ABSTRACT
An interesting development in the psychopharmacology of anxiolytics is the study of ‘distress calls’ of young animals in response to separation of the mother and/or siblings (Hofer and Shair, 1978). Rat pups react with ultrasonic calls of 35–55 kHz frequency to such separation. The number of these calls is reduced after treatment with benzodiazepines and this effect was not caused by sedation (Gardner and Brudham, 1987). In the present study we tested the effects of various serotonergic agents as there is ample evidence that 5–HT is involved in anxiety (Broekkamp, 1988; Soubrie, 1988). We therefore have adopted an experimental set–up in which the ultrasound production by rat pups of 9–11 days old (Hard et al., 1982) was measured under two conditions with varying stress levels. Additionally, we used a simple psychomotor test to verify whether drugs affected sensory and/or motor capabilities.
