Scorpion venom changes rat pup development.

Dorce, ALC, RG Bellot, VAC Dorce and ALA Nencioni. 2009. Effects of prenatal exposure to Tityus bahiensis scorpion venom on rat offspring development. Reproductive Toxicology doi:10.1016/j.reprotox.2009.04.008.

When pregnant rats are exposed to venom from a scorpion native to Brazil, their offspring develop differently than normal, reports a research team from the South American country.

This is one of a few studies to date to examine if scorpion venom poses a unique threat to developing offspring. The study clearly shows that baby rats are developmentally altered in many ways if their moms are "stung" while pregnant.

Scorpion stings are a public health problem in Brazil. Stings are painful and, depending on the species, can be fatal. While people try to avoid the arthropods, they still get stung. Pregnant women – who are heavier than they would otherwise be – might be less able to quickly escape a scorpion.

In the study, the pregnant rats responded to the venom from the Brazilian scorpion similarly to normal adults, with short-lived symptoms of fast breathing, salivation and rigid legs. 

But the young had a mixed bag of fast and slow growth and development. Overall, the baby rats grew and matured faster. Both male and females gained more weight than usual. There were also signs of abnormal brain development.

The rat pups that were exposed in the womb during the study, teethed and entered puberty earlier. Puberty onset was shortened in the females when the exposure was earlier in the pregnancy. However, a “sting” in later pregnancy delayed puberty in the male rats. These same males were more hyperactive, too.

Researchers simulated a scorpion sting by injecting two groups of pregnant rats with venom from Brazil's native brown scorpion (Tityus bahiensis) on different days during their pregnancies. They compared the physical, neurological and pubertal development of the baby rats born to the injected mothers with pups from other pregnant rats that were not injected.

The dose of scorpion venom that simulated a “sting” in the rats of this study is the same amount that causes a reaction in humans. The toxin in the venom acts on the nervous system affecting heart rhythm, breathing rate, lung fluid buildup, hypertension and shock. The poison can induce vomiting, diarrhea and saliva.

Future research will need to isolate the compound(s) and confirm if similar changes are seen in babies born to pregnant women who are stung by these ancient animals. In the meantime, pregnant women who live in Brazil and other areas with poisonous scorpions may consider being overly cautious to avoid contact with the creatures.