Nature Neuroscience5, 933 - 934 (2002)
Published online: 16 September 2002; | doi:10.1038/nn922
Sex chromosome genes directly affect brain sexual differentiation
Laura L. Carruth1, Ingrid Reisert2
& Arthur P. Arnold1
1
Department of Physiological Science and Laboratory of Neuroendocrinology, Brain Research Institute, University of California, Los Angeles, California 90095, USA
2
Abteilung Anatomie und Zellbiologie der Universität Ulm, Albert-Einstein-Allee 11, 89081 Ulm, Germany
Correspondence should be addressed to Arthur P. Arnold arnold@ucla.edu
Sex differences in the brain are caused by differences in gonadal secretions: higher levels of testosterone during fetal and neonatal life cause the male brain to develop differently than the female brain1. In contrast, genes encoded on the sex chromosomes are not thought to contribute directly to sex differences in brain development, even though male (XY) cells express Y-chromosome genes that are not present in female (XX) cells, and XX cells may have a higher dose of some X-chromosome genes. Using mice in which the genetic sex of the brain (XX versus XY) was independent of gonadal phenotype (testes versus ovaries), we found that XY and XX brain cells differed in phenotype, indicating that a brain cell's complement of sex chromosomes may contribute to its sexual differentiation.
