Pharmacological characterization of mouse hind paw oedema induced by Bothrops insularis (jararaca ilhoa) snake venom

Evaluation of the toxicological properties of Himantura imbricata Venom using a zebrafish model (Danio rerio)

The stingrays of the genus Himantura imbricata are present in all of the world's oceans, but the toxicity of their venoms has not yet been thoroughly characterized. The zebrafish as a toxicology model can be used for general toxicity testing of drugs and the investigation of toxicological mechanisms. The aim of this study was to evaluate the effect of crude venom from the stingray H. imbricata on the zebrafish Danio rerio. Juvenile zebrafish were injected with different concentrations of venom from H. imbricata via subcutaneous injections. The venom's effects were established via histological examination and hemolytic activity in zebrafish. The histopathological analysis revealed significant tissue damage in the organs of the zebrafish injected with venom, including liver necrosis and kidney degeneration. A blood examination revealed echinocytes, hemolysis, and nuclear abnormalities. Bodyweight estimations and histopathological attributes of the gills, heart, muscle, liver, intestine, eye, and brain were determined. The histological staining studies of the gills, liver, and intestine were measurably higher in the venom groups compared with the other two groups. Aggregately, the result shows that zebrafish may act as a valuable biomarker for alterations impelled by H. imbricata venom. The work delivers a useful model with substantial pharmacological potential for new drugs and a better comprehension of research on stingray venom.

Understanding Local Reactions Induced by Bothrops jararaca Venom: The Role of Inflammatory Mediators in Leukocyte-Endothelium Interactions

In recent years, extensive research has delved into the pathophysiology of local reactions triggered by Bothrops snake venoms. Even though antivenom works well at reducing death and systemic effects, it is still not very effective in treating local reactions because it cannot counteract damage that has already been triggered. This limitation might be attributed to certain molecules that amplify the venom-induced innate response. While evidence suggests endogenous mediators at the venom site play a role in this envenomation, in Brazil, the concurrent use of anti-inflammatory agents or other drugs alongside antivenom remains uncommon. This study evaluated the pharmacological mediation of alterations in leukocyte-endothelium interactions following the experimental envenomation of mice with Bothrops jararaca venom, the main culprit of snake-related accidents in Southeast Brazil. We treated envenomed mice with inhibitors of different pharmacological pathways and observed the cremaster muscle microcirculation with intravital microscopy. We found that eicosanoids related to cyclooxygenase pathways and nitric oxide significantly contributed to B. jararaca venom-induced alterations in leukocyte-endothelium interactions. Conversely, lipoxygenase-mediated eicosanoids, histamine, and serotonin had minimal participation. Notably, dexamethasone and antivenom treatment diminished B. jararaca venom-induced alterations in leukocyte-endothelium interactions. The limited efficacy of the antivenom in managing Bothrops venom-induced local reactions emphasizes the critical need for supplementary treatments to enhance therapeutic outcomes.

Medicinal plants of the upper Aswa River catchment of northern Uganda - a cultural crossroads

BACKGROUND

This paper presents a comparative inventory of medicinal plant taxa and their uses by smallholder farming communities of four cultures in the Aswa River catchment of northern Uganda, situated in the eastern Sudanian savanna parkland ecotype of sub-Saharan Africa. The purpose of the study was to document the ethnobotanical use of medicinal plants by the Lango, Acholi, Teso (Atesot) and Ethur (jo Abwor), in an historical moment before civil conflict and mass displacement of the respondent communities disrupted the inter-generational transmission of traditional technical knowledge within the study area.

METHODS

Following community consultations in four districts of northern Uganda during 1999-2000, interviews were conducted with holders of specialist knowledge on plants used as medicine on basis of a plant specimen allocated a voucher number and identified by the national herbarium. Use reports reflecting specific medicinal applications were compiled in aggregate to obtain a Relative Importance Index ranking. The commonality of medicinal taxa cited between each cultural interface was assessed by the Jaccard Index of Similarity, and the similarity of specific medicinal usage by taxon using Rahman's Similarity Index.

RESULTS

The data collected from 112 respondents comprise 280 medicinal use reports describing 263 applications for 62 medical conditions, citing 108 taxa from 44 botanical families of which Fabaceae comprised 20% of all use reports. No earlier mention could be found to corroborate 72 use reports (27% of the total), representing medicinal indications as yet undocumented, and potentially worthy of investigation. The RI values ranged between 15 and 94%, with 13 taxa having RI values above 50%. The JI ratios indicate the highest degree of similarity in the plant taxa used as medicine (21%) between the Lango and Teso cultures who share a common origin; however, Rahman's Similarity Index indicates the highest similarity of specific medicinal usage by taxon between the Lango and Acholi, who share a common language group through cultural assimilation over time.

CONCLUSIONS

As a comparative study, the results imply that cultural exchange and assimilation may be a greater driver of inter-cultural similarity of ethnopharmacological use of a given taxon, as compared to shared historical origins.

