Chronic treatment with a benzodiazepine agonist in vivo increases the actions of the benzodiazepine partial inverse agonist, FG7142, on the hippocampal slice in vitro

Effects of serotonergic anxiolytics on physical dependence on diazepam in mice

The effects of serotonergic anxiolytics on the development of physical dependence on diazepam were examined in mice. Co-administration of buspirone (5-HT1A agonist) or ondansetron (5-HT3 antagonist), but not mianserin (5-HT1C antagonist) or ketanserin (5-HT2 antagonist) with diazepam potentiated the hypersensitivity to FG 7142 following chronic treatment with diazepam. This potentiation was not ascribable to pharmacokinetic interactions between diazepam and buspirone or ondansetron. These results suggest that co-administration of buspirone or ondansetron with diazepam may potentiate the development of physical dependence on diazepam; 5-HT1A and 5-HT3 receptors may be partially involved in the development of physical dependence on diazepam.

Effects of Ca2+ channel blockers on physical dependence on diazepam in mice

The effects of Ca2+ channel blockers on the development of physical dependence on diazepam were examined in mice. Co-administration of flunarizine (T-type Ca2+ channel sensitive blocker), but not of either nifedipine or diltiazem (L-type Ca2+ channel sensitive blockers), with diazepam significantly suppressed the hypersensitivity to FG 7142 following chronic treatment with diazepam. The hypersensitivity to FG 7142 may reflect benzodiazepine withdrawal convulsions. These results suggest that flunarizine, but not nifedipine or diltiazem, may suppress the development of physical dependence on diazepam, and that T-type Ca2+ channels in the brain, rather than L-type Ca2+ channels, may be involved in the development of physical dependence on diazepam.