title: Neonatal Inhibition of DNA Methylation Alters Cell Phenotype in Sexually Dimorphic Regions of the Mouse Brain.
abstract: Many of the best-studied neural sex differences relate to differences in cell number and are due to the hormonal control of developmental cell death. However, several prominent neural sex differences persist even if cell death is eliminated. We hypothesized that these may reflect cell phenotype "decisions" that depend on epigenetic mechanisms, such as DNA methylation. To test this, we treated newborn mice with the DNA methyltransferase (DNMT) inhibitor zebularine, or vehicle, and examined two sexually dimorphic markers at weaning. As expected, control males had more cells immunoreactive for calbindin-D28k (CALB) in the medial preoptic area (mPOA) and fewer cells immunoreactive for estrogen receptor α (ERα) in the ventrolateral portion of the ventromedial nucleus of the hypothalamus (VMHvl) and the mPOA than did females. Neonatal DNMT inhibition markedly increased CALB cell number in both sexes and ERα cell density in males; as a result, the sex differences in ERα in the VMHvl and mPOA were completely eliminated in zebularine-treated animals. Zebularine treatment did not affect developmental cell death or the total density of Nissl-stained cells at weaning. Thus, a neonatal disruption of DNA methylation apparently has long-term effects on the proportion of cells expressing CALB and ERα, and some of these effects are sex specific. We also found that sex differences in CALB in the mPOA and ERα in the VMHvl persist in mice with a neuron-specific depletion of either Dnmt1 or Dnmt3b, indicating that neither DNMT alone is likely to be required for the sexually dimorphic expression of these markers.
authors.affiliation: Neuroscience Institute and Center for Behavioral Neuroscience, Georgia State University, Atlanta, Georgia 30302.
authors.forename: Morgan
authors.initials: M
authors.lastname: Mosley
authors.affiliation: Neuroscience Institute and Center for Behavioral Neuroscience, Georgia State University, Atlanta, Georgia 30302.
authors.forename: Jill
authors.initials: J
authors.lastname: Weathington
authors.affiliation: Neuroscience Institute and Center for Behavioral Neuroscience, Georgia State University, Atlanta, Georgia 30302.
authors.forename: Laura R
authors.initials: LR
authors.lastname: Cortes
authors.affiliation: Department of Biology, Neuroscience Institute and Center for Obesity Reversal, Georgia State University, Atlanta, Georgia 30302.
authors.forename: Emily
authors.initials: E
authors.lastname: Bruggeman
authors.affiliation: Neuroscience Institute and Center for Behavioral Neuroscience, Georgia State University, Atlanta, Georgia 30302.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Castillo-Ruiz
authors.affiliation: Department of Biology, Neuroscience Institute and Center for Obesity Reversal, Georgia State University, Atlanta, Georgia 30302.
authors.forename: Bingzhong
authors.initials: B
authors.lastname: Xue
authors.affiliation: Neuroscience Institute and Center for Behavioral Neuroscience, Georgia State University, Atlanta, Georgia 30302.
authors.forename: Nancy G
authors.initials: NG
authors.lastname: Forger
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001921:Brain / Q000166:cytology / Q000187:drug effects* / Q000254:growth & development; D003562:Cytidine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000037:antagonists & inhibitors*; D019175:DNA Methylation / Q000187:drug effects*; D015536:Down-Regulation / Q000187:drug effects; D005260:Female; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009474:Neurons / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D010641:Phenotype; D012727:Sex Characteristics; D019849:Sex Determination Processes / Q000187:drug effects / Q000235:genetics; D013997:Time Factors
chemical_list: D003562:Cytidine; C009131:pyrimidin-2-one beta-ribofuranoside; D000076123:DNA (Cytosine-5-)-Methyltransferase 1; D004248:DNA (Cytosine-5-)-Methyltransferases; C000619381:Dnmt1 protein, mouse