PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Scorpion Venoms”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources
PubMed2005

Purification and properties of hyaluronidase from Palamneus gravimanus (Indian black scorpion) venom.

Scorpion venoms are a rich source of enzymes. Some of the enzymes such as phospholipase A2, proteolytic enzymes and phosphodiesterase are well characterized. However, hyaluronidase has not been studied extensively. In this paper we describe the purification and characterization of hyaluronidase (Hyaluronate lyase, E.C.3.2.1.35) from the Palamneus gravimanus scorpion venom by a combination of gel filtration on Sephadex G-75 and ion-exchange chromatography on DEAE-cellulose. The optimal pH and temperature for its maximum activity of the isolated enzyme were 4.5 and 37 degrees C, respectively, and its K(m) was 47.61 microg/ml at 37 degrees C and its specific activity was 6411.7 +/- 117TRU/min per mg against 250 +/- 4.0 TRU/min per mg for the whole desiccated venom suggesting 25-fold purification. The molecular weight of the isolated enzyme was 52 +/- 1 kDa as estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and gel filtration chromatography on Sephadex G-75. The enzyme was stable for 30 days in the presence of NaCl; no loss of activity was observed up to 37 degrees degrees C and showed a sharp decrease in its activity at 40 degrees C. Heparin inhibited the enzyme activity.

Animals↗
PubMed2000

Neurotoxic effects of three fractions isolated from Tityus serrulatus scorpion venom.

Scorpion venoms contain low molecular weight basic polypeptides, neurotoxins, that are the principal toxic agents. These toxins act on ion channels, promoting a derangement that may result in an abnormal release of neurotransmitters. In the present study we investigated some of the effects of the F, H and J fractions isolated from Tityus serrulatus scorpion venom on the central nervous system of rodents. The venom was partially purified by gel filtration chromatography. The neurotoxic effect of these fractions was studied on convulsive activity after intravenous injection, and on electrographic activity and neuronal integrity of rat hippocampus when injected directly into this brain area. The results showed that intravenous injection of the F and H fractions induced convulsions, and intrahippocampal injection caused electrographic seizures in rats and neuronal damage in specific hippocampal areas. Fraction J injected intravenously reduced the general activity of mice in the open field but induced no changes when injected into the brain. These results suggest that scorpion toxins are able to act directly on the central nervous system promoting behavioural, electrographic and histological modifications.

Animals↗
PubMed2000

Effect of ligation of spleen vessels on left ventricular function and coronary blood flow in dogs injected with scorpion venom.

Scorpion sting may cause myocardial dysfunction in human victims, probably by increased O2 demand and decreased O2 supply. In dog, scorpion venom (SV) causes no myocardial dysfunction. Myocardium is probably protected by "autotransfusion" of blood from the spleen to the circulation, increasing coronary blood flow (CBF) and O2 delivery. We hypothesized that ligation of spleen vessels prior to injection of SV in dogs would prevent the autotransfusion of blood, thereby causing myocardial ischemia due to decreased CBF, simulating the hemodynamic pattern of human envenomation. We studied cardiac output (CO), CBF, left ventricular (LV) O2 delivery and contractility in 11 dogs injected with 0.07 mg/kg of SV (Leiurus quinquestriatus). Ligation of spleen vessels was performed on 6 of the 11 dogs prior to SV injection. 15 min after SV injection CO had increased by 186% in control dogs, while ligation of spleen vessels completely prevented CO elevation (p<0.001). In both groups, however, LV dp/dt increased by 400% and dp/dt/p by 170% (p<0.001). CBF increased by 350% and 550% in the spleen and control groups (p<0.001) respectively. This was associated with elevation of diastolic blood pressure and a decrease in coronary vascular resistance. LV O2 delivery increased (p<0.05) in both groups. At 60 minutes there was a decrease in CO, stroke work, and LV end systolic pressure in both groups, while LV contractility remained above baseline. Scorpion venom injection in dogs causes an initial increase in CO by auto-transfusion of blood from the spleen. Prevention of the autotransfusion does not preclude increases in CBF, O2 delivery and LV contractility.

