Role of cyclooxygenases 1 and 2 in the maintenance of colonic mucosal integrity in an experimental colitis model.

The role of cyclooxygenase (COXs) isoforms in maintaining colonic mucosal integrity is not fully understood. This study aimed to evaluate the role of COX-1 and -2 on colonic mucosal integrity in an experimental colitis model. Colitis was induced in Wistar rats by intracolonic administration of 2,4,6-trinitrobenzenesulfonic acid (20 mg + 50% ethanol). The control group (sham group) received saline only. After 7, 14, or 28 days, colonic samples were removed, and macroscopic lesion scores, wet weight, myeloperoxidase activity, and transepithelial electrical resistance (TER) were determined. In other rat groups, colonic samples from the sham group and a 7th day post-colitis group were mounted in Üssing chambers with the luminal side exposed to a buffer solution (control), acetylsalicylic acid (ASA), SC-560 (COX-1 inhibitor), or celecoxib (COX-2 inhibitor). TER and epithelial permeability to fluorescein were measured. The 7th day colitis group had higher macroscopic damage scores, wet weight, and myeloperoxidase activity and lower basal TER than the sham, 14th day colitis, and 28th day colitis groups. Inhibition of COX-1 but not COX-2 significantly decreased TER and increased permeability to fluorescein in the 7th day post-colitis group compared to the sham group. Additionally, ASA decreased the colonic mucosal integrity on day seven post-colitis compared to the sham group. A decrease in the colonic mucosa integrity in the experimental colitis model can be aggravated only by the inhibition of COX-1, which demonstrated the importance of this enzyme in the maintenance of colonic mucosal integrity.

Role of cyclooxygenases 1 and 2 in the maintenance of colonic mucosal integrity in an experimental colitis model

The role of cyclooxygenase (COXs) isoforms in maintaining colonic mucosal integrity is not fully understood. This study aimed to evaluate the role of COX-1 and -2 on colonic mucosal integrity in an experimental colitis model. Colitis was induced in Wistar rats by intracolonic administration of 2,4,6-trinitrobenzenesulfonic acid (20 mg + 50% ethanol). The control group (sham group) received saline only. After 7, 14, or 28 days, colonic samples were removed, and macroscopic lesion scores, wet weight, myeloperoxidase activity, and transepithelial electrical resistance (TER) were determined. In other rat groups, colonic samples from the sham group and a 7th day post-colitis group were mounted in Üssing chambers with the luminal side exposed to a buffer solution (control), acetylsalicylic acid (ASA), SC-560 (COX-1 inhibitor), or celecoxib (COX-2 inhibitor). TER and epithelial permeability to fluorescein were measured. The 7th day colitis group had higher macroscopic damage scores, wet weight, and myeloperoxidase activity and lower basal TER than the sham, 14th day colitis, and 28th day colitis groups. Inhibition of COX-1 but not COX-2 significantly decreased TER and increased permeability to fluorescein in the 7th day post-colitis group compared to the sham group. Additionally, ASA decreased the colonic mucosal integrity on day seven post-colitis compared to the sham group. A decrease in the colonic mucosa integrity in the experimental colitis model can be aggravated only by the inhibition of COX-1, which demonstrated the importance of this enzyme in the maintenance of colonic mucosal integrity.

Anti-Leishmania activity of essential oil of Myracrodruon urundeuva (Engl.) Fr. All.: Composition, cytotoxity and possible mechanisms of action.

Myracrodruon urundeuva (Engl.) Fr. All., commonly known as "aroeira-do-sertão", is a medicinal plant from Anacardiaceae family. In this study, the chemical composition of M. urundeuva essential oil (MuEO) was evaluated by gas chromatography-mass spectrometry (GC-MS), as well as its anti-Leishmania potential, cytotoxicity, and macrophage activation capability as possible antiprotozoal mechanism of action were assessed. Fourteen compounds were identified, which constituted 94.87% of total oil composition. The most abundant components were monoterpenes (80.35%), with ß-myrcene (42.46%), α-myrcene (37.23%), and caryophyllene (4.28%) as the major constituents. The MuEO inhibited the growth of promastigotes (IC50 205 ± 13.4 µg mL-1), axenic amastigotes (IC50 104.5 ± 11.82 µg mL-1) and decreased percentage of macrophage infection and number of amastigotes per macrophage (IC50 of 44.5 ± 4.37 µg⋅mL-1), suggesting significant anti-Leishmania activity. The cytotoxicity of MuEO was assessed by MTT test in Balb/c murine macrophages and by human erythrocytes lysis assay and low cytotoxicity for these cells was observed. The CC50 value against macrophages were 550 ± 29.21 µg mL-1, while cytotoxicity for erythrocytes was around 20% at the highest concentration assessed, with HC50 > 800 µg mL-1. While MuEO-induced anti-Leishmania activity is not mediated by increases in both lysosomal activity and nitric oxide production in macrophages, the results suggest the antiamastigote activity is associated with an immunomodulatory activity of macrophages due to an increase of phagocytic capability induced by MuEO. Thus, MuEO presented significant activity against Leishmania amazonensis, probably modulating the activation of macrophages, with low cytotoxicity to murine macrophages and human erythrocytes.

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

Our objective was to investigate the protective effect of Lawesson's reagent, an H2S donor, against alendronate (ALD)-induced gastric damage in rats. Rats were pretreated with saline or Lawesson's 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)-1ß], 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 Lawesson's reagent was administered. After 30 min, 30 mg/kg ALD was administered. ALD caused gastric damage (63.35 ± 9.8 mm(2)); increased levels of TNF-α, IL-1ß, 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 Lawesson's reagent (27 µmol/kg) attenuated ALD-mediated gastric damage (15.77 ± 5.3 mm(2)); reduced TNF-α, IL-1ß, 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 Lawesson's reagent. However, glibenclamide plus diazoxide did not alter the effects of Lawesson's reagent. Our results suggest that Lawesson's 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.

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

Our objective was to investigate the protective effect of Lawesson's reagent, an H2S donor, against alendronate (ALD)-induced gastric damage in rats. Rats were pretreated with saline or Lawesson's 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 Lawesson's 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 Lawesson's 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 Lawesson's reagent. However, glibenclamide plus diazoxide did not alter the effects of Lawesson's reagent. Our results suggest that Lawesson's 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.