André Luiz dos Reis Barbosa

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 (H2S) on ethanol-induced gastric lesions in mice and the influence of ATP-sensitive potassium (KATP) 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 Lawessons 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 Lawessons 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 Lawessons reagent treatment prevented ethanol-induced macroscopic and microscopic gastric damage in a dose-dependent manner. Administration of propargylglycine, an inhibitor of endogenous H2S synthesis, reversed gastric protection induced by l-cysteine. Glibenclamide reversed l-cysteine, NaHS, or Lawessons 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 H2S donors (NaHS or Lawessons reagent) in ethanol-induced macroscopic gastric damage. Likewise, in the presence of the TRPV1 antagonist capsazepine, the gastroprotective effects of l-cysteine, NaHS, or Lawessons reagent were also abolished. Our results suggest that H2S 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 KATP channels and afferent neurons/TRPV1 receptors is of primary importance.

Anti-inflammatory and antinociceptive activity of epiisopiloturine, an imidazole alkaloid isolated from Pilocarpus microphyllus.

The aim of this study was to investigate the antinociceptive and anti-inflammatory activities of epiisopiloturine (1), an imidazole alkaloid found in the leaves of Pilocarpus microphyllus. The anti-inflammatory activity of 1 was evaluated using several agents that induce paw edema and peritonitis in Swiss mice. Paw tissue and peritoneal fluid samples were obtained to determine myeloperoxidase (MPO) activity or tumor necrosis factor (TNF)-α and interleukin (IL)-1β levels. The antinociceptive activity was evaluated by acetic acid-induced writhing, the hot plate test, and pain induction using formalin. Compared to vehicle treatment, pretreatment with 1 (0.1, 0.3, and 1 mg/kg, ip) of mice significantly reduced carrageenan-induced paw edema (p < 0.05). Furthermore, compound 1 at a dose of 1 mg/kg effectively inhibited edema induced by dextran sulfate, serotonin, and bradykinin, but had no effect on histamine-induced edema. The administration of 1 (1 mg/kg) following carrageenan-induced peritonitis reduced total and differential peritoneal leukocyte counts and also carrageenan-induced paw MPO activity and TNF-α and IL-1β levels in the peritoneal cavity. Pretreatment with 1 also reduced acetic acid-induced writhing and inhibited the first and second phases of the formalin test, but did not alter response latency in the hot plate test. Pretreatment with naloxone reversed the antinociceptive effect of 1.

Role of KATP channels and TRPV1 receptors in hydrogen sulfide-enhanced gastric emptying of liquid in awake mice.

Hydrogen sulphide (H(2)S) has shown to relax gastrointestinal muscle. Here in, we evaluated the effects of H(2)S donors on gastric emptying and in pyloric sphincter muscle relaxation, and whether these effects involved K(ATP) channels or TRPV1 receptors. Mice were treated with l-cysteine (alone or with propargylglycine-an inhibitor of H(2)S synthesis), NaHS, Lawessons reagent (H(2)S donors) or saline. After 30 min, mice were gavaged with a liquid meal containing a nonabsorbable marker and then killed at 10, 20 or 30 min intervals to assess marker recovery from the stomach and intestine. This experiment was repeated in mice pre-treated with K(ATP) channel (glibenclamide) or TRPV1 receptor (capsazepine) antagonists. In addition, pyloric sphincter muscles were mounted in an organ bath, incubated with saline, glibenclamide or capsazepine, and NaHS dose-responses were determined. H(2)S donors and l-cysteine enhanced gastric emptying in a dose-dependent manner; propargylglycine reversed the effect of l-cysteine. Both glibenclamide and capsazepine abolished l-cysteine and H(2)S donors augmentation of gastric emptying. Dose-dependent inductions of pyloric sphincter relaxation by NaHS were abolished by glibenclamide or capsazepine. These data suggest that H(2)S donors-induced acceleration of gastric emptying and relaxation of pyloric sphincter muscle by K(ATP) channel and TRPV1 receptor activations.

Gabapentin, a Synthetic Analogue of Gamma Aminobutyric Acid, Reverses Systemic Acute Inflammation and Oxidative Stress in Mice

The aim of this study was to investigate the potential anti-inflammatory and anti-oxidant effects of gabapentin (GBP) in mice. The anti-inflammatory and anti-oxidant effects were evaluated using various mediators that induce paw edema, peritonitis model, myeloperoxidase (MPO) activity, proinflammatory cytokine levels, glutathione (GSH) consumption, and malondialdehyde (MDA) production in mice. Pretreatment of mice with GBP (1xa0mg/kg) significantly reduced carrageenan or dextran-induced paw edema (Pu2009<u20090.05) when compared to vehicle group. Adding to this, GBP (1xa0mg/kg) significantly inhibited paw edema induced by histamine, serotonin, bradikinin, 48/80 compound, and prostaglandin E2. In the carrageenan-induced peritonitis model, GBP significantly decreased total and differential leukocyte counts and reduced the levels of MPO activity in the plantar tissue and IL-1β and TNF-α concentrations in the peritoneal exudate. The same dose of GBP also decreased the MDA concentration and increased the levels of GSH into the peritoneal fluid. In summary, our results demonstrated that GBP exhibited anti-inflammatory activity in mice by reducing the action of inflammatory mediators, neutrophil migration and proinflammatory cytokine levels, and anti-oxidant properties by decreasing the concentration of MDA and increasing the GSH content. These observations raise the possibility that GBP could be used to improve tissue resistance to damage during inflammatory conditions.