The edematogenic effect of Micrurus lemniscatus venom is dependent on venom phospholipase A2 activity and modulated by non-neurogenic factors

Coral snakes mainly cause neurotoxic symptoms in human envenomation, but experimental studies have already demonstrated several pharmacological activities in addition to these effects. This investigation was carried out with the aim of evaluating (1) non-neurogenic mechanisms involved in the inflammatory response induced by Micrurus lemniscatus venom (MLV) in rat hind paws, (2) participation of PLA₂ in this response, and (3) neutralizing efficiency of commercial anti-elapid antivenom on edema. MLV promoted a rapid, significant increase in vascular permeability, influx of leukocytes, and disorganization of collagen bundles, as demonstrated by histological analysis. Several pretreatments were applied to establish the involvement of inflammatory mediators in MLV-induced edema (5 µg/paw). Treatment of animals with chlorpromazine reduced MLV-induced edema, indicating participation of TNF-α. However, the inefficiency of other pharmacological treatments suggests that eicosanoids, leukotrienes, and nitric oxide have no role in this type of edema formation. In contrast, PAF negatively modulates this venom-induced effect. MLV was recognized by anti-elapid serum, but this antivenom did not neutralize edema formation. Chemical modification of MLV with p-bromophenacyl bromide abrogated the phospholipase activity and markedly reduced edema, demonstrating PLA₂ participation in MLV-induced edema. In conclusion, the non-neurogenic inflammatory profile of MLV is characterized by TNF-α-mediated edema, participation of PLA₂ activity, and down-regulation by PAF. MLV induces an influx of leukocytes and destruction of collagen fibers at the site of its injection.

Actions of Cannabis sativa L. fixed oil and nano-emulsion on venom-induced inflammation of Bothrops moojeni snake in rats

BACKGROUND

Bothrops moojeni snake venom (VBm) has toxins that cause pronounced tissue damage and exacerbated inflammatory reaction. Cannabis sativa L. is a plant species that produces an oil (CSO) rich in unsaturated fatty acids. Nano-emulsions have several advantages, such as better stability and higher penetrating power in membranes. Therefore, this study evaluated the effect of a nano-emulsion based on this herbal derivative (NCS) against VBm-induced inflammation in Wistar rats.

METHODS

The CSO and NCS were submitted to physicochemical characterization. The inflammatory process was induced by the VBm (0.10 mg/kg) as follows: rat paw edema, peritonitis, analysis of leukocyte infiltrate in gastrocnemius muscle of rats and formation of granulomatous tissue.

RESULTS

No significant changes were observed when the NCS was submitted to the centrifugation and thermal stress tests. There was no phase separation, changes in density (0.978 ± 0.01 g/cm³) and viscosity (0.889 ± 0.15). The droplet diameter ranged from 119.7 ± 065 to 129.3 ± 0.15 nm and the polydispersity index ranged from 0.22 ± 0.008 to 0.23 ± 0.011. The results showed that treatments with CSO (200 and 400 mg/kg) and NCS (100 mg/kg) were able to decrease significantly (p < 0.001) the formation of edema and granulomatous tissue. The CSO and NCS groups significantly attenuated (p < 0.001) the recruitment of inflammatory cells in the tests for peritonitis and leukocyte infiltrate. The histopathological analysis of the gastrocnemius muscle showed a reduction in tissue damage caused by VBm.

CONCLUSION

The results obtained in this study showed anti-inflammatory activity of the CSO which may be due to a high UFA content. The nanosizing, as evidenced by the incorporation of the CSO in the NCS improved the effect and opens the perspective for the obtainment of a nanomedicine in which a kinetic stable phytotherapic can be used at low doses.

Inflammation Induced by Platelet-Activating Viperid Snake Venoms: Perspectives on Thromboinflammation

Envenomation by viperid snakes is characterized by systemic thrombotic syndrome and prominent local inflammation. To date, the mechanisms underlying inflammation and blood coagulation induced by Viperidae venoms have been viewed as distinct processes. However, studies on the mechanisms involved in these processes have revealed several factors and signaling molecules that simultaneously act in both the innate immune and hemostatic systems, suggesting an overlap between both systems during viper envenomation. Moreover, distinct classes of venom toxins involved in these effects have also been identified. However, the interplay between inflammation and hemostatic alterations, referred as to thromboinflammation, has never been addressed in the investigation of viper envenomation. Considering that platelets are important targets of viper snake venoms and are critical for the process of thromboinflammation, in this review, we summarize the inflammatory effects and mechanisms induced by viper snake venoms, particularly from the Bothrops genus, which strongly activate platelet functions and highlight selected venom components (metalloproteases and C-type lectins) that both stimulate platelet functions and exhibit pro-inflammatory activities, thus providing insights into the possible role(s) of thromboinflammation in viper envenomation.

