Scientists at the Icahn School of Medicine at Mount Sinai saw for the first time the fingerprints of concussions and other head injuries in the brains of deceased animals attacking their head – the musk python and bighorn sheep. The results are published in the journal Acta Neuropathologic It may conflict with the popular belief that traumatized animals do not suffer from TBI and support the idea that studies in animals with evolutionary brains similar to those in humans may help researchers understand and reduce TBI.
“Death and disability from TBI are a pervasive problem and need better solutions,” said Nicole Ackermans, PhD, postdoctoral fellow at Icahn Mount Sinai and study leader. “We have shown that animals that regularly participate in decapitation may in fact suffer the type of TBI seen in humans. This opens up the possibility that by studying these animals we can learn a lot about TBI.”
Dr. Ackermans and colleagues studied the brains of three deceased Greenland musk eels and four bighorn sheep, which were obtained from parks in Colorado and Utah and the Buffalo Zoo in New York.
Part of the reason these horned animals get brains is that they are known to engage in violent head-to-head collisions, usually in mating rituals and social hierarchies. For example, male muskrats often reach speeds of up to 30 miles per hour before impact. Although some studies have noted symptoms of TBI, such as acting in a stupor, none have directly tested whether the brains of muskrats and other devastated animals show any harm.
Another reason is that cattle — such as cows, sheep, buffalo, deer, and the animals in the study — had cerebral or folded brains, which have also been seen in humans.
“Our lab is trying to use evolution to help solve medical mysteries,” said Patrick R. Hof, professor of neuroscience at Icahn Mount Sinai and senior author of the study. “One of the difficulties with TBI research is that most of it is performed on the smooth brains of rodents. We thought that studying the brains of overwhelmed cows might provide a better model for understanding TBI in humans.”
When they first arrived, the animals’ brains appeared healthy, and brain scans showed that the overall structure of each animal’s brain was intact.
To look for signs of TBI damage, the researchers then sliced the brains into thin slices and treated the slices with antibodies made to detect phosphorylated tau proteins found in humans or mice. This form of tau is a hallmark of damage often seen in the brains of Alzheimer’s patients, or in people who have experienced traumatic brain injury, including chronic traumatic encephalopathy (CTE).
When they looked at the brains under a microscope, they saw that one of the antibodies stained the musk venom brains at easily detectable levels, while the large sheep’s brains had slightly detectable levels of staining with different antibodies.
“At first we were surprised. One of the challenges with these types of studies is that we don’t know if the antibodies used on humans and rodents would work on cow brains,” Dr. Ackermans said. “The fact that we detected these antibodies was important. She suggested that the brains of these animals, especially musk venom, suffer damage similar to traumatic brain injury.”
Further analysis supported the idea. For example, the prefrontal cortex of Musk brains contains high levels of tau protein synapses, especially near the surface of the cortex.
“This pattern sometimes appears in the brains of people with CTE,” Dr. Ackermans said. “Our results open the possibility that the brains of these animals can experience chronic and recurrent damage, as seen in some TBI patients.”
In contrast, when the researchers looked at brain slices of an Alzheimer’s patient, they saw a much more extensive and diffuse staining pattern.
Curiously, an old female musk has significantly more staining – about 20 times – than an older male and five times more than another female. This is the opposite of what the researchers hypothesized, as males are known to hit each other more aggressively and more aggressively than females.
This study left us with many interesting questions, such as: Why does the brain of female muskrats seem to be more harmful than the brains of males? Is this due to differences in skull anatomy? Why were big sheep’s brains so little damaged? And is it possible to harness the knowledge we gain from these animals to develop better treatments for TBI? Dr. Ackermans said.
reference: Ackermans NL, Varghese M, Williams TM, et al. Evidence for traumatic brain injury in the cow brain. Acta Neuropatol. Published online May 17, 2022. doi: 10.1007/s00401-022-02427-2
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