Tityus Serrulatus Research Articles

Molecular and functional characterization of metalloserrulases, new metalloproteases from the Tityus serrulatus venom gland

Tityus serrulatus is a Brazilian scorpion species with great medical significance. While the effects of neurotoxins have been extensively studied, little is known about the proteases expressed in the venom gland of this arthropod. In this study, clones from a T. serrulatus (Ts) venom gland cDNA library were selected according to homology to proteases. The sequences were aligned in the database and classified by homology. Similarity and identity analyses of the sequences were carried out, and a phylogenetic tree was constructed with the sequences of other proteases. These cDNA sequences correspond to ten different metalloproteases, named metalloserrulases (TsMS). TsMS 1–9 belong to the metzincin family, which has three domains: signal peptide, propeptide, and metalloprotease domain; while TsMS 10 belongs to the gluzincin family. The proteolytic activity of the venom was inferred from the cleavage of fibrinogen, and the residues recognized by the proteases were determined by cleavage of a tripeptide library using a fluorescence resonance energy transfer assay. The Ts venom showed proteolytic activity on fibrinogen and preferential cleavage close to the basic residues K and R. Its activity could be inhibited by EDTA, indicating that the venom from this scorpion predominantly consists of metalloproteases.

Clinical consequences of Tityus bahiensis and Tityus serrulatus scorpion stings in the region of Campinas, southeastern Brazil

Scorpion stings account for most envenomations by venomous animals in Brazil. A retrospective study (1994–2011) of the clinical consequences of Tityus scorpion stings in 1327 patients treated at a university hospital in Campinas, southeastern Brazil, is reported. The clinical classification, based on outcome, was: dry sting (no envenoming), class I (only local manifestations), class II (systemic manifestations), class III (life-threatening manifestations, such as shock and/or cardiac failure requiring inotropic/vasopressor agents, and/or respiratory failure), and fatal. The median patient age was 27 years (interquartile interval = 15–42 years). Scorpions were brought for identification in 47.2% of cases (Tityus bahiensis 27.7%; Tityus serrulatus 19.5%). Sting severity was classified and each accounted for the following percentage of cases: dry stings – 3.4%, class I – 79.6%, class II – 15.1%, class III – 1.8% and fatal – 0.1%. Pain was the primary local manifestation (95.5%). Systemic manifestations such as vomiting, agitation, sweating, dyspnea, bradycardia, tachycardia, tachypnea, somnolence/lethargy, cutaneous paleness, hypothermia and hypotension were detected in class II or class III + fatal groups, but were significantly more frequent in the latter group. Class III and fatal cases occurred only in children <15 years old, with scorpions being identified in 13/25 cases (T. serrulatus, n = 12; T. bahiensis, n = 1). Laboratory blood abnormalities (hyperglycemia, hypokalemia, leukocytosis, elevations in serum total CK, CK-MB and troponin T, bicarbonate consumption and an increase in base deficit and blood lactate), electrocardiographic changes (ST segment) and echocardiographic alterations (ventricular ejected fraction <54%) were frequently detected in class III patients. Seventeen patients developed pulmonary edema, 16 had cardiac failure and seven had cardiogenic shock. These results indicate that most scorpion stings involved only local manifestations, mainly pain; the greatest severity was associated with stings by T. serrulatus and in children <15 years old.

Total Chemical Synthesis of Biologically Active Fluorescent Dye‐Labeled Ts1 Toxin

AbstractTs1 toxin is a protein found in the venom of the Brazilian scorpion Tityus serrulatus. Ts1 binds to the domain II voltage sensor in the voltage‐gated sodium channel Nav and modifies its voltage dependence. In the work reported here, we established an efficient total chemical synthesis of the Ts1 protein using modern chemical ligation methods and demonstrated that it was fully active in modifying the voltage dependence of the rat skeletal muscle voltage‐gated sodium channel rNav1.4 expressed in oocytes. Total synthesis combined with click chemistry was used to label the Ts1 protein molecule with the fluorescent dyes Alexa‐Fluor 488 and Bodipy. Dye‐labeled Ts1 proteins retained their optical properties and bound to and modified the voltage dependence of the sodium channel Nav. Because of the highly specific binding of Ts1 toxin to Nav, successful chemical synthesis and labeling of Ts1 toxin provides an important tool for biophysical studies, histochemical studies, and opto‐pharmacological studies of the Nav protein.

