Neonatal testosterone and handedness in yearling rhesus monkeys (Macaca mulatta).
This study investigated the relationship between neonatal testosterone (T) and hand bias in young rhesus monkeys (Macaca mulatta). Subjects (n = 8 per group) included: neonatally androgen-suppressed males, using a Nal-Lys gonadotropin releasing hormone (GnRH) antagonist (Antide); androgen-suppressed males receiving T replacement by a long-acting T preparation (CDB); control males; and control females. Antide suppressed T to the female range, whereas CDB replacement produced supranormal levels. Visually guided reaching, in a social context, showed a population-level left-hand bias. Males with elevated T did not show a stronger left-hand bias than males with normal T, but did show a stronger bias for the preferred hand whether left or right. Males with Antide-suppressed T showed an intermediate degree of hand bias. Results suggest that high neonatal T levels affect laterality and raise the possibility that GnRH analogues influence brain development. These data suggest a broad influence of the CNS-pituitary-testicular axis on brain asymmetries and provide support for an early neonatal period of T-influenced brain differentiation.
Drea
C M
CM
Department of Physiology, Morehouse School of Medicine, Atlanta, GA 30310, USA.
Wallen
K
K
Akinbami
M A
MA
Mann
D R
DR
D000818:Animals; D000831:Animals, Newborn / Q000502:physiology*; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D008253:Macaca mulatta; D008297:Male; D012737:Sex Factors; D013739:Testosterone / Q000097:blood*
D013739:Testosterone