Phycobiliproteins of Arthrospira (Spirulina) maxima have attracted attention because of their potential therapeutic antioxidant properties. The aim of this study was to assess the possible antiulcerogenic activity of these phycobiliproteins (ExPhy) against ethanol-induced gastric ulcers in rats. To explore the possible mechanisms of action, we examined antioxidant defense enzymes (e.g., catalase, superoxide dismutase, and glutathione peroxidase), as well as the level of lipid peroxidation (MDA) and the histopathological changes in the gastric mucosa. Intragastric administration of ExPhy (100, 200, and 400 mg/kg body weight) significantly lowered the ulcer index value compared to the ulcer control group (p < 0.05). The greatest protection was provided by the concentration of 400 mg/kg. The histological study supported the observed gastroprotective activity of ExPhy, showing a reduced inflammatory response. Moreover, the alcohol-induced decrease in stomach antioxidant enzyme activity found in the ulcer control group was prevented by ExPhy pretreatment. Furthermore, ExPhy reversed the ethanol-induced increase in lipid peroxidation. In summary, the antiulcerogenic potential of ExPhy may be due, at least in part, to its anti-oxidant and anti-inflammatory effects.

Exposure to silica induces granulomatous lung inflammation evolving to fibrosis through yet unclear pathogenic mechanisms. We examined the expression of extracellular matrix remodeling molecules: collagenase 3, gelatinases A and B, and TIMP-1 and TIMP-2 in experimental lung silicosis. Rats were instilled with 50 mg of silica and sacrificed after 15 and 60 d. At 60 d a significant increase in lung collagen content was found (170.2 +/- 34.4 versus 88.2 +/- 20.8 microgram/mg in controls, p = 0.01). Gelatin zymography of bronchoalveolar lavage fluid (BALF) from 15 and 60 d revealed bands of progelatinase A and progelatinase B, and lung tissue zymograms showed in addition, the active gelatinase A form at 15 d. By in situ hybridization and immunohistochemistry, early silicotic granulomas exhibited intense staining for all matrix metalloproteinases (MMPs) and TIMPs assayed. Labeling was restricted inside granulomas and surrounding areas. Late silicotic granulomas at 60 d showed lower MMP expression than did early lesions, and in highly fibrotic nodules scarce signal was usually found. TIMP-1 and TIMP-2 showed a moderate reduction in 60-d silicotic nodules. These findings suggest that an imbalance in the expression of MMPs and TIMPs may be implicated in extracellular matrix remodeling and basement membrane disruption during experimental lung silicosis.

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