title: Pharmacological evidence for the involvement of the opioid system in the antidepressant-like effect of adenosine in the mouse forced swimming test.
abstract: This study investigated the involvement of the opioid system in the antidepressant-like effect of adenosine in the forced swimming test. The effect of adenosine (10 mg/kg, i.p.) was prevented by the pretreatment of mice with naloxone (1 mg/kg, i.p., a nonselective opioid receptor antagonist), naltrindole (3 mg/kg, i.p., a selective delta-opioid receptor antagonist), clocinnamox (1 mg/kg, i.p., an irreversible mu-opioid receptor antagonist), and 2-(3,4-dichlorophenyl)-Nmethyl-N-[(1S)-1-(3-isothiocyanatophenyl)-2-(1-pyrrolidinyl)ethyl]acetamide (DIPPA; 1 mg/kg, i.p., a selective kappa-opioid receptor antagonist), but not with naloxone methiodide (1 mg/kg, s.c., a nonselective opioid receptor antagonist that does not cross the blood-brain barrier). Naloxone also prevented the anti-immobility effect of cyclohexyladenosine (CHA, 0.1 mg/kg, i.p., a selective adenosine A(1) receptor agonist) and N6-[2-(3,5-dimethoxyphenyl)-2-(2-methylphenyl)ethyl]adenosine (DPMA, 1 mg/kg, i.p., a selective adenosine A(2A) receptor agonist). The administration of DIPPA (0.1 mg/kg, i.p.) or morphine (1 mg/kg, s.c., a nonselective opioid receptor agonist), but not naltrindole (0.3 mg/kg, i.p.) and clocinnamox (0.1 mg/kg, i.p.) potentiated the effect of a subeffective dose of adenosine (1 mg/kg, i.p.) in the forced swimming test, without affecting the locomotor activity. No additive effect in the immobility time was observed when mice were treated with morphine (5 mg/kg, s.c.) plus adenosine (10 mg/kg, i.p.). These results indicate that the anti-immobility effect of adenosine in the forced swimming test, via adenosine A(1) and A(2A) receptors, is mediated by an interaction with the opioid system, likely dependent on an activation of mu- and delta-opioid receptors and an inhibition of kappa-opioid receptors.
authors.affiliation: Departamento de Bioquímica, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Campus Universitário - Trindade-88040-900, Florianópolis-SC, Brazil.
authors.forename: Manuella P
authors.initials: MP
authors.lastname: Kaster
authors.forename: Josiane
authors.initials: J
authors.lastname: Budni
authors.forename: Adair R S
authors.initials: AR
authors.lastname: Santos
authors.forename: Ana Lúcia S
authors.initials: AL
authors.lastname: Rodrigues
mesh_terms: D000241:Adenosine / Q000378:metabolism* / Q000494:pharmacology; D058907:Adenosine A1 Receptor Agonists; D058908:Adenosine A2 Receptor Agonists; D000701:Analgesics, Opioid / Q000494:pharmacology; D000818:Animals; D000928:Antidepressive Agents / Q000378:metabolism* / Q000494:pharmacology; D003863:Depression / Q000188:drug therapy / Q000378:metabolism* / Q000503:physiopathology; D005260:Female; D051379:Mice; D009020:Morphine / Q000494:pharmacology; D009043:Motor Activity / Q000187:drug effects; D009292:Narcotic Antagonists / Q000494:pharmacology; D011957:Receptors, Opioid / Q000819:agonists / Q000378:metabolism*; D013550:Swimming
chemical_list: D058907:Adenosine A1 Receptor Agonists; D058908:Adenosine A2 Receptor Agonists; D000701:Analgesics, Opioid; D000928:Antidepressive Agents; D009292:Narcotic Antagonists; D011957:Receptors, Opioid; D009020:Morphine; D000241:Adenosine