well as the production of PGE(2) induced by LTB4. Therefore, besides reinforcing the role of endogenous LTB4 as an important mediator of inflamed joint hypernociception, these results also suggested that the mechanism of LTB4-induced articular hypernociception depends on prostanoid and neutrophil recruitment. Furthermore, the results also demonstrated clearly that LTB4-induced hypernociception depends on the additional release of endogenous LTs. Concluding, targeting LTB4 synthesis/action might constitute useful therapeutic approaches to inhibit articular inflammatory hypernociception.

Gastric damage induced by different doses of indomethacin in rats is variably affected by inhibiting iNOS or leukocyte infiltration

Aim: To evaluate the effect of inhibiting inducible nitric oxide synthase (iNOS), by aminoguanidine, or leukocyte infiltration, by fucoidin, on gastropathy induced by two different doses of indomethacin in rats. Methods: Rats were treated with saline, aminoguanidine (50 or 100 mg.kg(-1), i. p.) or fucoidin (25 mg.kg(-1), i. v.). Indomethacin was then given at a dose of 5 or 20 mg.kg(-1). At the end of 3 h, macroscopic gastric damage and myeloperoxidase (MPO) activity were assessed. Results: Aminoguanidine reduced the gastric damage induced by indomethacin at 20 mg.kg(-1), but increased gastric MPO activity. However, aminoguanidine did not influence the gastric damage induced by indomethacin at 5 mg.kg(-1). Fucoidin prevented both the gastric damage and the increase in gastric MPO activity induced by indomethacin at 20 mg. kg(-1), but not at 5 mg.kg(-1). Conclusion: Indomethacin at a dose of 20 mg.kg(-1), but not at 5 mg.kg(-1), induced gastropathy dependent on neutrophil infiltration and iNOS-generated NO.

The anxiolytic-like effects of cannabidiol injected into the bed nucleus of the stria terminalis are mediated by 5-HT1A receptors

Cannabidiol (CBD) is a non-psychotomimetic compound from Cannabis sativa that induces anxiolytic-like effects in rodents and humans after systemic administration. Previous results from our group showed that CBD injection into the bed nucleus of the stria terminalis (BNST) attenuates conditioned aversive responses. The aim of this study was to further investigate the role of this region on the anxiolytic effects of the CBD. Moreover, considering that CBD can activate 5-HT1A receptors, we also verified a possible involvement of these receptors in those effects. Male Wistar rats received injections of CBD (15, 30, or 60 nmol) into the BNST and were exposed to the elevated plus-maze (EPM) or to the Vogel conflict test (VCT), two widely used animal models of anxiety. CBD increased open arms exploration in the EPM as well as the number of punished licks in the VCT, suggesting an anxiolytic-like effect. The drug did not change the number of entries into the enclosed arms of the EPM nor interfered with water consumption or nociceptive threshold, discarding potential confounding factors in the two tests. Moreover, pretreatment with the 5-HT1A receptor antagonist WAY100635 (0.37 nmol) blocked the effects of CBD in both models. These results give further support to the proposal that BNST is involved in the anxiolytic-like effects of CBD observed after systemic administration, probably by facilitating local 5-HT1A receptor-mediated neurotransmission.

Facilitation of 5-HT(2A/2C)-mediated neurotransmission in the ventromedial hypothalamic nucleus decreases anxiety in the elevated T-maze

Previous evidence has shown that facilitation of GABA/benzodiazepine-mediated neurotransmission in the ventromedial hypothalamus (VMH) inhibits both escape and inhibitory avoidance responses generated in the elevated T-maze test of anxiety (ETM). These defensive behaviors have been associated with panic and generalized anxiety, respectively. Aside from GABA/benzodiazepine receptors, the VMH also contains a significant number of serotonin (5-HT) receptors, including 1A, 2A and 2C subtypes. The purpose of the present study was to investigate the effect of the activation of 5-HT(1A) and 5-HT(2A/2C) receptors in the VMH on defensive behavioral responses in rats submitted to the ETM. For that, male Wistar rats were treated intra-VMH with the 5-HT(1A) agonist 8-OH-DPAT, with the 5-HT(2A/2C) agonist DOI, with the 5-HT(2C) selective agonist MK-212, or with the 5-HT(2A/2C) antagonist ketanserin and 10 min after were submitted to the ETM. Results showed that both DOI and MK-212 significantly decreased avoidance measurements, an anxiolytic-like effect, without altering escape. 8-OH-DPAT and ketanserin were without effect, although the last drug attenuated the effects of DOI. None of the drugs altered locomotor activity in an open field. These results suggest that 5-HT(2A/2C) receptors of the VMH are involved in the regulation of inhibitory avoidance and might be of relevance to the physiopathology of generalized anxiety. (C) 2010 Elsevier B.V. All rights reserved.

