Reproductive toxic effects of Tityus serrulatus scorpion venom in rats

Effects of Androctonus mauritanicus envenomation on an experimental mouse model of pregnancy and on mouse offspring

Scorpion envenomation is a public health issue in Morocco, where Androctonus mauritanicus is considered the most dangerous scorpion. This scorpion is well adapted to urban environments, and the likelihood of human exposure to its venom is increasingly high, including during pregnancy. This study was designed to investigate whether a single subcutaneous injection of venom at a moderate envenomation dose in pregnant mice could lead to detrimental effects on maternal reproductive performance and offspring development. Prior to examining developmental neurotoxicity, we assessed the acute toxicity of Androctonus mauritanicus venom in mice. Subsequently, the venom (200 μg/kg) was administered to pregnant mice on gestational day 5 (GD5), 10 (GD10), or 15 (GD15). Using neurobehavioral, developmental, hematological, and biochemical approaches, we investigated the consequences of Androctonus mauritanicus envenomation in pregnant mice. Additionally, we examined the role of oxidative stress in the venom's deleterious effects on reproductive performance and offspring development. Our results show that Androctonus mauritanicus venom induces similar envenomation symptoms in pregnant and non-pregnant mice but causes vaginal bleeding and abortions when administered on gestational days 10 and 15. The venom also triggered biochemical, hematological, and enzymatic disruptions. Viability indices, lactation, and offspring growth were significantly reduced, along with noticeable morphological delays. Finally, sensorimotor functions of offspring exposed to venom in utero were severely impaired, affecting their social behavior, sensory maturation, and motor coordination. Based on the findings of this study, Androctonus mauritanicus venom administration during pregnancy at a moderate dose can lead to significant effects on physical development and reflex maturation during the postnatal period.

Scorpion serotherapy during pregnancy protects rat offspring from harmful effects of venom

Despite the numerous incidents of scorpion envenoming worldwide, little is known about the effects of maternal venom exposure and serotherapy on fetal development. The impact of antivenom on pregnant rats envenomed by Tityus serrulatus venom was examined. The venom caused alterations in the development of the offspring, yet the antivenom protected against these adverse effects and does not cause harm in itself, indicating the potential benefits of serotherapy.

Scorpion Envenomation of Lactating Rats Decreases the Seizure Threshold in Offspring

Few data are available in the literature describing the long-term effects of envenoming in the perinatal period. In this study, the relationship between envenoming of lactating rats and possible behavioral changes in the mother and in her offspring were investigated. Lactating Wistar rats received a single dose of T. serrulatus crude venom on postnatal days 2 (V2), 10 (V10) or 16 (V16), and had their maternal behavior evaluated. The seizure threshold was evaluated in adulthood offspring. A decrease in maternal care during envenoming was observed in V2 and V10 groups. The retrieval behavior was absent in the V2 group, and a lower seizure threshold in the adult offspring of all groups was observed. During envenoming, mothers stayed away from their offspring for a relatively long time. Maternal deprivation during the early postnatal period is one of the most potent stressors for pups and could be responsible, at least in part, for the decrease in the convulsive threshold of the offspring since stress is pointed to as a risk factor for epileptogenesis. Furthermore, the scorpionic accident generates an intense immune response, and inflammation in neonates increases the susceptibility to seizures in adulthood. Therefore, maternal envenoming during lactation can have adverse effects on offspring in adulthood.

The effects of antivenom administrations on the brain tissue of experimentally envenomed pregnant rats and their pups with Androctonus crassicauda scorpion venom during organogenesis period

