Growth of white matter in the adolescent brain: role of testosterone and androgen receptor.
The growth of white matter during human adolescence shows a striking sexual dimorphism; the volume of white matter increases with age slightly in girls and steeply in boys. Here, we provide evidence supporting the role of androgen receptor (AR) in mediating the effect of testosterone on white matter. In a large sample of typically developing adolescents (n = 408, 204 males), we used magnetic resonance imaging and acquired T1-weighted and magnetization transfer ratio (MTR) images. We also measured plasma levels of testosterone and genotyped a functional polymorphism in the AR gene, namely the number of CAG repeats in exon 1 believed to be inversely proportional to the AR transcriptional activity. We found that the testosterone-related increase of white-matter volume was stronger in male adolescents with the lower versus higher number of CAG repeats in the AR gene, with testosterone explaining, respectively, 26 and 8% of variance in the volume. The MTR results suggest that this growth is not related to myelination; the MTR decreased with age in male adolescents. We speculate that testosterone affects axonal caliber rather than the thickness of the myelin sheath.
Perrin
Jennifer S
JS
Brain and Body Centre, University of Nottingham, Nottingham NG72RD, United Kingdom.
Hervé
Pierre-Yves
PY
Leonard
Gabriel
G
Perron
Michel
M
Pike
G Bruce
GB
Pitiot
Alain
A
Richer
Louis
L
Veillette
Suzanne
S
Pausova
Zdenka
Z
Paus
Tomás
T
D000293:Adolescent; D000375:Aging / Q000378:metabolism; D001921:Brain / Q000166:cytology / Q000254:growth & development* / Q000378:metabolism*; D048429:Cell Size; D002648:Child; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009186:Myelin Sheath / Q000378:metabolism / Q000648:ultrastructure; D009413:Nerve Fibers, Myelinated / Q000378:metabolism* / Q000648:ultrastructure; D009434:Neural Pathways / Q000166:cytology / Q000254:growth & development / Q000378:metabolism; D011110:Polymorphism, Genetic / Q000235:genetics; D011944:Receptors, Androgen / Q000235:genetics / Q000378:metabolism*; D012727:Sex Characteristics; D013739:Testosterone / Q000097:blood* / Q000502:physiology; D018911:Trinucleotide Repeats / Q000235:genetics
D011944:Receptors, Androgen; D013739:Testosterone
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