title: Evidence for the involvement of the opioid system in the agmatine antidepressant-like effect in the forced swimming test.
abstract: This study investigated the involvement of the opioid system in the antidepressant-like effect of agmatine in the mouse forced swimming test (FST). The antidepressant-like effects of agmatine (10 mg/kg, i.p.), as well as those of fluoxetine (32 mg/kg, i.p, a selective serotonin reuptake inhibitor, SSRI) or morphine (5 mg/kg, s.c., a nonselective opioid receptor agonist) in the FST was completely blocked by pretreatment of mice with naloxone (1 mg/kg, i.p., a nonselective opioid receptor antagonist). Pretreatment of mice with naltrindole (3 mg/kg, i.p., a selective delta-opioid receptor antagonist), clocinnamox (1 mg/kg, i.p., an irreversible mu-opioid receptor antagonist), but not with 2-(3,4-dichlorophenyl)-N-methyl-N-[(1S)-1-(3-isothiocyanatophenyl)-2-(1-pyrrolidinyl)ethyl]acetamide (DIPPA; 1 mg/kg, i.p., a selective kappa-opioid receptor antagonist) completely blocked the anti-immobility effect of agmatine (10 mg/kg, i.p.) in the FST. These results firstly demonstrate that the antidepressant-like effects of agmatine in the FST seem to be mediated, at least in part, by an interaction with the opioid system, that involves an activation of delta- and mu-opioid receptors.
authors.affiliation: Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Campus Universitário, Trindade, Florianópolis, SC 88040-900, Brazil.
authors.forename: Andrea D E
authors.initials: AD
authors.lastname: Zomkowski
authors.forename: Adair R S
authors.initials: AR
authors.lastname: Santos
authors.forename: Ana L S
authors.initials: AL
authors.lastname: Rodrigues
mesh_terms: D000376:Agmatine / Q000494:pharmacology*; D000818:Animals; D000928:Antidepressive Agents / Q000494:pharmacology*; D003863:Depression / Q000188:drug therapy; D004195:Disease Models, Animal; D005260:Female; D008297:Male; D051379:Mice; D009043:Motor Activity / Q000187:drug effects*; D009292:Narcotic Antagonists; D011957:Receptors, Opioid / Q000819:agonists / Q000378:metabolism*; D013550:Swimming
chemical_list: D000928:Antidepressive Agents; D009292:Narcotic Antagonists; D011957:Receptors, Opioid; D000376:Agmatine