Animals↗
PubMed2004

Quantitative variability in the biodistribution and in toxinokinetic studies of the three main alpha toxins from the Androctonus australis hector scorpion venom.

Scorpion stings represent a medical problem in numerous countries. The scorpion Androctonus australis hector produces three alpha toxins (Aah I to III), which are responsible for most of the lethality in mammals. These toxins act on sodium channel and do not cross-react immunologically. We used RIA and ELISA to measure the concentrations of these three toxins in plasma, urine and different organs after i.v. and s.c. injections of water extracts of venoms in rabbits or mice. In both animals, the toxins rapidly appeared in plasma after s.c. injection as it was previously described for the whole venom. However, the toxins disappeared from the blood more quickly than did other main components of the venom. Thus, serotherapy must be initiated immediately to prevent the toxin from reaching its target. We also detected the toxins in urine, kidneys, heart and lungs, but not in the brain. However, the concentration of Aah II was always lower than that of Aah I. Analysis of five samples of venom collected in different areas of southern Tunisia showed that a large polymorphism exists for the three toxins. This is yet another difficulty for serotherapy as there is no cross-antigenicity between them.

Animals↗
PubMed1996

Immunoreactivity and pharmacokinetics of horse anti-scorpion venom F(ab')2-scorpion venom interactions.

The immunoreactivity and pharmacokinetics of a new horse F(ab')2 scorpion antivenom and its effect on Buthus occitanus mardochei venom plasma disposition in the rabbit were studied. The scorpion venom-specific F(ab')2 affinity constant determined by immunoradiometric assay was 1.6 +/- 0.6 10(8) M-1. One group received a F(ab')2 bolus dose of 9.57 mg.kg-1 i.v. bolus or i.m.. The plasma F(ab')2 concentration followed a biexponential decline after i.v. administration with distribution and elimination half-lives of 2.54 +/- 0.36 and 49.52 +/- 3.07 hr, respectively. The total volume of distribution (Vdss or Vd beta) was between 230 and 255 ml.kg-1. Total body clearance was 3.56 +/- 0.34 ml.kg-1.hr-1. After intramuscular administration, Tmax was 48 hr and the absolute bioavailability was 36%. Two other groups of rabbits received i.v.60 micrograms.kg-1 B. occitanus mardochei venom either alone (control group) or followed by 3 mg.kg-1 scorpion venom-specific F(ab')2 administered by intravenous infusion 1.75 hr later. In the rabbits treated with horse F(ab')2 antivenom the venom concentration profile was initially identical to that observed in the control group which received venom alone before F(ab')2 administration. Subsequent infusion of antivenom induced a 1.5-fold elevation of the plasma venom concentration with a Tmax 0.5 hr after F(ab')2 administration. The AUC was 10-fold higher in the F(ab')2-treated group than in the control group in the post-F(ab')2 infusion period. Twelve hours after F(ab')2 administration the venom disposition declined with a terminal half-life equal to that of F(ab')2 (49.49 +/- 7.53 hr). These data show the ability of F(ab')2 to alter venom pharmacokinetics and demonstrate that the scorpion toxins adopt the F(ab')2 elimination properties.

Animals↗
PubMed2002

Neurotoxic effects of fractions isolated from Tityus bahiensis scorpion venom (Perty, 1834).

Tityus serrulatus and Tityus bahiensis are considered to be the most venomous scorpions in Brazil and are responsible for most of the accidents that occur in our country. The main toxic agents in scorpion venoms are small basic polypeptides that act as neurotoxins. They cause a derangement of ion channels that result in abnormal release of neurotransmitters. In the present study we fractionated the venom of Tityus bahiensis and studied the effects of fractions P2, P3, P4, P5, P6 and P7, on the mammalian central nervous system. Intravenous injection of P5, P6 and P7 in rats induced spontaneous convulsion, intrahippocampal injection caused behavioural seizures, and P5 and P6 induced electrographic seizures. P5 caused neuronal damage in the CA1 area and P6 in the CA1, CA3 areas and hilus of the dentate gyrus (DG) of the hippocampus. Injection of P3 in the hippocampus did not induce convulsions or lesions. However, when injected intravenously in mice, this fraction reduced behavioural activity in an open field test. Unilateral injection of P4 in the hippocampus caused neuronal damage in the contralateral CA3, but not in the ipsilateral hippocampus. These results suggest that scorpion toxins present in the venom are able to act directly on the central nervous system promoting behavioural and histopathological effects.