A Sulfated-Polysaccharide Fraction from Seaweed Gracilaria birdiae Prevents Naproxen-Induced Gastrointestinal Damage in Rats

Red seaweeds synthesize a great variety of sulfated galactans. Sulfated polysaccharides (PLSs) from seaweed are comprised of substances with pharmaceutical and biomedical potential. The aim of the present study was to evaluate the protective effect of the PLS fraction extracted from the seaweed Gracilaria birdiae in rats with naproxen-induced gastrointestinal damage. Male Wistar rats were pretreated with 0.5% carboxymethylcellulose (control group—vehicle) or PLS (10, 30, and 90 mg/kg, p.o.) twice daily (at 09:00 and 21:00) for 2 days. After 1 h, naproxen (80 mg/kg, p.o.) was administered. The rats were killed on day two, 4 h after naproxen treatment. The stomachs were promptly excised, opened along the greater curvature, and measured using digital calipers. Furthermore, the guts of the animals were removed, and a 5-cm portion of the small intestine (jejunum and ileum) was used for the evaluation of macroscopic scores. Samples of the stomach and the small intestine were used for histological evaluation, morphometric analysis and in assays for glutathione (GSH) levels, malonyldialdehyde (MDA) concentration, and myeloperoxidase (MPO) activity. PLS treatment reduced the macroscopic and microscopic naproxen-induced gastrointestinal damage in a dose-dependent manner. Our results suggest that the PLS fraction has a protective effect against gastrointestinal damage through mechanisms that involve the inhibition of inflammatory cell infiltration and lipid peroxidation.

Carvacryl acetate, a derivative of carvacrol, reduces nociceptive and inflammatory response in mice

AIMSnThe present study aimed to investigate the potential anti-inflammatory and anti-nociceptive effects of carvacryl acetate, a derivative of carvacrol, in mice.nnnMAIN METHODSnThe anti-inflammatory activity was evaluated using various phlogistic agents that induce paw edema, peritonitis model, myeloperoxidase (MPO) activity, pro and anti-inflammatory cytokine levels. Evaluation of antinociceptive activity was conducted through acetic acid-induced writhing, hot plate test, formalin test, capsaicin and glutamate tests, as well as evaluation of motor performance on rotarod test.nnnKEY FINDINGSnPretreatment of mice with carvacryl acetate (75 mg/kg) significantly reduced carrageenan-induced paw edema (P<0.05) when compared to vehicle-treated group. Likewise, carvacryl acetate (75 mg/kg) strongly inhibited edema induced by histamine, serotonin, prostaglandin E2 and compound 48/80. In the peritonitis model, carvacryl acetate significantly decreased total and differential leukocyte counts, and reduced levels of myeloperoxidase and interleukin-1 beta (IL-1β) in the peritoneal exudate. The levels of IL-10, an anti-inflammatory cytokine, were enhanced by carvacryl acetate. Pretreatment with carvacryl acetate also decreased the number of acetic acid-induced writhing, increased the latency time of the animals on the hot plate and decreased paw licking time in the formalin, capsaicin and glutamate tests. The pretreatment with naloxone did not reverse the carvacryl acetate-mediated nociceptive effect.nnnSIGNIFICANCEnIn conclusion, the current study demonstrated that carvacryl acetate exhibited anti-inflammatory activity in mice by reducing inflammatory mediators, neutrophil migration and cytokine concentration, and anti-nociceptive activity due to the involvement of capsaicin and glutamate pathways.

Role of the NO/KATP pathway in the protective effect of a sulfated-polysaccharide fraction from the algae Hypnea musciformis against ethanol-induced gastric damage in mice

Seaweeds are the most abundant source of polysaccharides such as alginates and agar, as well as carrageenans. This study aimed to investigate the gastroprotective activity and the mechanism underlying this activity of a sulfated-polysaccharide fraction extracted from the algae Hypnea musciformis (Wulfen) J.V. Lamour. (Gigartinales-Rhodophyta). Mice were treated with sulfated-polysaccharide fraction (3, 10, 30, and 90 mg/kg, p.o.) and, after 30 min, they were administered 50% ethanol (0.5 mL/25 g, p.o.). After 1 h, gastric damage was measured using a planimeter. In addition, samples of the stomach tissue were obtained for histopathological examination and for assays to determine the glutathione and malondialdehyde levels. Other groups of mice were pretreated with NG-nitro-L-arginine methyl ester (L-NAME, 10 mg/kg, i.p.), aminoguanidine (100 mg/kg, i.p.), or glibenclamide (10 mg/kg, i.p.). After 30 min to the aminoguanidine group and 1 h to the other groups, sulfated-polysaccharide fraction (30 mg/kg, p.o.) was administered and gastric damage was induced as described above. Sulfated-polysaccharide fraction prevented ethanol-induced gastric injury in a dose-dependent manner. However, treatment with L-NAME or glibenclamide reversed this gastroprotective effect. Administration of aminoguanidine did not influence the effect of sulfated-polysaccharide fraction. Our results suggest that sulfated-polysaccharide fraction exerts a protective effect against ethanol-induced gastric damage via activation of the NO/KATP pathway.

