RESUMEN
Background: Almost all Tityus characterized toxins are from subgenera Atreus and Tityus, there are only a few data about toxins produced by Archaeotityus, an ancient group in Tityus genus. Methods: Tityus (Archaeotityus) mattogrossensis crude venom was fractionated by high performance liquid chromatography, the major fractions were tested in a frog sciatic nerve single sucrose-gap technique. Two fractions (Tm1 and Tm2) were isolated, partially sequenced by MALDI-TOF/MS and electrophysiological assayed on HEK293 Nav 1.3, HEK293 Nav 1.6, DUM and DRG cells. Results: The sucrose-gap technique showed neurotoxicity in four fractions. One fraction caused a delay of action potential repolarization and other three caused a reduction in amplitude. An electrophysiological assay showed that Tm1 is active on HEK293 Nav 1.3, HEK293 Nav 1.6, DUM and DRG cells, and Tm2 on HEK293 Nav 1.3 and DRG cells, but not in HEK293 Nav 1.6. In addition, Tm1 and Tm2 did promote a shift to more negative potentials strongly suggesting that both are α-NaScTx. Conclusion: Although Tityus (Archaeotityus) mattogrossensis is considered an ancient group in Tityus genus, the primary structure of Tm1 and Tm2 is more related to Tityus subgenus. The patch clamp electrophysiological tests suggest that Tm1 and Tm2 are NaScTx, and also promoted no shift to more negative potentials, strongly suggesting that both are α-NaScTx. This paper aimed to explore and characterize for the first time toxins from the ancient scorpion Tityus (Archaeotityus) mattogrossensis.(AU)
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Animales , Venenos de Escorpión/aislamiento & purificación , Venenos de Escorpión/clasificación , Cromatografía Liquida/métodos , Sacarosa/análisis , Fenómenos Electrofisiológicos/fisiologíaRESUMEN
Introduction: A few scorpions are dangerous to humans. Their medical relevance was the initial driving force for venom research. By classical biochemistry and molecular cloning, several venom peptides and their coding transcripts were characterized, mainly those related to toxins. The discovery of other components with novel activities and potential applications has revitalized the interest in the field in the last decade and a half. Nontoxic scorpion species have also attracted major interest.Areas covered: Advances in the identification of scorpion venom components via high-throughput venomics (genomics, transcriptomics and proteomics) up to 2019 are summarized. A classification system for venom-related transcripts and proteins, together with an intuitive systematic nomenclature for RNAseq-generated transcripts are proposed. Venom components classified as Na+, K+, Ca2+, Cl- and TRP channel toxins, enzymes, protease inhibitors, host defense peptides and other peptidic molecules are briefly reviewed, giving a comprehensive picture of the venom.Expert opinion: Modern high-throughput technologies applied to scorpion venom studies have resulted in a dramatic increase in both, the number and diversity of available sequences, leading to a deeper understanding of the composition of scorpion venoms. Still, many newly-discovered venom constituents remain to be characterized, to complete the puzzle of scorpion venoms.
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Venenos de Escorpión/química , Animales , Inhibidores Enzimáticos/química , Inhibidores Enzimáticos/clasificación , Inhibidores Enzimáticos/toxicidad , Humanos , Moduladores del Transporte de Membrana/química , Moduladores del Transporte de Membrana/clasificación , Moduladores del Transporte de Membrana/toxicidad , Venenos de Escorpión/clasificación , Venenos de Escorpión/toxicidadRESUMEN
The number and types of venom components that affect ion-channel function are reviewed. These are the most important venom components responsible for human intoxication, deserving medical attention, often requiring the use of specific anti-venoms. Special emphasis is given to peptides that recognize Na(+)-, K(+)- and Ca(++)-channels of excitable cells. Knowledge generated by direct isolation of peptides from venom and components deduced from cloned genes, whose amino acid sequences are deposited into databanks are nowadays in the order of 1.5 thousands, out of an estimate biodiversity closed to 300,000. Here the diversity of components is briefly reviewed with mention to specific references. Structural characteristic are discussed with examples taken from published work. The principal mechanisms of action of the three different types of peptides are also reviewed. Na(+)-channel specific venom components usually are modifier of the open and closing kinetic mechanisms of the ion-channels, whereas peptides affecting K(+)-channels are normally pore blocking agents. The Ryanodine Ca(++)-channel specific peptides are known for causing sub-conducting stages of the channels conductance and some were shown to be able to internalize penetrating inside the muscle cells.