Anti-ophidian activity of Bredemeyera floribunda Willd. (Polygalaceae) root extract on the local effects induced by Bothrops jararacussu venom

Bredemeyera floribunda roots are popularly used to treat snakebites in the semiarid region of Northeast Brazil, and previous studies indicate the anti-ophidian actions of triterpenoid saponins found in its roots. To assess B. floribunda root extract (BFRE) activity against the effects of Bothrops jararacussu venom (BjuV), antiphospholipasic, antiproteolytic, antihemorrhagic, antinecrotic, and anti-edematogenic activities were investigated in mice. Phytochemical analysis revealed the presence of saponins, flavonoids, and sugars, with rutin and saccharose being the major constituents of BFRE. Acute toxicity was determined and BFRE was nontoxic to mice. Phospholipase A2 and proteolytic activities induced by BjuV were inhibited in vitro by BFRE at all concentrations tested herein. BFRE (150 mg/kg) inhibited paw edema induced by BjuV (50 µg/animal), reducing total edema calculated by area under the curve, but carrageenan-induced paw edema was unchanged. Hemorrhagic and necrotizing actions of BjuV (50 µg/animal) were considerably decreased by BFRE treatment. Thus, BFRE blocked the toxic actions of B. jararacussu venom despite having no anti-inflammatory activity, which points to a direct inhibition of venom's toxins, as demonstrated in the in vitro assays. The larger amounts of rutin found in BFRE may play a role in this inhibition, since 3',4'-OH flavonoids are known inhibitors of phospholipases A2.

Effects of Bothrops alternatus venom in zebrafish: a histopathological study

Zebrafish is an excellent model organism for studying tissue alterations caused by Bothrops alternatus venom (BAV) and for screening new anti-venom drugs. To study tissue alterations following exposure to BAV and the roles that glucocorticoids play in these tissue reactions, zebrafish were randomly divided into five groups: the free injection control group (FIC), the phosphate-buffered saline injection control group (PIC), the venom injected group (VI), the group treated with dexamethasone 1 h before venom injection (D1hBVI) and the group treated with dexamethasone 1 h after venom injection (D1hAVI). The concentration of BAV injected was 0.13 mg/mL and each fish received an injection of 20 μL. Body weight measurements and histopathological characteristics of the gills, kidneys, liver, and intestine were determined. Histopathological analyses showed necrosis, inflammation and weight gain in animals that received BAV. The histological alteration indices of the gills, liver, kidneys, and intestines were statistically higher in the animal groups treated with BAV. These alteration indices were lower in the D1hBVI and D1hAVI groups compared to the group treated with BAV alone. The D1hBVI group is presented with minor alterations. A significant difference in the histological alterations index was observed in the intestinal tissue of the FIC group compared to the PIC group. Cumulatively, zebrafish may serve as a useful biomarker for alterations induced by BAV. Interestingly, dexamethasone reduced the damage caused by BAV in the organs studied, which suggests that zebrafish might be useful for screening new drugs that can mitigate tissue damage caused by snakebites.

Edema and Nociception Induced by Philodryas patagoniensis Venom in Mice: A Pharmacological Evaluation with Implications for the Accident Treatment

We have investigated the mechanisms involved in the genesis of edema and nociception induced by Philodryas patagoniensis venom (PpV) injected into the footpad of mice. PpV induced dose-related edema and nociceptive effects. Pretreatment of mice with cyclooxygenase inhibitor (indomethacin), but not with cyclooxygenase 2 inhibitor (celecoxib) markedly inhibited both effects. Pretreatments with H₁ receptor antagonist (promethazine) or with dual histamine-serotonin inhibitor (cyproheptadine) failed in inhibiting both effects. In groups pretreated with captopril (angiotensin-converting enzyme inhibitor) the edema was unaltered, but nociception was clearly increased, suggesting the participation of kinins in the pathophysiology of the nociception but not of the edema-forming effect of PpV. When PpV was treated with EDTA, the nociception was similar to the one induced by untreated venom, but edema was markedly reduced. We concluded that PpV-induced edema and nociception have cyclooxygenase eicosanoids as the main mediators and no participation of vasoactive amines. Kinins seem to participate in nociception but not in edema induced by PpV. The results also suggest that metalloproteinases are the main compounds responsible for the edema, but not for the nociception induced by this venom.