Total chemical synthesis of biologically active fluorescent dye-labeled Ts1 toxin.

Ts1 toxin is a protein found in the venom of the Brazilian scorpion Tityus serrulatus. Ts1 binds to the domain II voltage sensor in the voltage-gated sodium channel Nav and modifies its voltage dependence. In the work reported here, we established an efficient total chemical synthesis of the Ts1 protein using modern chemical ligation methods and demonstrated that it was fully active in modifying the voltage dependence of the rat skeletal muscle voltage-gated sodium channel rNav1.4 expressed in oocytes. Total synthesis combined with click chemistry was used to label the Ts1 protein molecule with the fluorescent dyes Alexa-Fluor 488 and Bodipy. Dye-labeled Ts1 proteins retained their optical properties and bound to and modified the voltage dependence of the sodium channel Nav. Because of the highly specific binding of Ts1 toxin to Nav, successful chemical synthesis and labeling of Ts1 toxin provides an important tool for biophysical studies, histochemical studies, and opto-pharmacological studies of the Nav protein.

Tityus serrulatus scorpion venom improves survival and lung inflammation in lethal sepsis induced by CLP in mice

Tityus serrulatus venom (Tsv) modifies the behavior of immune cells and induces the production of inflammatory and anti-inflammatory cytokines; such action may interfere with physiological or pathological states. Because sepsis is characterized as an inflammatory disorder, the aim of present study was to investigate the effect of a non-lethal dose of Tsv in mice submitted to a polymicrobial infection by cecal ligation and puncture (CLP) model. The parameters evaluated were survival index, cellularity on lymphoid organs, peritoneal cavity and brochoalveolar space, production of IL-10, IL-12, IL-6, TNF-α, IFN-γ and MCP-1, pulmonary inflammation and oxidative burst. The results demonstrated that in sharp contrast to CLP group in which sepsis was lethal in a 24 h period all mice pretreated with Tsv survived even 60 h after CLP. Lung inflammation, another hallmark of CLP group, was also dramatically down regulated in Tsv/CLP group. Despite pretreatment with Tsv did not reduce the inflammatory serum cytokines when compared to CLP group; there was an increase in IL-10. In conclusion, subcutaneous Tsv administration 6 h before CLP was able to control the harmful effects of sepsis (lethality and lung inflammation). We suggest that both systemic IL-10 and oxidative burst are involved in this effect.

Biochemical and physiological characterization of a new Na+-channel specific peptide from the venom of the Argentinean scorpion Tityus trivittatus

A new peptide with 61 amino acids cross-linked by 4 disulfide bridges, with molecular weight of 6938.12Da, and an amidated C-terminal amino acid residue was purified and characterized. The primary structure was obtained by direct Edman degradation and sequencing its gene. The peptide is lethal to mammals and was shown to be similar (95% identity) to toxin Ts1 (gamma toxin) from the Brazilian scorpion Tityus serrulatus; it was named Tt1g (from T. trivittatus toxin 1 gamma-like). Tt1g was assayed on several sub-types of Na+-channels showing displacement of the currents to more negative voltages, being the hNav1.3 the most affected channel. This toxin displays characteristics typical to the β-type sodium scorpion toxins. Lethality tests and physiological assays indicate that this peptide is probably the most important toxic component of this species of scorpion, known for causing human fatalities in the South American continent.