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Canales Iónicos/química , Venenos de Escorpión/química , Secuencia de Aminoácidos , Modelos Moleculares , Venenos de Escorpión/clasificación , Relación Estructura-ActividadRESUMEN
BACKGROUND: The scorpion Tityus stigmurus is widely distributed in Northeastern Brazil and known to cause severe human envenoming, inducing pain, hyposthesia, edema, erythema, paresthesia, headaches and vomiting. The present study uses a transcriptomic approach to characterize the gene expression profile from the non-stimulated venom gland of Tityus stigmurus scorpion. RESULTS: A cDNA library was constructed and 540 clones were sequenced and grouped into 153 clusters, with one or more ESTs (expressed sequence tags). Forty-one percent of ESTs belong to recognized toxin-coding sequences, with transcripts encoding antimicrobial toxins (AMP-like) being the most abundant, followed by alfa KTx- like, beta KTx-like, beta NaTx-like and alfa NaTx-like. Our analysis indicated that 34% of the transcripts encode "other possible venom molecules", which correspond to anionic peptides, hypothetical secreted peptides, metalloproteinases, cystein-rich peptides and lectins. Fifteen percent of ESTs are similar to cellular transcripts. Sequences without good matches corresponded to 11%. CONCLUSIONS: This investigation provides the first global view of gene expression of the venom gland from Tityus stigmurus under resting conditions. This approach enables characterization of a large number of venom gland component molecules, which belong either to known or non yet described types of venom peptides and proteins from the Buthidae family.
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Perfilación de la Expresión Génica , Venenos de Escorpión/genética , Escorpiones/metabolismo , Secuencia de Aminoácidos , Animales , Péptidos Catiónicos Antimicrobianos/química , Péptidos Catiónicos Antimicrobianos/metabolismo , Etiquetas de Secuencia Expresada , Biblioteca de Genes , Proteínas de Unión a Factor de Crecimiento Similar a la Insulina/química , Proteínas de Unión a Factor de Crecimiento Similar a la Insulina/metabolismo , Lectinas/química , Lectinas/metabolismo , Datos de Secuencia Molecular , Neurotoxinas/química , Neurotoxinas/metabolismo , Péptidos/química , Péptidos/metabolismo , Venenos de Escorpión/clasificación , Venenos de Escorpión/metabolismo , Alineación de SecuenciaRESUMEN
BACKGROUND: Colombia and Brazil are affected by severe cases of scorpionism. In Colombia the most dangerous accidents are caused by Tityus pachyurus that is widely distributed around this country. In the Brazilian Amazonian region scorpion stings are a common event caused by Tityus obscurus. The main objective of this work was to perform the molecular cloning of the putative Na(+)-channel scorpion toxins (NaScTxs) from T. pachyurus and T. obscurus venom glands and to analyze their phylogenetic relationship with other known NaScTxs from Tityus species. METHODOLOGY/PRINCIPAL FINDINGS: cDNA libraries from venom glands of these two species were constructed and five nucleotide sequences from T. pachyurus were identified as putative modulators of Na(+)-channels, and were named Tpa4, Tpa5, Tpa6, Tpa7 and Tpa8; the latter being the first anti-insect excitatory ß-class NaScTx in Tityus scorpion venom to be described. Fifteen sequences from T. obscurus were identified as putative NaScTxs, among which three had been previously described, and the others were named To4 to To15. The peptides Tpa4, Tpa5, Tpa6, To6, To7, To9, To10 and To14 are closely related to the α-class NaScTxs, whereas Tpa7, Tpa8, To4, To8, To12 and To15 sequences are more related to the ß-class NaScTxs. To5 is possibly an arthropod specific toxin. To11 and To13 share sequence similarities with both α and ß NaScTxs. By means of phylogenetic analysis using the Maximum Parsimony method and the known NaScTxs from Tityus species, these toxins were clustered into 14 distinct groups. CONCLUSIONS/SIGNIFICANCE: This communication describes new putative NaScTxs from T. pachyurus and T. obscurus and their phylogenetic analysis. The results indicate clear geographic separation between scorpions of Tityus genus inhabiting the Amazonian and Mountain Andes regions and those distributed over the Southern of the Amazonian rainforest. Based on the consensus sequences for the different clusters, a new nomenclature for the NaScTxs is proposed.
