Effects of minor tranquilizers and neuroleptics on open-field behavior in rats

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Abstract
Minor tranquilizers (diazepam, nitrazepam, oxazepam, bromazepam, medazepam, fludiazepam and meprobamate) at low doses increased ambulation scores to 145-288% of control rats. Nitrazepam, diazepam and bromazepam (potent, minor tranquilizers) increased the ambulation at lower doses. Fludiazepam and nitrazepam showed a maximum increase in ambulation at the same dose. Fludiazepam, nitrazepam and diazepam had potent inhibitory effects on defecation. Trifluperidol, haloperidol and ID-4708 1-[3-(2-amino-4-fluorobenzoylpropyl]-4-hydroxy-4-(3-trifluoromethylphenyl)piperidine] a new butyrophenone derivative, and chlorpromazine at low doses reduced ambulation, while at higher doses inhibited defecation. They reduced ambulation and elicited a recovery in defecation rates in methamphetamine-treated rats. Clozapine, thioridazine and floropipamide inhibited defecation at nearly the same doses which reduced ambulation in rats not given the methamphetamine treatment. They reduced ambulation but did not produce a recovery in the defecation rates in methamphetamine-treated rats. Neuroleptics such as clozapine, which rarely induce extrapyramidal side-effect, inhibited defecation at nearly the same doses which reduce ambulation. In methamphetamine-treated rats, haloperidol was 31 times more potent than chlorpromazine in inhibiting activity noted with ambulation. This ratio in the open-field test was close to the potency ratio of these drugs as antipsychotic agents.