title: Early-life environmental intervention may increase the number of neurons, astrocytes, and cellular proliferation in the hippocampus of rats.
abstract: Neonatal handling reduces the stress response in adulthood due to a feedback mechanism. The present study analyzed the effects of repeated neonatal environmental intervention (daily handling during the first 10 days after birth) on neuron-, astroglial cell density, and cellular proliferation of the hippocampal (CA1, CA2, and CA3) pyramidal cell layers in female rats. Pups were divided into two groups, nonhandled and handled, which were submitted to repeated handling sessions between postnatal days 1 and 10. Histological and immunohistochemical procedures were used to determine changes in neuron density, astroglial cell density, and cellular proliferation. We found an increase in neuron density in each pyramidal cell layer of the hippocampus (CA1, CA2, and CA3) in female rats (11 and 90 day old) that were handled during the neonatal period. Furthermore, we found an increase in astroglial cell density in both hemispheres of the brain in the handled group. Finally, we observed an increase in cellular proliferation in both hippocampi (CA1, CA2, and CA3) of the brain in female pups (11 days old) handled during the neonatal period. This study demonstrates that an early-life environmental intervention may induce morphological changes in a structure involved with several functions, including the stress response. The results of the current study suggest that neonatal handling may influence the animals' responses to environmental adversities later in life.
authors.affiliation: Departamento de Ciências Morfológicas, Anatomia Humana, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Campus Universitário, Trindade, Florianópolis, SC, Brazil. ijawinkel@yahoo.com.br
authors.forename: Elisa C
authors.initials: EC
authors.lastname: Winkelmann-Duarte
authors.forename: Camila B
authors.initials: CB
authors.lastname: Padilha-Hoffmann
authors.forename: Daniel F
authors.initials: DF
authors.lastname: Martins
authors.forename: Artur F S
authors.initials: AF
authors.lastname: Schuh
authors.forename: Marilda C
authors.initials: MC
authors.lastname: Fernandes
authors.forename: Ricardo
authors.initials: R
authors.lastname: Santin
authors.forename: Suelen
authors.initials: S
authors.lastname: Merlo
authors.forename: Gilberto L
authors.initials: GL
authors.lastname: Sanvitto
authors.forename: Aldo B
authors.initials: AB
authors.lastname: Lucion
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001253:Astrocytes / Q000166:cytology / Q000502:physiology*; D002452:Cell Count; D049109:Cell Proliferation; D004780:Environment, Controlled; D005260:Female; D006624:Hippocampus / Q000166:cytology* / Q000254:growth & development*; D008297:Male; D055495:Neurogenesis / Q000502:physiology*; D009474:Neurons / Q000166:cytology / Q000502:physiology*; D011247:Pregnancy; D051381:Rats; D017208:Rats, Wistar