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Filogenia , Venenos de Escorpión/clasificación , Venenos de Escorpión/metabolismo , Escorpiones/patogenicidad , Canales de Sodio/metabolismo , Secuencia de Aminoácidos , Animales , Brasil , Clonación Molecular , Colombia , Biología Computacional , Biblioteca de Genes , Datos de Secuencia Molecular , Picaduras de Escorpión/genética , Picaduras de Escorpión/metabolismo , Venenos de Escorpión/genética , Escorpiones/clasificación , Homología de Secuencia de Aminoácido , Canales de Sodio/genética , Especificidad de la Especie , Espectrometría de Masa por Ionización de Electrospray , Espectrometría de Masa por Láser de Matriz Asistida de Ionización DesorciónRESUMEN
We provide a mitochondrial DNA-based phylogenetic hypothesis for 21 Tityus species collected in Venezuela, Trinidad, Brazil and Panama, including 12 taxa known to be toxic to humans. Our phylogenetic reconstruction is based on 850 nucleotides of the combined cytochrome oxidase subunit I and 16S rRNA genes for most species, and centered on Venezuelan scorpions owing to the detailed taxonomic and biogeographic information available for Tityus in this region. The principal phylogenetic result was the strong support for mtDNA clades representing geographical groupings associated with the Perijá mountain range, the Mérida Andes, or the central and eastern coastal ranges in Venezuela, suggesting that vicariance has been a potent force in the diversification of local scorpions. Venezuelan Tityus species have been organized by González-Sponga into three artificial morphological groups, "androcottoides", "discrepans", and "nematochirus", based on the array of ventral carinae in metasomal segments II-IV. We also incorporated a fourth morphological group ("Tityus clathratus"), recently documented in Venezuela. Our results do not support the clustering of the species in the "androcottoides" and "discrepans" morphological groups, which include the majority of taxa of medical importance, but provided support for the "nematochirus" species group. T. clathratus was found to cluster with the Brazilian T. serrulatus and T. bahiensis. Divergence times of most clades are consistent with major events in the geological history of northern Venezuela and suggest that many Venezuelan Tityus species formed in the late Miocene and the Pliocene. In turn, we used the Tityus mtDNA phylogeny to determine the potential utility of phylogenetic systematics to predict Tityus venom antigenic reactivity by testing the recognition of T. nororientalis, T. discrepans, T. zulianus, T. perijanensis, and T. clathratus venoms by anti-T. discrepans horse antibodies. Cross-reactivity was significantly higher for the closely related eastern (T. nororientalis) and central coastal (T. discrepans) species in comparison to the distantly related Andean (T. zulianus) and Perijá (T. perijanensis) species. Reactivity of T. clathratus low mol. mass toxic components towards anti-T. serrulatus and anti-T. discrepans antivenoms was low, suggesting that venom components produced by the subgenus Archaeotityus (which encompass "clathratus" species) diverge antigenically from other Tityus scorpions.
