Flumazenil-sensitive dose-related physical dependence in planarians produced by two benzodiazepine and one non-benzodiazepine benzodiazepine-receptor agonists.
Two benzodiazepine (midazolam and clorazepate) and one non-benzodiazepine (zolpidem) benzodiazepine-receptor agonists produced dose-related physical dependence, as evidenced by abstinence-induced decrease in planarian locomotor velocity (pLMV) when drug-exposed planarians were placed into drug-free water, but not when they were placed into drug-containing water (i.e., an abstinence-induced withdrawal, since the effect was only obtained in the removal of drug and not in the continued presence of drug). We have previously shown that the decrease in pLMV is associated with specific and transient withdrawal signs. In the present study, the selective benzodiazepine-receptor antagonist flumazenil significantly antagonized (P<0.05), by co-application, the ability of each agonist to produce the withdrawal. These results: (1) suggest that benzodiazepine-receptor agonists, for two different chemical categories, produce dose-related physical dependence manifested as abstinence-induced withdrawal in this simple and convenient model, and (2) in the absence of cloning or radioligand binding literature, suggest a possible specific interaction site (receptor?) for these compounds in planarians.
Raffa
Robert B
RB
Department of Pharmaceutical Sciences, Temple University School of Pharmacy, 3307 N. Broad Street, Philadelphia, PA 19140, USA. robert.raffa@temple.edu
Cavallo
Federica
F
Capasso
Anna
A
D000704:Analysis of Variance; D000818:Animals; D001569:Benzodiazepines / Q000008:administration & dosage / Q000494:pharmacology; D003009:Clorazepate Dipotassium / Q000008:administration & dosage / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005442:Flumazenil / Q000494:pharmacology; D018755:GABA Agonists / Q000008:administration & dosage / Q000494:pharmacology; D018757:GABA Modulators / Q000008:administration & dosage / Q000494:pharmacology*; D008124:Locomotion / Q000187:drug effects; D008874:Midazolam / Q000008:administration & dosage / Q000494:pharmacology*; D010932:Planarians; D011725:Pyridines / Q000008:administration & dosage / Q000494:pharmacology*; D011963:Receptors, GABA-A / Q000187:drug effects*; D015203:Reproducibility of Results; D013375:Substance Withdrawal Syndrome; D019966:Substance-Related Disorders; D000077334:Zolpidem
D018755:GABA Agonists; D018757:GABA Modulators; D011725:Pyridines; D011963:Receptors, GABA-A; D001569:Benzodiazepines; D005442:Flumazenil; D003009:Clorazepate Dipotassium; D000077334:Zolpidem; D008874:Midazolam