Rense: Mother's Touch can Alter Baby's Genes

[Guest guest]

Comments?

Misty L. Trepke

http://www.searching-alteratives.com

 

Mother's Touch Can Alter Baby's Genes - Research

By Anne McIlroy

The Globe and Mail

4-6-4

 

To an infant, a mother's touch is warm and comforting. Now a Canadian

researcher has found out how it can also trigger profound changes

beneath the skin -- how a caregiver's touch can physically alter a

baby's genes. McGill University's Michael Meaney's revolutionary

findings may finally end the long debate over whether heredity or

the environment play the primary role in shaping an individual's

personality.

 

The nature-nurture debate has become less fierce in recent years:

Many scientists now accept that a mysterious dance between genes and

environment determines who we become. Dr. Meaney and his colleagues

have uncovered an important step in that dance, by showing for the

first time how conditioning can change the chemical structure of the

genes we inherit -- in effect, switching them on or off.

 

Their work is with rats. But his team has just begun a $4-million,

five-year study that could be the first in the world to confirm that

it also applies to humans.

 

There are two different kinds of rat mothers -- those that lick

their pups a lot and those that don't. Dr. Meaney found that, under

provocation, the high-licking mothers' offspring produced less of

the stress hormone cortisol. They are more stable individuals that

are not as easily panicked.

 

Picture half a dozen rats in a cage, eating. Dr. Meaney claps his

hands loudly, and all the animals freeze. Some rats almost

immediately go back to gobbling their food, realizing that the

researcher doesn't pose a real threat. But others will remain

immobilized for up to 10 minutes, and may never go back their lunch.

The difference? The timid rats are the offspring of mothers who

didn't lick them much.

 

How can licking make that much of a difference in personality -- is

it due to their genes, or the way they were raised? The answer is

both. In essence, the high-licking moms produce changes in their

babies' DNA. Their pink tongues somehow flick on the same chemical

switch that turns genes on and off in a developing embryo.

 

In the fetus, this process -- which scientists call methylation --

allows development of the brain and organs to proceed in an orderly

fashion. In the baby rats, the high-licking mothers somehow switch

on a gene that restricts the production of cortisol. The low-licking

mothers do not, so their pups produce much higher levels of the

stress hormone.

 

Cortisol helps prepare the body to deal with a threat -- such as the

possibility that a clapping researcher means them harm. In short

bursts, it can save an animal's life. But over the long term, a

heightened stress response has been linked to diabetes, heart

disease, mental illness and other serious ailments in both humans

and lab animals.

 

" We have now studied that particular gene down to the level where we

know what maternal care is doing to turn it on or off, " says Dr.

Meaney.

 

He sees his work as helping to reframe the nature-nurture debate,

which dates back to at least the 13th century. Extremists on one

side have argued that all animal behaviour is instinctive. Hard-

liners on the other side have taken the position that experience

alone determines behaviour. The argument flares every decade or so,

most recently with the mapping of the human genome. Now, the

question is no longer whether genes are more important than

the environment, says Dr. Meaney. The question is how the environment

physically alters genes to produce individual differences.

 

The genetic changes in the baby rats affected not only the stress

response but also cognitive development, since high levels of

cortisol inhibits the growth of the hippocampus, a part of the brain

involved in memory and learning. Cortisol may also influence how

well young animals pay attention. Alison Fleming, a researcher at

the University of Toronto, has found that rats brought up without

mothers -- and that don't have attentive researchers stroking them

with paint brushes to stimulate licking -- grow up with more

attention problems than animals that get that physical stimulation.

 

Could the same things be true in humans? We don't regularly lick our

babies or stroke them with paint brushes, and Dr. Meaney isn't

suggesting that anyone start. His hypothesis is that tactile contact

has the same effect. " Mothers don't lick their babies, but they hold

them. And they probably tickle them and touch them and stroke them

and rub their hair. "

 

There is already indirect evidence that parental care influences how

future adults will respond to stress. In one study, young men and

women who said their mothers and fathers did a poor job in raising

them became much more stressed in an experiment designed to test how

they react under pressure. They were asked to perform rapid mental

arithmetic problems, and a buzzer would go off every time they were

wrong.

 

Now Dr. Meaney and his number of colleagues across the country are

looking for evidence of genetic changes related to human parenting,

from touching to more subtle interactions. They want to know how

parental care affects genes in human babies.

 

Does the kind of parents you have influence your genes, causing you

to produce different amounts of the proteins involved in stress and

learning and behaviour? And do those changes make a major difference

in children's lives? Most intriguing to Dr. Meaney is the question

of whether early damage can be reversed.

 

To find answers, they are turning to a group of depressed and

pregnant women in Hamilton. Mothers suffering from severe depression

often have trouble bonding with the children and tend not to respond

as quickly to their cues.

 

" Some don't bond, some don't bond well. Some of these moms will do

the instrumental things, but not the affectionate things. They will

feed, bathe, change [diapers]. But there is nothing on their faces, "

says Dr. Meir Steiner, a McMaster University researcher. " Some women

are so irritable, they cannot tolerate the behaviour of the baby,

the noise, the crying. They say they want to crawl out of their

skin. "

 

In an ambitious experiment called the MAVAN project, for Maternal

Adversity Vulnerability and Neurodevelopment, Drs. Steiner, Meaney

and others will follow both the depressed mothers and a control

group of healthy mothers before they give birth, and closely monitor

the moms and their children for more than four years afterwards. The

$4-million study is funded by the Canadian Institutes of Health

Research.

