title: Cellular mechanisms underlying the effects of an early experience on cognitive abilities and affective states.
abstract: In the present study we investigated the effects of neonatal handling, an animal model of early experience, on spatial learning and memory, on hippocampal glucocorticoid (GR), mineralocorticoid (MR) and type 1A serotonin (5-HT1A) receptors, as well as brain derived neurotrophic factor (BDNF), and on circulating leptin levels, of male rats.
  
  
  METHODS
  Spatial learning and memory following an acute restraint stress (30 min) were assessed in the Morris water maze. Hippocampal GR, MR and BDNF levels were determined immunocytochemically. 5-HT1A receptors were quantified by in vitro binding autoradiography. Circulating leptin levels, following a chronic forced swimming stress, were measured by radioimmunoassay (RIA). Data were statistically analyzed by analysis of variance (ANOVA).
  
  
  RESULTS
  Neonatal handling increased the ability of male rats for spatial learning and memory. It also resulted in increased GR/MR ratio, BDNF and 5-HT1A receptor levels in the hippocampus. Furthermore, leptin levels, body weight and food consumption during chronic forced swimming stress were reduced as a result of handling.
  
  
  CONCLUSIONS
  Neonatal handling is shown to have a beneficial effect in the males, improving their cognitive abilities. This effect on behavior could be mediated by the handling-induced increase in hippocampal GR/MR ratio and BDNF levels. The handling-induced changes in BDNF and 5-HT1A receptors could underlie the previously documented effect of handling in preventing "depression". Furthermore, handling is shown to prevent other maladaptive states such as stress-induced hyperphagia, obesity and resistance to leptin.
authors.affiliation: Lab. Biology-Biochemistry, Dept. Basic Sciences, Faculty of Nursing, University of Athens, Papadiamantopoulou 123, 115 27 Athens, Greece.
authors.forename: Efstathios
authors.initials: E
authors.lastname: Garoflos
authors.affiliation: Lab. Biology-Biochemistry, Dept. Basic Sciences, Faculty of Nursing, University of Athens, Papadiamantopoulou 123, 115 27 Athens, Greece.
authors.forename: Theofanis
authors.initials: T
authors.lastname: Panagiotaropoulos
authors.affiliation: Lab. Biology-Biochemistry, Dept. Basic Sciences, Faculty of Nursing, University of Athens, Papadiamantopoulou 123, 115 27 Athens, Greece.
authors.forename: Stavroula
authors.initials: S
authors.lastname: Pondiki
authors.affiliation: Lab. Biology-Biochemistry, Dept. Basic Sciences, Faculty of Nursing, University of Athens, Papadiamantopoulou 123, 115 27 Athens, Greece.
authors.forename: Antonios
authors.initials: A
authors.lastname: Stamatakis
authors.affiliation: Lab. Biology-Biochemistry, Dept. Basic Sciences, Faculty of Nursing, University of Athens, Papadiamantopoulou 123, 115 27 Athens, Greece.
authors.forename: Eleni
authors.initials: E
authors.lastname: Philippidis
authors.affiliation: Lab. Biology-Biochemistry, Dept. Basic Sciences, Faculty of Nursing, University of Athens, Papadiamantopoulou 123, 115 27 Athens, Greece.
authors.forename: Fotini
authors.initials: F
authors.lastname: Stylianopoulou