title: Environmental tobacco smoke in the early postnatal period induces impairment in brain myelination.
abstract: Environmental tobacco smoke (ETS) is associated with high morbidity and mortality, mainly in children. However, few studies focus on the brain development effects of ETS exposure. Myelination mainly occurs in the early years of life in humans and the first three postnatal weeks in rodents and is sensitive to xenobiotics exposure. This study investigated the effects of early postnatal ETS exposure on myelination. BALB/c mice were exposed to ETS generated from 3R4F reference research cigarettes from the third to the fourteenth days of life. The myelination of nerve fibers in the optic nerve by morphometric analysis and the levels of Olig1 and myelin basic protein (MBP) were evaluated in the cerebellum, diencephalon, telencephalon, and brainstem in infancy, adolescence, and adulthood. Infant mice exposed to ETS showed a decrease in the percentage of myelinated fibers in the optic nerve, compared with controls. ETS induced a decrease in Olig1 protein levels in the cerebellum and brainstem and an increase in MBP levels in the cerebellum at infant. It was also found a decrease in MBP levels in the telencephalon and brainstem at adolescence and in the cerebellum and diencephalon at adulthood. The present study demonstrates that exposure to ETS, in a critical phase of development, affects the percentage of myelinated fibers and myelin-specific proteins in infant mice. Although we did not observe differences in the morphological analysis in adolescence and adulthood, there was a decrease in MBP levels in distinctive brain regions suggesting a delayed effect in adolescence and adulthood.
authors.affiliation: Department of Clinical and Toxicological Analysis, Faculdade de Ciências Farmacêuticas, School of Pharmaceutical Sciences, University of São Paulo, Av Prof Lineu Prestes, 580 Bl 13B, São Paulo, SP, CEP 05508-000, Brazil.
authors.forename: Larissa H
authors.initials: LH
authors.lastname: Torres
authors.affiliation: Department of Pathology, School of Medicine, University of São Paulo, São Paulo, Brazil.
authors.forename: Raquel
authors.initials: R
authors.lastname: Annoni
authors.affiliation: Department of Clinical and Toxicological Analysis, Faculdade de Ciências Farmacêuticas, School of Pharmaceutical Sciences, University of São Paulo, Av Prof Lineu Prestes, 580 Bl 13B, São Paulo, SP, CEP 05508-000, Brazil.
authors.forename: Natalia T
authors.initials: NT
authors.lastname: Balestrin
authors.affiliation: Department of Clinical and Toxicological Analysis, Faculdade de Ciências Farmacêuticas, School of Pharmaceutical Sciences, University of São Paulo, Av Prof Lineu Prestes, 580 Bl 13B, São Paulo, SP, CEP 05508-000, Brazil.
authors.forename: Priscila L
authors.initials: PL
authors.lastname: Coleto
authors.affiliation: Department of Clinical and Toxicological Analysis, Faculdade de Ciências Farmacêuticas, School of Pharmaceutical Sciences, University of São Paulo, Av Prof Lineu Prestes, 580 Bl 13B, São Paulo, SP, CEP 05508-000, Brazil.
authors.forename: Stephanie O
authors.initials: SO
authors.lastname: Duro
authors.affiliation: Department of Clinical and Toxicological Analysis, Faculdade de Ciências Farmacêuticas, School of Pharmaceutical Sciences, University of São Paulo, Av Prof Lineu Prestes, 580 Bl 13B, São Paulo, SP, CEP 05508-000, Brazil.
authors.forename: Raphael C T
authors.initials: RC
authors.lastname: Garcia
authors.affiliation: Department of Clinical Pathology, School of Medicine, University of São Paulo, São Paulo, Brazil.
authors.forename: Maurílio
authors.initials: M
authors.lastname: Pacheco-Neto
authors.affiliation: Department of Pathology, School of Medicine, University of São Paulo, São Paulo, Brazil.
authors.forename: Thais
authors.initials: T
authors.lastname: Mauad
authors.affiliation: Department of Pharmacology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil.
authors.forename: Rosana
authors.initials: R
authors.lastname: Camarini
authors.affiliation: Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil.
authors.forename: Luiz R G
authors.initials: LR
authors.lastname: Britto
authors.affiliation: Department of Clinical and Toxicological Analysis, Faculdade de Ciências Farmacêuticas, School of Pharmaceutical Sciences, University of São Paulo, Av Prof Lineu Prestes, 580 Bl 13B, São Paulo, SP, CEP 05508-000, Brazil. tmarcour@usp.br.
authors.forename: Tania
authors.initials: T
authors.lastname: Marcourakis
mesh_terms: D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn; D051792:Basic Helix-Loop-Helix Proteins / Q000378:metabolism; D001921:Brain / Q000473:pathology*; D004781:Environmental Exposure / Q000009:adverse effects*; D051379:Mice; D008807:Mice, Inbred BALB C; D004676:Myelin Basic Protein / Q000378:metabolism; D009186:Myelin Sheath / Q000473:pathology*; D009900:Optic Nerve / Q000473:pathology; D014028:Tobacco Smoke Pollution / Q000009:adverse effects*
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D004676:Myelin Basic Protein; D014028:Tobacco Smoke Pollution; C494786:Olig1 protein, mouse
keywords: Brain development; Environmental tobacco smoke; Myelination