Anti-inflammatory and anti-necrotic effects of lectins from Canavalia ensiformis and Canavalia brasiliensis in experimental acute pancreatitis.

Lectins isolated from Canavalia ensiformis (ConA) and Canavalia brasiliensis (ConBr) are promising molecules to prevent cell death. Acute pancreatitis, characterized by acinar cell necrosis and inflammation, presents significant morbidity and mortality. This study has investigated the effects of ConA and ConBr in experimental acute pancreatitis and pancreatic acinar cell death induced by bile acid. Pancreatitis was induced by retrograde pancreatic ductal injection of 3% sodium taurocholate (Na-TC) in male Swiss mice. ConA or ConBr (0.1, 1 or 10 mg/kg) were intravenously applied to mice 1 h and 12 h after induction. After 24 h, the severity of pancreatitis was evaluated by serum amylase and lipase, histopathological changes and myeloperoxidase assay. Pancreatic acinar cells were incubated with ConA (200 µg/ml) or ConBr (200 µg/ml) and taurolithocholic acid 3-sulfate (TLCS; 500 µM). Necrosis and changes in mitochondrial membrane potential (ΔÑ°m) were detected by fluorescence confocal microscopy. Treatment (post-insult) with ConA and ConBr decreased pancreatic damage caused by retrograde injection of Na-TC in mice, reducing pancreatic neutrophil infiltration, edema and necrosis. In addition, ConA and ConBr decreased pancreatic acinar cell necrosis and depolarization of ΔÑ°m caused by TLCS. The inhibition of necrosis was prevented by the lectin domain blockade. In conclusion, ConA and ConBr markedly inhibited in vitro and in vivo damage, effects partly dependent on the interaction with mannose residues on acinar cells. These data support the potential application of these proteins for treatment of acute pancreatitis.

The polysaccharide-rich tea of Ximenia americana barks prevents indomethacin-induced gastrointestinal damage via neutrophil inhibition.

ETHNOPHARMACOLOGICAL RELEVANCE: Barks of Ximenia americana are used by the population to treat gastrointestinal inflammatory disorders. Indomethacin is a non-selective non-steroidal anti-inflammatory drug that induces marked gastrointestinal damage. AIMS OF THE STUDIES: To evaluate the gastroprotective activity of total polysaccharides contained in the extract (TPL-Xa) or tea (Tea-Xa) of Ximenia americana barks in the mice gastric damage induced by indomethacin. MATERIALS AND METHODS: TPL-Xa was obtained by a combination of NaOH extraction and ethanol precipitation. Tea-Xa was prepared in distilled water boiled during 5 min. Animals received p.o. 0.9% NaCl (saline - control group), TPL-Xa (1-90 mg/kg) or Tea-Xa 1 h before gastritis induction by indomethacin (20 mg/kg). Mice were sacrificed 7 h after gastritis induction and analyzed for the following parameters: stomach lesions measurement; histological evaluation; myeloperoxidase (MPO) activity; nitrate/nitrite and cytokine levels; leukocyte adhesion and rolling by intravital microscopy. RESULTS: TPL-Xa reduced macroscopic and microscopic damage, MPO activity (59%), leukocyte rolling (86%) and adhesion (84%), nitrite/nitrate ratio (100%) and IL-8 (69%), but increased IL-4 (50%). Tea-Xa (12.8 yield; 39.3% carbohydrate, including 25.8% uronic acid; 4% protein) reduced macroscopic damage (62%) and MPO activity (50%). CONCLUSION: TPL and Tea of Ximenia americana barks ameliorate the gastric injury induced by indomethacin in mice, an effect that was dependent on the reduction of neutrophil infiltration.

Sensorial, structural and functional response of rats subjected to hind limb immobilization.

AIMS: This study analyzed the sensorial, structural and functional response of rats subjected to paw immobilization. MAIN METHODS: Animal pelvis, hip, knee and ankle were immobilized using waterproof tape during two weeks for assessment of sensorial response to thermal (hot plate test) and mechanical stimuli (Von Frey test), motor system structure (histology and radiography) and muscle function (soleus contractility). KEY FINDINGS: Disuse animals became more responsive to thermal stimuli (49%), although less responsive to mechanical challenge (58%). Disuse animals showed local injuries such as reduction in muscle fiber diameter (16.7% in gastrocnemius, 5.7% in soleus), contractile activity (55% of the control maximal tonic contraction) and tibia cortical thickness (9.3%), besides increased nitrite:protein ratio, suggestive of protein degradation. Disuse also evoked systemic adaptations that include increase in serum lactate dehydrogenase (36.1%) and alkaline phosphatase (400%), but reduction in calcium (8.4%) and total serum protein (5.5%), especially albumin (34.2%). SIGNIFICANCE: Two weeks of functional paw disuse leads to local and systemic harmful adaptive changes in sensorial and structural systems. This study brings new insights into nervous and motor system mechanism associated with therapeutic limb immobilization in muscle and skeletal pathological conditions.