Chronic neonatal treatment with CGS 8216: effects on the behaviour of adolescent rats

A review of 25 years of the social interaction test

The social interaction test of anxiety was developed 25 years ago to provide an ethologically based test that was sensitive to both anxiolytic and anxiogenic effects. It is sensitive to a number of environmental and physiological factors that can affect anxiety. It has detected anxiogenic effects of peptides such as corticotropin-releasing factor (CRF) and adrenocorticotropic hormone (ACTH), and anxiolytic effects of neuropeptide Y and substance P receptor antagonists. It has successfully identified neuropharmacological sites of action of anxiogenic compounds and drug withdrawal. Effects of compounds acting on the gamma-aminobutyric acid (GABA) and 5-hydroxytryptamine (5-HT) systems have been extensively investigated after both systemic administration and microinjection into specific brain regions. The use of this test has, thus, played a crucial role in unravelling the neural basis of anxiety. It is hoped that in the next 25 years, the test will play a crucial role in determining the genetic basis of anxiety disorders.

Evaluation of perinatal flumazenil effects on the behavior of female RLA/Verh rats in anxiety tests and shuttle box avoidance

The present study investigated the effects of perinatal flumazenil (Ro 15-1788, a benzodiazepine receptor antagonist), given from gestational day 15 to the 14th day after giving birth, at two doses (3.5 and 6.3 mg/kg/ day) on the behavior of female RLA/Verh rats. This rat line has been selectively bred for non-acquisition of two-way active avoidance. Offspring of treated/non-treated dams were tested when adults for two-way active (shuttle box) avoidance acquisition. For comparison reasons additional offspring coming from the same treatments were used in an hyponeophagia test and in both an open field and a plus maze tests. The results show that perinatal flumazenil, specially the lower dose (and also the highest dose, although only in the final phases of the shuttle box training) was able to improve two-way active avoidance acquisition, as it has been previously found with males, whereas it failed to show any effect in the hyponeophagia task, the open field and the plus-maze tests. As two-way active avoidance acquisition can be enhanced both by reducing emotionality/anxiety or by improving memory, it is suggested that flumazenil treatment could have affected either one or both processes.

Benzodiazepines and the developing rat: a critical review

This paper reviews: the development of benzodiazepine binding-sites and the GABA system; the evidence that prenatal exposure to benzodiazepines can cause malformations; other persisting effects of developmental exposure to benzodiazepines; and the behavioral effects of benzodiazepines (and other relevant drugs) in immature animals. The review concentrates on the rat, since fundamental work in other species is scarce. The data on neurochemical development are found to be generally consistent; however, reports that the enhancement of benzodiazepine binding by GABA varies with age are controversial. The physical development of the rat is disturbed only by extremely high doses of benzodiazepines. The evidence for persisting effects after early exposure to benzodiazepines is impressive at first sight, but in most studies, confounding variables have not been eliminated. Startle and some learning tasks are affected by prenatal diazepam; submissiveness is affected by neonatal lorazepam; social behaviour and convulsions are affected by neonatal CGS 8216. Benzodiazepines inhibit chemically-induced seizures in neonatal rats, but the developmental profile of sensitivity to the convulsants is disputed. Benzodiazepines stimulate motor behavior in the neonatal rat.

What can be learned from the effects of benzodiazepines on exploratory behavior?

The purpose of this review is to assess the value of using tests of exploratory behavior to study the actions of benzodiazepines. The methods of measuring exploration and the factors influencing it are briefly described. The effects of benzodiazepines on exploratory behavior of rats and mice are reviewed; and the dangers of interpreting the results of such tests in terms of any of the clinical effects of the benzodiazepines is stressed. Finally, the interactions between benzodiazepines and other drugs acting at the GABA-benzodiazepine receptor complex are described. The results of these experiments caution against global classification of compounds as benzodiazepine "antagonists."