Experimental Bothrops atrox envenomation: Efficacy of antivenom therapy and the combination of Bothrops antivenom with dexamethasone

Bothrops atrox snakes are the leading cause of snake bites in Northern Brazil. The venom of this snake is not included in the antigen pool used to obtain the Bothrops antivenom. There are discrepancies in reports on the effectiveness of this antivenom to treat victims bitten by B. atrox snakes. However, these studies were performed using a pre-incubation of the venom with the antivenom and, thus, did not simulate a true case of envenomation treatment. In addition, the local lesions induced by Bothrops venoms are not well resolved by antivenom therapy. Here, we investigated the efficacy of the Bothrops antivenom in treating the signs and symptoms caused by B. atrox venom in mice and evaluated whether the combination of dexamethasone and antivenom therapy enhanced the healing of local lesions induced by this envenomation. In animals that were administered the antivenom 10 minutes after the envenomation, we observed an important reduction of edema, dermonecrosis, and myonecrosis. When the antivenom was given 45 minutes after the envenomation, the edema and myonecrosis were reduced, and the fibrinogen levels and platelet counts were restored. The groups treated with the combination of antivenom and dexamethasone had an enhanced decrease in edema and a faster recovery of the damaged skeletal muscle. Our results show that Bothrops antivenom effectively treats the envenomation caused by Bothrops atrox and that the use of dexamethasone as an adjunct to the antivenom therapy could be useful to improve the treatment of local symptoms observed in envenomation caused by Bothrops snakes.

Bothrops atrox is the dominant species responsible for accidental human snake bites in Northern Brazil. The efficacy of antivenom therapy to correct the systemic disturbances, including hemostatic disorders, caused by Brazilian Bothrops is well known. However, two fundamental issues need to be addressed in this region. (1) There are concerns regarding the effectiveness of the antivenom to treat Bothrops snake bites in this region since Bothrops atrox venom is not used as an antigen to obtain the Bothrops antivenom in Brazil, and (2) the efficacy of the antivenom therapy in reversing local injuries induced by Bothrops venoms is low. Thus, our study aimed to assess the effectiveness of antivenom therapy alone or in combination with dexamethasone to treat experimental envenomation induced by Bothrops atrox venom in mice. Our results showed that the Brazilian Bothrops antivenom effectively reversed the systemic disturbances caused by this envenomation and combining the antivenom therapy with dexamethasone accelerated the regression of inflammatory edema and the regeneration of skeletal muscle that was damaged by the venom.

Comparative analysis of local effects caused by Bothrops alternatus and Bothrops moojeni snake venoms: enzymatic contributions and inflammatory modulations

Bothropic envenomation is characterised by severe local damage caused by the toxic action of venom components and aggravated by induced inflammation. In this comparative study, the local inflammatory effects caused by the venoms of Bothrops alternatus and Bothrops moojeni, two snakes of epidemiological importance in Brazil, were investigated. The toxic action of venom components induced by bothropic venom was also characterised. Herein, the oedema, hyperalgesia and myotoxicity induced by bothropic venom were monitored for various lengths of time after venom injection in experimental animals. The intensity of the local effects caused by B. moojeni venom is considerably more potent than B. alternatus venom. Our results also indicate that metalloproteases and phospholipases A2 have a central role in the local damage induced by bothropic venoms, but serine proteases also contribute to the effects of these venoms. Furthermore, we observed that specific anti-inflammatory drugs were able to considerably reduce the oedema, the pain and the muscle damage caused by both venoms. The inflammatory reaction induced by B. moojeni venom is mediated by eicosanoid action, histamine and nitric oxide, with significant participation of bradykinin on the hyperalgesic and myotoxic effects of this venom. These mediators also participate to inflammation caused by B. alternatus venom. However, the inefficient anti-inflammatory effects of some local modulation suggest that histamine, leukotrienes and nitric oxide have little role in the oedema or myotoxicity caused by B. alternatus venom.

Mast cells and histamine play an important role in edema and leukocyte recruitment induced by Potamotrygon motoro stingray venom in mice

This work aimed to investigate mechanisms underlying the inflammatory response caused by Potamotrygon motoro stingray venom (PmV) in mouse paws. Pre-treatment of animals with a mast cell degranulation inhibitor (cromolyn) diminished edema (62% of inhibition) and leukocyte influx into the site of PmV injection. Promethazine (histamine type 1 receptor antagonist) or thioperamide (histamine type 3 and 4 receptor antagonist) also decreased edema (up to 30%) and leukocyte numbers, mainly neutrophils (40-50 %). Cimetidine (histamine type 2 receptor antagonist) had no effect on PmV-induced inflammation. In the RBL-2H3 lineage of mast cells, PmV caused proper cell activation, in a dose-dependent manner, with release of PGD2 and PGE2. In addition, the role of COXs products on PmV inflammatory response was evaluated. Indomethacin (COX-1/COX-2 inhibitor) or etoricoxib (COX-2 inhibitor) partially diminished edema (around 20%) in PmV-injected mice. Indomethacin, but not etoricoxib, modulated neutrophil influx into the site of venom injection. In conclusion, mast cell degranulation and histamine, besides COXs products, play an important role in PmV-induced reaction. Since PmV mechanism of action remains unknown, hindering accurate treatment, clinical studies can be performed to validate the prescription of antihistaminic drugs, besides NSAIDs, to patients injured by freshwater stingrays.

