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Effects of acute and long‐term typical or atypical neuroleptics on morphine‐induced behavioural effects in mice
Author(s) -
Hollais André W,
Patti Camilla L,
Zanin Karina A,
Fukushiro Daniela F,
Berro Laís F,
Carvalho Rita C,
Kameda Sonia R,
FrussaFilho Roberto
Publication year - 2014
Publication title -
clinical and experimental pharmacology and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 103
eISSN - 1440-1681
pISSN - 0305-1870
DOI - 10.1111/1440-1681.12203
Subject(s) - haloperidol , ziprasidone , open field , morphine , pharmacology , dopaminergic , anesthesia , context (archaeology) , medicine , psychology , antipsychotic , schizophrenia (object oriented programming) , dopamine , psychiatry , paleontology , biology
Summary It has been suggested that the high prevalence of drug abuse in schizophrenics is related to chronic treatment with typical neuroleptics and dopaminergic supersensitivity that develops as a consequence. Within this context, atypical neuroleptics do not seem to induce this phenomenon. In the present study, we investigated the effects of acute administration or withdrawal from long‐term administration of haloperidol and/or ziprasidone on morphine‐induced open‐field behaviour in mice. In the first experiment, mice were given a single injection of haloperidol (1 mg/kg, i.p.) or several doses of ziprasidone (2, 4 or 6 mg/kg, i.p.) and motor activity was quantified by the open‐field test. The aim of the second experiment was to verify the effects of an acute injection of haloperidol (1 mg/kg) or ziprasidone (6 mg/kg) on 20 mg/kg morphine‐induced behaviours in the open‐field test. In the third experiment, mice were treated with 1 mg/kg haloperidol and/or 2, 4 or 6 mg/kg ziprasidone for 20 days. Seventy‐two hours after the last injection, mice were injected with 20 mg/kg, i.p., morphine and then subjected to the open‐field test. Acute haloperidol or ziprasidone decreased spontaneous general activity and abolished morphine‐induced locomotor stimulation. Withdrawal from haloperidol or ziprasidone did not modify morphine‐elicited behaviours in the open‐field test. The results suggest that withdrawal from neuroleptic treatments does not contribute to the acute effect of morphine in schizophrenic patients.