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Venenos de Escorpión/clasificación , Escorpiones/clasificación , Animales , Especificidad de Anticuerpos , Antígenos/clasificación , Antígenos/genética , Antígenos/inmunología , Antivenenos/genética , Antivenenos/farmacología , Reacciones Cruzadas , ADN Mitocondrial/química , ADN Mitocondrial/genética , Ensayo de Inmunoadsorción Enzimática , Geografía , Filogenia , ARN Ribosómico 16S/genética , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa , Venenos de Escorpión/genética , Venenos de Escorpión/inmunología , Escorpiones/genética , Escorpiones/inmunología , Especificidad de la Especie , VenezuelaRESUMEN
In the period between June 2008 and August 2009, three cases of stings of Euscorpius scorpions indigenous to Italy were treated at two different emergency departments (ED) in hospitals of the Piedmont region, northwest Italy: Santa Croce e Carle General Hospital in Cuneo, and Santissima Annunziata Hospital in Savigliano. Scorpion stings in Italy are rare and not well documented in the literature; this situation may raise doubts among medical personnel as to how such lesions are best treated. Analysis of the incidents confirms that the venom of Euscorpius do not provokes systemic poisoning in humans and in these cases even dermatological reactions were not significant.(AU)
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Animales , Venenos de Escorpión/clasificación , Italia , Servicios Médicos de Urgencia , Dermatología/tendenciasRESUMEN
The present study aimed to investigate the effects of Mesobuthus tamulus gangeticus Pocock (Buthidae) venom on albino mice (NIH strain). Whole venom was obtained by electrical stimulation and its toxicity was determined in albino mice by subcutaneous envenomation. The venom LD50 was 2.5 mg kg-1 of mouse body weight. Toxic effects on different biochemical and enzymatic parameters in blood serum and other tissues of albino mice were determined after experimental envenomation with sublethal doses of M. tamulus gangeticus venom. Increased levels of glucose, uric acid and cholesterol, as well as decreased serum total proteins, were observed at 2 and 4 hours after the envenomation. In the liver and muscles, glycogen content dropped after venom injection. Moreover, M. tamulus gangeticus venom elevated the enzymatic activity of acid phosphatase (ACP), lactic dehydrogenase (LDH) and alanine aminotransferase (ALT) in the serum of albino mice. In conclusion, M. tamulus gangeticus can be considered a lethal scorpion species.(AU)
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Animales , Venenos de Escorpión/clasificación , Ratas/sangre , Hipoglucemia/metabolismo , Glucosa/análisis , Ácido Úrico/análisis , Colesterol/análisisRESUMEN
We have characterized earlier the long-term behavioural, electroencephalographic and histopatologicfeatures after a single TsTx microinjection, consisting of a neuropeptide isolated from the Tityus serrulatusscorpion venom, into the hippocampus of rats. TsTx was able to induce status epilepticus (SE)and developed later epilepsy. The present study was designed to investigate the outcomes of diazepamplus pentobarbital administered at 30 min, 1, 2 or 6 h after the beginning of TsTx-induced SE, on thedevelopment of spontaneous recurrent motor seizures (SRMSs), mossy fibre sprouting and hippocampalneurodegeneration in rats. The administration of diazepam (DZ) + pentobarbital (PB) 30 min after thebeginning of the TsTx-induced SE was able to markedly reduce the frequency of the SRMSs and preventthe development of mossy fibres sprouting and hippocampal lesion. In the other groups the augmentof the extent of hipocampal neurodegeneration, the frequency of SRMSs and degree of aberrant mossyfibre sproutingwas directly proportional to the time that the animalswere subjected to TsTx-induced SE.In conclusion, our results point out that the early blockade of the TsTx-induced SE with diazepam pluspentobarbital,was effective treatment against later epilepsy development. The effectiveness of this treatmentdepends on the time that the animals were subjected to the SE. Furthermore, the TsTx model couldbe a useful tool to study antiepileptogenic drugs in chronic epileptic animals, neuronal degeneration, aswell as for the mechanisms underlying epilepsy.