Animals↗
PubMed2005

Direct vs. mediated effects of scorpion venom: an experimental study of the effects of a second challenge with scorpion venom.

OBJECTIVE: To assess the respective roles of venom and of catecholamines following scorpion envenomation and to verify whether a second challenge with scorpion venom induces the same consequences than a first one. DESIGN AND SETTING: Controlled animal study in a university research laboratory. SUBJECTS: Anesthetized and ventilated dogs. INTERVENTIONS: Fifteen dogs received intravenously a sublethal dose of scorpion venom (0.05 mg/kg). In the reenvenomated group (n=5) a second venom challenge with one-half sublethal venom dose was performed 30 min after the first one. The control group (n=10) received saline. Five additional animals served as sham. MEASUREMENTS AND RESULTS: Plasma toxin and catecholamine levels and a set of usual hemodynamic measurements were repeatedly measured in the first hour following envenomation. In the reenvenomated group another set of measurements was performed 5 min after the second challenge. Changes in toxin, catecholamines, and the main hemodynamic parameters were compared between the study groups. Initial peak toxin levels were similar in the two groups. They induced a striking increase in circulating catecholamines, a fall in heart rate, and an increase in mean arterial and pulmonary artery occluded pressures and in systemic vascular resistance. In the reenvenomated group the second challenge with scorpion venom achieved a toxin blood level similar to the first peak. However, it was not associated with a significant effect either on catecholamines release or on hemodynamics. Subsequent trends in hemodynamic changes were similar to those observed in the control group. CONCLUSIONS: These data emphasize the limited role of direct effects of scorpion venom on the cardiovascular system and the key role of catecholamines.

Animals↗
PubMedDate not supplied

Preparation of a potent anti-scorpion-venom-serum against the venom of red scorpion (Buthus tamalus).

A number of children and adults, especially pregnant women succumb to the sting by red Scorpion (Buthus tamalus) in Konkan region--particularly on the coastal line. No specific antiserum or any other antidote is available to treat a victim of scorpion bite and hence the need to prepare a potent antiserum. Red Scorpion (B. tamalus) venom is a mixture of a number of protein moieties and neurotoxins of low molecular weight. Therefore, the venom is poor in antigenic composition and it is difficult to get antibodies specific to neutralise lethal factor/factors. Using Bentonite as an adjuvant and extending the period of immunization a potent antiserum has been prepared capable of neutralising the lethal factor/factors. In vivo testing carried out in albino mice, guinea pigs, dogs and langurs confirms this finding and shows that the antiserum is quite effective in neutralising the scorpion venom to save the life of envenomated animals.

Adult↗
PubMed1989

Stimulation of dopamine release in the rat neostriatum in vivo by activation of the voltage-sensitive sodium channel by scorpion venom neurotoxin.

Scorpion venom neurotoxins open sodium channels and thus may enhance neurotransmitter release by increasing membrane permeability to sodium. This study carried out in vivo examined the effects of the scorpion Androctonus australis neurotoxin (ScAaTx) on the levels of dopamine (DA) in push-pull perfusates of the striatum of chloral hydrate-anaesthetised rats. ScAaTx (2.5, 5.0 and 10.0 ng/microliters) stimulated DA release in a dose-dependent manner. The release of DA induced by ScAaTx (10 ng/microliters) was completely blocked when the brain site was perfused with Ca2+-free CSF containing 2 mM EGTA or in the presence of TTX (10(-5) M). These results indicate that the potent stimulatory effects of ScAaTx on neostriatal DA release in vivo are mediated via voltage-sensitive sodium channels.

Animals↗
PubMed2005

Characterization of a novel cDNA encoding a short venom peptide derived from venom gland of scorpion Buthus martensii Karsch: trans-splicing may play an important role in the diversification of scorpion venom peptides.