This study aims to show the changing effects of Androctonus crassicauda venom and A. crasicauda specific antivenom during pregnancy in brain tissue of dams and their pups. Totally, 12 pregnant-Wistar Albino rats were randomly divided into two groups as venom-antivenom administration (n = 6) and control groups (n = 6). In venom-antivenom administration group (VAV), the sublethal dose of A. crassicauda venom dissolved in 1 mL physiological saline solution was subcutaneously (s.c.) injected into pregnant rats during organogenesis period (between 7 and 13 days of pregnancy). Four hours after each venom injection, 1 mL/s.c. dose of the specific anti-venom was administered to rats of VAV group. The rats in control group were given sterile saline solution 1 mL/s.c. In both groups, the fetuses were surgically delivered on the 21st day of pregnancy; dams and pups were sacrificed on postnatal 21 days, and their brain tissues were removed. The brain tissue of dams and their pups were evaluated histopathologically and immunohistochemically. To show the neuronal damages, 8-hydroxy-2-deoxyguanosine (8-OHDG) and amyloid beta precursor protein (ABPP) immunoexpressions were scored in cerebrum, cerebellum, pons and medulla oblongata of brain. To show the neuroprotection, reelin and beta-arrestin immunoexpressions were scored again in the same way. In this context, 8-OHDG immunoexpressions were increased in neocortex, hippocampus and nucleus accumbens when compared with that of control group. Amyloid beta precursor protein was negative in both groups. Reelin and beta-arrestin partly increased in fore and mid brain of VAV group as a reaction against neuronal damages when compared with that of control pups. The authors believe that prompt intervention using anti-venom to scorpion envenomation can partly stop neuronal damages. This neuroprotection may be increased to high and serial doses of anti-venom to save neonatal lives.

Safety evaluation of the venom from scorpion Rhopalurus junceus: Assessment of oral short term, subchronic toxicity and teratogenic effect

Rhopalurus junceus is the most common scorpion in Cuba and the venom is often used as a natural product for anti-cancer therapy. Despite this, no study has been published concerning its toxicological profile. The aim of the study was characterizing the short-term, subchronic toxicity and the teratogenic potential of Rhopalurus junceus scorpion venom by oral route in mice. Short-term oral toxicity was test in both sexes NMRI mice that received 100 mg/kg/day of scorpion venom extract for 28 days. For the subchronic study, mice were administered with three doses (0.1, 10, and 100 mg/kg) by oral route for 90 days. Teratogenic potential was tested in pregnant mice administered from day 6-15 post conception. Significant differences were observed in body weight and food intake of animal treated for short-term and subchronic assays. Variations in serum urea and cholesterol were observed after 90 days oral treatment. Spontaneous findings not related to the treatment were reveal in histology evaluation. Exposure in pregnant mice did not produce maternal toxicity. Signs of embryo-fetal toxicity were not observed. The current study provides evidence that exposure to low or moderate dose of Rhopalurus junceus scorpion venom by oral route did not affect health of animals and has low impact on reproductive physiology.

Perinatal effects of scorpion venoms: maternal and offspring development

Scorpion envenomation is a public health problem, especially in tropical and subtropical countries. Considering the high incidence of scorpionism in some areas, pregnant women and nursing mothers may be possible victims. Scorpion stings alter the release of neurotransmitters and some cytokines. These mediators act as organizers and programmers in the adequate formation of the nerves, and non-physiological concentrations of them during the brain organization originate disorders and diseases that can appear later in the life of the individual. Despite the importance of this subject, there are only a few studies showing the effects of scorpion venom on maternal reproductive development, in the morphology and physical and behavioral development of offspring. The present review article summarizes the major findings on this issue. Biochemical changes in the blood – such as hyperglycemia, increase on the level of sodium and on the creatinine concentration – are observed after scorpion sting in humans and experimental animals. Some studies in the literature demonstrate that the scorpion venom affects the maternal reproductive development in humans and in experimental animals, increasing the frequency and amplitude of uterine contraction and the number of resorptions. The venom can also lead to some alterations in the embryonic or fetal development increasing the total weight of fetuses and of some organs. Moreover, it affects the general activity and locomotion during childhood and adulthood, and the anxiety level in adult females and males. It also alters the number of hippocampal neurons and interferes in the level of some cytokines. Altogether, it is evident that the venom, when administered during the pregnancy or lactation, affects the development of the offspring. Studies are being conducted to determine the actual participation of the venom in the development of the offspring, and to what extent they are detrimental to animal development.