Ipomoea asarifolia neutralizes inflammation induced by Tityus serrulatus scorpion venom

Ethnopharmacological relevanceEnvenoming caused by scorpion sting is a serious public health problem. In Brazil, 13,038 accidents caused by venomous animals have been reported. Of this total, 53% of the cases and 14 deaths were caused by scorpions. Furthermore, Tityus serrulatus (Buthidae) is the most dangerous scorpion due to the high toxicity of its venom. The treatment is the common supportive therapy and the serum therapy, but some people do not have access to both therapies and seek healing through the use of medical plants. Aim of the studyThis study evaluated the ability of the crude extract and fractions from the leaves of Ipomoea asarifolia in neutralizing the main biological effects caused by Tityus serrulatus envenoming in mice. Materials and methodsBALB/c mice were pretreated (i.v.) with 100μλ of aqueous extracts and fractions dichloromethane, ethyl acetate, and n-butanol (CH2Cl2, EtOAc, and n-BuOH, respectively) of Ipomoea asarifolia, rutin or saline. Then, the animals received 100μλ (i.p.) of venom of Tityus serrulatus (0.8mg/kg). After six hours, the peritoneal lavage was performed with PBS and the number cells were determined using a Neubauer chamber. The supernatants were collected for determination of cytokines, such as IL-6, IL-12, and IL-1β. ResultsThe aqueous extract, fractions and rutin, at all doses, significantly reduced cell migration, which was endorsed by the reduction of the levels of certain cytokines. ConclusionThis is the first study that demonstrated the potential effect of Ipomoea asarifolia against inflammation caused by Tityus serrulatus venom, suggesting that these extracts and/or their bioactive molecules, especially the flavonoid rutin, have potential use in the therapy of this envenomation.

Electrophysiological Characterization of Ts6 and Ts7, K+ Channel Toxins Isolated through an Improved Tityus serrulatus Venom Purification Procedure

In Brazil, Tityus serrulatus (Ts) is the species responsible for most of the scorpion related accidents. Among the Ts toxins, the neurotoxins with action on potassium channels (α-KTx) present high interest, due to their effect in the envenoming process and the ion channel specificity they display. The α-KTx toxins family is the most relevant because its toxins can be used as therapeutic tools for specific target cells. The improved isolation method provided toxins with high resolution, obtaining pure Ts6 and Ts7 in two chromatographic steps. The effects of Ts6 and Ts7 toxins were evaluated in 14 different types of potassium channels using the voltage-clamp technique with two-microelectrodes. Ts6 toxin shows high affinity for Kv1.2, Kv1.3 and Shaker IR, blocking these channels in low concentrations. Moreover, Ts6 blocks the Kv1.3 channel in picomolar concentrations with an IC50 of 0.55 nM and therefore could be of valuable assistance to further designing immunosuppressive therapeutics. Ts7 toxin blocks multiple subtypes channels, showing low selectivity among the channels analyzed. This work also stands out in its attempt to elucidate the residues important for interacting with each channel and, in the near future, to model a desired drug.

Functional and structural study comparing the C-terminal amidated β-neurotoxin Ts1 with its isoform Ts1-G isolated from Tityus serrulatus venom

Mature Ts1, the main neurotoxin from Tityus serrulatus venom, has its C-terminal Cys amidated, while the isolated isoform of Ts1, named Ts1-G, keeps the non-amidated Gly residue at the C-terminal region, allowing the study of the comparative functional importance of amidation at the C-terminal between these two native toxins. Voltage dependent sodium current measurements showed that the affinity of Ts1-G for sodium channels is smaller than that of the mature Ts1, confirming the important role played by the C-terminal amidation in determining Ts1 activity.

