title: Fluoxetine exposure during adolescence alters responses to aversive stimuli in adulthood.
abstract: The mechanisms underlying the enduring neurobiological consequences of antidepressant exposure during adolescence are poorly understood. Here, we assessed the long-term effects of exposure to fluoxetine (FLX), a selective serotonin reuptake inhibitor, during adolescence on behavioral reactivity to emotion-eliciting stimuli. We administered FLX (10 mg/kg, bi-daily, for 15 d) to male adolescent [postnatal day 35 (P35) to P49] C57BL/6 mice. Three weeks after treatment (P70), reactivity to aversive stimuli (i.e., social defeat stress, forced swimming, and elevated plus maze) was assessed. We also examined the effects of FLX on the expression of extracellular signal-regulated kinase (ERK) 1/2-related signaling within the ventral tegmental area (VTA) of adolescent mice and Sprague Dawley rats. Adolescent FLX exposure suppressed depression-like behavior, as measured by the social interaction and forced swim tests, while enhancing anxiety-like responses in the elevated plus maze in adulthood. This complex behavioral profile was accompanied by decreases in ERK2 mRNA and protein phosphorylation within the VTA, while stress alone resulted in opposite neurobiological effects. Pharmacological (U0126) inhibition, as well as virus-mediated downregulation of ERK within the VTA mimicked the antidepressant-like profile observed after juvenile FLX treatment. Conversely, overexpression of ERK2 induced a depressive-like response, regardless of FLX pre-exposure. These findings demonstrate that exposure to FLX during adolescence modulates responsiveness to emotion-eliciting stimuli in adulthood, at least partially, via long-lasting adaptations in ERK-related signaling within the VTA. Our results further delineate the role ERK plays in regulating mood-related behaviors across the lifespan.
authors.affiliation: Department of Psychology, California State University, San Bernardino, California 92407, Department of Psychology and Program in Neuroscience, Florida State University, Tallahassee, Florida 32306, Fishberg Department of Neuroscience, Mount Sinai School of Medicine, New York, New York 10029, Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, Maryland 21201, and Massachusetts Institute of Technology, Cambridge, Massachusetts 02139.
authors.forename: Sergio D
authors.initials: SD
authors.lastname: Iñiguez
authors.forename: Lyonna F
authors.initials: LF
authors.lastname: Alcantara
authors.forename: Brandon L
authors.initials: BL
authors.lastname: Warren
authors.forename: Lace M
authors.initials: LM
authors.lastname: Riggs
authors.forename: Eric M
authors.initials: EM
authors.lastname: Parise
authors.forename: Vincent
authors.initials: V
authors.lastname: Vialou
authors.forename: Katherine N
authors.initials: KN
authors.lastname: Wright
authors.forename: Genesis
authors.initials: G
authors.lastname: Dayrit
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Nieto
authors.forename: Matthew B
authors.initials: MB
authors.lastname: Wilkinson
authors.forename: Mary K
authors.initials: MK
authors.lastname: Lobo
authors.forename: Rachael L
authors.initials: RL
authors.lastname: Neve
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Nestler
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Bolaños-Guzmán
mesh_terms: D000367:Age Factors; D000818:Animals; D018687:Antidepressive Agents, Second-Generation / Q000494:pharmacology / Q000627:therapeutic use*; D001362:Avoidance Learning / Q000187:drug effects* / Q000502:physiology; D003863:Depression / Q000188:drug therapy* / Q000201:enzymology / Q000523:psychology; D005473:Fluoxetine / Q000494:pharmacology / Q000627:therapeutic use*; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D051381:Rats; D017207:Rats, Sprague-Dawley; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology
chemical_list: D018687:Antidepressive Agents, Second-Generation; D005473:Fluoxetine
keywords: ERK; MAPK; SSRI; anxiety; depression; stress