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Behavioral effects of methylazoxymethanol-induced micrencephaly
S A Ferguson1, F D Racey, M G Paule
1Division of Neurotoxicology, National Center for Toxicological Research, U.S. Food and Drug Administration, Jefferson, Arkansas 72079.
Behavioral Neuroscience
|December 1, 1993
Summary
Methylazoxymethanol acetate (MAM) induced micrencephaly in rats, resulting in significant brain weight reduction. Despite this, MAM-treated rats showed remarkable functional sparing, with behavioral abnormalities less pronounced than expected.
Area of Science:
- Neuroscience
- Developmental Biology
- Behavioral Science
Background:
- Reports of functionally normal humans with micrencephaly or cortical hypoplasia.
- Micrencephaly is a condition characterized by an abnormally small brain.
Purpose of the Study:
- To investigate the behavioral effects of induced micrencephaly in a rat model.
- To compare behavioral outcomes in micrencephalic rats with human clinical findings.
Main Methods:
- Administration of methylazoxymethanol acetate (MAM) to pregnant rats on gestational day 14.
- Assessment of offspring behavior through various tests from weaning into adulthood.
- Measurement of forebrain weight in MAM-treated and control rats.
Main Results:
- MAM-treated rats exhibited significantly reduced forebrain weight (less than 2/3 of controls).
- Increased hyperactivity was observed only in prolonged tests or after amphetamine administration.
- MAM rats displayed hypoactivity in certain conditions, including light avoidance, and appeared hyperreactive to stimuli.
- Behavioral changes were less severe than the reduction in brain weight.
Conclusions:
- Induced micrencephaly in rats demonstrates significant functional sparing, similar to human clinical observations.
- Behavioral abnormalities in micrencephalic rats are less pronounced than the structural brain deficits.
- The study highlights the brain's capacity for compensation despite significant developmental insults.