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Masculino , Femenino , Humanos , Animales , Diazepam/uso terapéutico , Pentobarbital/uso terapéutico , Venenos de Escorpión/análisis , Venenos de Escorpión/clasificación , Venenos de Escorpión/uso terapéutico , Epilepsia/inmunología , Epilepsia/prevención & controlRESUMEN
Tityus serrulatus scorpion venom (TSV) consists of a very complex mixture of molecules and demonstrates significant immunomodulatory activities capable of stimulating immune functions in vivo. The purpose of this study was to compare the crude TSV with fractionated toxins extracted from this venom in order to determine which toxin(s) presented immunomodulatory effects on peritoneal macrophages. TSV was fractionated using gel filtration chromatography resulting in 5 heterogeneous fractions. The effects of these different fractions were analysed in vitro using detection by means of cytokines, oxygen intermediate metabolites (H2O2), and nitric oxide (NO) in supernatants of peritoneal macrophages. Several functional bioassays were employed: tumor necrosis factor (TNF) activity was assayed by measuring its cytotoxic activity in L929 cells, and other cytokines were assayed by enzyme-linked immunosorbent assay, whereas NO levels were detected by Griess colorimetric reactions in culture supernatant of macrophages exposed to different fractions. In vitro studies revealed that all fractions studied here presented an increment in H2O2, NO, and cytokines levels. The more pronounced increments were observed in macrophage cultures exposed to fraction FII which demonstrated that (a) the highest levels of IL-1á, IL-â, and TNF were observed after 12 hours and that (b) the maximum levels of IFN-ã and NO were observed after 72 hours. Taken together, these data indicate that fractions have a differential immunomodulating effect on macrophage secretion, and that FII is a potent activator of TNF production of macrophages.
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Humanos , Animales , Venenos de Escorpión/clasificaciónRESUMEN
The effects of the main component of the Tityus serrulatus scorpion venom, toxin TsTX-I, were studied on the contractility and release of neurotransmitters in the rat vas deferens. Since TsTX-I is known to act on sodium channels, we used veratridine, another sodium channel agent, for comparison. 2. Toxin TsTX-I induced concentration-dependent contractions with an EC(50) value of 47.8+/-0.1 nM and a maximum effect of 84.4+/-10.4% of that for BaCl(2). 3. Contractions by TsTX-I were abolished by denervation or tetrodotoxin (0.1 microM), showing that the toxin effects depend on the integrity of sympathetic nerve terminals.
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Animales , Ratas , Venenos de Escorpión/clasificación , Receptores Adrenérgicos , Toxinas Biológicas , Adenosina Trifosfato , Adenosina Trifosfato/envenenamientoRESUMEN
Cn12 isolated from the venom of the scorpion Centruroides noxius has 67 amino-acid residues, closely packed with four disulfide bridges. Its primary structure and disulfide bridges were determined. Cn12 is not lethal to mammals and arthropods in vivo at doses up to 100 microg per animal. Its 3D structure was determined by proton NMR using 850 distance constraints, 36 phi angles derived from 36 coupling constants obtained by two different methods, and 22 hydrogen bonds. The overall structure has a two and half turn alpha-helix (residues 24-32), three strands of antiparallel beta-sheet (residues 2-4, 37-40 and 45-48), and a type II turn (residues 41-44). The amino-acid sequence of Cn12 resembles the beta scorpion toxin class, although patch-clamp experiments showed the induction of supplementary slow inactivation of Na(+) channels in F-11 cells (mouse neuroblastoma N18TG-2 x rat DRG2), which means that it behaves more like an alpha scorpion toxin. This behaviour prompted us to analyse Na(+) channel binding sites using information from 112 Na(+) channel gene clones available in the literature, focusing on the extracytoplasmic loops of the S5-S6 transmembrane segments of domain I and the S3-S4 segments of domain IV, sites considered to be responsible for binding alpha scorpion toxins.