A novel cDNA clone (named BmKT-u) which is a hybrid molecule of the 5'-terminal region of BmKT' cDNA and the 3'-terminal region of an undocumented cDNA (named BmKu), was isolated from a cDNA library made from the venom gland of scorpion Buthus martensii Karsch. BmKT-u codes for a 30 amino acid residue precursor peptide composed of a 20-residue signal sequence, and a putative 10-residue novel mature peptide. Northern blot hybridization showed BmKT-u cDNA is generated from a transcript. RT-PCR experiments excluded the possibility that BmKT-u cDNA is an artifact generated during reverse transcription. Genomic amplifications performed with three pairs of BmKT-u gene-specific primers showed the BmKT-u gene does not exist in the genome of the scorpion as a single transcriptional unit. Genomic cloning for BmKT' showed that the BmKT' gene contains an intron of 509 bp inserted into the region encoding the C-terminal region of the signal peptide. A sequence alignment comparison of the cDNA of BmKT-u with genomic BmKT' revealed that the junction site of the hybrid molecule is located at the 5'-splicing site of the intron. The data suggest that the BmKT-u transcript is a naturally occurring mature mRNA that is generated by trans-splicing. Trans-splicing may contribute to the diversity of venom peptides from venomous animals.

Amino Acid Sequence↗
PubMed1998

Effects of antivenom serotherapy on hemodynamic pathophysiology in dogs injected with L. quinquestriatus scorpion venom.

In dogs, scorpion venom causes an immediate increase in cardiac output that declines below baseline values within one hour. We tested the hypotheses that antivenom given before venom injection may prevent changes in cardiac output, while antivenom given after the inotropic stage of envenomation cannot reverse cardiac output decline. Twenty-five anesthetized, mechanically ventilated dogs were given 0.1 mg/kg i.v. venom of the scorpion Leiurus quinquestriatus. The dogs were randomized into 4 groups: 5 dogs were given venom alone (control group) and 6 dogs were given 6 ml of antivenom one minute before venom injection while 8 and 6 dogs were given 6 ml of antivenom 20 and 60 min after venom injection, respectively. Parameters reflecting respiratory and circulatory functions were measured for 180 min after venom injection. Scorpion venom caused a gradual decrease in heart rate, an initial elevation of systemic and pulmonary blood pressure and cardiac output followed by a decline in these parameters. PO2, pH and HCO3- gradually decreased, while PCO2 gradually increased from baseline. Antivenom given before venom injection prevented all the effects induced by the venom. Antivenom given at 20 and 60 min after venom injection had no effect on cardiac output and HCO3- decline, but caused an increase in heart rate, PO2 and pH and a decrease in PCO2. We assume that antivenom clears free toxins from the circulation, and since cardiac output and HCO3- did not improve after this clearance, we conclude that following intravenous venom injection, heart and circulation are rapidly affected by the toxins or by other substances released by the venom which do not respond to antivenom. Improvements in respiration and heart rate with antivenom given after venom injection may be secondary to reversion of cholinergic effects of the venom. Improvement in respiration may be also explained by reversion of the toxic effects on Ca2+ activated K+ channels of bronchial smooth muscle. All these effects may be secondary to clearance of toxins by the antivenom.

Animals↗
PubMed1999

Effects of adrenergic-receptor blockade and ligation of spleen vessels on the hemodynamics of dogs injected with scorpion venom.