Molecular, Immunological, and Biological Characterization of Tityus serrulatus Venom Hyaluronidase: New Insights into Its Role in Envenomation

BackgroundScorpionism is a public health problem in Brazil, and Tityus serrulatus (Ts) is primarily responsible for severe accidents. The main toxic components of Ts venom are low-molecular-weight neurotoxins; however, the venom also contains poorly characterized high-molecular-weight enzymes. Hyaluronidase is one such enzyme that has been poorly characterized.Methods and principal findingsWe examined clones from a cDNA library of the Ts venom gland and described two novel isoforms of hyaluronidase, TsHyal-1 and TsHyal-2. The isoforms are 83% identical, and alignment of their predicted amino acid sequences with other hyaluronidases showed conserved residues between evolutionarily distant organisms. We performed gel filtration followed by reversed-phase chromatography to purify native hyaluronidase from Ts venom. Purified native Ts hyaluronidase was used to produce anti-hyaluronidase serum in rabbits. As little as 0.94 µl of anti-hyaluronidase serum neutralized 1 LD50 (13.2 µg) of Ts venom hyaluronidase activity in vitro. In vivo neutralization assays showed that 121.6 µl of anti-hyaluronidase serum inhibited mouse death 100%, whereas 60.8 µl and 15.2 µl of serum delayed mouse death. Inhibition of death was also achieved by using the hyaluronidase pharmacological inhibitor aristolochic acid. Addition of native Ts hyaluronidase (0.418 µg) to pre-neutralized Ts venom (13.2 µg venom+0.94 µl anti-hyaluronidase serum) reversed mouse survival. We used the SPOT method to map TsHyal-1 and TsHyal-2 epitopes. More peptides were recognized by anti-hyaluronidase serum in TsHyal-1 than in TsHyal-2. Epitopes common to both isoforms included active site residues.ConclusionsHyaluronidase inhibition and immunoneutralization reduced the toxic effects of Ts venom. Our results have implications in scorpionism therapy and challenge the notion that only neurotoxins are important to the envenoming process.

TLR2, TLR4 and CD14 Recognize Venom-Associated Molecular Patterns from Tityus serrulatus to Induce Macrophage-Derived Inflammatory Mediators

Scorpion sting-induced human envenomation provokes an intense inflammatory reaction. However, the mechanisms behind the recognition of scorpion venom and the induction of mediator release in mammalian cells are unknown. We demonstrated that TLR2, TLR4 and CD14 receptors sense Tityus serrulatus venom (TsV) and its major component, toxin 1 (Ts1), to mediate cytokine and lipid mediator production. Additionally, we demonstrated that TsV induces TLR2- and TLR4/MyD88-dependent NF-κB activation and TLR4-dependent and TLR2/MyD88-independent c-Jun activation. Similar to TsV, Ts1 induces MyD88-dependent NF-κB phosphorylation via TLR2 and TLR4 receptors, while c-Jun activation is dependent on neither TLR2 nor TLR4/MyD88. Therefore, we propose the term venom-associated molecular pattern (VAMP) to refer to molecules that are introduced into the host by stings and are recognized by PRRs, resulting in inflammation.

Integrated pest management programme in hospital environment

Urban pests are known to infest health service facilities, especially in a warm, wet neotropical climate. In practice, pest control services for health service facilities are generally outsourced and in most cases are not properly monitored. To address this problem, an integrated pest management (IPM) programme was developed at a hospital in the municipality of Botucatu, state of Sao Paulo, Brazil, by the infection control committee. The method of control applied used spreadsheet pest reports to monitor the presence of vectors. These reports were forwarded to the committee and used to implement several actions of integrated pest control. In 2011, a total of 183 occurrences were recorded by the infection control committee, 5% lower than the number of incidents recorded in 2010, the first year of integrated pest control. In 2012, the total number of occurrences decreased to 159 events, demonstrating the IPM effects. Three years after the implementation of the programme, the predominant pests in the hospital were scorpions (30%), ants (19%) and spiders (16%), with Tityus serrulatus, Paratrechina longicornis and Loxosceles sp as the predominant species, respectively. The presence of scorpions in a hospital environment is not documented in the literature, although these animals are common in urban ecosystems. These results demonstrate that integrated pest control in hospitals is effective and should be conducted on a continuous basis. We suggest the use of this approach by all health services located in neotropical environments.

