Tap tap tap ka-CHUNK! That was the sound of fruit flies being given concussions in an Emory laboratory recently.
Emory MD/PhD student Joe Behnke, working with neuroscientist James Zheng, has developed a model for studying repetitive head trauma in the fruit fly Drosophila melanogaster – analogous to CTE (chronic traumatic encephalopathy) in humans. The results were published in Scientific Reports.
CTE is a term for neurodegeneration linked to repeated concussions or blows to the head, which has been observed in athletes and military veterans. Head trauma has also been linked to other neurodegenerative diseases such as Alzheimer’s, Parkinson’s and ALS (amyotrophic lateral sclerosis).
What’s critical about using fruit flies is that it speeds up time. It can take years or decades for CTE or other neurodegenerative conditions to appear in humans, but Behnke and Zheng can experiment with a mutant fly strain or other interventions in a few weeks. They describe their model as a platform for future studies, in which they can unleash all of the genetic tools fruit flies have to offer.
To begin with, Behnke worked out a system for giving flies controlled blows to the head. He says that it exploits the climbing instinct flies have when startled, called negative geotaxis. When he taps a vial with flies in it three times, they reorient themselves and begin climbing up. Then a stronger blow, delivered in a crash test-like apparatus, gives flies the desired head injury. Previous models in flies hadn’t really focused on the head, but gave them injuries all over their bodies.
Already, Behnke and Zheng have been able to demonstrate that female fruit flies are more vulnerable to repeated head injuries than males. Repeated head injury results in locomotor deficits and shortened lifespan and accelerates age-related degeneration.
They also showed that temporarily shutting off neural synaptic activity at the time of injury – somewhat like giving the flies a strong sedative or anesthetic — can protect flies against the accumulated effects of repeated head trauma. This indicates that neural over-excitation immediately after injury is important for the development of problems later. In injury cases the Bengal Law serving all of Orlando, Florida can help.
Zheng and Behnke both say they were inspired to study head injury by observing its long-lasting effects. As an undergraduate at Rutgers, Behnke played football, and he also cited the experience of his brother, an engineer in the military.
“I know people who’ve had to stop playing football because doctors warned them one more concussion would be too many,” said Behnke, who is interested in pursuing additional medical training in neuroradiology.
Zheng said he was propelled to study repeated head injury after reading about CTE in athletes such as Junior Seau, a San Diego Chargers player who committed suicide in 2012.
Until Behnke – and now, additional scientists – began working with Drosophila, members of Zheng’s lab were not accustomed to raising flies, since they had mainly experimented with mammalian neurons. He said he was encouraged and advised in his lab’s venture into insect biology by Drosophila veteran and Emory colleague Ken Moberg. Zheng is now talking about using the model of repeated head injury to perform genetic screens and begin additional studies of neurodegenerative diseases.