Internal Pudendal Artery from Type 2 Diabetic Female Rats Demonstrate Elevated Endothelin-1-Mediated Constriction

Introduction. Diabetes is a risk factor for female sexual dysfunction (FSD). FSD has several etiologies, including a vasculogenic component that could be exacerbated in diabetes. The internal pudendal artery supplies blood to the vagina and clitoris and diabetes-associated functional abnormalities in this vascular bed may contribute to FSD. Aim. The Goto-Kakizaki (GK) rat is a non-obese model of type 2 diabetes with elevated endothelin-1 (ET-1) activity. We hypothesize that female GK rats have diminished sexual responses and that the internal pudendal arteries demonstrate increased ET-1 constrictor sensitivity. Methods. Female Wistar and GK rats were used. Apomorphine (APO)-mediated genital vasocongestive arousal (GVA) was measured. Functional contraction (ET-1 and phenylephrine) and relaxation (acetylcholine, ACh) in the presence or absence of the ETA receptor antagonist (ET(A)R; atrasentan) or Rho-kinase inhibitor (Y-27632) were assessed in the internal pudendal and mesenteric arteries. Protein expression of ET-1 and RhoA/Rho-kinase signaling pathway was determined in the internal pudendal and mesenteric arteries. Main Outcome Measure. APO-mediated GVAs; contraction and relaxation of internal pudendal and mesenteric arteries; ET-1/RhoA/Rho-kinase protein expression. Results. GK rats demonstrated no APO-induced GVAs. Internal pudendal arteries, but not mesenteric arteries, from GK rats exhibited greater contractile sensitivity to ET-1 compared with Wistar arteries. ETAR blockade reduced ET-1-mediated constriction in GK internal pudendal and mesenteric arteries. Rho-kinase inhibition reduced ET-1-mediated constriction of GK internal pudendal but not mesenteric arteries; however, it had no effect on arteries from Wistar rats. RhoA protein expression was elevated in GK internal pudendal arteries. At the highest concentrations, ACh-mediated relaxation was greater in the GK internal pudendal artery; however, no difference was observed in the mesenteric artery. Conclusions. Female GK rats demonstrate decreased sexual responses that may be because of increased constrictor sensitivity to the ET-1/RhoA/Rho-kinase signaling in the internal pudendal artery. Allahdadi KJ, Hannan JL, Ergul A, Tostes RC, and Webb RC. Internal pudendal artery from type 2 diabetic female rats demonstrate elevated endothelin-1-mediated constriction. J Sex Med 2011;8:2472-2483.

Phosphoinositide-3 Kinase gamma Activity Contributes to Sepsis and Organ Damage by Altering Neutrophil Recruitment

Rationale Sepsis is a leading cause of death in the intensive care unit, characterized by a systemic inflammatory response (SIRS) and bacterial infection, which can often induce multiorgan damage and failure. Leukocyte recruitment, required to limit bacterial spread, depends on phosphoinositide-3 kinase gamma (PI3K gamma) signaling in vitro; however, the role of this enzyme in polymicrobial sepsis has remained unclear. Objectives: This study aimed to determine the specific role of the kinase activity of PI3K gamma in the pathogenesis of sepsis and multiorgan damage. Methods. PI3K gamma wild-type, knockout, and kinase-dead mice were exposed to cecal ligation and perforation induced sepsis and assessed for survival; pulmonary, hepatic, and cardiovascular damage; coagulation derangements; systemic inflammation; bacterial spread; and neutrophil recruitment. Additionally, wild-type mice were treated either before or after the onset of sepsis with a PI3K gamma inhibitor and assessed for survival, neutrophil recruitment, and bacterial spread. Measurements and Main Results: Both genetic and pharmaceutical PI3K gamma kinase inhibition significantly improved survival, reduced multiorgan damage, and limited bacterial decompartmentalization, while modestly affecting SIRS. Protection resulted from both neutrophil-independent mechanisms, involving improved cardiovascular function, and neutrophil-dependent mechanisms, through reduced susceptibility to neutrophil migration failure during severe sepsis by maintaining neutrophil surface expression of the chemokine receptor, CXCR2. Furthermore, PI3K gamma pharmacological inhibition significantly decreased mortality and improved neutrophil migration and bacterial control, even when administered during established septic shock. Conclusions: This study establishes PI3K gamma as a key molecule in the pathogenesis of septic infection and the transition from SIRS to organ damage and identifies it as a novel possible therapeutic target.

