A recent study in animals has shown that the brain’s ability to recover from an injury like stroke is hampered by the exposure to environmental lead in early life.
A recent study in animals has shown that the brain’s ability to recover from an injury like stroke is hampered by the exposure to environmental lead in early life.
It is known that exposure to lead early in life tends to augment the risk of cancer, renal disease, hypertension and cardiovascular disease later in life, and in the process also increases the risk for stroke and brain damage.
The study was led by Jay Schneider, Ph.D., professor of Pathology, Anatomy and Cell Biology and Neurology at Jefferson Medical College of Thomas Jefferson University in Philadelphia and postdoctoral fellow Emmanuel Decamp, Ph.D. He is also the director of the Parkinson’s Disease Research Unit at Thomas Jefferson University.
He wanted to find out if it was possible for lad to alter the potential for plasticity i.e. the ability of the brain to compensate for an injury.
The researchers studied young rats that were given a lead supplemented diet and compared them to In earlier work in the lab, they found that even brief exposures to lead affected neurotrophic factors in the brain important for growth and maintenance of neurons and their connections. They made each group to go under some simple behavioral tests before causing a small stroke in a Dr. Schneider and his group of researchers saw remarkable recovery after a brief period of time in the control group, “as compensatory processes take over,” however the limb function was not completely back to normal. “In contrast, those animals that were exposed to lead earlier in life had worse outcomes in the same period after the stroke. There was significant difference in the brain’s ability to compensate for that injury,” said Dr. Schneider. He explained that, as the study was brief they did not have any idea if in a longer period of time the lead-exposed animals would catch up in their recovery to the controls. There was some recovery in the lead group, but later it leveled off. The control group continued to get better. “That’s one of the questions we would like to pursue in further studies – whether lead exposure slows or attenuates the recovery process after a brain injury,” he said. According to Dr. Schneider, it is eminent that other forms of brain plasticity like learning and memory suffered from the damaging effects of lead exposure. “Brain plasticity generally refers to the brain’s ability to be molded by experience as well as its ability to reorganize anatomically and functionally and recover from injury,” said Dr. Schneider. He added: “It’s why people who have relatively small strokes can recover function. The brain has an innate ability to reorganize and repair itself. Our data suggest that lead exposure may compromise or alter this capacity for remodeling that may impair recovery of function following brain injury.”
The next step for the group would be to see if such a trend translates to recovery from other types of injury, such as traumatic brain injury. They would also like to explore the notion that childhood lead exposure increases the risk of a child having a poorer outcome from an acquired brain injury. Dr. Schneider explained that impairment of plasticity was one important aspect of lead poisoning. He said: “The data we have begin to support that. We want to look at the effects of different levels of lead exposure on the outcome from acquired brain injury and see how different types and extents of exposures correspond with the expression of injury and recovery of function. Then, we want to try to nail down the biological processes responsible.” The study was reported in the journal NeuroToxicology.
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