Tracking Voltage-Dependent Conformational Changes of the VSD in Nav with LRET

Voltage-gated sodium channels (Nav) are fundamental for the generation and the propagation of action potentials. Mammalian Nav alpha subunits are single macromolecules organized in four different domains (DI-DIV). Each is composed of 6 transmembrane segments (S1-S6) from which S1-S4 constitute the voltage sensing domain (VSD) and with S5 and S6 constituting the pore. While Nav function has been studied extensively, the exact structural mechanisms of gating are not fully understood. Recently, the crystal structure of the prokaryotic sodium channel, NavAb, has been solved, but NavAb is a homotetrameric protein in contract to the mammalian Navs. Thus many questions were not answered by the prokaryotic channel structures. To resolve the voltage dependent conformational changes of Nav, we tracked conformational changes of the VSD from each domain of the rat skeletal muscle sodium channel (Nav1.4) using Lanthanide-based Resonance Energy Transfer (LRET), a FRET technique that allows for precise measurement of intermolecular distances by taking advantage of the special properties of lanthanide as an energy donor. We prepared Nav1.4 constructs with a genetically encoded lanthanide binding tag (LBT), which holds a lanthanide (Tb3+) ion with high affinity, inserted at the top of the S4 segment in each domain. Also, we synthesized two toxins conjugated to dyes to function as acceptors: the pore-blocking small molecule tetrodotoxin conjugated with a HiLyte fluor488 (TTX-F), and the peptide β scorpion toxin Ts1, from the Brazilian scorpion Tityus serrulatus, conjugated with Alexa488 (Ts1-Alexa488). Having several donor positions (Tb3+ ions in LBT's) and two different acceptor positions (TTX-F and Ts1-Alexa488), we calculated multiple distances in voltage-clamped Xenopus laevis oocytes expressing our Nav1.4 constructs that remained functionally active. The results provide new insight to structure-function information in mammalian Nav channels. Support: 13POST14800031 (AHA), MOP-10053 (CIHR), GM68044-07, U54GM087519 and GM030376.

Antarease-like Zn-metalloproteases are ubiquitous in the venom of different scorpion genera

BackgroundThe venoms of several scorpion species have long been associated with pancreatitis in animal models and humans. Antarease, a Zn-metalloprotease from Tityus serrulatus, is able to penetrate intact pancreatic tissue and disrupts the normal vesicular traffic necessary for secretion, so it could play a relevant role in the onset of acute pancreatitis. MethodsThe cDNA libraries from five different scorpion species were screened for antarease homologs with specific primers. The amplified PCR products were cloned and sequenced. A structural model was constructed to assess the functionality of the putative metalloproteases. A phylogenetic analysis was performed to identify clustering patterns of these venom components. ResultsAntarease-like sequences were amplified from all the screened cDNA libraries. The complete sequence of the antarease from T. serrulatus was obtained. The structural model of the putative antarease from Tityus trivittatus shows that it may adopt a catalytically active conformation, sharing relevant structural elements with previously reported metalloproteases of the ADAM family. The phylogenetic analysis reveals that the reported sequences cluster in groups that correlate with the geographical localization of the respective species. ConclusionsAntareases are ubiquitous to a broad range of scorpion species, where they could be catalytically active enzymes. These molecules can be used to describe the evolution of scorpion venoms under different ecogeographic constrains. General significanceFor the first time the complete sequence of the antareases is reported. It is demonstrated that antareases are common in the venom of different scorpion species. They are now proposed as targets for antivenom therapies.