Gastroprotective effect of heme-oxygenase 1/biliverdin/CO pathway in ethanol-induced gastric damage in mice

Our objective was to evaluate the role of heme-oxygenase 1 (HO-1)/biliverdin/CO pathway in gastric defense against ethanol-induced gastric damage in mice. Mice were pre-treated with saline, hemin (HO-1 inducer), biliverdin (HO-1 product), dimanganese decacarbonyl (DMDC, CO donor) or zinc protoporphyrin IX (ZnPP IX, HO-1 antagonist). Another group received soluble guanylate cyclase (sGC) inhibitor (ODQ) 30 min before hemin, biliverdin or DMDC. After 30 min, gastric damage was induced by ethanol. After one hour, rats were sacrificed. Gastric lesions were measured using a computer planimetry program, and gastric corpus pieces were assayed for malonylaldehyde (MDA), glutathione (GSH) or bilirubin. HO-1 expression was determined after saline or ethanol administration by polymerase chain reaction (PCR) or immunohistochemistry. Ethanol (25% or 50%) induced gastric damage, increased MDA levels and reduced GSH in the gastric tissue. Ethanol 50% increased HO-1 mRNA transcripts, HO-1 immunoreactivity, and bilirubin concentration in gastric mucosa. Pre-treatment with hemin reduced gastric damage and MDA formation and increased GSH concentration in the gastric mucosa. ZnPP IX amplified the ethanol-induced gastric lesion, increased MDA formation and decreased GSH concentration in gastric mucosa. Biliverdin and DMDC reduced gastric damage and MDA formation and increased GSH concentration in the gastric tissue. ODQ completely abolished the DMDC protective gastric effect However, effects of hemin or biliverdin did not change with ODQ treatment. Our results suggest that HO-1/biliverdin/CO pathway plays a protective role against ethanol-induced gastric damage through mechanisms that can be dependent (CO) or independent (biliverdin) of sGC activation. (C) 2010 Elsevier B.V. All rights reserved.

The lateral habenula regulates defensive behaviors through changes in 5-HT-mediated neurotransmission in the dorsal periaqueductal gray matter

Chemical stimulation of the lateral nucleus of the habenula (LHb), an area implicated in the regulation of serotonergic activity in raphe nuclei, affects the acquisition of inhibitory avoidance and escape expression of rats submitted to the elevated T-maze test of anxiety. Here, we investigated whether facilitation of 5-HT-mediated neurotransmission in the dorsal periaqueductal gray (dPAG) accounts for the behavioral consequences in the elevated T-maze induced by chemical stimulation of the LHb. The dPAG in the midbrain, which is innervated by 5-HT fibers originating from the dorsal raphe nucleus (DRN), has been consistently implicated in the genesis/regulation of anxiety- and fear-related defensive responses. The results showed that intra-dPAG injection of WAY-100635 or ketanserin, 5-HT(1A) and 5-HT(2A/2C) receptor antagonists, respectively, counteracted the anti-escape effect caused by bilateral intra-LHb injection of kainic acid (60 pmol/0.2 mu l). Ketanserin, but not WAY-100635, blocked kainic acid`s facilitatory effect on inhibitory avoidance acquisition. Overall, the results suggest that the pathway connecting the LHb to the DRN is involved in the control of 5-HT release in the dPAG, and facilitation of 5-HT-mediated neurotransmission in the latter area distinctively impacts upon the expression of anxiety- and fear-related defensive behaviors. While stimulation of 5-HT(1A) receptors selectively affects escape performance, 5-HT(2A/2C) receptors modulate both inhibitory avoidance and escape. (C) 2010 Elsevier Ireland Ltd. All rights reserved.

Vascular proinflammatory responses by aldosterone are mediated via c-Src trafficking to cholesterol-rich microdomains: role of PDGFR

