A team of researchers at Emory University in Atlanta, Georgia, US, found that minor head injuries during early life could lead to neurodegenerative conditions later in life. They used fruit flies as a model and discovered that female fruit flies could experience delayed brain deterioration if they had chronic immune suppression after mating following an early-life head injury.
The research, which appears in an article in eLife, is significant in enhancing our knowledge of the sex-specific reactions to traumatic brain injury. The editors describe it as a crucial study that offers compelling evidence of the immune and reproductive pathways that could play a role in these differences.
Environmental factors such as minor head injuries can greatly raise the likelihood of neurodegeneration in the future. However, establishing a direct link between early-life exposure to mild head trauma and the later development of neurodegenerative conditions is difficult and remains a challenge. It is crucial to gain a better understanding of this connection. rnrnIt’s still unclear how sex and age impact the results. “Fruit flies have short lifespans, which allows scientists to observe brain injury-related changes throughout their entire lives,” explains Changtian Ye, a graduate student in the Emory Neuroscience Program and a member of James Zheng’s lab at the Emory University School of Medicine. “We recently created a fruit fly model of mild traumatic brain injury that enables us to administer mild headfirst impacts and then monitor the effects in male and female flies from the time of injury to the development of brain impairments later in life.” Ye and his team are using this model to track the effects.The researchers and their team observed the effects of mild traumatic brain injury on the behavior of flies. While the injury initially caused only minor immediate deficits in the flies, it ultimately led to more significant brain-related behavioral problems and degeneration later in life, and these issues became worse as the flies aged. Moreover, these effects were more pronounced in female flies, impacting their ability to climb and move, and resulting in more brain damage compared to male flies.
The researchers also discovered that female flies that had mated experienced more severe outcomes than those that had not. They were able to identify a protein called ‘sex peptide’ which seemed to play a role in this difference.The study identified sex peptide, a protein transferred to the female reproductive tract through semen during mating, as a key factor in making female flies more susceptible to the harmful effects of brain injury. The analysis of the flies’ RNA data suggested that mated females exposed to sex peptide experience chronic suppression of their innate immune defence networks, which makes them more vulnerable to neurodegeneration after mild head trauma. These findings support the notion that even mild head injuries can pose a significant threat to brain health, particularly for females. The authors emphasize the need for further research to explore potential interventions.Research is required to determine if comparable processes occur in other species. “Our study establishes a direct connection between early head trauma and later-in-life neurodegeneration, highlighting the differences in injury response between sexes and the influence of age during and after injury,” says senior author James Zheng, Principle Investigator at the Zheng Lab, Emory University School of Medicine. “It will be intriguing to find out if this connection exists in other organisms, and to analyze the genetic components and molecular players involved in the sex-specific development of neurodegenerative conditions following mild head trauma.