OBJECTIVE: In dogs, scorpion venom evokes a rapid increase in cardiac output (CO) that decreases below baseline level in 1 hr. The changes in CO have recently been shown to be related to the effect of the venom on venous return. In the present study, we tested the hypothesis that changes in determinants of venous return are secondary to sympathoadrenal stimulation evoked by the venom, which causes splenic contracture in the first stage of envenomation leading to increased mean circulatory pressure (MCP) and CO. Persistence of adrenergic response is the main factor leading to the second stage of envenomation, characterized by an increase in resistance to venous return (Rv) and a decrease in CO. DESIGN: Repeated measures, prospective study in dogs. SETTING: University-affiliated research laboratory. SUBJECTS: Mixed-breed dogs injected with scorpion venom. INTERVENTIONS: The effects of alpha- and beta-adrenergic-receptor blockade (blockade group, n = 9 dogs) and effects of ligation of spleen vessels (spleen ligation group, n = 11 dogs) following intravenous injection of scorpion venom from Leiurus quinquestriatus (0.05 mg/kg) were tested on the determinants of venous return and compared with the effects of scorpion venom alone (control group, n = 6 dogs). MEASUREMENTS AND MAIN RESULTS: Scorpion venom in the control group caused a marked increase in CO from 2.9+/-0.2 SD L/min to 6.5+/-2.2 L/min (p<.001) and MCP from 8.7+/-2.7 torr (1.2+/-0.35 kPa) to 21.6+/-1.4 torr (2.9+/-0.19 kPa) (p<.001) within 5 mins after venom injection. Cardiac output and MCP markedly decreased at 60 mins to 1.8+/-0.3 L/min (p<.001) and 7.3+/-3.8 torr (1.0+/-0.5 kPa) (p<.05), respectively. Rv did not change at 5 mins but increased from 196+/-50 dyne x sec/cm5 to 335+/-102 dyne x sec/cm5 (p<.01) at 60 mins. Adrenergic-receptor blockade attenuated the increase of CO and MCP at 5 mins, from 2.1+/-0.5 L/min to 2.7+/-1 L/min (p<.001) and from 5.6+/-2.0 torr (0.8+/-0.27 kPa) to 7.5+/-2.3 torr (1.0+/-0.31 kPa) (p<.05), respectively. By 60 mins, both CO and MCP returned to baseline, while Rv was not affected and was maintained at 204+/-158 dyne x sec/cm5. Ligation of spleen vessels prevented a CO increase at 5 mins and it was maintained at baseline value (2.5+/-0.6 L/min). However, MCP increased from 7.9+/-0.5 torr to 12+/-1.3 torr (p<.05). At 60 mins, CO decreased to 1.6+/-0.7 L/min (p<.01) while MCP returned to baseline. The changes in MCP were accompanied by significant increases of Rv from 152+/-24 dyne x sec/cm5 to 383+/-93 dyne x sec/cm5 (p<.001) at 5 mins, and 510+/-175 dyne x sec/cm5 (p<.01) at 60 mins. CONCLUSIONS: The changes in CO and MCP following scorpion venom injection in dogs are in part related to sympathetic stimulation. Adrenergic-receptor blockade attenuated the initial inotropic effect of the venom and completely prevented a late decrease in CO and MCP. The increase in Rv is the most important factor for late decrease in CO, and results from persistent adrenergic-receptor stimulation. In addition, an Rv increase apparently expresses vasoconstriction and redistribution of blood flow. The initial increase in CO and MCP is explained mainly by adrenergic-receptor effects on the spleen leading to augmented circulatory blood volume.

Analysis of Variance↗
PubMed1996

Body distribution of Tityus serrulatus scorpion venom in mice and effects of scorpion antivenom.

In the present study we report the distribution of Tityus serrulatus scorpion venom in serum and various tissues of CFI mice and the efficacy of antivenom in reducing venom concentration. The animals were injected s.c. with 10 micrograms of scorpion venom, divided into groups of four animals and killed at different times from 15 min to 24 hr. Blood samples and samples of different tissues (heart, lung, liver, kidney, spleen, brain and injection site) were collected. Maximum venom levels occurred at 15 min in the kidney and liver and at 30 min in serum, lung, heart and spleen. After 2 hr the venom decreased rapidly in serum and in all other organs until venom levels were no longer detectable after 8 hr. No venom was detected in the central nervous system. In another experiment, 10 microliters of scorpion antivenom was injected i.v. together with the venom, and a rapid reduction of venom concentration was observed in the blood and tissues. In the third experiment, anti-scorpion venom was injected i.v. 1 hr after venom administration, and partial reduction of venom concentration was detected in tissues (lung and kidney). These studies contribute to the elaboration of more objective treatment that may result in a more economic, efficient and controlled use of scorpion antivenom in stings involving humans.

