title: Temporary Depletion of Microglia during the Early Postnatal Period Induces Lasting Sex-Dependent and Sex-Independent Effects on Behavior in Rats.
abstract: Microglia are the primary immune cells of the brain and function in multiple ways to facilitate proper brain development. However, our current understanding of how these cells influence the later expression of normal behaviors is lacking. Using the laboratory rat, we administered liposomal clodronate centrally to selectively deplete microglia in the developing postnatal brain. We then assessed a range of developmental, juvenile, and adult behaviors. Liposomal clodronate treatment on postnatal days 0, 2, and 4 depleted microglia with recovery by about 10 days of age and induced a hyperlocomotive phenotype, observable in the second postnatal week. Temporary microglia depletion also increased juvenile locomotion in the open field test and decreased anxiety-like behaviors in the open field and elevated plus maze. These same rats displayed reductions in predator odor-induced avoidance behavior, but increased their risk assessment behaviors compared with vehicle-treated controls. In adulthood, postnatal microglia depletion resulted in significant deficits in male-specific sex behaviors. Using factor analysis, we identified two underlying traits-behavioral disinhibition and locomotion-as being significantly altered by postnatal microglia depletion. These findings further implicate microglia as being critically important to the development of juvenile and adult behavior.
authors.affiliation: Program in Neuroscience, University of Maryland School of Medicine , Baltimore, MD 21201.
authors.forename: Jonathan W
authors.identifier: 0000-0003-2990-6765
authors.initials: JW
authors.lastname: VanRyzin
authors.affiliation: Department of Pharmacology, University of Maryland School of Medicine , Baltimore, MD 21201.
authors.forename: Stacey J
authors.identifier: 0000-0001-5540-4027
authors.initials: SJ
authors.lastname: Yu
authors.affiliation: Department of Pharmacology, University of Maryland School of Medicine , Baltimore, MD 21201.
authors.forename: Miguel
authors.identifier: 0000-0001-7863-5880
authors.initials: M
authors.lastname: Perez-Pouchoulen
authors.affiliation: Program in Neuroscience, University of Maryland School of Medicine, Baltimore, MD 21201; Department of Pharmacology, University of Maryland School of Medicine, Baltimore, MD 21201.
authors.forename: Margaret M
authors.identifier: 0000-0003-2243-4726
authors.initials: MM
authors.lastname: McCarthy
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001007:Anxiety / Q000503:physiopathology; D001362:Avoidance Learning / Q000502:physiology; D001522:Behavior, Animal / Q000502:physiology*; D001921:Brain / Q000254:growth & development* / Q000473:pathology / Q000502:physiology*; D004002:Clodronic Acid; D005260:Female; D007266:Inhibition, Psychological; D008081:Liposomes; D008297:Male; D017628:Microglia / Q000473:pathology / Q000502:physiology*; D023421:Models, Animal; D009043:Motor Activity / Q000502:physiology; D011235:Predatory Behavior; D017207:Rats, Sprague-Dawley; D012309:Risk-Taking; D012727:Sex Characteristics
chemical_list: D008081:Liposomes; D004002:Clodronic Acid
keywords: behavior; liposomal clodronate; microglia; postnatal development