Brainstem Structures Are Primarily Affected in an Experimental Model of Severe Scorpion Envenomation

Severe scorpion envenoming (SSE) is more frequent in children and is characterized by systemic dysfunctions with a mortality rate of up to 9%. Recent evidence shows that the central nervous system (CNS) plays a key role in triggering the cascade of symptoms present in SSE. The age-dependent role of the CNS in SSE lethality may be summarized in 3 hypotheses: (1) the shown increased blood brain barrier permeability of infants to the toxins would especially and primarily compromise neurovegetative control areas, (2) the neurons within these areas have high affinity to the toxins, and (3) the neurovascular interaction is such that SSE metabolically compromises proper function of toxin-targeted areas. A pharmacological magnetic resonance imaging paradigm was used to evaluate localized hemodynamic changes in relative cerebral blood volume (rCBV) for 30 min after the injection of TsTX, the most lethal toxin from the venom of the Tityus serrulatus scorpion. The brainstem showed significant rCBV reduction 1 min after TsTX administration, whereas rostral brain areas had delayed increase in rCBV (confirmed by laser Doppler measurements of cortical cerebral blood flow). Moreover, metabolic activity by 14C-2-deoxyglucose autoradiography showed the highest relative increase at the brainstem. To test whether TsTX has high affinity to brainstem neurons, the lateral ventricle was injected with Alexa Fluor 568 TsTX. Although some neurons showed intense fluorescence, the labeling pattern suggests that specific neurons were targeted. Altogether, these results suggest that brainstem areas involved in neurovegetative control are most likely within the primary structures triggering the cascade of symptoms present in SSE.

Malnutrition alters the cardiovascular responses induced by central injection of tityustoxin in Fischer rats

Scorpion envenoming and malnutrition are considered two important public health problems in Brazil, involving mainly children. Both these conditions are more common among the economically stratified lower income portion of the population, thus suggesting that these factors should be analyzed concomitantly. It is known that cardiorespiratory manifestations, as cardiac arrhythmias, arterial hypertension and hypotension, pulmonary edema and circulatory failure are the main “causa mortis” of scorpion envenomation. Additionally, there are evidences in the literature that deficiencies in dietary intake endanger the CNS and modify the cardiovascular homeostasis. Then, the objective of this work is to evaluate the protein malnourished effect on cardiovascular responses induced by tityustoxin (TsTX, an α-type toxin extracted from the Tityus serrulatus scorpion venom). Fischer rats (n = 20) were injected i.c.v. with TsTX and divided in control and malnorished groups, which were, respectively, submitted to a control and a low-protein diet. Arterial pressure recordings were done until death of the animals. Although both groups presented an increased mean arterial pressure after TsTX injection, this increase was smaller and delayed in malnourished rats, when compared to control rats. In addition, heart rate increased only in rats from the control group. Finally, malnourished rats had an increase in survival time (9:9/13.5 vs. 15.5:10.5/18 min; p = 0.0009). In summary, our results suggest that the protein restriction attenuates the cardiovascular manifestations resulting from TsTX action on CNS.

Serrumab: A novel human single chain-fragment antibody with multiple scorpion toxin-neutralizing capacities

In Brazil, scorpion envenomation is an important public health problem. The yellow scorpion, Tityus serrulatus (Ts), is considered the most dangerous species in the country, being responsible for the most severe clinical cases of envenomation. Currently, the administration of serum produced in horses is recognized and used as a treatment for accidents with scorpions. However, horse herds’ maintenance is costly and the antibodies are heterologous, which can cause anaphylaxis and Serum Sickness. In the present work, a human monoclonal fragment antibody, Serrumab, has been analysed. Toxin neutralizing effects of Serrumab were evaluated using a two-electrode voltage-clamp technique. The results show that Serrumab presented a high neutralizing effect against Ts β-toxins (Ts1, 43.2% and Ts2, 68.8%) and none or low neutralizing effect against α-toxins (Ts3, 0% and Ts5, 10%). Additional experiments demonstrated that Serrumab was also able to neutralize the action of toxins from other scorpion genus (Css II, 45.96% and Lqh III, 100%/β- and α-toxins, respectively). This work indicated that Serrumab is able to neutralize many toxins in Ts venom, and could being considered as a neutralizing antibody for formulating a human anti-scorpion serum in Brazil. Additionally, this work demonstrated that Serrumab could neutralize different toxins from distinct scorpion genus. All these results reinforce the idea that Serrumab is a scFv antibody with multiple neutralizing capacities and a promising candidate for inclusion in scorpion anti-venoms against different genera.

