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Freshwater stingray accidents cause an immediate, intense, and unrelieved pain which is followed by edema, erythema and necrosis formation. Treatment for stingray envenomation is based on administration of analgesic, antipyretic and anti-inflammatory drugs. Concerning pain control, it is prescribed to immerse punctured limb on hot water to alleviate pain. There are no studies demonstrating specific targets on which stingray venom acts to promote pain. Therefore, the aim of this work was to investigate some mechanisms of Potamotrygon motoro venom (PmV) that contribute to nociception induction. Evaluating spontaneous pain behavior in mice injected i.pl. with PmV, it was seen that PmV induced both neurogenic and inflammatory pain. PmV also induced hyperalgesia in both mice and rats, evaluated through electronic von Frey and rat paw pressure test, respectively. Partial inhibition of hyperalgesia was observed in mice treated with cromolyn or promethazine, which indicated that mast cell and histamine via H1 receptor participate in the inflammatory pain. To search for some targets involved in PmVinduced hyperalgesia, the participation of TRPV1, calcium channels, neurokinins, CGRP, and norepinephrine, was evaluated in rats. It was seen that PmV-induced hyperalgesia occurs with the participation of neurokinins, mainly via NK1 receptor, CGRP, and calcium influx, through both P/Q and L-type voltage-dependent calcium channels, besides TRPV1 activation. The data presented herein indicate that PmV causes hyperalgesia in rodents which is dependent on the participation of several neuroinflammatory mediators. [ABSTRACT FROM AUTHOR]

An outbreak of a novel disease characterized by serious hemorrhage in the abdomen, ascites and bleaching of the liver was recorded in the freshwater cultured stingray Potamotrygon motoro , which is a cartilaginous fish related to sharks, in Panyu, Guangdong province of South China. The bacterial isolates from the lesions of diseased P. motoro exhibited the same phenotypic traits and biochemical characteristics and were identified for the first time as Citrobacter freundii according to biochemical characteristics and molecular identification with the 16S rRNA gene. In challenge trials, P. motoro injected intraperitoneal with the C. freundii P2 developed similar pathological signs to the naturally diseased fish. Furthermore, histopathology of diseased fish infected with C. freundii showed moderate lipid degeneration in the liver, macrophage aggregations of the lymphoid tissue in the spleen, and microglia aggregation in the brain. [ABSTRACT FROM AUTHOR]

Ethnopharmacological relevance Animal oils and fats from the fishes Electrophorus electricus and Potamotrygon motoro , the reptiles Boa constrictor , Chelonoidis denticulata ( Geochelone denticulata ) and Melanosuchus niger and the riverine dolphin Inia geoffrensis are used as anti-inflammatory agents in the Peruvian Amazon. The aim of the study was to assess the topic anti-inflammatory effect of the oils/fats as well as to evaluate its antimicrobial activity and fatty acid composition. Materials and methods The oils/fats were purchased from a traditional store at the Iquitos market of Belen, Peru. The topic anti-inflammatory effect was evaluated by the mice ear edema induced by arachidonic acid (AA) and 12-O-tetradecanoylphorbol-13-acetate (TPA) at the dose of 3 mg oil/ear. Indomethacine and nimesulide were used as reference anti-inflammatory drugs. The application resembles the traditional topical use of the oils. The antimicrobial effect of the oils/fats was assessed by the microdilution test against reference strains of Escherichia coli , Staphylococcus aureus and Salmonella enteritidis . The fatty acid composition of the oils/fats (as methyl esters) was determined by GC and GC–MS analysis after saponification. Results All oils/fats showed topic anti-inflammatory activity, with better effect in the TPA-induced mice ear edema assay. The most active drugs were Potamotrygon motoro , Melanosuchus niger and Geochelone denticulata . In the AA-induced assay, the best activity was found for Potamotrygon motoro and Electrophorus electricus oil. The oil of Electrophorus electricus also showed a weak antimicrobial effect with MIC values of 250 µg/mL against Escherichia coli ATCC 25922 and Salmonella enteritidis -MI. The main fatty acids in the oils were oleic, palmitic and linoleic acids. Conclusions Topical application of all the oils/fats investigated showed anti-inflammatory activity in the mice ear edema assay. The effect can be related with the identity and composition of the fatty acids in the samples. This study gives support to the traditional use of animal oils/fats as ant-inflammatory agents in the Peruvian Amazon. However, new alternative should be encouraged due to the conservation status of several of the animal sources of the crude drugs. [ABSTRACT FROM AUTHOR]

Abstract: Invasion by bacteria can influence the course of healing of wounds acquired in aquatic environment. In this study, the bacteria present in Potamotrygon motoro stingray mucus and in the Alto Paraná river water were identified, and their ability to induce tissue injury and resist antibiotics was determined. Biochemical identification analysis showed that 97% of all bacterial isolates were Gram negative, Aeromonas spp., Enterobacter cloacae and Citrobacter freundii being the species most prevalent. Gelatinase and caseinase were produced by Aeromonas hydrophila, Aeromonas sobria and Pseudomonas aeruginosa strains. Erythrocyte hemolysis assay showed that A. sobria, A. hydrophila and to a lesser extent, other Gram-negative bacteria produced hemolysin. It was also observed that molecules released in culture by these bacteria were toxic to human epithelial cells. Antibiogram results showed that 68% of all bacterial isolates were resistant to at least one type of antibiotic, mainly B-lactams. Finally, it was demonstrated that although P. motoro venom was toxic to epithelial cells it did not influence bacterial proliferation. In summary, the results obtained in this work indicate that during the accident, the mucus of P. motoro and the environmental water may transfer into the wound pathogenic multi-resistant bacteria with the potential to cause severe secondary infections. [Copyright &y& Elsevier]

Abstract: Freshwater stingrays (Potamotrygon motoro) are known to cause human accidents through a sting located in its tail. In the State of Goiás, this accident happens especially during the fishing season of the Araguaia River. The P. motoro venom extracted from the sting presented hyaluronidase activity. The enzyme was purified by gel filtration on Sephacryl S-100 and ion-exchange chromatography on SP-Sepharose. A typical procedure provided 376.4-fold purification with a 2.94% yield. The molecular weight of the purified enzyme was 79kDa as estimated by gel filtration on Sephacryl S-100. The K m and V max values for hyaluronidase, using hyaluronic acid as substrate, were 4.91μg/ml and 2.02U/min, respectively. The pH optimum for the enzyme was pH 4.2 and maximum activity was obtained at 40°C. The hyaluronidase from P. motoro was shown to be heat instable, being stabilized by bovine albumin and DTT, and inhibited by Fe2+, Mn2+, Cu2+ and heparin. [Copyright &y& Elsevier]