Oral gabapentin treatment accentuates nerve and peripheral inflammatory responses following experimental nerve constriction in Wistar rats

Gabapentin (GBP) is an anti-convulsive drug often used as analgesic to control neuropathic pain. This study aimed at evaluating whether oral GBP treatment could improve nerve inflammation response after sciatic nerve constriction in association with selected pain and motor spontaneous behavior assessments in Wistar rats. We evaluated nerve myeloperoxidase (MPO) and inflammatory cytokines on the 5th day post-injury, time in which nerve inflammation is ongoing. In addition, the role of GBP on carrageenan-induced paw edema and peritoneal cell migration was analyzed. GBP was given by gavage at doses of 30, 60 and 120mg/kg, 60min prior to chronic constriction of the sciatic nerve (CCSN) and during 5 days post-injury, 12/12h. CCSN animals treated with saline were used as controls and for behavioral and inflammation assessments untreated sham-operated rats were also used. On the 5th day, GBP (60 and 120mg/kg) alleviated heat-induced hyperalgesia and significantly increased delta walking scores in CCSN animals, the latter suggesting excitatory effects rather than sedation. GBP (60mg/kg) significantly increased nerve MPO, TNF-α, and IL-1β levels, comparing with the saline group. GBP (120mg/kg) reduced the anti-inflammatory cytokine IL-10 nerve levels compared with the CCSN saline group. Furthermore, GBP (60 and 120mg/kg) increased carrageenan-induced paw edema and peritoneal macrophage migration compared with the CCSN saline group. Altogether our findings suggest that GBP accentuates nerve and peripheral inflammatory response, however confirmed its analgesic effect likely due to an independent CNS-mediated mechanism, and raise some concerns about potential GBP inflammatory side effects in widespread clinical use.

The hydrogen sulfide donor, Lawesson's reagent, prevents alendronate-induced gastric damage in rats

Our objective was to investigate the protective effect of Lawessons reagent, an H2S donor, against alendronate (ALD)-induced gastric damage in rats. Rats were pretreated with saline or Lawessons reagent (3, 9, or 27 µmol/kg, po) once daily for 4 days. After 30 min, gastric damage was induced by ALD (30 mg/kg) administration by gavage. On the last day of treatment, the animals were killed 4 h after ALD administration. Gastric lesions were measured using a computer planimetry program, and gastric corpus pieces were assayed for malondialdehyde (MDA), glutathione (GSH), proinflammatory cytokines [tumor necrosis factor (TNF)-α and interleukin (IL)-1β], and myeloperoxidase (MPO). Other groups were pretreated with glibenclamide (5 mg/kg, ip) or with glibenclamide (5 mg/kg, ip)+diazoxide (3 mg/kg, ip). After 1 h, 27 µmol/kg Lawessons reagent was administered. After 30 min, 30 mg/kg ALD was administered. ALD caused gastric damage (63.35±9.8 mm2); increased levels of TNF-α, IL-1β, and MDA (2311±302.3 pg/mL, 901.9±106.2 pg/mL, 121.1±4.3 nmol/g, respectively); increased MPO activity (26.1±3.8 U/mg); and reduced GSH levels (180.3±21.9 µg/g). ALD also increased cystathionine-γ-lyase immunoreactivity in the gastric mucosa. Pretreatment with Lawessons reagent (27 µmol/kg) attenuated ALD-mediated gastric damage (15.77±5.3 mm2); reduced TNF-α, IL-1β, and MDA formation (1502±150.2 pg/mL, 632.3±43.4 pg/mL, 78.4±7.6 nmol/g, respectively); lowered MPO activity (11.7±2.8 U/mg); and increased the level of GSH in the gastric tissue (397.9±40.2 µg/g). Glibenclamide alone reversed the gastric protective effect of Lawessons reagent. However, glibenclamide plus diazoxide did not alter the effects of Lawessons reagent. Our results suggest that Lawessons reagent plays a protective role against ALD-induced gastric damage through mechanisms that depend at least in part on activation of ATP-sensitive potassium (KATP) channels.

Influence of early mother-infant contact on dyadic behaviour during the first month of life.

An experimental group of 30 newborn infants had contact with their mothers for half an hour in the delivery room, and a control group followed the usual hospital routine, being shown briefly to their mothers before being taken to the nursery. In both groups permanent rooming‐in began from the sixth hour of life. The infants behaviour was assessed one. three and 28 days after birth by means of the Brazelton scale, and the behaviour of the dyad was observed during feeding on the third and 28th day. Infants in the experimental group interacted significantly better on days three and 28. and their mothers had higher scores for affectionate behaviour on the 28th day.