 

All of the depressed women will be offered treatment -- it wouldn't

be ethical to withhold it. But past studies have shown that a third

are likely not to respond. When the babies are born, they will be

tested for 22 genes that may make them vulnerable to aggressive or

anti-social behaviour as well as learning disabilities such as

attention deficit disorder. Researchers suspect these genes are

affected by parental care. Their goal is to find out whether a child

with a genetic vulnerability and a depressed mother will get

into more trouble than a child with similar genes but with a healthy

mother.

 

The most obvious example is fetal alcohol syndrome: Babies

born to mothers who drank heavily during pregnancy have smaller,

less developed brains.

 

Researchers also know that women who smoke, drink, are highly

stressed or are deprived of protein during pregnancy are more likely

to give birth to babies with low birth weights. These babies are

more prone to a variety of health problems, including high blood

pressure, and are more at risk for attention deficit disorder.

 

The second group that will be studied is in Montreal, selected from

a group of 5,000 children who took part in an earlier study on pre-

term labour. Some were born with low birth weights, while others

were of average size. These children will also undergo genetic

tests. The researchers already have reams of data about the mothers'

pregnancies, and will go on to monitor how they interact with their

children.

 

These data should show, for example, whether low-birth-weight babies

genetically predisposed to attention deficit fare better with

attentive mothers than similar children whose mothers are less

engaged.

 

New rat studies in Dr. Meaney's lab certainly offer hope that there

will be a difference. Researchers have found that poor maternal care

means that a number of genes in the brain involved in memory don't

get activated. But if you take those rats -- including those who are

past puberty -- and put them in an enriched environment, the genes

are turned on.

 

" You really, literally can reverse it, " he says.

 

Not only that, but if you have a female rat pup born to a low-

licking mother removed to live with a high-licking surrogate mother,

she will become a high-licking mother when she grows up. On the

other hand, if a high-licking mother is subjected to high stress,

she will pay less attention to her offspring.

 

However, Dr. Meaney emphasizes that the consequences of less-

attentive maternal care may not always be bad. Dr. Meaney's theory

is that the low-licking rats are at the bottom of the social

hierarchy, and as a result lead more stressful lives. In this

situation, helping offspring develop a good strong response to

stress may be a good thing. For example, the extra cortisol makes

the animals less aggressive and so less likely to get into fights.

It may be nature's way of helping the animals adapt to their future

environment.

 

In human studies, researchers in Montreal have found that in poorer

neighbourhoods with high crime rates, the boys who don't get into

much trouble actually have higher levels of cortisol than boys who

join gangs and begin stealing cars. Their stress levels seem to make

them more fearful and less likely to partake in risky business.

 

There are many other examples in the natural world of organisms

preparing their offspring for the specific environmental challenges

they will face. Radishes that are harassed by caterpillars produce

chemicals that are toxic to the insects, and grow spines on their

leaves. Plants that come from those radishes' seeds will also have

spiny leaves, and high levels of the toxic chemicals.

 

" We are looking at something that happens pretty generally across all

biology, " says Dr. Meaney. " Nature didn't rip up the blueprint when

it got to us. "

 

Much remains unknown, but Dr. Meaney believes the mechanism he

identified in the gene that restricts cortisol production in rats is

the same one at work in all cases where a parent influences the

expression of a gene. His work is part of the burgeoning field of

epigenetics -- the study of changes to genetic material that don't

involve altering the sequence of the four nucleotides -- C, G, T and

A -- that make up our genetic code.

 

" The whole world knows it really isn't just a question of genes, or

just a question of environment, " says Dr. Meaney. " It is the

interaction between the two of them. Fine, it makes sense

intuitively, but what does it mean when the environment interacts

with the gene. How? That is what we are showing. "

 

- Anne McIlroy is The Globe and Mail's science reporter.

 

Stress test Researchers have evidence that stress may actually start

to harm children in the womb. Among infants and toddlers, high and

chronic levels of stress can make learning more difficult, perhaps

even shrinking the part of the brain associated with memory. Stress

may also make kids fat.

 

Experts say the following may be signs a child is unduly stressed.

If the problem persists more than a few weeks, medical assistance

may be in order.

 

Physical problems: Stomach trouble, headaches or difficulty falling

asleep can be signs of childhood stress.

 

Worrying out loud: A stressed youngster may seek continual

reassurance, and ask parents repeatedly about hypothetical disasters

(for instance, their divorce or death).

 

Avoiding situations: If children don't want to go to class or shun

after-school activities, it may be because they find those

environments overly stressful. -- Anne McIlroy

 

Mother nature Can parents help their offspring adapt to the

particular environment they will face? Plants and animals do.

 

Radishes When infested by caterpillars; radish plants grow spiny

leaves and produce a natural insecticide. The seeds will produce

radishes that already have those defences.

 

Skink lizards If you expose a skink to the smell of its predators, a

snake, it will become hypersensitive to that smell. The offspring of

that skink will be four times more sensitive to the smell of snake

than their skink babies

 

Rats Rat pups born to mothers that do not lick them very much

develop high levels of the stress hormone, cortisol. Researchers

suspect these rats are born into a lower status in the social

hierarchy and a strong stress response may help them avoid dangerous

confrontations.

 

© Copyright 2004 Bell Globemedia Publishing Inc. .

http://www.theglobeandmail.com/servlet/story/RTGAM.

20040405.wstartzero0405/BNStory/specialScienceandHealth/