FOR IMMEDIATE RELEASE
Contact:
Donna Krupa
703.527.7357 (direct
dial)
703.967.2751 (cell) or
djkrupa1@aol.com
DIFFERENCES IN RESPONSE TO AMPHETAMINES FOUND BETWEEN
MALES AND FEMALES PRE-PUBERTY
While some Internet sites advise
parents that stimulants have the same effect on children as adults, new
research on mice indicates this is not the case. Researchers conclude that
further differentiation must be made based on gender
PITTSBURGH, Pa. -- Amphetamine-like drugs are
used to treat attention-deficit-hyperactivity disorder (ADHD). These
stimulants help people with ADHD learn. They also improve the ability to
concentrate, make one less easily distracted, make one less impulsive, and
improve one’s memory. Children with ADHD are provided drugs like Ritalin
upon the recommendation of a physician. Yet, there is little in the research
that suggests male and female children may exhibit biological differences in
the responses to these stimulants.
Newly released research findings from experiments with
mice have established a maturational response to drugs between the known
postnatal (up to seven-10 days in rats and mice) and pubertal (around
five-six weeks in rats and mice) stages. The findings reveal that
differences between males and females in response to drugs begins at an
earlier stage than previously believed. During the period after birth,
female mice displayed a higher sensitivity to amphetamine well before the
onset of puberty, but also well after the early postnatal determination of
hormone regulation.
These findings offer a new understanding of male/female
differences in brain function and the response to stimuli.
The previous literature focused on two general stages
of maturation: (1) The early postnatal "critical period" when sex
differences in later hormonal regulation are established (for comparison,
mice are born at a stage of brain maturation roughly comparable with a
seven-month human fetus) and (2) The time of puberty when sex differences in
structure, function, and behavior are manifested.
The authors of the current study, “Differential Sex
Effects on Exploratory Behavior in Young Mice Following Selective Monomine
Depletion" are Cecile Goodrich Ph.D. (now at Drexel University) and Valerie
Robinson. Their findings are being presented at Genomes and Hormones:
An Integrative Approach to Gender Differences in Physiology, an American
Physiological Society (APS) conference being held October 17-20, 2001, at
the Westin Convention Center, Pittsburgh, Pa.
Methodology
To conduct the study, the investigators depleted brain
transmitters from the brains of lab mice -- either serotonin (a
vascoconstrictor) or catecholamines, (Pyrocatechols
with an alkylamine side chain definition) both of which are major
elements in response to stress. Behavior was observed at six ages (14, 15,
17, 19, 21, or 28 days). The mice littermates received either p-chlorophenylalanine
(pCPA) to deplete the seratonin or a saline solution. Other litters
received either a-methyl-p-tyrosine
(AMPT) to deplete the catecholarmines or olive oil (for the control group).
Results
Locomotion was observed 24 hours after administration.
Locomotion and auditory startle responses were assessed. Analysis revealed
that:
v
The female mice treated with pCPA showed significant increases
at 19 and 21 days in locomotive ability; males displayed no changes.
v
PCPA females displayed significant increases in startle
behavior at 14 days; males had no significant changes.
v
Female mice treated with AMPT had significant decreases in
locomotion at 21 and 28 days; male mice decreased their activity at 21 and
28 days. Females in this group displayed significant decreases in startle
behavior at 15, 19 and 21 days, whereas males showed no changes from the
control group.
Conclusions
The two transmitter systems (serotonin and
catecholamines) are known to have different patterns of maturation. This
new information on gender differences suggests that additional research may
be required to determine the effects of administering stimulants to young
boys and girls prior to puberty.
Certain Internet websites advise parents that
stimulants have the same effect on children as adults. That is not the case;
now further differentiation must be made in considering gender. These
animal tests could be an important first step in offering responsible
guidance.
-end-
The
American Physiological Society (APS) was founded in 1887 to foster basic and
applied science, much of it relating to human health. The Bethesda,
MD-based Society has more than 10,000 members and publishes 3,800 articles
in its 14 peer-reviewed journals every year.
***
Editor’s Note: To receive a copy of the abstracts, to interview speakers or
for more information, contact Donna Krupa at 703.527.7357(direct dial),
703.967.2751 (cell) or djkrupa1@aol.com.
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