title: Antidepressant-like effect of extract from Polygala paniculata: involvement of the monoaminergic systems.
abstract: BACKGROUND
  Polygala paniculata Linnaeus (Polygalaceae) has shown neuroprotective effects, but there is no report about its antidepressant potential.
  
  
  OBJECTIVE
  The antidepressant-like effect of the hydroalcoholic extract from P. paniculata and some of the possible mechanisms involved in this effect were investigated in forced swimming test (FST).
  
  
  METHODS
  Mice received extract by oral route and were submitted to FST and open-field test. Animals were forced to swim and the total immobility time was registered (6-min period). A reduction in the immobility time is considered an antidepressant-like effect. In order to investigate the involvement of the monoaminergic systems, mice were treated with pharmacological antagonists before administration of the extract.
  
  
  RESULTS
  The acute administration of the hydroalcoholic extract from P. paniculata produced an antidepressant-like effect, since it significantly reduced the immobility time in FST (0.01-30 mg/kg) as compared to control group, without changing locomotor activity. Pretreatment of mice with yohimbine (1 mg/kg, i.p., α₂-adrenoceptor antagonist), propranolol (1 mg/kg, i.p., β-adrenoceptor antagonist), SCH23390 (0.05 mg/kg, s.c., dopamine D₁ receptor antagonist) or sulpiride (50 mg/kg, i.p., dopamine D₂ receptor antagonist) prevented the antidepressant-like effect of the extract in FST (30 mg/kg). Moreover, ketanserin (5 mg/kg, i.p., preferential 5-HT(2A) receptor antagonist) enhanced the effect of the extract in FST.
  
  
  CONCLUSIONS
  The results of the present study indicate that the extract from P. paniculata has an antidepressant-like action that is likely mediated by an interaction with the serotonergic (5-HT2A receptors), noradrenergic (α₂ and β-receptor) and dopaminergic (D₁ and D₂ receptors) systems.
authors.affiliation: Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Campus Universitário-Trindade, Florianópolis-SC, Brazil.
authors.forename: Luis E B
authors.initials: LE
authors.lastname: Bettio
authors.forename: Daniele G
authors.initials: DG
authors.lastname: Machado
authors.forename: Mauricio P
authors.initials: MP
authors.lastname: Cunha
authors.forename: Juliano C
authors.initials: JC
authors.lastname: Capra
authors.forename: Fabiana C
authors.initials: FC
authors.lastname: Missau
authors.forename: Adair R S
authors.initials: AR
authors.lastname: Santos
authors.forename: Moacir G
authors.initials: MG
authors.lastname: Pizzolatti
authors.forename: Ana Lúcia S
authors.initials: AL
authors.lastname: Rodrigues
mesh_terms: D018674:Adrenergic Antagonists / Q000494:pharmacology; D000818:Animals; D000928:Antidepressive Agents / Q000494:pharmacology*; D015306:Biogenic Monoamines / Q000378:metabolism*; D004298:Dopamine / Q000502:physiology; D018492:Dopamine Antagonists / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D005260:Female; D046353:Immobility Response, Tonic / Q000187:drug effects; D051379:Mice; D009043:Motor Activity / Q000187:drug effects; D009638:Norepinephrine / Q000502:physiology; D010936:Plant Extracts / Q000037:antagonists & inhibitors / Q000494:pharmacology; D031801:Polygala / Q000737:chemistry*; D012701:Serotonin / Q000502:physiology; D012702:Serotonin Antagonists / Q000494:pharmacology; D013550:Swimming / Q000523:psychology
chemical_list: D018674:Adrenergic Antagonists; D000928:Antidepressive Agents; D015306:Biogenic Monoamines; D018492:Dopamine Antagonists; D010936:Plant Extracts; D012702:Serotonin Antagonists; D012701:Serotonin; D004298:Dopamine; D009638:Norepinephrine