Effect of maternal exposure to Tityus bahiensis scorpion venom during lactation on the offspring of rats

Scorpion stings are a public health problem in Brazil and lactating women may be affected. We aimed to study the effects of Tityus bahiensis venom in the offspring of rats treated during lactation. Mothers received a subcutaneous injection of saline (1.0ml/kg) or venom (2.5mg/kg) or an intraperitoneal injection of LPS (lipopolysaccharide) (100μg/kg) on postnatal (PN) days 2 (PN2), 10 (PN10) or 16 (PN16). The offspring were evaluated during the childhood and adulthood. Pups showed a delay in physical and reflexological development, and a decrease in motor activity. Adults displayed low anxiety. There was an increase in the number of viable neuronal cells in hippocampal areas CA1 and CA4. The levels of IFN-γ (interferon-gamma) increased in the experimental groups. Several of the parameters analyzed showed important differences between the sexes. Thus, the scorpion venom affects the development in the offspring of mothers envenomed during the lactation.

Tityus serrulatus venom--A lethal cocktail

Tityus serrulatus (Ts) is the main scorpion species of medical importance in Brazil. Ts venom is composed of several compounds such as mucus, inorganic salts, lipids, amines, nucleotides, enzymes, kallikrein inhibitor, natriuretic peptide, proteins with high molecular mass, peptides, free amino acids and neurotoxins. Neurotoxins are considered the most responsible for the envenoming syndrome due to their pharmacological action on ion channels such as voltage-gated sodium (Nav) and potassium (Kv) channels. The major goal of this review is to present important advances in Ts envenoming research, correlating both the crude Ts venom and isolated toxins with alterations observed in all human systems. The most remarkable event lies in the Ts induced massive releasing of neurotransmitters influencing, directly or indirectly, the entire body. Ts venom proved to extremely affect nervous and muscular systems, to modulate the immune system, to induce cardiac disorders, to cause pulmonary edema, to decrease urinary flow and to alter endocrine, exocrine, reproductive, integumentary, skeletal and digestive functions. Therefore, Ts venom possesses toxins affecting all anatomic systems, making it a lethal cocktail. However, its low lethality may be due to the low venom mass injected, to the different venom compositions, the body characteristics and health conditions of the victim and the local of Ts sting. Furthermore, we also described the different treatments employed during envenoming cases. In particular, throughout the review, an effort will be made to provide information from an extensive documented studies concerning Ts venom in vitro, in animals and in humans (a total of 151 references).

Tityus bahiensis scorpion venom injected to dams during pregnancy affects some cytokines of fetuses

Due to the high incidence of scorpion stings in Brazil, pregnant women are among the possible victims. Cytokines are important during the pregnancy, and scorpion venoms can change their release. We evaluated the levels of some cytokines in the fetuses after the treatment of pregnant rats with the Tityus bahiensis scorpion venom. The concentration of some of them is altered and can be responsible for the effects previously observed on innate reflexes, and the physical and behavioral development of the offspring.

Mild reproductive effects of the Tityus bahiensis scorpion venom in rats

Background

Scorpion envenoming is a public health problem in Brazil, where Tityus serrulatus and T. bahiensis are considered the most dangerous scorpions. They are well adapted to urbanized environments, and there is an increasing probability of human exposure to these venoms, including during pregnancy. Not much is known about the effects of prenatal exposure to the venom, and no information is available to aid in the rational treatment of victims stung during pregnancy. Thus, this study aimed to investigate whether venom from the scorpion T. bahiensis administered once to pregnant female rats at a dose that causes a moderate envenomation may lead to deleterious effects on the reproductive performance of the dams and on the development of their offspring. This is the first work demonstrating that T. bahiensis venom, when administered experimentally to rats, alters maternal reproductive performance and the morphological development of fetuses. The venom was given to dams on the 5th (GD5) or on the 10th (GD10) gestational day. After laparotomy, on GD21, fetuses and placentas were counted, weighed and externally analyzed. The corpora lutea were counted. The sex and vitality of fetuses were evaluated, and each litter was then randomly divided for visceral or skeletal analyses. Data were analyzed by ANOVA followed by the Tukey-Kramer test and Fisher’s exact test. The significance level for all tests was set at p < 0.05.

Results

GD5 group presented an increased number of pre-implantation losses. Weight gains in fetuses and placentas were observed in the GD5 and GD10 groups. Weights of the heart and lungs were elevated in GD5 and GD10 and liver weight in GD10.