Animals↗
PubMed1981

Further evidence for the involvement of Na+ channels in the release of adrenal catecholamine: the effect of scorpion venom and grayanotoxin I.

1 The effects of venom from the scorpion, Leiurus quinquestriatus, and grayanotoxin I on catecholamine secretion were studied in the perfused adrenal glands of guinea-pig. 2 Scorpion venom (0.1 to 10 micrograms/ml) caused a dose-dependent increase in catecholamine output. The response to the venom was partially inhibited by atropine (0.5 mM) plus hexamethonium (1mM). The dose-response curve was shifted to the right in the presence of these blocking agents. 3 Grayanotoxin I (0.1 to 0.5 mM) caused a dose-dependent increase in catecholamine output which was significantly reduced by atropine (0.5 mM) plus hexamethonium (1 mM). However, when grayanotoxin I (0.1 mM) was applied together with scorpion venom (0.1 micrograms/ml, a concentration which alone, was almost ineffective) the maximum catecholamine output was reached even in the presence of atropine plus hexamethonium. 4 Tetrodotoxin (0.1 or 0.2 microM) reversibly inhibited the secretory response induced by scorpion venom (10 micrograms/ml) and grayanotoxin I (0.1 mM) plus scorpion venom (0.1 micrograms/ml). 5 Scorpion venom and grayanotoxin I plus scorpion venus did not cause catecholamine secretion in the absence of extracellular Na+ or Ca2+ ions. However, the secretory response was restored by reintroduction of Na+ or Ca2+ ions. 6 It is suggested that both scorpion venom and grayanotoxin I activate Na+ channels on the chromaffin cell and result in catecholamine secretion.

Adrenal Glands↗
PubMed2005

Activation of the complement system and leukocyte recruitment by Tityus serrulatus scorpion venom.

The scorpion Tityus serrulatus is considered one of the most dangerous species in Brazil. Its venom evokes an inflammatory response, although the exact mechanism of this effect is still unknown. The aim of the present study was to investigate the effect of Tityus serrulatus venom (TsV) on the complement system (CS) and on leukocyte recruitment. Complement consumption by TsV was evaluated using in vitro hemolytic assays, immunoelectrophoresis and two-dimensional immunoelectrophoresis of complement components (factor B and C3). In order to evaluate neutrophil migration induced in normal human serum (NHS) in the presence of TsV, in vitro chemotaxis assays were performed using the Boyden chamber model. In vitro TsV induced a concentration- and time-dependent reduction in hemolytic activity of the classical/lectin and alternative complement pathways, with samples of 43.0 microg and 43.4 microg, respectively, inhibiting 50% of the lytic activity. Alterations in C3 and factor B electrophoretic mobility after incubation of NHS with TsV, were identical to those obtained with zymosan (positive control). Incubation of NHS with TsV induced neutrophil chemotaxis similar to that observed with zymosan-activated serum. Our results show that TsV activates the CS, leading to factor B and C3 cleavage, to reduction of serum lytic activity and generation of complement chemotactic factors. Therefore, CS may play an important role in the inflammatory response observed upon scorpion envenomation.

Animals↗
PubMed2001

A naturally occurring non-coding fusion transcript derived from scorpion venom gland: implication for the regulation of scorpion toxin gene expression.

Scorpion venom glands synthesize and secrete a great number of low molecular mass toxic peptides for prey and defense. Many cDNAs and genomic genes encoding these toxins have been isolated and sequenced. However, their expression regulation mechanism is not yet known at present. During screening of a cDNA library prepared from venom glands of the scorpion Buthus martensii Karsch, we isolated a natural fusion cDNA composed of the 5'-untranslated region (UTR) and upstream coding sequence of a long-chain toxin transcript and the downstream coding sequence and 3'-UTR of a short-chain toxin transcript. The junction site is just the overlapping region of 11 nucleotides (GGCAAGGAAAT) between the two wild transcripts, and thus leads to the formation of an early stop codon, which will cause premature translation. Based on the above observations, combined with the genomic data, we proposed a characteristic regulation mechanism of scorpion toxin genes, in which trans-splicing and nonsense mediated mRNA decay are involved.

3' Untranslated Regions↗