To Food - Scientists are finding that your nose and eyes could be
tricking you into eating more than you want to. (7/12/02)
Brain on Drugs - Scientists looking directly at the brains of drug
users have found that methamphetamine damages the brain and its effects
continue long after people stop using it. (3/6/01)
Elsewhere on the web
of Drug Abuse
Transporterâ€™s Involvement in Neuropsychiatric Disorders
There's no substitute for a mother's love.
As this ScienCentral News video reports, neuroscientists have found that when
kids are deprived of this love, it could affect the way their brains are wired
and make them more prone to abuse drugs as adults.
Motherâ€™s Love: The Anti-Drug?
While many individuals experiment with drugs, only some people become addicted
to them, according to Wayne
Brake, assistant professor of Neuroscience at the University of California
Santa Barbara, and his colleagues Michael Meaney and Alain Gratton at McGill
University in Canada.
They also report that
previous studies have attributed drug abuse to an abnormal dopamine system
in the brain. Dopamine is a brain chemical that is released by certain nerve
cells and is associated with feelings of pleasure and reward. Brake says that
if the dopamine system is compromised in humans, “it could lead to greater
susceptibility for drug dependence and perhaps greater vulnerability to develop
certain psychiatric illnesses.”
He also says that studies published in research journals report that those
who are abused or neglected as children tend to abuse drugs more often as adults.
So in a study published in the journal Pscyhoneuroendocrinology,
Wayne and his colleagues speculated that a trauma early in childhood, such as
being separated from oneâ€™s mother, would affect the dopamine system in
The researchers decided to test the idea on rats. They separated rat babies
from their mothers for several hours a day during the first two weeks of their
lives. This evokes stress in the mother who eventually, “spends less time
licking and grooming and nursing and caring for her pups”, according to
Wayne. Then they waited until the rats were 3 months old, at which time they
are considered adults. They tested the ratsâ€™ sensitivity to different
doses of drugs like cocaine and amphetamine. Wayne says that although all the
rats responded to high doses of the drugs, the rats separated from their mothers
“were much more responsive or hyper in response to the drugs at lower
Next, Wayne and his team wanted to know if their theory about dopamine was
correct. When they analyzed the brain tissue, they found that the rats separated
from their mothers released a lot more dopamine than those that grew up next
to mom. According to Wayne, this suggests that the dopamine system in the brain
is functioning at a higher level in the rats that were separated from their
The researchers dug further to find out what was causing this change in dopamine
levels and found that the separated animals showed a decrease in a protein in
the brain called dopamine transporters.
The system works like this. Dopamine is released into the space between two
nerve cells, stimulating the neighboring nerve cell. In normal animals, once
the signal has been sent, dopamine is taken back up by the dopamine transporters
into the cell from which it was released. This function is called dopamine reuptake.
“This,” says Wayne, “is what regulates the amount of dopamine
released in the brain and how much motivational drive we have to take drugs”.
When there is a decrease in the amount of dopamine transporters in the brain,
the dopamine reuptake does not happen as it normally would. This means the dopamine
signals last longer and are stronger than those in normal individuals.
Brakeâ€™s team also studied a number of genes in the front part or prefrontal
cortex of the ratâ€™s brain. They found that several genes that are involved
in the development of the dopamine system were either turned on or off or changed
in their expression.
Wayne says all this appears to be regulated by the care a mother gives early
in the ratâ€™s life. He explains, “while we donâ€™t know a lot
about their (genes) exact nature, we do know that it may be important for generating
how the adult brain will be wired later on”.
The team plans to examine the genes individually to confirm the reliability
of the changes in the genes and to study their role in brain development.
Brake points out that although we cannot automatically translate the findings
in rats to humans, the study does show that in the brains of mammals, a motherâ€™s
care is extremely important for brain development.
This study was funded by grants from the National
Institute on Drug Abuse, and the Canadian
Institutes of Health Research.