Aims We demonstrated c-Src activation as a novel non-genomic signalling pathway for aldosterone in vascular smooth muscle cells (VSMCs). Here, we investigated molecular mechanisms and biological responses of this phenomenon, focusing on the role of lipid rafts/caveolae and platelet-derived growth factor receptor (PDGFR) in c-Src-regulated proinflammatory responses by aldosterone. Methods and results Studies were performed in cultured VSMCs from Wistar-Kyoto (WKY) rats and caveolin-1 knockout (Cav 1(-/-)) and wild-type mice. Aldosterone stimulation increased c-Src phosphorylation and trafficking to lipid rafts/caveolae. Cholesterol depletion with methyl-beta-cyclodextrin abrogated aldosterone-induced phosphorylation of c-Src and its target, Pyk2. Aldosterone effects were recovered by cholesterol reload. Aldosterone-induced c-Src and cortactin phosphorylation was reduced in caveolin-1-silenced and Cav 1(-/-) VSMCs. PDGFR is phosphorylated by aldosterone within cholesterol-rich fractions of VSMCs. AG1296, a PDGFR inhibitor, prevented c-Src phosphorylation and translocation to cholesterol-rich fractions. Aldosterone induced an increase in adhesion molecule protein content and promoted monocyte adhesion to VSMCs, responses that were inhibited an by cholesterol depletion, caveolin-1 deficiency, AG1296 and PP2, a c-Src inhibitor. Mineralocorticoid receptor (MR) content in flotillin-2-rich fractions and co-immunoprecipitation with c-Src and PDGFR increased upon aldosterone stimulation, indicating MR-lipid raft/signalling association. Conclusion We demonstrate that aldosterone-mediated c-Src trafficking/activation and proinflammatory signalling involve lipid rafts/caveolae via PDGFR.

ANGIOTENSIN III MODULATES THE NOCICEPTIVE CONTROL MEDIATED BY THE PERIAQUEDUCTAL GRAY MATTER

Endogenous angiotensin (Ang) II and/or an Ang II-derived peptide, acting on Ang type I (AT(1)) and Ang type 2 (AT(2)) receptors, can carry out part of the nociceptive control modulated by periaqueductal gray matter (PAG). However, neither the identity of this putative Ang-peptide, nor its relationship to Ang II antinociceptive activity was clarified. Therefore, we have used tail-flick and incision allodynia models combined with an HPLC time course of Ang metabolism, to study the Ang III antinociceptive effect in the rat ventrolateral (vi) PAG using peptidase inhibitors and receptor antagonists. Ang III injection into the vIPAG increased tail-flick latency, which was fully blocked by Losartan and CGP 42,112A, but not by divalinal-Ang IV, indicating that. Ang III effect was mediated by AT(1) and AT(2) receptors, but not by the AT(4) receptor. Ang III injected into the vIPAG reduced incision allodynia. Incubation of Ang II with punches of vIPAG homogenate formed Ang III, Ang (1-7) and Ang IV. Amastatin (AM) inhibited the formation of Ang III from Ang II by homogenate, and blocked the antinociceptive activity of Ang II injection into vIPAG, suggesting that aminopeptidase A (APA) formed Ang III from Ang II. Ang III can also be formed from Ang I by a vIPAG alternative pathway. Therefore, the present work shows, for the first time, that: (i) Ang III, acting on AT(1) and AT(2) receptors, can elicit vIPAG-mediated antinociception, (ii) the conversion of Ang II to Ang III in the vIPAG is required to elicit antinociception, and (iii) the antinociceptive activity of endogenous Ang II in vIPAG can be ascribed preponderantly to Ang III. (C) 2009 IBRO. Published by Elsevier Ltd. All rights reserved.

Dysregulation of renal transient receptor potential melastatin 6/7 but not paracellin-1 in aldosterone-induced hypertension and kidney damage in a model of hereditary hypomagnesemia

Rationale Hyperaldosteronism, important in hypertension, is associated with electrolyte alterations, including hypomagnesemia, through unknown mechanisms. Objective To test whether aldosterone influences renal Mg(2+) transporters, (transient receptor potential melastatin (TRPM) 6, TRPM7, paracellin-1) leading to hypomagnesemia, hypertension and target organ damage and whether in a background of magnesium deficiency, this is exaggerated. Methods and results Aldosterone effects in mice selectively bred for high-normal (MgH) or low (MgL) intracellular Mg(2+) were studied. Male MgH and MgL mice received aldosterone (350 mu g/kg per day, 3 weeks). SBP was elevated in MgL. Aldosterone increased blood pressure and albuminuria and increased urinary Mg(2+) concentration in MgH and MgL, with greater effects in MgL. Activity of renal TRPM6 and TRPM7 was lower in vehicle-treated MgL than MgH. Aldosterone increased activity of TRPM6 in MgH and inhibited activity in MgL. TRPM7 and paracellin-1 were unaffected by aldosterone. Aldosterone-induced albuminuria in MgL was associated with increased renal fibrosis, increased oxidative stress, activation of mitogen-activated protein kinases and nuclear factor-NF-kappa B and podocyte injury. Mg(2+) supplementation (0.75% Mg(2+)) in aldosterone-treated MgL normalized plasma Mg(2+), increased TRPM6 activity and ameliorated hypertension and renal injury. Hence, in a model of inherited hypomagnesemia, TRPM6 and TRPM7, but not paracellin-1, are downregulated. Aldosterone further decreased TRPM6 activity in hypomagnesemic mice, a phenomenon associated with hypertension and kidney damage. Such effects were prevented by Mg(2+) supplementation. Conclusion Amplified target organ damage in aldosterone-induced hypertension in hypomagnesemic conditions is associated with dysfunctional Mg(2+)-sensitive renal TRPM6 channels. Novel mechanisms for renal effects of aldosterone and insights into putative beneficial actions of Mg(2+), particularly in hyperaldosteronism, are identified. J Hypertens 29: 1400-1410 (C) 2011 Wolters Kluwer Health vertical bar Lippincott Williams & Wilkins.

