Chronic benzodiazepine administration: effects in vivo and in vitro

Chronic benzodiazepine administration is associated with neurochemical alterations in the GABAergic system, as determined in a variety of animal models and tissue culture systems. In animals, effects of chronic benzodiazepine agonists on receptor binding are uncertain, but several studies indicate a decrease in GABA-dependent chloride uptake. In contrast, limited data indicate that chloride uptake is increased after chronic antagonist administration, and results of inverse agonist administration are uncertain. Most animal studies are limited by lack of attention to drug choice and to pharmacokinetic variables, and by failure to determined delivered drug concentrations. More limited data in tissue culture systems are conflicting with regard to effects on benzodiazepine binding, but recent studies indicate that GABA-dependent chloride uptake may be decreased after chronic agonist exposure, and increased after chronic antagonist and inverse agonist administration. Data from these systems may complement results obtained in intact animals, and cultures may allow more detailed examination of the kinetics and specificity of drug effects.