Mel Robertson, Biology professor at the Queen's University in Canada, is making use of insect models to examine how breathing is controlled by the nervous system when stress is induced through high temperatures and oxygen deprivation. The researchers have discovered that the locust's reaction to extreme heat is quite similar to a disturbance in mammals associated with human migraines and stroke. The locust goes into comma by temporarily shutting down and conserving energy when conditions are dangerous. This coma has many of the same characteristics observed in people at the onset of a migraine.
"We feel there may be an evolutionary link between the two," suggested Dr. Robertson.
In the study, the researchers tracked the locust breathing cycles, controlled by a collection of nerve cells in the central nervous system. With heat or lack of oxygen, the insects initially breathe more quickly and then go into a coma. When the temperature comes down again, or oxygen levels rise, they recover.
"We find that the point of coma is always associated with a surge of extra-cellular potassium ions: the same as has been observed in human brain tissue during surgeryFor the nervous system to work properly, potassium should be high inside cells and low outside, she points out. "What we're seeing is a failure of that ability to maintain this equilibrium - but in fact, in the locust, it appears to be an adaptive response to protect the system," said PhD student Corinne Rodgers.
Earlier research carried out in Dr. Robertson's lab has demonstrated a genetic component to this response, indicating that there may be an evolutionary link to what happens during migraines in people.
"It's possible, for example, that the brain architecture necessary for increased sensitivity also predisposes areas of some people's brains to become over-excited, and that migraines provide a means of temporarily 'shutting things down,'" he suggested.
Though, migraine has been linked with this disturbance for a long time now, the mechanisms responsible for this phenomenon are not yet well understood. And this understanding will be key to designing new migraine treatments.
"We found that we could precondition the locust system to be more stress-tolerant. If the mechanisms are the same as those in humans, then similar manipulations could help to protect brain function under stressful conditions, such as those leading to migraine. Something is triggering events like this. Maybe we can just bias that slightly, so it won't trigger as often, or the consequences will not be as severe," said Dr. Robertson.
The findings are published on-line in the journal PLoS ONE.