Inflammatory mediators involved in the paw edema and hyperalgesia induced by Batroxase, a metalloproteinase isolated from Bothrops atrox snake venom

Snake venom metalloproteinases have been described as responsible for several inflammatory effects. In this study, we investigated the edema and hyperalgesia induced in rats by Batroxase, a P-I metalloproteinase from Bothrops atrox venom, along with possible inflammatory mediators involved in these responses. Batroxase or sterile saline was injected into rat paws and the edema and hyperalgesic effects were evaluated for 6h by using a plethysmometer and a Von Frey system, respectively. Batroxase induced significant edematogenic and hyperalgesic peak responses in the first hours after administration. The inflammatory mediators involved in these responses were assayed by pretreatment of animals with synthesis inhibitors or receptor antagonists. Peak responses were significantly reduced by administration of the glucocorticoid dexamethasone, the H1 receptor antagonist diphenhydramine and the FLAP inhibitor MK-886. Rat paws injected with compound 48/80, a mast cell degranulating agent, followed by Batroxase injection resulted in significant reduction of the edema and hyperalgesia. However, Batroxase itself induced minor degranulation of RBL-2H3 mast cells in vitro. Additionally, the inflammatory responses did not seem to be related to prostaglandins, bradykinin or nitric oxide. Our results indicate a major involvement of histamine and leukotrienes in the edema and hyperalgesia induced by Batroxase, which could be related, at least in part, to mast cell degranulation.

Bothrops jararacussu snake venom-induces a local inflammatory response in a prostanoid- and neutrophil-dependent manner

Local tissue reactions provoked by Bothrops venoms are characterized by edema, hemorrhage, pain, and inflammation; however, the mechanisms of tissue damage vary depending upon the species of snake. Here, we investigated the mechanisms involved in the local inflammatory response induced by the Bothrops jararacussu venom (BjcuV). Female Swiss mice were injected with either saline, BjcuV (0.125-8 μg/paw) or loratadine (an H1 receptor antagonist), compound 48/80 (for mast cell depletion), capsaicin (for C-fiber desensitization), infliximab (an anti-TNF-α antibody), indomethacin (a non-specific COX inhibitor), celecoxib (a selective COX-2 inhibitor) or fucoidan (a P- and L-selectins modulator) given before BjcuV injection. Paw edema was measured by plethysmography. In addition, paw tissues were collected for the measurement of myeloperoxidase activity, TNF-α and IL-1 levels, and COX-2 immunoexpression. The direct chemotactic effect of BjcuV and the in vitro calcium dynamic in neutrophils were also investigated. BjcuV caused an edematogenic response with increased local production of TNF-α and IL-1β as well as COX-2 expression. Both edema and neutrophil migration were prevented by pretreatment with indomethacin, celecoxib or fucoidan. Furthermore, BjcuV induced a direct in vitro neutrophil chemotaxis by increasing intracellular calcium. Therefore, BjcuV induces an early onset edema dependent upon prostanoid production and neutrophil migration.

Characterization of inflammatory response induced by Potamotrygon motoro stingray venom in mice

Freshwater stingray accidents cause intense pain followed by edema, erythema, and necrosis formation. Treatment for stingray envenomation is based on administration of analgesic, antipyretic, and anti-inflammatory drugs. This report evaluated the local inflammatory reaction—including edema formation, leukocyte recruitment, release of inflammatory mediators, and histopathological changes—after the intraplantar injection of Potamotrygon motoro stingray venom in mice. Edema was observed as soon as 15 min after venom injection, peaking at 30 min, and lasted up to 48 h. In addition, P. motoro venom increased neutrophil counts in the site of injection, at all time periods and venom doses analyzed. Increased eosinophil and lymphocyte counts were detected mainly at 24 h. Moreover, monocytes/macrophages were observed in large amounts at 24 and 48 h. Microscopically, the venom induced leukocyte migration to the injured tissue, edema, mast cell degranulation, angiogenesis, and epidermal damage. Inflammatory mediator release (IL-6, MCP-1 and KC) was detected as soon as 1 h after venom injection, and it increased significantly at 4 h. At 24 h, the venom induced only the production of MCP-1. These results show that this stingray venom evokes a complex inflammatory reaction, with rapid and persistent edema formation, leukocyte recruitment, and release of cytokines and chemokines.

