title: Sex differences in microglial colonization of the developing rat brain.
abstract: Microglia are the resident immune cells within the brain and their production of immune molecules such as cytokines and chemokines is critical for the processes of normal brain development including neurogenesis, axonal migration, synapse formation, and programmed cell death. Notably, sex differences exist in many of these processes throughout brain development; however, it is unknown whether a sex difference concurrently exists in the colonization, number, or morphology of microglia within the developing brain. We demonstrate for the first time that the number and morphology of microglia throughout development is dependent upon the sex and age of the individual, as well as the brain region of interest. Males have overall more microglia early in postnatal development [postnatal day (P) 4], whereas females have more microglia with an activated/amoeboid morphology later in development, as juveniles and adults (P30-60). Finally, gene expression of a large number of cytokines, chemokines and their receptors shifts dramatically over development, and is highly dependent upon sex. Taken together, these data warrant further research into the role that sex-dependent mechanisms may play in microglial colonization, number, and function, and their potential contribution to neural development, function, or potential dysfunction.
authors.affiliation: Department of Psychology and Neuroscience, Duke University, Durham, North Carolina, USA. jaclyn.schwarz@duke.edu
authors.forename: Jaclyn M
authors.initials: JM
authors.lastname: Schwarz
authors.forename: Paige W
authors.initials: PW
authors.lastname: Sholar
authors.forename: Staci D
authors.initials: SD
authors.lastname: Bilbo
mesh_terms: D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn; D001921:Brain / Q000166:cytology* / Q000254:growth & development*; D002135:Calcium-Binding Proteins / Q000235:genetics / Q000378:metabolism; D002452:Cell Count; D054370:Chemokine CXCL9 / Q000378:metabolism; D004622:Embryo, Mammalian; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005434:Flow Cytometry; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D016753:Interleukin-10 / Q000378:metabolism; D053583:Interleukin-1beta / Q000378:metabolism; D008297:Male; D008840:Microfilament Proteins / Q000235:genetics / Q000378:metabolism; D017628:Microglia / Q000502:physiology*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D012727:Sex Characteristics
chemical_list: C100745:Aif1 protein, rat; C505723:CXCL9 protein, rat; D002135:Calcium-Binding Proteins; D054370:Chemokine CXCL9; D053583:Interleukin-1beta; D008840:Microfilament Proteins; D012333:RNA, Messenger; D016753:Interleukin-10