title: Maternal separation attenuates the effect of adolescent social isolation on HPA axis responsiveness in adult rats.
abstract: Adverse early life experiences that occur during childhood and adolescence can have negative impacts on behavior later in life. The main goal of our work was to assess how the association between stressful experiences during neonatal and adolescent periods may influence stress responsiveness and brain plasticity in adult rats. Stressful experiences included maternal separation and social isolation at weaning. Three hours of separation from the pups (3-14 PND) significantly increased frequencies of maternal arched-back nursing and licking-grooming across the first two weeks postpartum. Separation also induced a long-lasting increase in dams blood levels of corticosterone. Maternal separation did not modify brain and plasma allopregnanolone and corticosterone levels in adult offspring, but they demonstrate partial recovery from the reduction induced by social isolation during adolescence. Moreover, the enhancement of corticosterone and allopregnanolone levels induced by foot shock stress in socially isolated animals that were subjected to maternal separation was markedly reduced with respect to that observed in animals that were just socially isolated. All experimental groups showed a significant reduction of BDNF and Arc protein expression in the hippocampus. However, the reduction of BDNF observed in animals that were maternally separated and subjected to social isolation was less significantly pronounced than in animals that were just socially isolated. The results sustained the mismatch hypothesis stating that aversive experiences early in life trigger adaptive processes, thereby rendering an individual to be better adapted to aversive challenges later in life.
authors.affiliation: Department of Life and Environmental Sciences, University of Cagliari, Cagliari 09100, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Biggio
authors.affiliation: C.N.R., Institute of Neuroscience, Cagliari 09100, Italy.
authors.forename: M G
authors.initials: MG
authors.lastname: Pisu
authors.affiliation: Department of Life and Environmental Sciences, University of Cagliari, Cagliari 09100, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Garau
authors.affiliation: Department of Life and Environmental Sciences, University of Cagliari, Cagliari 09100, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Boero
authors.affiliation: Department of Life and Environmental Sciences, University of Cagliari, Cagliari 09100, Italy.
authors.forename: V
authors.initials: V
authors.lastname: Locci
authors.affiliation: Nanobiotechnology Laboratory, University of Cagliari, Cagliari 09100, Italy; C.N.R., Institute of Neuroscience, Cagliari 09100, Italy.
authors.forename: M C
authors.initials: MC
authors.lastname: Mostallino
authors.affiliation: Nanobiotechnology Laboratory, University of Cagliari, Cagliari 09100, Italy.
authors.forename: P
authors.initials: P
authors.lastname: Olla
authors.affiliation: Nanobiotechnology Laboratory, University of Cagliari, Cagliari 09100, Italy.
authors.forename: C
authors.initials: C
authors.lastname: Utzeri
authors.affiliation: Department of Life and Environmental Sciences, University of Cagliari, Cagliari 09100, Italy; Center of Excellence for Neurobiology of Dependence, University of Cagliari, Cagliari 09100, Italy. Electronic address: mserra@unica.it.
authors.forename: M
authors.initials: M
authors.lastname: Serra
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000502:physiology; D003345:Corticosterone / Q000097:blood*; D005260:Female; D007030:Hypothalamo-Hypophyseal System / Q000503:physiopathology*; D008297:Male; D008426:Maternal Deprivation; D010913:Pituitary-Adrenal System / Q000503:physiopathology*; D011280:Pregnanolone / Q000097:blood; D051381:Rats; D012934:Social Isolation; D013315:Stress, Psychological / Q000097:blood / Q000503:physiopathology*
chemical_list: D011280:Pregnanolone; D003345:Corticosterone
keywords: Allopregnanolone; BDNF; HPA axis; Maternal separation; Rat; Social isolation