Biochemical and pharmacological characterization of PhTX-I a new myotoxic phospholipase A2 isolated from Porthidium hyoprora snake venom

This paper reports the biochemical and pharmacological characterization of a new myotoxic PLA(2) (EC 3.1.1.4) called PhTX-I, purified from Porthidium hyoprora venom by one step analytical chromatography reverse phase HPLC. The homogeneity of the PhTX-I fraction and its molecular mass were initially evaluated by SDS-PAGE and confirmed by MALDI-TOF spectrometry, indicating a molecular mass of 14.249Da and constituted of a single polipeptidic chain. Amino acid sequence was determined by "de novo sequencing," in tandem mass spectrometry, belonging to D49-PLA(2) enzyme class and exhibiting high identity (44-90%) with other myotoxics PLA(2) from snake venoms. The enzymatic investigation showed maximal activity at pH 8 and 35-45°C. This activity was dependent on Ca(2+), other cations (Mg(2+), Mn(2+), Cd(2+) and Zn(2+)) reduced notably the enzymatic activity, suggesting that the arrangement of the catalytic site presents an exclusive structure for Ca(2+). Ex vivo, whole venom and PhTX-I PLA(2) caused blockade of the neuromuscular transmission in young chick biventer cervicis preparations similar to other isolated snake venom toxins from the Bothrops genus. In vivo, both induced local myotoxicity and systemic interleukin-6 response upon intramuscular injection, additionally, induced moderate footpad edema. In vitro, both induced low cytotoxicity in skeletal muscle myoblasts, however PhTX-I PLA(2) was able to lyse myotubes.

Inflammatory events induced by brown spider venom and its recombinant dermonecrotic toxin: a pharmacological investigation

Accidents involving Brown spider (Loxosceles sp.) venom produce a massive inflammatory response in injured region. This venom has a complex mixture of different toxins, and the dermonecrotic toxin is the major contributor to toxic effects. The ability of Loxosceles intermedia venom and a recombinant isoform of dermonecrotic toxin to induce edema and increase in vascular permeability was investigated. These toxins were injected into hind paws and caused a marked dose and time-dependent edema and increase in vascular permeability in mice. Furthermore, the enzymatic activity of venom toxins may be primal for these effects. A mutated recombinant isoform of dermonecrotic toxin, that has only residual enzymatic activity, was not able to induce these inflammatory events. Besides the previous heating of toxins markedly reduced the paw edema and vascular permeability showing that thermolabile constituents can trigger these effects. In addition, the ability of these venom toxins to evoke inflammatory events was partially reduced in compound 48/80-pretreated animals, suggesting that mast cells may be involved in these responses. Pretreating mice with histamine (prometazine and cetirizine) and serotonin (methysergide) receptor antagonists significantly attenuated toxins induced edema and vascular permeability. Moreover, HPLC analysis of whole venom showed the presence of histamine sufficient to induce inflammatory responses. In conclusion, these inflammatory events may result from the activation of mast cells, which in turn release bioamines and may be related to intrinsic histamine content of venom.

Cytotoxic, thrombolytic and edematogenic activities of leucurolysin-a, a metalloproteinase from Bothrops leucurus snake venom

Leucurolysin-a (leuc-a), a 23 kDa non-hemorrhagic metalloproteinase, is found in venom of the viper Bothrops leucurus. Here, we examine the biological consequences of leuc-a, including thrombolytic activity, direct effects on endothelial cells in culture and edematogenic activity in vivo. We demonstrate fibrinolytic activity of leuc-a, in which the protease specifically degrades alpha, beta, and gamma-gamma chains. While not causing hemorrhaging, leuc-a does cause thrombolytic activities in whole blood clots. Endothelial cells are highly resistant to leuc-a in culture. Cell viability suffered only when cells were exposed to large quantities of the protease. Nevertheless, leuc-a induces changes in cell morphology. The impact of leuc-a on cell adhesion was confirmed by an adhesion assay, in which cell adhesion to fibronectin decreased due to leuc-a. This mild cellular impact is unlike that of crude venom, where lower concentrations triggered cell death and a greater reduction in cell adhesion. Also, leuc-a increased microvessel permeability with marked edema in mice peritoneum and foot pads. These effects are similar to those of other P-I class SVPMs. These in vivo effects were weaker when crude venom was tested. In conclusion, albeit not showing significant hemorrhagic activity, leuc-a can induce a prominent edema which appears to be significant in the local effects observed after B. leucurus venom accidents.

Perfil clínico e imunológico de bovinos experimentalmente inoculados com veneno bruto e iodado de Bothrops alternatus