Hydrogen Sulfide Prevents Ethanol-Induced Gastric Damage in Mice: Role of ATP-Sensitive Potassium Channels and Capsaicin-Sensitive Primary Afferent Neurons

The aim of this study was to evaluate the protective effect of hydrogen sulfide (H(2)S) on ethanol-induced gastric lesions in mice and the influence of ATP-sensitive potassium (K(ATP)) channels, capsaicin-sensitive sensory afferent neurons, and transient receptor potential vanilloid (TRPV) 1 receptors on such an effect. Saline and L-cysteine alone or with propargylglycine, sodium hydrogen sulfide (NaHS), or Lawesson`s reagent were administrated for testing purposes. For other experiments, mice were pretreated with glibenclamide, neurotoxic doses of capsaicin, or capsazepine. Afterward, mice received L-cysteine, NaHS, or Lawesson`s reagent. After 30 min, 50% ethanol was administrated by gavage. After 1 h, mice were sacrificed, and gastric damage was evaluated by macroscopic and microscopic analyses. L-Cysteine, NaHS, and Lawesson`s reagent treatment prevented ethanol-induced macroscopic and microscopic gastric damage in a dose-dependent manner. Administration of propargylglycine, an inhibitor of endogenous H(2)S synthesis, reversed gastric protection induced by L-cysteine. Glibenclamide reversed L-cysteine, NaHS, or Lawesson`s reagent gastroprotective effects against ethanol-induced macroscopic damage in a dose-dependent manner. Chemical ablation of sensory afferent neurons by capsaicin reversed gastroprotective effects of L-cysteine or H(2)S donors (NaHS or Lawesson`s reagent) in ethanol-induced macroscopic gastric damage. Likewise, in the presence of the TRPV1 antagonist capsazepine, the gastroprotective effects of L-cysteine, NaHS, or Lawesson`s reagent were also abolished. Our results suggest that H(2)S prevents ethanol-induced gastric damage. Although there are many mechanisms through which this effect can occur, our data support the hypothesis that the activation of K(ATP) channels and afferent neurons/TRPV1 receptors is of primary importance.

Inhibition of hydrogen sulphide formation reduces cisplatin-induced renal damage

Background. Cisplatin (CP)-induced renal damage is associated with inflammation. Hydrogen sulphide (H(2)S) is involved in models of inflammation. This study evaluates the effect of DL-propargylglycine (PAG), an inhibitor of endogenous H(2)S formation, on the renal damage induced by CP. Methods. The rats were injected with CP (5 mg/kg, i.p.) or PAG(5 mg/kg twice a day, i.p.) for 4 days, starting 1 h before CP injection. Control rats were injected with 0.15 M NaCl or PAG only. Blood and urine samples were collected 5 days after saline or CP injections for renal function evaluation. The kidneys were removed for tumour necrosis factor (TNF)-alpha quantification, histological, immunohistochemical and Western blot analysis. The cystathionine gamma-lyase (CSE) activity and expression were assessed. The direct toxicity of H(2)S in renal tubular cells was evaluated by the incubation of these cells with NaHS, a donor of H(2)S. Results. CP-treated rats presented increases in plasma creatinine levels and in sodium and potassium fractional excretions associated with tubulointerstitial lesions in the outer medulla. Increased expression of TNF-alpha, macrophages, neutrophils and T lymphocytes, associated with increased H(2)S formation rate and CSE expression, were also observed in the outer medulla from CP-injected rats. All these alterations were reduced by treatment with PAG. A direct toxicity of NaHS for renal tubular epithelial cells was not observed. Conclusions. Treatment with PAG reduces the renal damage induced by CP. This effect seems to be related to the H2S formation and the restriction of the inflammation in the kidneys from PAG+CP-treated rats.