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Estructura Secundaria de Proteína , Venenos de Escorpión/metabolismo , Escorpiones/metabolismo , Secuencia de Aminoácidos , Animales , Sitios de Unión , Humanos , Enlace de Hidrógeno , Espectroscopía de Resonancia Magnética , Ratones , Modelos Moleculares , Datos de Secuencia Molecular , Técnicas de Placa-Clamp , Filogenia , Unión Proteica , Estructura Terciaria de Proteína , Ratas , Venenos de Escorpión/química , Venenos de Escorpión/clasificación , Venenos de Escorpión/genética , Alineación de Secuencia , Canales de Sodio/química , Canales de Sodio/metabolismoRESUMEN
Purpose: To characterize the long-term behavioral, electroencephalographic (EEG) and histopathologic features after a single TsTx microinjection into the hippocampus of rats. Method: TsTx, 2 ìg, or 1 ìl of 0.1 M phosphate buffer was injected into the right dorsal hippocampus of the rat. EEG records and behavioral observations were made over a period of 10 h after injection. For a period of 4 months, the animals were observed for the occurrence of convulsive seizures. At the end of the experiment, the brains were processed by the neo-Timm and Nissi methods. Results: After intrahippocampal TsTx injection, three distinct phases were observed: (a) an immediate period that lasted 1 day, during which the motor and electrographic seizures characteristic of status epilepticus (SE) were seen; (b) a silent period (31-49 days), characterized by normal EEG and behavior; and (c) a period of spontaneous recurrent seizures (SRSs). The seizure frequency was one to two per week. Four months after TsTx injection, hippocampal neuronal loss and mossy fiber sprouting in the supragranular layer of the dentate gyrus were observed. Conclusions: The SRSs observed in this study may be associated with the TsTx-induced SE and brain damage. All animals injected with the toxin showed massive pyramidal neuronal loss in the dorsal hippocampus as well as intense gliosis and atrophy. Mossy fiber sprouting in the supragranular layer of the dentate gyrus was observed in those animals that had SRSs. The effects observed may be due, at least in part, to TsTx-enhanced release of glutamate in hippocampal pathways.
Asunto(s)
Masculino , Femenino , Humanos , Animales , Fibras Musgosas del Hipocampo , Hipocampo/anomalías , Venenos de Escorpión/clasificación , Venenos de Escorpión , Venenos de Escorpión/toxicidad , EpilepsiaRESUMEN
Twenty-three novel sequences similar to Ergtoxin (ErgTx) were obtained by direct sequencing of peptides or deduced from gene cloned using cDNAs of venomous glands of Centruroides (C.) elegans, C. exilicauda, C. gracilis, C. limpidus limpidus, C. noxius and C. sculpturatus. These peptides have from 42 to 47 amino acid residues cross-linked by four disulfide bridges. They share sequence similarities (60-98% compared with ErgTx1) and were shown to block ERG K(+)-channels of F-11 clone (N18TG-2xrat DRG) cultured cells. An unrooted phylogenetic tree analysis of these peptides showed that they conform at least five different subfamilies, of which three are novel subfamilies.
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Bloqueadores de los Canales de Potasio/clasificación , Venenos de Escorpión/clasificación , Venenos de Escorpión/genética , Secuencia de Aminoácidos , Animales , Clonación Molecular , Conductividad Eléctrica , Genes , Ratones , Datos de Secuencia Molecular , Péptidos/genética , Péptidos/farmacología , Filogenia , Bloqueadores de los Canales de Potasio/farmacología , Canales de Potasio/fisiología , Venenos de Escorpión/farmacología , Alineación de Secuencia , Células Tumorales CultivadasRESUMEN
TsTx is a scorpion á-type toxin that binds to site 3 of the Na+ channels in a voltage-dependent mode, slowing or blocking the inactivation mechanism of these channels (Possani et al., Eur J Biochem 1999). This binding increases depolarization time of the channel and consequently induces excessive neurotransmitter release. Previously we reported that hippocampal injection of TsTx induces clonic convulsions, electrographic seizures, and hippocampal damage. This investigation was designed to characterize the long-term behavioral, electroencephalographic (EEG), and histopathologic features after a single TsTx injection into the rat hippocampus.
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Animales , Neurotoxinas , Venenos de Escorpión/clasificaciónRESUMEN
A new peptide, Tc1, containing only 23 amino acids closely packed by three disulfide bridges was isolated from the Amazonian scorpion Tityus cambridgei. It blocks reversibly the Shaker B K(+)-channels with a K(d) of 65 nM and displaces binding of noxiustoxin to mouse brain synaptosome membranes. It is the shortest known peptide from scorpion venom that recognizes K(+)-channels and constitutes a new structural subfamily of toxin, classified as alphaKTx 13.1.
