RESUMO

The mechanism underlying the role of tumor necrosis factor alpha (TNF-α) in the development of inflammatory hyperalgesia has been extensively studied, mainly the role of TNF-α in the release of pro-inflammatory cytokines. The current concept relies in the fact that TNF-α stimulates the cascade release of other pro-inflammatory cytokines, such as IL-1ß, IL-6, and IL-8 (CINC-1 in rats), triggering the release of the final inflammatory mediator prostaglandin E2 (PGE2 ) and sympathetic amines that directly sensitize the nociceptors. However, this may not be the sole mechanism involved as the blockade of TNF-α synthesis by thalidomide prevents hyperalgesia without interrupting the synthesis of IL-1ß, IL-6, and CINC-1. Therefore, we hypothesized that activation of TNF-α receptor type 1 (TNFR1) by TNF-α increases nociceptors' susceptibility to the action of PGE2 and dopamine. We have found out that intrathecal administration of oligodeoxynucleotide-antisense (ODN-AS) against TNFR1 or thalidomide prevented carrageenan-induced hyperalgesia. The co-administration of TNF-α with a subthreshold dose of PGE2 or dopamine that does not induce hyperalgesia by itself in the hind paw of Wistar rats pretreated with dexamethasone (to prevent the endogenous release of cytokines) induced a robust hyperalgesia that was prevented by intrathecal treatment with ODN-AS against TNFR1. We consider that the activation of neuronal TNFR1 by TNF-α decisively increases the susceptibility of the peripheral afferent neuron to the action of final inflammatory mediators - PGE2 and dopamine - that ultimately induce hyperalgesia. This mechanism may also underlie the analgesic action of thalidomide.

Assuntos

RESUMO

The monoterpene ß-myrcene has been widely used in cosmetics, food and beverages, and it is normally found in essential oil from citrus fruit. The aim of this study was to investigate the anti-ulcer effects of ß-myrcene on experimental models of ulcers that are induced by ethanol, NSAIDs (non-steroidal anti-inflammatory drugs), stress, Helicobacter pylori, ischaemia-reperfusion injury (I/R) and cysteamine in order to compare with the essential oil of Citrus aurantium and its major compound limonene. The results indicate that the oral administration of ß-myrcene at a dose of 7.50mg/kg has important anti-ulcer activity with significantly decreased gastric and duodenal lesions as well as increased gastric mucus production. The results showed treatment with ß-myrcene caused a significant increase in mucosal malondialdehyde level (MDA), an important index of oxidative tissue damage. The ß-myrcene was also endowed with marked enhancement of antioxidant enzyme activity from GR system as evidenced by the decreased activity of superoxide dismutase (SOD) and increased levels of glutathione peroxidase (GPx), glutathione reductase (GR), and total glutathione in gastric tissue. Our results also shown that treatment with ß-myrcene is not involved with thioredoxin reductase (TrxR) activity. Our results reveal, for the first time, the importance of ß-myrcene as an inhibitor of gastric and duodenal ulcers and demonstrate that an increase in the levels of gastric mucosa defence factors is involved in the anti-ulcer activity of ß-myrcene.

Assuntos

RESUMO

Peptic ulcers are a common disorder of the entire gastrointestinal tract, its etiology has not been completely elucidated. The basic physiopathological of peptic ulcers result from an imbalance between some endogenous aggressive factor and cytoprotective factors. The treatment of this disease is usually done with antacids or proton pump, but are currently being used plants derivated compounds. We evaluated the gastroprotective properties and its possible mechanisms of action of the essential oil from Protium heptaphyllum (Aubl.) Marchand, Burseraceae (BB). The formation of ulcers, were evaluated in three experimental models, through the induction of gastric lesions by ethanol, nonsteroidal anti-inflammatory drugs and acetic acid. The mechanisms of action were evaluated through the pylorus ligature experiment, western blot, GSH, GR, SOD, GPx, MDA and MPO activities. BB significantly inhibited the formation of ulcers induced by the three different models, increased the GSH and GR levels and maintained the same levels of SOD and GPx of the sham group, inhibited MPO and MDA, did not produce significant modification in gastric juice content and showed increased COX-2 and EGF. BB exerts its gastroprotective activity, possibly, by increasing COX-2 and EGF expression and due to its possible antioxidant property.

RESUMO

The hemolytic, anti-inflammatory and antinociceptive properties from hydrolyzed extract Agave sisalana Perrine ex Engelm., Asparagaceae (HEAS) was evaluated on classic inflammation models. Male Swiss mice and male Wistars rats received HEAS (500 mg/kg) in two administration p.o. and i.p. in saline solution 0.9 percent. The acid hydrolysis inhibited the hemolytic action of saponins due to the retreat of side chain sugar. The treatment of the ear induced oedema by xylene with HEAS significantly reduced in two routes 13±1.5 and 10±0.63 mg, respectively, p.o. and i.p., in comparison with controls 27±1.5 saline and 13.5±1.2 AAS. The HEAS also diminished edema induced by carrageenin 43±1.58 mg (p.o.) and 17±1.26 mg (i.p.), when compared with control groups 52±1.58 mg (saline) and 10.05±1.58 (indomethacin). HEAS showed analgesic effects in abdominal constrictions 30.7 percent (p.o.), 88.7 percent (i.p.) comparable to that produced by (AAS) 70.6 percent. However in granuloma cotton pellet a chronic model of inflammation just the i.p. pathway decreased granulomatous tissue (20.4±1.32 mg) compared with controls 30.5±2.53 mg (saline) and 20.2±2.18 mg (dexamethasone). These data suggest that HEAS has anti-inflammatory and analgesic activity on acute and chronic processes.

As propriedades hemolítica, anti-inflamatória e antinociceptiva do extrato hidrolisado de Agave sisalana Perrine ex Engelm, Aparagaceae (HEAS) foram avaliadas em modelos clássicos de inflamação. Camundongos Swiss e ratos Wistars machos receberam HEAS (500 mg/kg) em duas vias de administração p.o e i.p em solução salina 0.9 por cento. A hidrólise ácida inibiu a ação hemolítica das saponinas através da retirada das cadeias laterais de açúcar. O tratamento com HEAS reduziu significativamente o edema de orelha induzido por xilol em duas vias 13±1.5 e 10±0.63 mg respectivamente, p.o e i.p, em comparação com os controles 27±1.5 salina e 13.5±1.2 AAS. O HEAS também diminuiu o edema induzido por carragenina 43±1.58 mg (p.o) e 17±1.26 mg (i.p), quando comparado com os grupos controle 52±1.58 (salina) e 10.05±1.58 (indometacina). HEAS apresentou efeito analgésico em modelo de contorções abdominais 30.7 por cento (p.o), 88.7 por cento (i.p) comparado com aquele produzido pelo (AAS) 70.6 por cento. Contudo, no modelo crônico de inflamação granuloma cotton pellet apenas a via i.p diminuiu o tecido granulomatoso (20.4±1.32 mg) comparado com os controles 30.5±2.53 (salina) e 20.2±2.18 mg (dexametasona). Esses dados sugerem que o HEAS possui atividades anti-inflamatória e analgésica em processos agudos e crônicos.