Equipment based on high power UV and white light LEDs to collect and observe scorpions (Arachnida: Scorpiones) and other fluorescent organisms

We introduce a new, high quality, low cost and versatile LEDs-based handset device that emits high power UV and white light, which can be used interchangeably. It offers power control and has long battery life. Even though it is optimized to detect and collect scorpions under low light conditions, it can also be used with other groups of fluorescent organisms. The device achieved superior performance in field and laboratory trials when compared with a 12 LEDs low power UV flashlight, and a 46 W black fluorescent light lamp, to locate Tityus serrulatus Lutz & Mello, 1922.

Isolation, homology modeling and renal effects of a C-type natriuretic peptide from the venom of the Brazilian yellow scorpion (Tityus serrulatus)

Mammalian natriuretic peptides (NPs) have been extensively investigated for use as therapeutic agents in the treatment of cardiovascular diseases. Here, we describe the isolation, sequencing and tridimensional homology modeling of the first C-type natriuretic peptide isolated from scorpion venom. In addition, its effects on the renal function of rats and on the mRNA expression of natriuretic peptide receptors in the kidneys are delineated. Fractionation of Tityus serrulatus venom using chromatographic techniques yielded a peptide with a molecular mass of 2190.64 Da, which exhibited the pattern of disulfide bridges that is characteristic of a C-type NP (TsNP, T. serrulatus Natriuretic Peptide). In the isolated perfused rat kidney assay, treatment with two concentrations of TsNP (0.03 and 0.1 μg/mL) increased the perfusion pressure, glomerular filtration rate and urinary flow. After 60 min of treatment at both concentrations, the percentages of sodium, potassium and chloride transport were decreased, and the urinary cGMP concentration was elevated. Natriuretic peptide receptor-A (NPR-A) mRNA expression was down regulated in the kidneys treated with both concentrations of TsNP, whereas NPR-B, NPR-C and CG-C mRNAs were up regulated at the 0.1 μg/mL concentration. In conclusion, this work describes the isolation and modeling of the first natriuretic peptide isolated from scorpion venom. In addition, examinations of the renal actions of TsNP indicate that its effects may be related to the activation of NPR-B, NPR-C and GC-C.

Another record of significant regional variation in toxicity of Tityus serrulatus venom in Brazil: A step towards understanding the possible role of sodium channel modulators

The scorpion Tityus serrulatus is responsible for the most severe accidents that have been registered in Brazil, mainly in the state of Minas Gerais (MG), being the lung edema (LE), the main cause of death in these accidents. Although an increased in the number of accidents caused to this species in Federal District (Distrito Federal – DF), it seems that this particular species is not responsible for severe scorpionism cases in this region. Given this observation, we tested the toxicity in mice and compared the ability of T. serrulatus venom from DF (Ts-DF) and Minas Gerais State (Ts-MG) to induce LE in rats. The LD50 of Ts-DF venom was 51.6 μg/mouse, almost twice (1.98) higher than that obtained for Ts-MG venom. The ability of venom (0.5 mg/kg) to induce LE in rats was determined by the wet weight differences between treated and untreated lungs, by pulmonary morphological analyses and by pulmonary vascular permeability (PVP) using the Evans blue protocol. Significant differences in the wet weight of lungs and changes in PVP were found in Ts-MG venom treated rats when compared to rats treated with Ts-DF venom or untreated rats (p < 0.001), but no differences occurred when comparing rats treated with Ts-DF venom and untreated rats (p < 0.05). These results were confirmed by evaluation of pulmonary morphology. Comparison of chromatographic profiles obtained from these venoms (Ts-DF and Ts-MG) using the fractal dimension (D) analysis and the molecular mass fingerprint of the chromatographic fractions showed a higher number of components between 35 and 40% acetonitrile in Ts-MG venom than in Ts-DF venom, indicating a higher diversity of sodium channel modulators in that venom.