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

French Scorpionism (Mainland and Oversea Territories): Narrative Review of Scorpion Species, Scorpion Venom, and Envenoming Management

Sixty-seven scorpion species have been described in France and its territories, where they have been found to be heterogeneously distributed. Indeed, only one species can be found on Réunion Island, while 38 species exist in French Guiana. The number of stings is also heterogenous, with up to 90 stings per 100,000 inhabitants occurring annually. Scorpion species can frequently be determined through simple visual factors, including species of medical importance (i.e., Buthus, Centruroides and Tityus). Scorpion venom is composed of local enzymes and peptides with a cysteine-stabilized α/β motif (NaTxs, Ktxs, Calcines), which allow for venom diffusion and the prey's incapacitation, respectively. Harmful scorpion species are limited to Centruroides pococki in the French West Indies, which can induce severe envenoming, and the Tityus obscurus and Tityus silvestris in French Guiana, which can cause fatalities in children and can induce severe envenoming, respectively. Envenomation by one of these scorpions requires hospital monitoring as long as systemic symptoms persist. Typical management includes the use of a lidocaine patch, pain killers, and local antiseptic. In the case of heart failure, the use of dobutamine can improve survival, and pregnant women must consult an obstetrician because of the elevated risk of preterm birth or stillbirth. France does not have scorpion antivenom, as scorpion stings are generally not fatal.

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 Tityus bahiensis scorpion venom on the contractility of jejunum, vas deferens, and the aorta is differentially affected by tetrodotoxin

The pharmacological effects of the crude venom of the scorpion Tityus serrulatus or its isolated toxins have been widely studied. However, few studies are available on Tityus bahiensis venom. We recently discovered that T. serrulaus venom leads to the release of tetrodotoxin-resistant acetylcholine. Thus, our objective was to verify whether T. bahiensis venom could have a similar action in the jejunum. Furthermore, we evaluated the possibility that this action occur in other tissues innervated by the autonomic nervous system. Thus, organ bath studies were conducted to evaluate the contractile and relaxant effects of venom on the jejunum, vas deferens and aorta of rats in the presence or absence of tetrodotoxin. We observed that jejunum, vas deferens and aorta contracted when the T. bahiensis venom was applied. In the jejunum, the venom reveals a contractile component resistant to tetrodotoxin. It also was able to relax pre-contracted preparations of jejunum and aorta but not vas deferens. Only in the aorta, the relaxation was resistant to tetrodotoxin. The effects of scorpion venoms are attributed to its action on ionic channels leading to neuronal depolarization and neurotransmitter release. Our results indicated that a similar mechanism is present in the observed effects of the venom. However, another mechanism must be present in the venom-induced contraction in the jejunum and relaxation in the aorta. Possible involvement of tetrodotoxin-resistant sodium channels or non-neuronal release of neurotransmitters is discussed. We emphasize that the study of the Tityus scorpion's venom, especially T. bahiensis, is of great importance because it can unveil unknown pharmacological and physiological mechanisms of excitable cells.

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.