title: Differential sensitivity to SSRI and tricyclic antidepressants in juvenile and adult mice of three strains.
abstract: Clinical studies have shown differential efficacy of several antidepressants in children and adolescents compared to adults, yet few animal studies have sought to characterize this phenomenon. We compared effects of fluoxetine and imipramine in two common behavioral assays that hold high predictive validity for antidepressant activity, tail suspension and forced swim test, using juvenile (5 weeks) and adult (12 weeks) mice from 3 strains. C57BL/6J-Tyr(c-Brd) (C57), hybrid C57BL/6J-Tyr(c-Brd)x129S5/SvEvBrd (F2), and Balb/cAnNTac (Balb/C) mice were tested in forced swim test and tail suspension after i.p. dosing with either fluoxetine or imipramine. Brain tissues were analyzed to evaluate levels of VMAT2, a possible modulator of age-dependent sensitivity to antidepressants. Imipramine had more consistent antidepressant effect across age groups and strains. Imipramine increased struggle in mice of both ages. Fluoxetine did not have an effect on immobility in Balb/C of both ages in tail suspension. Fluoxetine also did not increase forced swim struggle behavior in juvenile mice of all strains, but was effective in increasing struggle in adults. Juvenile mice had higher immobility and lower struggle than adults in forced swim, and juveniles also had higher immobility in tail suspension test for Balb/C and C57. In addition, VMAT2 levels were increased in juveniles. These results confirm that standard antidepressants produce effects in both juveniles and adults but age-related differences were evident in both tests. Further examination of these effects is needed to determine whether it may be related to age-dependent difference in the clinical response to antidepressants of these classes.
authors.affiliation: Department of Neuroscience, Lexicon Pharmaceuticals, Inc, The Woodlands, TX 77381, USA.
authors.forename: Sara S
authors.initials: SS
authors.lastname: Mason
authors.forename: Kevin B
authors.initials: KB
authors.lastname: Baker
authors.forename: Kristina W
authors.initials: KW
authors.lastname: Davis
authors.forename: Vladimir M
authors.initials: VM
authors.lastname: Pogorelov
authors.forename: Murtaza M
authors.initials: MM
authors.lastname: Malbari
authors.forename: Ruth
authors.initials: R
authors.lastname: Ritter
authors.forename: Stephen P
authors.initials: SP
authors.lastname: Wray
authors.forename: Brenda
authors.initials: B
authors.lastname: Gerhardt
authors.forename: Thomas H
authors.initials: TH
authors.lastname: Lanthorn
authors.forename: Katerina V
authors.initials: KV
authors.lastname: Savelieva
mesh_terms: D000375:Aging / Q000502:physiology*; D000818:Animals; D000929:Antidepressive Agents, Tricyclic / Q000494:pharmacology*; D001522:Behavior, Animal / Q000187:drug effects; D005473:Fluoxetine / Q000494:pharmacology; D019417:Hindlimb Suspension; D007099:Imipramine / Q000494:pharmacology; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D009043:Motor Activity / Q000187:drug effects; D011110:Polymorphism, Genetic; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017367:Selective Serotonin Reuptake Inhibitors / Q000494:pharmacology*; D013550:Swimming; D014365:Tryptophan Hydroxylase / Q000235:genetics; D050493:Vesicular Monoamine Transport Proteins / Q000378:metabolism
chemical_list: D000929:Antidepressive Agents, Tricyclic; D005473:Fluoxetine; D007099:Imipramine; D017367:Selective Serotonin Reuptake Inhibitors; D014365:Tryptophan Hydroxylase; D050493:Vesicular Monoamine Transport Proteins; C487802:Tph2 protein, mouse