Conclusions

Moderate envenomation by T. bahiensis scorpion venom alters maternal reproductive performance and fetal development. However, these are preliminary results whose causes should be investigated more carefully in future studies.

Effects of a toxin isolated from Tityus bahiensis scorpion venom on the hippocampus of rats

AIMS

The objective of the present study was to determine the effects of a toxin from T. bahiensis scorpion venom on the hippocampus of rats. This toxin, called Tb V-4, was chosen since it shows remarkable convulsive activity.

MAIN METHODS

Male Wistar rats weighing 250g were used. The toxin (1.0μg/μl) was injected into the hippocampus. The animals were then submitted to electroencephalographic and behavioral examinations or to microdialysis to determine the levels of neurotransmitters. The location of the implanted guide cannulae and electrodes was checked histologically. The number of cells in the CA1, CA3 and CA4 areas of the hippocampus was determined by light microscopy. Changes in the concentration of cytosolic free calcium were evaluated by confocal microscopy.

KEY FINDINGS

The toxin evoked behavioral alterations such as wet dog shakes, myoclonus, yawning and orofacial automatisms. Electroencephalographic recordings exhibited alterations such as isolated or grouped spikes and epileptic-like discharges. Injection of the toxin augmented glutamate concentration in the extracellular fluid in some animals. There was also a decrease in the number of pyramidal cells, mainly in the CA1 and CA4 areas for some rats. In some slices of the hippocampus, an increase in intracellular calcium mobilization was seen.

SIGNIFICANCE

The present results suggest that the Tb V-4 toxin may be responsible for the epileptic and behavioral effects observed with the crude venom. We suggest that the convulsive and degenerative effects induced by the toxin could be due to the enhanced release of excitatory amino acids involved in the most important pathways of the hippocampus.

Effects of in utero exposure to Tityus bahiensis scorpion venom in adult rats

The toxicity of Tityus bahiensis scorpion venom is well known, but there are little data about the damage in offspring of dams that were exposed to the venom during pregnancy. The objective of this work was to determine the toxic effects of venom in adult offspring of Wistar rats exposed to venom in utero. Dams were divided into a control group, subcutaneously injected with saline solution on the 10th (GD10) and 16th (GD16) days, and two experimental groups, subcutaneously injected with venom (2.5mg/kg) on GD10 or GD16, respectively. Adult offspring were evaluated according to behavioral development and neuronal integrity in the hippocampus. Tests performed in the activity box and in the enriched environment demonstrated that males from GD10 had motor decrease. Females from GD10 showed a depressive-like state and were more anxious, as demonstrated by the forced swimming test and social interaction. The plus-maze discriminative avoidance task demonstrated that GD16 males had lower levels of anxiety. The number of neuronal cells was decreased in CA1, CA3 and CA4 hippocampal areas of males and females from GD10 group and in CA1 of females and CA4 of males from GD16 group. Thus, we conclude that venom exposure in pregnant dams causes subtle alteration in the behavioral and neuronal development of offspring in adult life in a gender-dependent manner.

Central effects of Tityus serrulatus and Tityus bahiensis scorpion venoms after intraperitoneal injection in rats

A great number of studies on scorpion venoms associate their effects to the autonomic nervous system, and few data are available about their action on the central nervous system (CNS). The aim of this work was to evaluate some central effects after intraperitoneal injection of Tityus serrulatus or T. bahiensis scorpion venoms. The hippocampal concentration of some neurotransmitters and their metabolites were determined. Electroencephalographic and behavioral observations were performed, and all brains were removed for histopathological analysis of hippocampal areas. Both venoms induced electrographic and behavioral alterations despite T. bahiensis venom affects less the electrographic activity than T. serrulatus venom. Neurochemical analysis demonstrated no alteration in the extracellular levels of almost all the neurotransmitters evaluated, at least in the hippocampus, and no neuronal loss in this area was observed. Meanwhile, extracellular concentration of HVA increased up to 10 times in approximately 1/3 of the animals of both groups. Scorpion venoms seem to exert a small but important central effect. More studies in this field are necessary because they may be useful in developing new strategies to reduce the damage caused by scorpion stings.