title: Dopamine receptor mechanism(s) and antinociception and tolerance induced by swim stress in formalin test.
abstract: In the present study, involvement of D1 and D2 dopamine receptors in the antinociception and tolerance induced by water swim stress in the formalin test has been investigated. Water swim stress at 20 degrees C temperature induced antinociception in both phases of the formalin test. Intraperitoneal administration of the D2 dopamine receptor antagonist, sulpiride (25 and 50 mg/kg) reduced swim stress-induced antinociception in the second phase of the formalin test. A higher dose of the D1 dopamine receptor antagonist, SCH23390 (0.1 mg/kg, intraperitoneal) also reduced swim stress-induced antinociception in both phases of the test. Exposure to 3 min water swimming stress, once daily for 3 days, induced tolerance to swim stress-induced antinociception in the second phase of the formalin test. Administration of sulpiride (12.5, 25 and 50 mg/kg), during exposure to water swimming stress (once daily for 3 days), decreased tolerance in the second phase, whereas the antagonist (12.5 and 50 mg/kg) increased pain scores in the first phase of the formalin test. Sulpiride (25 mg/kg) treatment however, once daily for 3 days with no water swimming stress, did not alter swim stress-induced antinociception (0.5, 1 and 3 min tests). Similarly, repeated treatment with SCH23390 (0.05 mg/kg) and water swimming stress did not alter tolerance induced by water swimming stress. Repeated administration of the antagonist in the absence of water swimming stress also did not change swim stress-induced antinociception. The results may indicate a possible involvement of both dopamine D1 and D2 receptors in the antinociception induced by swim stress and D2 receptor mechanism in the tolerance induced by repeated swim stress.
authors.affiliation: Behavioral Laboratory, Tehran Medical Unit, Azad University, Tehran, Iran.
authors.forename: Soheila
authors.initials: S
authors.lastname: Fazli-Tabaei
authors.forename: Seyed-Hossein
authors.initials: SH
authors.lastname: Yahyavi
authors.forename: Maryam
authors.initials: M
authors.lastname: Nouri
authors.forename: Hamed
authors.initials: H
authors.lastname: Zartab
authors.forename: Golrokh
authors.initials: G
authors.lastname: Javid
authors.forename: Sanam
authors.initials: S
authors.lastname: Loghavi
authors.forename: Mohammad-Reza
authors.initials: MR
authors.lastname: Zarrindast
mesh_terms: D000698:Analgesia; D000818:Animals; D001552:Benzazepines / Q000494:pharmacology; D018491:Dopamine Agonists / Q000494:pharmacology; D018492:Dopamine Antagonists / Q000494:pharmacology; D005557:Formaldehyde; D008297:Male; D051379:Mice; D010147:Pain Measurement / Q000187:drug effects*; D011954:Receptors, Dopamine / Q000187:drug effects*; D017447:Receptors, Dopamine D1 / Q000187:drug effects; D017448:Receptors, Dopamine D2 / Q000187:drug effects; D013315:Stress, Psychological / Q000523:psychology*; D013469:Sulpiride / Q000494:pharmacology; D013550:Swimming / Q000523:psychology*
chemical_list: D001552:Benzazepines; D018491:Dopamine Agonists; D018492:Dopamine Antagonists; D011954:Receptors, Dopamine; D017447:Receptors, Dopamine D1; D017448:Receptors, Dopamine D2; D005557:Formaldehyde; D013469:Sulpiride