Dez novilhas mestiças, distribuídas em dois grupos experimentais (n=5) receberam na altura média da face cranial do membro anterior direito, entre as articulações umerorradioulnar e do carpo, por via intramuscular superficial, 0,15mg/kg de veneno de Bothrops alternatus bruto ou iodado. Todos os animais foram avaliados clinicamente antes - tempo zero - e às 6 e 10h, no 2º, 3º, 4º, 5º, 8º, 11º, 18º e 25º dias após a inoculação dos venenos. Dois animais do grupo que recebeu veneno bruto foram a óbito às 53h e 78h e os sobreviventes apresentaram apatia, letargia, anorexia, postura indicativa de dor, melena, petéquias e sufusões nas mucosas, aumento do tempo de preenchimento capilar, enfartamento ganglionar regional, aumento das freqüências respiratória e cardíaca, redução da freqüência de pulsação arterial periférica, elevação da temperatura retal e diminuição da movimentação ruminal. No local da inoculação do veneno bruto houve sangramento e ulceração dérmica, além de aumento significativo na circunferência e dobra da pele do membro inoculado, revelando formação de edema. Todos os animais também foram avaliados imunologicamente no 17º, 24º, 31º, 45º, 60º e 180º dia. Somente os que receberam veneno bruto produziram anticorpos, detectados até o 45º dia. Os que receberam veneno botrópico iodado apresentaram alterações gerais e locais de menor intensidade, porém sem produção de IgG nos tempos pesquisados, demonstrando que a iodação alterou a composição bioquímica do veneno, diminuindo sua toxicidade e imunogenicidade.

Enzymatic and immunochemical characterization of Bothrops insularis venom and its neutralization by polyspecific Bothrops antivenom

Herein we compared the biological activities of Bothrops insularis and Bothrops jararaca venoms as well as their neutralization by polyspecific Bothrops antivenom (PBA). On account of that, we investigated their antigenic cross-reactivity and the neutralization of lethal, myotoxic and defibrinating activities by polyspecific and species-specific antivenoms. Silver-stained SDS-PAGE gels evidenced many common bands particularly above 47 kDa between B. jararaca and B. insularis venoms. However, some protein bands between 46 and 28 kDa were observed exclusively in B. jararaca venom. Both venoms presented gelatinolytic, caseinolytic, fibrinogenolytic and phospholipase A(2) activities. No hyaluronidase activity was detected in both venoms by zymography. Polyspecific and species-specific antivenoms showed similar titers to B. jararaca and B. insularis venoms by ELISA, and recognized similar components by immunoblotting. The PBA was effective in neutralizing the lethal, myotoxic and defibrinating activities of both venoms as well as to abrogate microcirculatory disturbances induced by B. insularis venom. No statistically significant difference was observed for minimal hemorrhagic doses between both venoms. Antigenic cross-reactivity was evident between both venoms. Since toxic and enzymatic activities were similar, we speculate that B. insularis venoms can induce a local damage in humans comparable to that observed in other Bothrops venoms. Besides, the PBA was effective in neutralizing the toxic activities of B. insularis venom.

Role of cyclooxygenases in oedema-forming activity of bothropic venoms

The venoms of Bothrops asper (BaV) and Bothrops jararaca (BjV), two of the most medically important poisonous snakes of Latin America, cause pronounced oedema in the victims through poorly understood mechanisms. In the present study, we examined the possible role of cyclooxygenases (COX) in the genesis of mouse paw oedema caused by BaV and BjV injections. BaV at 2.5 microg/paw and BjV at 0.75 microg/paw induced significant oedema that persisted for up to 6h following subplantar injection. Treatment with indomethacin (2 mg/kg), rofecoxib, (10 mg/kg), or dexamethasone (2 mg/kg) significantly reduced the BaV- and BjV-induced oedema formation. Treatment with SC-560 (30 mg/kg) significantly reduced the oedema formation induced by BjV but had no effect on that induced by BaV. Both venoms induced significant increases in the levels of prostaglandin E(2) (PGE(2)) and the expression of COX-1 and COX-2 in paw tissue. The peak of oedema formation and PGE(2) release correlated with marked expression of COX-2 in the paw tissue. These results demonstrate that injection of BaV and BjV results in a rapid increase in oedema formation that is, at least partially, mediated by arachidonic acid metabolites formed by COX-2. In the case of BjV, COX-1-derived prostanoids also appear to contribute significantly to the inflammatory changes.

Purification, sequencing and structural analysis of two acidic phospholipases A2 from the venom of Bothrops insularis (jararaca ilhoa)

Bothrops snake venoms contain a variety of phospholipases (PLA(2)), some of which are myotoxic. In this work, we used reverse-phase HPLC and mass spectrometry to purify and sequence two PLA(2) from the venom of Bothrops insularis. The two enzymes, designated here as BinTX-I and BinTx-II, were acidic (pI 5.05 and 4.49) Asp49 PLA(2), with molecular masses of 13,975 and 13,788, respectively. The amino acid sequence and molecular mass of BinTX-I were identical to those of a PLA(2) previously isolated from this venom (PA2_BOTIN, SwissProt accession number ) while those of BinTX-II indicated that this was a new enzyme. Multiple sequence alignments with other Bothrops PLA(2) showed that the amino acids His48, Asp49, Tyr52 and Asp99, which are important for enzymatic activity, were fully conserved, as were the 14 cysteine residues involved in disulfide bond formation, in addition to various other residues. A phylogenetic analysis showed that BinTX-I and BinTX-II grouped with other acidic Asp49 PLA(2) from Bothrops venoms, and computer modeling indicated that these enzymes had the characteristic structure of bothropic PLA(2) that consisted of three alpha-helices, a beta-wing, a short helix and a calcium-binding loop. BinTX-I (30 microg/paw) produced mouse hind paw edema that was maximal after 1h compared to after 3h with venom (10 and 100 microg/paw); in both cases, the edema decreased after 6h. BinTX-1 and venom (40 microg/ml each) produced time-dependent neuromuscular blockade in chick biventer cervicis preparations that reached 40% and 95%, respectively, after 120 min. BinTX-I also produced muscle fiber damage and an elevation in CK, as also seen with venom. These results indicate that BinTX-I contributes to the neuromuscular activity and tissue damage caused by B. insularis venom in vitro and in vivo.