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Neurotoxinas/metabolismo , Péptidos/metabolismo , Bloqueadores de los Canales de Potasio , Venenos de Escorpión/metabolismo , Escorpiones/metabolismo , Secuencia de Aminoácidos , Animales , Línea Celular , Ratones , Datos de Secuencia Molecular , Neurotoxinas/clasificación , Neurotoxinas/aislamiento & purificación , Péptidos/clasificación , Péptidos/aislamiento & purificación , Canales de Potasio/genética , Venenos de Escorpión/clasificación , Venenos de Escorpión/aislamiento & purificación , Canales de Potasio de la Superfamilia Shaker , Spodoptera/citología , Sinaptosomas/metabolismoRESUMEN
Scorpion venoms contain low molecular weight basic polypeptides, neurotoxins, that are the principal toxicagents. 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 serrulatusscorpion 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 electrographicactivity and neuronal integrity of rat hippocampus when injected directly into this brain area. The results showedthat intravenous injection of the F and H fractions induced convulsions, and intrahippocampal injection caused electrographicseizures in rats and neuronal damage in specific hippocampal areas. Fraction J injected intravenously reduced thegeneral activity of mice in the open field but induced no changes when injected into the brain. These results suggest thatscorpion toxins are able to act directly on the central nervous system promoting behavioural, electrographic and histologicalmodifications.
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Masculino , Femenino , Humanos , Animales , Venenos de Escorpión/clasificación , Venenos de Escorpión/toxicidadRESUMEN
The effects of intrahippocampal administration of a neuropeptide (TS-8F toxin) isolated from Tityus serrulatus scorpion venom have been determined on behavior, limbic seizures, and neuronal degeneration in rats. Behavioral observation showed orofacial automatism, wet dog shakes, and myoclonus. Concomitantly, the electroencephalographic record showed high-frequency and high-voltage spikes that evolved to seizure activity in the hippocampus and cortex. Seven days after TS-8F toxin microinjection, neuronal damage was observed in CA1 and CA2 pyramidal cells and in granular cells of the dentate gyrus. The results suggest that TS-8F toxin may be responsible, at least in part, by the epileptic effects observed with the crude venom. Thus, this toxin may be a useful tool in the study of some neurobiological process.
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Animales , Venenos de Escorpión/clasificación , Venenos de Escorpión/toxicidad , NeurotoxinasRESUMEN
No periodo de janeiro de 1984 a maio de 1994, de 239 criancas com ate 15 anos de idade, picadas por escorpioes pertencentes as especies T. bahiensis (84,9 por cento) e T. serrulatus (15,1 por cento), 17 apresentaram envenenamento grave...
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Humanos , Recién Nacido , Lactante , Preescolar , Niño , Adolescente , Antivenenos/farmacología , Venenos de Escorpión/antagonistas & inhibidores , Antivenenos/uso terapéutico , Mordeduras y Picaduras/epidemiología , Estudios de Cohortes , Signos y Síntomas , Venenos de Escorpión/clasificaciónRESUMEN
This study was designed to investigate the effect of T. serrulatus scorpion venom on dopamine (DA) and gamma amino butyric acid (GABA) concentrations in different regions of the brain. The ratio of homovanillic acid (HVA) to DA, and the glutamic acid decarboxylase (GAD) activity were determined following intravenous or intracerebral venom injections. The increase in the HYA/DA ratio in the striatum after i.v. or intrastriatal injection could indicate an increase in DA turnover. One hour after i.v. injection of the venom GAD activity was shown to be decreased in the striatum and hypothalamus. After 24 hr GAD activity increased in the striatum and decreased in the hypothalamus and brain stem. These results could indicate different effects of the venom on the GABA system in different areas of the brain. After intrastriatal injection of the scorpion venom, the animals showed stereotyped behavior and rotation activity. Following intrahippocampal injection, myoclonus and orofacial automatisms, which constitute pro-convulsive signals, were observed. These behavioral alterations could be, at least in part, related to the GABA and dopamine alterations caused by the venom, since stereotypy, circling behavior and convulsions are dependent on dopamine and/or GABA.