Bothrops jararaca and Crotalus durissus terrificus venoms elicit distinct responses regarding to production of prostaglandins E2 and D2, and expression of cyclooxygenases

Prostaglandins (PGs), synthesized by cyclooxygenases, play important roles in many pathophysiological processes including inflammation and hyperalgesia. In this study the profiles of PGE(2) and PGD(2) production secondary to injection of Bothrops jararaca venom (BjV), with inflammatory activity or Crotalus durissus terrificus venom (CdtV), with anti-inflammatory and antinociceptive properties, into mice were evaluated, and the ability of these venoms to induce expression of cyclooxygenases-1 (COX-1) and -2 (COX-2) was investigated. Intraperitoneal injection of BjV but not of CdtV induced the release and PGD(2) at 30 min and of PGE(2) from 3 up to 12 h after injection. Moreover, BjV up-regulated expression of COX-2 but not of the constitutive COX-1, suggesting that expressed COX-2 provides more substrate for synthesis of PGs by the respective terminal synthases, being the critical enzyme for PGs production in the late periods of BjV effect. In contrast, CdtV does not have any effect on constitutive COX-1 and do not induce expression of COX-2. Therefore, differences between BjV and CdtV in the ability to regulate PGs synthesis can account for their distinct effects with regard to inflammation. Moreover, inhibition of COX-2 by selective drugs may be of value to counteract the severe local inflammation induced by BjV in the victims.

A randomized, double-blind, placebo-controlled trial of antivenom for local effects of green pit viper bites

Although systemic administration of antivenom can promptly reverse coagulopathy, efficacy on local effects of viper venom remains to be determined. Currently, there has been no proven specific treatment for snakebite patients with severe local effects. This study is a randomized, double-blind, placebo-controlled trial. Patients bitten by green pit vipers (Trimeresurus albolabris or T. macrops) with marked limb swelling, but no severe coagulopathy requiring antivenom, were randomized to receive either equine F(ab')2 antivenom, or placebo. Twenty-eight cases were included, 14 in each group, and they had their limb circumferences measured on days 1, 2, 4 and 6 after interventions. The percentage reduction in limb circumference was significantly better in the antivenom group compared with the placebo group (ANOVA, P = 0.03), especially in the first 24 h (1.14 vs. 3.62%, in placebo and antivenom group, respectively, P = 0.014). The reduction in pain score was similar. The plasma venom levels were not different at presentation but lower in the antivenom group 24h after intervention (P = 0.033). These data suggest that intravenous antivenom could accelerate local oedema resolution in humans. However, the degree is not clinically significant, and, therefore, general use is not recommended.

Phylogenesis of constitutively formed nitric oxide in non-mammals

It is widely recognized that nitric oxide (NO) in mammalian tissues is produced from L-arginine via catalysis by NO synthase (NOS) isoforms such as neuronal NOS (nNOS) and endothelial NOS (eNOS) that are constitutively expressed mainly in the central and peripheral nervous system and vascular endothelial cells, respectively. This review concentrates only on these constitutive NOS (cNOS) isoforms while excluding information about iNOS, which is induced mainly in macrophages upon stimulation by cytokines and polysaccharides. The NO signaling pathway plays a crucial role in the functional regulation of mammalian tissues and organs. Evidence has also been accumulated for the role of NO in invertebrates and non-mammalian vertebrates. Expression of nNOS in the brain and peripheral nervous system is widely determined by staining with NADPH (reduced nicotinamide adenine dinucleotide phosphate) diaphorase or NOS immunoreactivity, and functional roles of NO formed by nNOS are evidenced in the early phylogenetic stages (invertebrates and fishes). On the other hand, the endothelium mainly produces vasodilating prostanoids rather than NO or does not liberate endothelium-derived relaxing factor (EDRF) (fishes), and the ability of endothelial cells to liberate NO is observed later in phylogenetic stages (amphibians). This review article summarizes various types of interesting information obtained from lower organisms (invertebrates, fishes, amphibians, reptiles, and birds) about the properties and distribution of nNOS and eNOS and also the roles of NO produced by the cNOS as an important intercellular signaling molecule.